“a bare outpost of learned european culture on the edge … · “a bare outpost of learned...

Isis, 2004, 95:1–33� 2004 by The History of Science Society. All rights reserved.0021-1753/04/9501-0001$10.00

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“A Bare Outpost of LearnedEuropean Culture on the Edge of the

Jungles of Java”

Johan Maurits Mohr (1716–1775) and theEmergence of Instrumental and Institutional

Science in Dutch Colonial Indonesia

By Huib J. Zuidervaart* and Rob H. Van Gent**

ABSTRACT

The transits of Venus in 1761 and 1769 appear to mark the starting point of instrumentalscience in the Dutch East Indies (now Indonesia). This essay examines the conditions thattriggered and constituted instrumental and institutional science on Indonesian soil in thelate eighteenth century. In 1765 the Reverend J. M. Mohr, whose wife had received a largeinheritance, undertook to build a fully equipped private observatory in Batavia (now Ja-karta). There he made several major astronomical and meteorological observations. Mohr’sinitiative inspired other Europeans living on Java around 1770 to start a scientific move-ment. Because of the lack of governmental and other support, it was not until 1778 thatthis offspring of the Dutch-Indonesian Enlightenment became a reality. The BataviaaschGenootschap van Kunsten en Wetenschappen tried from the beginning to put into effectthe program Mohr had outlined. The members even bought his instruments from hiswidow, intending to continue his measurements. For a number of reasons, however, thisinstrumental program was more than the society could support. Around 1790 instrumentalscience in the former Dutch East Indies came to a standstill, not to be resumed for severaldecades.

I N THE MOMENTOUS DECADE when the Venus transits of 1761 and 1769 took place,it could justly be argued, the best-equipped observatory on Dutch soil was to be found

not in the Netherlands itself but under the tropical skies of faraway Batavia, on the island

* Museum Boerhaave, P.O. Box 11 280, 2301 EG Leiden, The Netherlands.** Institute for History and Foundations of Mathematics and the Natural Sciences, Utrecht, The Netherlands.We are grateful to Maud Peereboom-Engelberts for her advice concerning the English translation of this article.

2 “A BARE OUTPOST OF LEARNED EUROPEAN CULTURE . . .”

of Java in the Dutch East Indies (present-day Jakarta in the Republic of Indonesia). There,in the mid 1760s, the German-Dutch Reformed parson Johan Maurits Mohr erected a well-equipped—almost royal—private observatory that, though it survived only briefly, wasunsurpassed in that corner of the world for more than 150 years.1 But at the time of thefirst transit, in 1761, there was no clue that such a monumental observatory would beerected so soon. It was only at the very last moment, and with very modest means, thatthe 1761 transit was observed in Batavia at all. So questions arise: What persuaded aclergyman with no scientific background, living in a purely commercial setting, to erectsuch a huge astronomical building with no support apart from his wife’s inheritance? Whydid he make these efforts? Where did they lead? In other words, What triggered the riseof instrumental science in this part of Asia, and what were its consequences?

In recent years the study and practice of science in a colonial context has attracted muchattention from historians of science. The scientific component of the Dutch colonial en-terprise, however, remains underexplored. Although much of the later period has beenilluminated by Lewis Pyenson in his scholarly study on Indonesian colonial science, thestory of events that took place in the eighteenth century remains almost untold. The effortsmade by the Dutch present an interesting contrast to those of other colonizing countries,such as Britain and France, that deserves a more thorough investigation. Harry Woolf, inhis influential study of the eighteenth-century transits of Venus, has outlined the costlyefforts made in the name of the monarchs of Great Britain, France, Sweden, and Russiato support various astronomical expeditions; the pressing question arises, then, as to whythe leading authorities of the wealthy Dutch Republic—with a de facto imperial court inBatavia and a heavy dependency on the astronomically oriented art of navigation—failedto do more.2 This essay aims to narrow this gap in our knowledge and understanding ofthis period of Dutch colonial rule.

THE DUTCH UNITED EAST INDIA COMPANY AND ITS ATTITUDE TOWARD SCIENCE

In the late eighteenth century the Indonesian islands had been ruled for more than 150years by the Dutch United East India Company (Verenigde Oostindische Compagnie[VOC]). This precursor of a multinational company was founded in the Dutch Republicin 1602 under pressure from the counsel-general of the seven united provinces, the StatenGeneraal. The company united several rival Dutch trading companies that had sprung upin the aftermath of the successful “First Voyage” (Eerste Scheepvaart) to the East, orga-nized in 1595–1597 by the Amsterdam Far Lands Company (Compagnie van Verre).

The VOC was strongly backed by the central authorities of the Dutch Republic and wassupplied with considerable capital from private investors. It was governed by a general

1 A. Pannekoek, “Astronomy,” in Science in the Netherlands East Indies, ed. L. M. R. Rutten (Amsterdam:De Bussy, [1929]), pp. 126–132; Lewis Pyenson, “Stars of the Southern Heavens,” in Empire of Reason: ExactSciences in Indonesia, 1840–1940 (Leiden: Brill, 1989), pp. 19–82; Rob H. van Gent, De Reizende Astronoom:Nederlandse Sterrenkundige Expedities naar de Oost en de West (Leiden: Museum Boerhaave, 1993); and HuibJ. Zuidervaart, Van “Konstgenoten” en Hemelse Fenomenen: Nederlandse Sterrenkunde in de Achttiende Eeuw[with an English summary] (Rotterdam: Erasmus, 1999), pp. 280–283, 314–320, 330–331.

2 Pyenson, Empire of Reason; and Harry Woolf, The Transits of Venus: A Study of Eighteenth-Century Science(Princeton, N.J.: Princeton Univ. Press, 1959). Pyenson’s work was part of a trilogy surveying the exact sciencesin the colonial empires occupied by Germany, the Netherlands, and France. See also Lewis Pyenson, CulturalImperialism and Exact Sciences: German Expansion Overseas, 1900–1930 (New York: Lang, 1985); and Pyen-son, Civilizing Mission: Exact Sciences and French Overseas Expansion, 1830–1940 (Baltimore/London: JohnsHopkins Univ. Press, 1993). An overview of scholarly work on the history of science in a colonial setting isgiven in Roy MacLeod, ed., Nature and Empire: Science and the Colonial Enterprise, Osiris, 2nd Ser., 2000, 15.

HUIB J. ZUIDERVAART AND ROB H. VAN GENT 3

board of seventeen directors (bewindhebbers), known as the “seventeen gentleman”(Heeren XVII), who were chosen on a proportional basis from the directors of the sixparticipating chambers. The largest shareholder was the Chamber of Amsterdam, whichowned 50 percent of the company’s capital and fleet. Second was the Chamber of theProvince of Zeeland (25 percent), followed by the chambers of the cities of Delft, Rotter-dam, Hoorn, and Enkhuizen (61⁄4 percent each). In the eighteenth century the VOC was inpossession of several strongholds spread along the coasts of Africa and Asia. It was alsoby far the largest of the European companies trading with the Orient. Thanks to a patentgranted to the VOC by the Staten Generaal, the company could act almost as a sovereignstate in its overseas dependencies. The settlements of the VOC were administered by alocal governor, who reported to a governor-general in Batavia. The size of its fleet andtonnage shipped annually outranked those of all its competitors combined.3 After a pros-perous expansion period during the seventeenth century and gradual decline during thesecond half of the eighteenth century, the company was dissolved in 1799, when it raninto severe financial problems after the disastrous conclusion of the Fourth Anglo-DutchWar of 1780–1784 and the collapse of the Dutch Republic in 1795.

Above all, the VOC was a commercial company, with no mission other than to make aprofit. The colonial policy of the Dutch therefore was quite different from that of most ofthe other European colonizers: the aim of the VOC was the profitable exploitation of thecolonies, not the domination or colonization of the peoples or lands involved.

Nonetheless, from the outset some attention was given to the education of the localpopulation, especially in Christian belief and morality. Science, however, never played asignificant role in the policy of the VOC. It was only through the effort of various inquis-itive individuals that some scientific investigations were carried out on the flora, fauna,and geology of the Far East.4 Scholarly books and scientific instruments were rarelyshipped to Batavia. Only when commercial interests made it necessary did the VOC orderscientific books or instruments: for instance, when the Japanese shogun requested infor-mation on European society and science, such goods were shipped to the trading post ofDeshima in the harbor of Nagasaki.5

BATAVIA AND THE PROBLEM OF THE SOLAR PARALLAX

The VOC’s lack of interest in science is illustrated by the following case study. One ofthe major astronomical problems of early eighteenth-century science was the determinationof the mean distance between the Earth and the Sun. This astronomical parameter (or thesolar parallax, which was directly related to it) was considered a fundamental constant in

3 See Jaap R. Bruijn and Femme S. Gaastra, eds., Ships, Sailors, and Spices: East India Companies and TheirShipping in the Sixteenth, Seventeenth, and Eighteenth Centuries (Amsterdam: NEHA, 1993).

4 On education of the local populace see W. R. van Hoevell, “Geschiedkundig Overzigt van de beoefeningvan Kunsten en Wetenschappen in Neerland’s Indie,” Tijdschrift voor Neerland’s Indie, 1839, 1st Ser., 2(2):1–115, esp. pp. 1–12. Regarding early scientific investigations see J. Bethlehem and A. C. Meijer, eds., VOC enCultuur: Wetenschappelijke en culturele relaties tussen Europa en Azie ten tijde van de Verenigde OostindischeCompagnie (Amsterdam: Schiphouwer & Brinkman, 1993); and M. J. Sirks, Indisch Natuuronderzoek: Eenbeknopte geschiedenis van de beoefening der natuurwetenschappen in de Nederlandsche Kolonien (Amsterdam:Koloniaal Instituut, 1915).

5 Until 1853 this contact with the Dutch was the only way in which Japanese scholars could access Westernscience and medicine. See Charles R. Boxer, Jan Compagnie in Japan, 1600–1817: An Essay on the Cultural,Artistic, and Scientific Influence Exercised by the Hollanders in Japan from the Seventeenth to the NineteenthCenturies (1936; Tokyo/New York: Oxford Univ. Press, 1968), Chs. 1, 3; and Grant K. Goodman, Japan: TheDutch Experience (London: Athlone, 1986).


the heliocentric planetary system. However, it was very difficult to determine this param-eter with satisfying accuracy. In 1716 Edmund Halley, the future English astronomer royal,came forward with a method to determine the solar parallax. Halley pointed to two rareastronomical events: in June 1761 and again in June 1769 there would be a precise align-ment of the Earth, the inner planet Venus, and the Sun. From the perspective of an observeron Earth, Venus would pass across the disk of the Sun. As the positions and the orbits ofall the planets in the solar system are linked according to the laws described by Keplerand Newton, Halley realized that this rare event offered an opportunity to a solve theparallax problem. As early as 1691 he wrote: “This sight [of a transit of Venus] which isby far the noblest astronomy affords, is denied to mortals for a whole century, by the strictlaws of motion. It will be afterwards shown, that by this observation alone, the distanceof the sun, from the earth, might be determined.” Halley published his proposals forobserving the transits in three articles in the Philosophical Transactions between 1691 and1716. If the precise geographical location of an observer was known, he insisted, it shouldbe possible to determine the astronomical unit by comparing different sets of observations.Considerations of accuracy required that observations be made at locations spread overthe planet. One of the preferred spots for an observation, Halley strongly recommended,was Batavia on the Indonesian island of Java.6

Around 1760 astronomers throughout the Western world focused their attention on theimminent Venus transit of June 1761. One of the first to take initiative was the Frenchastronomer Joseph-Nicolas Delisle (1688–1768). In November 1759 he presented a me-moire on the upcoming transit to the Academie Royale des Sciences. The main purposeof Delisle’s article was to present a mappemonde of the most favorable places for obser-vations of the transit. Halley’s proposal of 1716 had already listed a number of sites: theNorth American Hudson Bay, he suggested would be the spot where the passage shouldhave the longest duration. But Delisle pointed out that while this was strictly true, it wouldbe useless to take observations at Hudson Bay: his own calculations showed that at thatspot both the ingress and the egress of Venus would occur below the horizon. Otherplaces—for instance, in the Far East—were preferable. Delisle’s initiative triggered someaction. One of his colleagues, Le Gentil de la Galaisiere, suggested traveling to Pondichery,a French colony on the shore of Coromandel (India). And off he went: in March 1760 LeGentil departed from the harbor of Brest, not to be seen again for ten years. A next stepwas taken in April 1760, when the Russian tsarina Catherine the Great invited the Aca-demie Royale des Sciences to send an astronomer on an expedition to Siberia. Jean-BaptisteChappe d’Auteroche accepted the offer and traveled to St. Petersburg later that year.7 Evenwith these important observation posts occupied, Delisle still hoped to arrange for obser-vations in the Malaysian Archipelago, for, as Halley had pointed out, from this spot thetransit could be seen completely and with a long duration.

Accordingly, on 18 May 1760 Delisle wrote to the Dutch astronomer Dirk Klinkenberg

6 Quoted in Woolf, Transits of Venus (cit. n. 2), p. 15. See also Edmund Halley, “Methodus singularis quasolis parallaxis,” Philosophical Transactions, 1716, no. 347, pp. 454–464; “Batavia” is mentioned on p. 460.

7 J. N. Delisle, Memoire [et mappemonde] presente au Roi le 27 avril 1760, au sujet du passage de Venus surle Soleil, qui doit arriver le 6 juin 1761 (Paris, 1760). The next spring Delisle published Avertissement au sujetdes observations qu’il conviendra de faire le 6 juin 1761, Venus passant sur le Soleil (Paris, 1761). See alsoWoolf, Transits of Venus, p. 55. Le Gentil would stay in the Far East more then ten years, deprived by cloudyskies of observations of both transits of Venus. After his return to France he found his estate dispersed by hisheirs, who in the meantime had claimed that he had died. On Chappe d’Auteroche see Angus Armitage, “Chapped’Auteroche: A Pathfinder for Astronomy,” Annals of Science, 1954, 10:277–293.


(1709–1799), an official correspondent of the Academie Royale des Sciences, asking forhelp in arranging an observation post in Batavia in the Dutch East Indies. Ten years before,in 1751, Klinkenberg had helped Delisle in sending a French astronomical expedition, ledby Nicolas-Louis Lacaille, to Dutch territory at the Cape of Good Hope. Lacaille’s expe-dition was completely financed by the French king, but its success had depended in largepart on the cooperation of the Dutch authorities, including the VOC. At that time the Dutchcount Willem Bentinck van Rhoon had secured the personal support of the Dutch stad-holder William IV of Orange for the expedition. So, as before, Klinkenberg went to CountBentinck for help. His reaction is known only from Klinkenberg’s reply to Delisle: Ben-tinck was prepared to arrange for a Dutch vessel to take a representative of the FrenchAcademie to Batavia. But this was the only help the Dutch authorities were willing togive. There was no interest at all in sending a Dutch astronomical expedition to the EastIndies, because—as Klinkenberg put it in the draft of his letter to Delisle—“the usefulnessof astronomy to mankind was not sufficiently appreciated in Dutch society.” According toKlinkenberg, the only other possibility was to ask a qualified person already in Batavia toobserve the transit “with a proper attitude” and whatever instruments happened to be onhand.8

Delisle knew what to do. To secure the cooperation of the Dutch authorities, he sentseveral copies of his memoire with the mappemonde of premier observing sites to theNetherlands. Then he went to Versailles to plead with the French king for a royal grant,with which he hoped to equip a French expedition to the Dutch East Indies. He recom-mended his own assistant, Charles Messier, as the best candidate for an expedition toBatavia. But a complication arose: while they waited for the royal answer, rumors spreadthat a British expedition was going to the Malaysian Archipelago. Ironically, Delisle him-self had triggered the British developments. For in May 1760, on the same day on whichhe had written to Klinkenberg—and despite the ongoing French-English war—he alsosent his mappemonde to London. In his accompanying letter to the English astronomerJohn Bevis, Delisle had pleaded for British action regarding the coming transits. He hadappealed to national pride, reminding his correspondent that the method for using transitobservations to determine the solar parallax had been developed by a famous Britishscholar. This appeal to patriotic sentiment worked: Delisle’s letter was read at a meetingof the Royal Society, and support was found to equip two British expeditions. A firstmission, manned by the astronomers Charles Mason and Jeremiah Dixon, would be sentto an English trading post on the coast of Sumatra in the Gulf of Bengal. A secondexpedition, led by the astronomer Nevil Maskelyne, would travel to the British colony onthe Isle of St. Helena. The British scientists, too, briefly considered asking the Dutch EastIndia Company for help in transporting Mason and Dixon to the Far East. Dutch vesselssailed for the Malaysian Archipelago much more frequently than those of the English

8 J. N. Delisle to Dirk Klinkenberg, 18 May 1760, Rijksarchief Noord-Holland, Haarlem, Archives of theKoninklijke Nederlandse Instituut, no. 32: Klinkenberg Correspondence, 132 [received 26 May 1760], andArchives Nationales, Paris, Delisle Correspondence, XIV, 176; and Klinkenberg to Delisle, 6 June 1760, Klin-kenberg Correspondence, 133, and Delisle Correspondence, XIV, 178. See also Woolf, Transits of Venus, p. 68(“omdat het nut dat de astronomie aan de menschelijke samenleeving heeft toegebracht, en nog kan toebrengen,hier [in de Nederlanden] niet na waerde geprijseerd werd, en niet genoeg bekend is”). We found no record ofBentinck’s actions on this subject in the correspondence of William Bentinck van Rhoon preserved in the EgertonPapers, nos. 1745–1749, 1862, British Library, London. On Lacaille’s expedition see Woolf, Transits of Venus,pp. 35–40; Angus Armitage, “The Astronomical Work of Nicolas-Louis de Lacaille,” Ann. Sci., 1956, 12:163–191; Davis S. Evans, Lacaille: Astronomer, Traveler: With a New Translation of His Journal (Tucson, Ariz.:Pachart, 1992); and Zuidervaart, “Konstgenoten” en Hemelse Fenomenen (cit. n. 1), pp. 252–268.


trading companies.9 But the “Dutch connection” was not put into practice. In retrospect,this was apparently a bad decision. Sailing for the Gulf of Bengal on a British vessel,Mason and Dixon were caught up in a fight with a French warship that caused seriousdelays. As a result, they never reached the Far East: their expedition was stranded insouthern Africa, at the Cape of Good Hope. By an act of fate, then, one of the foreign-funded transit expeditions wound up on Dutch-governed territory.

In the meantime, in August 1760, the French Academie Royale des Sciences had givenits advice on Delisle’s request to mount additional expeditions. Once the British intentionsto observe the transit in Sumatra became known, the need for a French expedition to nearbyBatavia faded. For a time the French considered sending an astronomer to the AfricanGold Coast, where both the Dutch and the Portuguese had trading posts, but eventuallythis idea was abandoned. Instead, the astronomer Alexandre-Guy Pingre was sent to aFrench colony in East Africa: to the Isle of Rodrigues, near Madagascar.10

In October 1760 Delisle could inform Klinkenberg that there was no longer any needfor Dutch transport to the East Indies. However, Batavia was far too promising an obser-vation post to give up without one last effort. Besides, Delisle argued, there were no reliableastronomical coordinates for Batavia, so any data provided in the course of observationsof the Venus transit there would be useful for navigational purposes. Delisle again askedwhether there was any VOC official, already on the spot, who could make observations:a single skilled Dutch mathematician, capable of handling some nautical instruments,would suffice. This simple effort, he promised, would produce results in which “all nationswould be interested, not only for the sake of Astronomy, but also for the advancement ofGeography.”11

Delisle’s supplication was not made in vain. In November 1760 Klinkenberg repliedthat the prospects for a proper observation in Batavia remained meager but that somehope glimmered on the horizon. He had given Delisle’s last letter to Count Bentinck andto the Leiden professor of philosophy Jean Nicolas Sebastien Allamand. The latter hadpromised to write to Governor-General Jacob Mossel of the VOC at Batavia, asking himto look for “an able person on the spot” and persuade him to make the necessary obser-vations. The same request would be sent to the governors-general of the Dutch settlementsat Ceylon and at the Cape colony, accompanied by a copy of Delisle’s instructions onmaking the observations. The fate of Allamand’s letters is not known.12 However, a re-

9 Cf. Reynard to Klinkenberg, 19 June 1760, Klinkenberg Correspondence, 134. See also A. Vosmaer toDelisle, 17 June 1760, Delisle Correspondence, XIV, 189. A list of the distribution of Delisle’s mappemonde ispublished in Woolf, Transits of Venus, pp. 209–211. For Delisle’s appeal to British astronomy see Delisle toJohn Bevis, May 1760, Delisle Correspondence, XIV, 177; the Royal Society’s response is discussed in Woolf,Transits of Venus, pp. 71, 78. On Maskelyne see Derek Howse, Nevil Maskelyne: The Seaman’s Astronomer(Cambridge: Cambridge Univ. Press, 1989).

10 Woolf, Transits of Venus, p. 66; and Angus Armitage, “The Pilgrimage of Pingre (1711–1796): An Astronomer-Monk of Eighteenth Century France,” Ann. Sci., 1953, 9:47–63.

11 Delisle to Klinkenberg, 17 Oct. 1760, Klinkenberg Correspondence, 142 [received 28 Oct. 1760], and DelisleCorrespondence, XIV, 191. A copy of this letter was sent on 31 Oct. 1760 to the Dutch astronomers Johan Lulofsand Nicolaas Struyck. The latter had organized Dutch support for the expedition led by Lacaille to South Africain 1751. See H. J. Zuidervaart, “Early Quantification of Scientific Knowledge: Nicolaas Struyck (1686–1769)as Collector of Empirical Gathered Data,” in The Statistical Mind in a Pre-statistical Era: The Netherlands,1750–1850, ed. Paul M. M. Klep and Ida H. Stamhuis (Amsterdam: Aksant, 2002), pp. 125–148.

12 Klinkenberg to Delisle, 29 Nov. 1760, Klinkenberg Correspondence, 147, and Delisle Correspondence, XIV,198 a–c. A survey in the archives of the VOC in the National Archives of the Netherlands at The Hague hasproduced no information on this subject; we thank A. C. Meijer, staff member, National Archives of the Neth-erlands. At the Cape colony observations were made by the British astronomers Mason and Dixon. In Ceylonno observations were made: a local uprising during the spring and summer of 1761 left no room for topics of


construction of the chain of events at Batavia in June 1761 suggests that in all likelihoodit was Governor-General Mossel himself who ordered the observation of the Venus transit.

THE TRANSIT OF 1761, OBSERVED IN BATAVIA

At first glance, Mossel would seem to have had bad luck, for the person best equipped tomake the observations, the naval officer Lieutenant Pieter Hermanus Ohdem, had returnedto Holland in the summer of 1760. Appointed in 1743, Ohdem had been “preceptor inmathematics and navigation” at the Naval Academy (Academie de Marine) of Batavia,founded earlier that year.13 In 1753, two years before this academy was closed, he hadbeen named examiner of the sea maps compiled and drawn by the department of map-makers of the VOC at Batavia. In 1759 Ohdem had made Batavian observations of Halley’scomet that were published in the Verhandelingen (transactions) of the Hollandsche Maat-schappij der Weetenschappen (Dutch Society of Sciences) in Haarlem.14 In his articleOhdem lamented the fact that he had to make his observations without access to a per-manent and elevated platform and without the help of an assistant. For the positionalmeasurements of the comet Ohdem had used a small portable alt-azimuthal instrument(probably a kind of theodolite), equipped with a small telescope.

With Ohdem back in Holland, the most likely candidate was his next in line at thedepartment of mapmakers of the VOC, Lieutenant-Captain Gerrit de Haan (d. 1769), atrained and highly skilled surveyor. In 1749 Gerrit de Haan had been appointed in Dor-drecht as an official surveyor to the “Hof van Holland, Zeeland en West-Friesland.” Thatsame year he traveled to Batavia, where he soon became head of the department of VOCmapmakers. In this capacity De Haan made a very important atlas that provided a completeoverview of the territories colonized by the VOC.15

And, indeed, it was evidently De Haan who was instructed to observe the transit. To-

scientific interest. See Lodewijk Wagenaar, Galle: VOC-vestiging in Ceylon: Beschrijving van een kolonialesamenleving aan de vooravond van de Singalese opstand tegen het Nederlandse gezag, 1760 (Amsterdam:Bataafsche Leeuw, 1994).

13 On Ohdem see J. Van der Bilt, Venus tegen de Zonneschijf: 1761, 1769: Een bladzijde uit de geschiedenisder Nederlandse Sterrenkunde (Groningen/Batavia, 1940), p. 52; and G. Schilder, “Het cartografisch bedrijf vande VOC,” in De VOC in de kaart gekeken: Cartografie en navigatie van de Verenigde Oostindische Compagnie1602–1799, ed. P. van Mil and M. Scharloo (’s Gravenhage: SDU, 1988), pp. 17–45, esp. p. 42. On the NavalAcademy see F. de Haan, “De ‘Academie de Marine’ te Batavia, 1743–1755,” Tijdschrift Bataviaasch Genoot-schap der Wetenschappen, 1895, 38:551–621.

14 Pieter H. Ohdem, “Berigt van de Comeet van het jaar 1759, in Batavia waargenomen,” Verhandelingenuitgegeeven door de Hollandsche Maatschappye der Weetenschappen te Haarlem, 1761, 6(1):421–435. InitiallyOhdem had reported his astronomical observations to Leiden University. Together with some simple meteoro-logical observations, made at Batavia in the years 1758–1760 by the medical doctor S. C. Kriel, they wereoffered by H. D. Gaubius, professor of medicine at Leiden, to the Hollandsche Maatschappij der Weetenschappen(HMW). See H. D. Gaubius to C. C. H. van der Aa (secretary of the HMW), 28 Aug. 1760, Rijkarchief Noord-Holland, Haarlem, HMW Archives. See also the advice of Johan Lulofs (professor of astronomy) to Van der Aa,11 Sept. 1760, HMW Archives. The meteorological observations were printed in the next volume of the trans-actions: S. C. Kriel, “Waarnemingen te Batavia, gedaan door de heer Kriel M. D. aldaar,” Verhandel. HollandscheMaatsch. Weetensch. Haarlem, 1762, 6(2):9–60.

15 E. Muller and K. Zandvliet, eds., Admissies als landmeter in Nederland voor 1811: Bronnen voor de ges-chiedenis van de landmeetkunde en haar toepassingen in de administratie, architectuur, kartografie en vesting-en waterbouwkunde (Alphen aan de Rijn: Canaletto, 1987), p. 179 (no. 630). Gerrit de Haan, Ligtende Zeefakkeloff de geheele Oost Indisch Waterweerelt, manuscript atlas in two volumes, is preserved in the VOC Archives(VELH 156), held in the Nationaal Archief in the Hague; it is mentioned in Schilder, “Het cartografisch bedrijfvan de VOC” (cit. n. 13), p. 40 n 61. The archival records of the VOC are described in M. A. P. Meilink-Roelofsz,R. Raben, and H. Spijkerman, eds., The Archives of the Dutch East India Company (1602–1795) (The Hague,1992); they will hereafter be cited as NA/VOC, with inventory number and date as available and necessary.


gether with an assistant, Pieter Jan Soele, a skipper who was also employed by the VOC,he made all the necessary preparations. In the early morning of 6 June 1761 they took offfor the outskirts of Batavia, headed for “Kliphoff,” the estate of Johan Maurits Mohr,parson of the local Portuguese church.16 But Mohr was not merely a reverend. He was alsoa man of learning with a solid reputation as a translator; it seems likely, then, that Governor-General Mossel had sought Mohr’s help in translating Delisle’s French instructions forobserving the transit. While translating Delisle’s memoire Mohr must have offered hisseaside residence, with its unimpeded view of the horizon, as a suitable vantage point formaking the observations.

As planned, De Haan and Soele went to work. Both the ingress of Venus on the solardisk and its egress were observed with the observer’s eye at about 10 feet above sea leveland without any cloud interference. The effort was a complete success. According to thereport of the observation, published in 1763, their instruments were modest but of goodquality. At their disposal was a universal octant made by the London instrument-makerGeorge Adams and a few accurate pocket watches, one of which showed seconds. Therate of these watches was tested by Soele from several observations of the Sun’s altitude.Mohr—who, with a friend, observed De Haan and Soele at work—had brought two ofhis own Gregorian reflectors, also made by Adams, with focal lengths of 18 and 27 inches,respectively. During the transit these telescopes were probably used to project an imageof the solar disk on a screen. Normally such telescopes were used in the colonies to observeships far out at sea.17

As one might expect, the designated observers De Haan and Soele prepared a report oftheir observation, which they duly sent to the Netherlands with one of the first shipsreturning there. Probably as a courtesy—in return for the opportunity to use “Kliphoff”—they also delivered a copy of their report to Mohr. This led to unexpected results, however,for now Mohr too prepared a report in which he retrospectively appointed himself as theleader of the observation team. Why he acted in this way is at first glance mysterious; wewill try to reconstruct Mohr’s intentions later in this essay.

In his report of the observation, written in January 1762, more then half a year after theevent, Mohr claimed that the account of De Haan and Soele was far below the standardsrequired for a scientific report. He found their report not only “far too clumsy and ineffi-cient, but in a way also defective and too inferior for an official account.”18 He thereforedistanced him from De Haan and Soele’s results, stating that their report was sent to theNetherlands without his knowledge or consent.

As the German astronomer Johann Encke noted in the nineteenth century, the valuesgiven by Mohr in his account were not reliable. This was confirmed by the astronomer-historian Johan van der Bilt, who reported in his 1940 monograph on the Dutch transit

16 “Kliphoff” was located about an hour’s journey to the east of Batavia, near Fort Antjol at the mouth of theAntjol River. On modern municipal maps of Jakarta this corresponds with the Ancol “Dreamland” AmusementPark, situated halfway between the “Old Harbor” and the “New Harbor.” See the manuscript map of Bataviadrawn by D. M. Barbier in 1798, reproduced in Van Mil and Scharloo, eds., De VOC in de kaart gekeken(cit. n. 13), Fig. 101.

17 For this terrestrial use of reflecting telescopes see Daniel Brand, Cape of Good Hope, to Jan Hendrik vanSwinden, Franeker, 6 Mar. 1777, University Library, Leiden, BPL 755.

18 Lulofs to Van der Aa, 6 Feb. 1763 (offering Mohr’s report), HMW Archives. A second draft of Mohr’sreport was delivered later that year by Mohr’s “worthiest master,” Nicolas Engelhardt (1696–1765), professorof philosophy at Groningen. See J. M. Mohr to Nicolas Engelhardt, 5 May 1762, HMW Archives. See alsoEngelhardt to Van der Aa, 10 May 1763, HMW Archives; and HMW Notulen (“minutes”), fol. 357, 10 May1763, HMW Archives.


observations that “the solar heights given by Mohr do not fit with the correspondingtimes.”19 Van der Bilt suspected that something had gone wrong with the clocks. Mohrhimself was aware that this had been a weak point in the observations. The clocks usedwere ordinary pocket watches, and Mohr had expressed skepticism about the results theyproduced. Besides, the micrometers and dark glasses recommended in Delisle’s instruc-tions had not been available, and as a consequence the bright sunlight had prevented themfrom observing the ingress and egress completely. Nevertheless, Mohr thought that theirreported results were a good approximation of the truth. He hoped that these Batavianobservations would help in the effort to find a better value for the solar parallax; he wascertain that they would contribute to glorifying the Lord who in his wisdom had createdthis amazing universe.

As was the usual practice with important documents, Mohr sent two copies of his reportto the Netherlands on different ships: one was addressed to Leiden University and theother to his alma mater, the University of Groningen. Mohr’s report was printed in 1763in the Verhandelingen of the Hollandsche Maatschappij der Weetenschappen.20 The origi-nal report, by De Haan and Soele, was never made public. It seems to have been lost.

THE CAREER OF JOHAN MAURITS MOHR

From 1762 onward, then, Mohr presented himself as an astronomer. To find out why hedid so, we must consider his biography more carefully. Since his settlement in the DutchEast Indies, Mohr had acquired quite a reputation as a scholar.21 In the strictly commercialsetting of Batavia, scholarly status was extremely rare; such an asset would certainly haveimproved his standing in Batavian society.

Born in 1716 in Eppingen, Germany, the son of a minister of the Reformed Church,Mohr enrolled at the University of Groningen as a student in theology in August 1733.The matriculation rolls note that he was entered “free of fee,” suggesting that he camefrom an impoverished family. In 1736 he completed his studies with a public disputationon the role of biblical visions. Later that year he was appointed minister to the Dutch EastIndia Church with a modest monthly allowance of 90 Dutch guilders.22 The following yearMohr set sail on the Dutch East Indiaman Oostrust and, after a call at the Dutch provi-sioning station at the Cape of Good Hope, arrived at Batavia on 24 October 1737. Aftertwo years of service as a vicar in Batavia, Mohr was commissioned to lead the Portuguese

19 Van der Bilt, Venus tegen de Zonneschijf (cit. n. 13), p. 58.20 Lulofs to Van der Aa, 6 Feb. 1763; and Mohr to Engelhardt, 5 May 1762. For the eventual publication see

J. M. Mohr, “Waarneminge over den schijnbaaren loop van Venus over de zonneschijf, in zijn begin, midden eneinde, den 6 Juni 1761,” Verhandel. Hollandsche Maatsch. Weetensch. Haarlem, 1763, 7(1):380–391.

21 The main biographies of Mohr are P. Melvill van Carnbee, “Iets over den Nederlandschen SterrekundigeJohan Maurits Mohr, te Batavia,” Tijdschr. Neerland’s Indie, 1st Ser., 1844, 6(4):172–179; J. S. van Coevorden,“Nog iets over den Nederlandschen Sterrekundige Johan Maurits Mohr, te Batavia,” ibid., 1845, 7(3):270–272;P. A. Leupe, “Berigten: Johan Maurits Mohr,” Tijdschrift voor Indische Taal-, Land- en Volkenkunde, 1859, 8[� 3rd Ser., 2]: 317–318; Leupe, “Iets over den Nederlandschen Sterrekundige Johan Maurits Mohr te Batavia,”Bijdragen tot de Taal-, Land- en Volkenkunde van Nederlandsch Indie, 1864, 11 [� 2nd Ser., 7]: 160–168; P. J.Veth, “Johan Mauritz Mohr,” De Gids, 1885, 49(3) [� 4th Ser., 3]: 55–87; S. Kalff, “Eene Indische Sterrewacht,”De Indische Gids, 1921, 43:409–423; and J. van der Bilt, “De sterrewacht van J. M. Mohr: Een rechtzetting eneen aanvulling,” Hemel en Dampkring, 1942, 40:69–73.

22 Daniel Benedictus Mohr from Eppingen, who may have been J. M. Mohr’s younger brother, likewise en-rolled “free of fee” as a student of philosophy at the same academy in September 1735. See J. A. Feith andJ. G. C. Joosting, Album Studiosorum Academiae Groninganae (Groningen: Historisch Genootschap, 1915),pp. 182, 185. For the text pertaining to the disputation see J. M. Mohr, Dissertatio theologica de Abrahamivisione (Groningen, 1736). On his appointment as minister see NA/VOC, no. 256, 10 Dec. 1736.


community at the Dutch settlement at Galle in Ceylon. However, he requested permissionto stay in Batavia to perfect his knowledge of the Portuguese language. Shortly afterwardhe got married. His Ceylonese appointment was cancelled in February 1739, when, havinggiven proof of his ability to preach in Portuguese, he was appointed to lead the Portuguesecommunity of Batavia instead. When G. W. Baron van Imhoff, then governor-general ofBatavia, founded a Naval Academy and a Theological Seminary in 1743, Mohr—as a“man of learning and of good qualities who is dearly beloved in the Indies”—was ap-pointed the first rector of the seminary.23 During his tenure as rector he produced severalbooks, which raised his status as a scholar. Mohr was especially known for his literarywork as a translator of the Bible into both the local Malayan and the Portuguese languages.Thanks to this scholarly work, he was one of the few persons in Batavia with academiccontacts in the Netherlands.24

After ten years of service, Mohr resigned as rector in November 1753. His secondmarriage, the year before, was perhaps one of the reasons for this resignation. Mohr’s firstwife, Johanna Cornelia van der Sluys, had died in September 1750. In April 1752 hemarried Anna Elisabeth van ’t Hoff, the Asian-raised daughter and principal heiress of Janvan ’t Hoff, a very wealthy official of the VOC.25 Mohr’s new bride also had money ofher own, being the widow of two wealthy men, Gabriel Hendrik van Gehren (d. ca. 1741)and Willem Cornelis Visboom (d. ca. 1747). Each of her earlier marriages had produceda son. In her marriage with Mohr she would give birth to a daughter: Johanna MauritiaMohr, christened on 22 November 1761.26

23 NA/VOC, no. 761, pp. 414–415; no. 763, pp. 270–272; no. 775, pp. 390–401. See also J. R. Bruijn, F. S.Gaastra, and I. Schoffer, eds., Dutch-Asiatic Shipping in the Seventeenth and Eighteenth Centuries, 3 vols. (TheHague: Nijhoff, 1979–1987), Vol. 2, no. 3052.7. The Oostrust, built in 1721, was one of the largest vessels inthis fleet of eighteen ships bound for Ceylon and Batavia. The history of the Theological Seminary of Bataviais described in Van Hoevell, “Geschiedkundig Overzigt van de beoefening van Kunsten en Wetenschappen inNeerlands Indie” (cit. n. 4), pp. 41–44; and J. A. van der Chijs, De Latijnsche Scholen van 1642 en 1666,alsmede het Seminarium van 1745 te Batavia: Proeve eener geschiedenis van het onderwijs in NederlandschIndie (Batavia: Lange, 1860). The Theological Seminary was erected along the Verburgsgracht, just outside thecity walls, near the Rotterdammer Poort (the Eastern Gate). This is the present-day Jalan Kampung Muka Timur,between the old City Hall (Stadhuis) and the Railway Museum.

24 For more details about Mohr’s publications see John Landwehr, VOC: A Bibliography of PublicationsRelating to the Dutch East India Company, 1602–1800 (Utrecht, 1992). They include J. M. Mohr and L. A.Bohmer, Do Velho Testamento: O Primeiro Tomo (Batavia, 1748); Mohr, Breviario da doutrina da verdade(Batavia, 1750) (this title is not listed in Landwehr’s volume); Mohr and Bohmer, Do Velho Testamento: OSegundo Tomo (Batavia, 1753); Mohr and H. P. van de Werth, Al-Kawl al-’Atik iya-itu segala surat PerdjandjianLama, 4 vols. ([Batavia], 1758); Mohr and Van de Werth, Indjil al-kudus ’Tsa al Masih, lya Itu, segala suratPerdjanddj ian Baharu ([Batavia], 1758); and Mohr, O Novo Testamento (Batavia, 1773). For examples of Mohr’sacademic contacts see Mohr to J. Schultens (the famous Leiden orientalist), 28 Apr. 1759, 1 Nov. 1759, Univ.Library, Leiden, BPL 245a.

25 Veth, “Johan Mauritz Mohr” (cit. n. 21), p. 74; and Melvill van Carnbee, “Iets over den NederlandschenSterrekundige Johan Maurits Mohr” (cit. n. 21), p. 176. The seminary was closed shortly after Mohr’s resignation,having had little impact. Only two of its pupils went to the Netherlands to complete their education in theology,and only one of them became a vicar. Jan van ’t Hoff was an officer of the Civilian Cavalry (Ritmeester derburger Cavallerije) and a member of the Water Board of the Batavia Outskirts (Heemraad der BatviaascheOmmelanden). In his will, drawn up in 1761, he named his daughter as his principal heir: NA/VOC, nos. 6895,9931.

26 The elder son, Johannes Gabriel van Gehren (born in 1742), studied law at the University of Leiden (enrolled10 Jan. 1760), where in 1763 he defended his thesis “De repetitione dotis.” He became a member of the Boardof Aldermen (Scheepen) of Batavia in 1767 and a member of the Justice Council (Raad van Justitie) in 1768.The second son, Jan Cornelis Visboom (born in 1748), was employed at the General Secretariat of Batavia, firstas a clerk (in 1765) and then as a bookkeeper (in 1766). See. N. W. du Rieu, Album Studiosorum AcademiaeLugduno Batavae MDLXXV–MDCCCLXXV (The Hague, 1875), p. 1066. Johanna Mauritia Mohr was mentionedas a beneficiary in the will drawn up by her half-brother Jan Cornelis Visboom on 6 Nov. 1775, shortly afterMohr’s death. In 1782, at the age of twenty-one, she would become the fourth bride of David Johan Smith


SCIENTIFIC STATUS AS A SOCIAL MOTIVATION FOR PRACTICING ASTRONOMY

It was primarily his reputation as a scholar that had enabled Mohr to rise socially in thestatus-conscious Batavian society. It was probably only because he was highly respectedthat he had been able to make such an advantageous second marriage. His scholarly workalso made him a personal friend of Governor-General Mossel, who in 1758 provided thefunds that enabled Mohr to print the four volumes of his Malayan Bible translation. WhenMossel died suddenly, in May 1761, Mohr was asked to join the officials of the VOC inthe impressive, almost royal, funeral procession that walked behind the casket.27 So Mohrknew about the value of status.

In 1763, his reputation bolstered as a result of his report on the 1761 Venus observations,Mohr was named a member of the Hollandsche Maatschappij der Weetenschappen. Theappointment came shortly after his father-in-law had died and his wife had inherited alarge fortune.28 A few months later the couple decided to build a large country house, inthe style of Louis XIV, on the prestigious Molenvliet canal, and Mohr included an astro-nomical observatory in the plans for the luxurious building. In 1763, as well, he commis-sioned the Leiden professor of astronomy Johan Lulofs to purchase astronomical andmeteorological instruments up to the value of 3,000 Dutch guilders. Getting these instru-ments was evidently no simple matter: some two and a half years elapsed between thetime the equipment was ordered and its arrival in Batavia.

In the meantime, in September 1765, Mohr obtained official permission to build on hisnewly erected country house an astronomical observatory 80 feet or more above groundlevel. According to one of Mohr’s contemporaries, the construction of this six-story edificeset the couple back some 80,000 “rijksdaalders”—the equivalent of about 200,000 guil-ders. This was roughly twice the cost of “Buitenzorg,” the nearby palace of the governor-general (the present “Bogor”). How overwhelming the construction was is illustrated bytwo striking drawings of the observatory and its setting made in the early 1770s by theDanish artist Johannes Rach (1720–1783).29 The first drawing (see Figure 1) presents aview of Mohr’s observatory as seen from a distance along the stately entrance gate andlane. The second drawing (see the cover illustration) depicts the observatory from a pointmuch closer and shows a small Chinese temple in the foreground.

In 1768, in a letter to the Hollandsche Maatschappij der Weetenschappen, Mohr ac-knowledged that the honor of being appointed a member had prompted him to build hisobservatory. The three colored architectural drawings that accompanied this letter testify,however, that the assertion of social status must have been a major motivation for building

(1740–1792), who was twice her age. Smith was a close relative of former governor-general Van de Parra. SeeJean Gelman Taylor, The Social World of Batavia: European and Eurasian in Dutch Asia (Madison: Univ.Wisconsin Press, 1983), p. 206. See also NA/VOC, nos. 6847, 177, 219; and Kalff, “Eene Indische Sterrewacht”(cit. n. 21), p. 419.

27 Nederlandsche Jaerboeken, 1762, 16(1):461–470, esp. p. 467. On the social structure of Batavian societysee Taylor, Social World of Batavia.

28 Mohr was elected to the Dutch society on 24 May 1763; see Verhandel. Hollandsche Maatsch. Weetensch.Haarlem, 1763, 7:vii, xxvii. He was recommended for the appointment by the Leiden professor Johan Lulofs ina letter written 6 Feb. 1763. Jan van ’t Hoff was buried on 22 Apr. 1763: CBG, Batavia, Hollandsche Kerk, B1761–66, fiche 16.

29 The cost is noted in a letter of Friedrich Baron von Wurmb, dated 30 Oct. 1775, printed in Briefe des Herrnvon Wurmb und des Herrn Baron von Wollzogen auf ihren Reisen nach Afrika und Ostindien in den Jahren 1774bis 1792 (Gotha, 1794), pp. 104–135, esp. pp. 123–124. Initially held privately, these drawings were at somepoint acquired by the Batavian Society of Arts and Sciences. They are now preserved in the National Library ofIndonesia (Arsip Nasional Indonesia) in Jakarta. See Max de Bruijn and Bas Kist, Johannes Rach, 1720–1783:Artist in Indonesia and Asia (Jakarta: National Library; Amsterdam: Rijksmuseum, 2001).


Figure 1. View of Mohr’s observatory from a distance, as seen along the stately entrance gate andlane from the Molenvlietse dike. Drawing in ink by Johannes Rach. (National Library, Jakarta.)

such a luxurious edifice. The first view (see Figure 2), depicting the main entrance on theeastern side of the building, shows a four-story structure—lavishly decorated with celestialfigures (stars, a half moon, and a radiant sun), classical gods (Mercury and Neptune), andallegorical statues of the muses holding mathematical and astronomical instruments—onwhich an octagonal tower seems to be precariously balanced. To the right of the mainentrance the name “J. Bittner” (the architect, presumably) and that of the draftsman, “J.Clement,” can be distinguished. Another view, of the northern side of the building, showsa much sturdier arrangement (see Figure 3). Finally, a third diagram depicts the layout ofthe ground floor. From the scale in feet and rods given on this diagram, the observatorycan be inferred to have been 80 feet (221⁄2 meters) in width and 62 feet (171⁄2 meters) long,with a total height of about 108 feet (301⁄2 meters).30 Both the design of the octagonaltower and the astronomical imagery seem to have been inspired to a large extent by thewell-known frontispiece of Urania’s temple in Johannes Kepler’s Rudolphine Tables of1627.

Though its magnificence could only have enhanced his social status, Mohr pointed toother motives. In 1768, in a letter to Thomas Hope, one of the seventeen directors of the

30 The first two drawings, from the HMW Archives, are reproduced in Van der Bilt, “De sterrewacht van J. M.Mohr” (cit. n. 21); and G. C. Molewijk, “Twee onbekende afbeeldingen van de achttiende-eeuwse sterrenwachtte Batavia,” Jambatan: Tijdschrift voor de Geschiedenis van Indonesie, 1987, 5:132–136. During our investi-gations in Dec. 1998 these drawings and Mohr’s accompanying letter of 20 Jan. 1768 (excerpted by Van derBilt) were not found in the HMW Archives. See HMW Notulen, Vol. 2, fol. 534, 6 Sept. 1768, HMW Archives.Neither Bittner nor Clement could be traced in the VOC Archives. “J. Clement” was perhaps the “J. F. Clement”who engraved several plates for Carsten Niebuhr’s report of a Danish expedition to Arabia (1761–1769). Thedimensions are calculated on the assumption that the Amsterdam rod (� 12 feet � 3.40 meter) was used.


Figure 2. Front view (eastern face) of Mohr’s observatory. Architectural drawing by J. Clement.(Hollandsche Maatschappij der Wetenschappen, Haarlem.)

VOC, he offered the following fashionable physico-theological statement to explain whyhe built an observatory:

For some years I have dedicated myself, along with other useful sciences, to physics andastronomy, one of my oldest and most favorite passions, with the intention of raising its statusand promoting these sciences as most suited to fighting ignorance and superstition, so muchprevalent in this country. This with the purpose of filling the hearts of the people with reasonable


Figure 3. Side view (northern face) of Mohr’s observatory. Architectural drawing by J. Clement.(Hollandsche Maatschappij der Wetenschappen, Haarlem.)

and lofty thoughts about the works of their Creator, worthy of making them susceptible toreligion.31

31 Mohr to Thomas Hope, 2 Nov. 1768, printed in Leupe, “Iets over den Nederlandschen Sterrekundige JohanMaurits Mohr te Batavia” (cit. n. 21), pp. 164–167; and Veth, “Johan Mauritz Mohr” (cit. n. 21), pp. 67, 75–77.


MOHR’S ASTRONOMICAL INSTRUMENTS AND THEIR PROVENANCE

As already noted, in 1763—after his decision to promote himself as an astronomer—Mohr had commissioned the Leiden professor Lulofs to buy astronomical and meteoro-logical instruments for him. The records of the General Council of the VOC confirm thatLulofs assisted Mohr in choosing, ordering, and shipping these specialized instruments.In October 1765 four crates containing various mathematical and astronomical instrumentswere sent to Batavia. Four more crates followed two years later. After Lulofs’s death in1768, orders were placed with the Leiden instrument-maker Jan Paauw.32 This time thearchives reveal more particulars about the shipments. In October 1770 Paauw sent withone of the ships of the Amsterdam chamber of the VOC “an astronomical clock 6 feethigh, 17 inches wide and 12 inches deep and a pair of Adams’ globes of two feet indiameter.” Also shipped were “a 2-foot radius astronomical quadrant with its pedestal intwo crates, one measuring 21⁄2 feet wide, 2 feet deep and 1 foot high and the other mea-suring 3 feet on all sides; an ‘equal-altitude’ instrument 2 feet wide and deep, 6 to 8 inchesin height and a ‘parallactic machine’ whose size cannot be accurately stated and a seaoctant 21⁄2 feet long, 11⁄2 inch in width and 8 inches high.” In October 1773 this wasfollowed by the delivery of three little boxes containing instruments: “an 18-foot longastronomical telescope, in three segments; a ‘heliometer’ to measure the quantity of rain-water fallen [obviously this was a rain gauge or ‘pluviometer’], mounted on a pedestal;an anemometer [or wind-speed meter] and a compass with a direction finder.”33 Unfortu-nately, apart from the globes, no details are given with regard to the manufacturers of theinstruments. Some of them may have been made by Paauw himself, but others were prob-ably of foreign origin.

MOHR’S OBSERVATIONS OF THE TRANSITS OF 1769

Further particulars about the instruments Mohr purchased are found in his memoirs on the1769 transit of Venus. It is striking how much Mohr’s situation had changed in eight years.In 1761 he had been more or less an outsider, watching the observational activities of DeHaan and Soele; they had few instruments at their disposal and lacked accurate knowledgeof the geographical coordinates of Batavia. In 1769, in contrast, Mohr was the owner ofa marvelous new observatory, equipped with some of the best observational instrumentsthe European market had to offer. He had been working with these instruments since 1767,determining as accurately as possible the latitude and longitude of his observatory, interalia by observing the satellites of Jupiter.34 So all the conditions necessary for an accurate

32 NA/VOC, nos. 60 (draft), 132 (copy), 177 (fair copy), 19 Oct. 1765; and NA/VOC, nos. 61 (draft), 133(copy), 178 (fair copy), 14 Oct. 1767. See also Van der Bilt, Venus tegen de Zonneschijf (cit. n. 13), p. 53. Afterthe death of Jan van Musschenbroek in 1748, Jan Paauw, Jr. (ca. 1723–1803), was one of the principal scientificinstrument-makers in the Netherlands. He supplied several scientific instruments for the physical cabinets of theacademies of Leiden, Utrecht, Franeker, and Harderwijk as well for private cabinets. See M. Rooseboom, Bij-drage tot de geschiedenis der instrumentmakerskunst in de Noordelijke Nederlanden tot omstreeks 1840 (Leiden:Rijksmuseum voor de Geschiedenis der Natuurwetenschappen, 1950), pp. 110–112.

33 NA/VOC, nos. 63 (draft), 133 (copy), 180 (fair copy), 15 Oct. 1770; and NA/VOC, nos. 66 (draft), 134(copy), 182 (fair copy), 19 Oct. 1773. At that time an azimuth compass (peilkompas) was a piece of standardmeteorological equipment.

34 Mohr’s best instruments, like an astronomical clock, the astronomical quadrant, and an achromatic telescopemade after Dollond’s new invention of 1759, would not arrive until 1770–1773. In his letter of 20 Jan. 1768 tothe Hollandsche Maatschappij der Weetenschappen in Haarlem (cit. n. 30), Mohr referred (without giving muchdetail) to several observations that he had collected while his observatory was still under construction. The


determination of the solar parallax seemed to be fulfilled. Nonetheless, the 1769 obser-vation almost failed. It was very cloudy that day, and at sunrise the Sun was not visible atall. But by eight o’clock the clouds had disappeared, and the disk of the Sun appearedbright in the morning sky. As calculations had predicted that at sunrise Venus would alreadybe on the solar disk, Mohr had equipped his 31⁄2-foot focal length Dollond-made Gregorianreflector with a frame of silk threads in order to establish the place of the planet on theSun’s surface. Although he knew that his heliometer objective glass would be more effec-tive in locating the planet on the solar disk, because of the limited field of his telescopehe could use the heliometer (see Frontispiece) only when Venus was very close to the edgeof the disk. Nevertheless, in the end he could report: “Under this favourable condition ofthe sky I could observe the egress of Venus with this telescope bright, sharp and precisely”(see Figure 4). During the observations he was assisted by an unnamed friend who countedout the seconds on the timekeeper, an astronomical pendulum clock with a Graham-typeescapement made by the London clockmaker John Shelton. Shelton regulators were alsoused by the Venus expeditions set up by the Royal Society of London.35 Another instrumentMohr used in 1769 was a 21⁄2-foot astronomical quadrant made in London, with an azi-muthal scale, mounted on a pedestal.

Mohr waited to observe the transit of Mercury in November 1769 before sending hisreports to the Netherlands by VOC ship. Another account of his observations reachedEurope by way of the circumnavigator and explorer James Cook (1728–1779). In the fallof 1770 Cook was forced to call at Batavia when his ship, the Endeavour, needed repairs,and during this stay he paid a visit to Mohr and his observatory. Just a few hours beforethe Endeavour weighed anchor, Mohr gave Cook a Latin version of his report on bothtransits. On his arrival in England in July 1771 Cook sent these observations to the RoyalSociety, where on 21 November they were read out to the members. Mohr’s report wasprinted in the same year’s issue of the Philosophical Transactions.36

VISITORS TO A “PRINCELY” OBSERVATORY

There were others who were delighted with these new scientific developments in the DutchEast Indies. The French naturalist and circumnavigator Louis-Antoine de Bougainville

latitude determinations would be based on meridian altitude measurements of Procyon (� CMi) and Sirius (�CMa), two bright stars passing near the zenith at Batavia and thus minimally susceptible to errors caused byuncertainties as to the correction for refraction. The longitude would be obtained from timed eclipses of the twoinnermost moons (Io and Europa) of Jupiter and an occultation of Antares (� Sco) by the Moon, after comparingthese with the times for the meridian of Paris as listed in the Connoissance des temps for 1767. In his memoirson the Venus transit of 1769 (Latin version only) and the Mercury transit of 1769, Mohr announced the prepa-ration of a memoir on the longitude of Batavia to be sent to Dutch society. However, this memoir was eithernever completed or failed to arrive in Haarlem.

35 J. M. Mohr, “Waarneeming van Venus, by haaren uitgang van de Zonne-schyf, gedaan den 4. Juny 1769.te Batavia op het Observatorium (liggende op 6 gr. 12 min. Zuider br.),” Verhandel. Hollandsche Maatsch.Weetensch. Haarlem, 1770, 12:123–130; see also Van der Bilt, Venus tegen de Zonneschijf (cit. n. 13), p. 67.Regarding Shelton’s regulators see H. Alan Lloyd, “Description of a Clock by John Shelton, Owned by the RoyalSociety and Used by Maskelyne on His Visit to St. Helena in 1761, and Probably by Mason and Dixon inPennsylvania,” Proceedings of the American Philosophical Society, 1950, 94:268–271; and Charles Green andJames Cook, “Observations Made, by Appointment of the Royal Society, [in 1769] at King George’s Island inthe South Sea,” Phil. Trans., 1772, 61:397–421.

36 J. M. Mohr, “Waarneeming van Mercurius by zynen uitgang van de Zonne-schyf, gedaan den 10. Nov. 1769.te Batavia op het Observatorium,” Verhandel. Hollandsche Maatsch. Weetensch. Haarlem, 1770, 12:131–134;and Mohr, “Transitus Veneris & Mercurii in eorum Exitue Disco Solis, 4to Mensis Junii & 10mo Novembris,1769, observatus,” Phil. Trans., 1772, 61:433–436. See also J. C. Beaglehole, ed., The Journals of CaptainJames Cook on His Voyages of Discovery, 4 vols. plus portfolio (Cambridge: Cambridge Univ. Press, 1968),Vol. 1, pp. 694–695.


Figure 4. Manuscript drawing by Mohr of his observation of the Venus transit of 1769. (HollandscheMaatschappij der Wetenschappen, Haarlem.)

(1729–1811), for example, called at Batavia in October 1768, during a twenty-eight-monthjourney around the world. Together with the astronomer Pierre Antoine Veron (1736–1770), who was assigned to this French expedition with instructions to observe the 1769transit of Venus, de Bougainville paid a visit to Mohr’s observatory. He wrote enthusias-tically in his diary:

We could never be tired with walking in the environs of Batavia. Every European, though hebe used to live in the greatest capitals, must be struck with the magnificence of the countryaround it. This is adorned with houses and elegant gardens, which are kept in order, in thattaste and with that neatness which is peculiarly observable in all the Dutch possessions. I canventure to assert that these environs surpass those of the greatest cities in France, and approachthe magnificence of those of Paris. I ought not to omit mentioning a monument, which a privateperson has there erected to the Muses. Mr. Mohr, the first clergyman at Batavia, a man ofimmense riches, but more valuable on account of his knowledge and taste for the sciences, hasbuilt an observatory, in a garden belonging to one of his country-houses, which would be anornament to any royal palace. This building, which is scarce completed, has cost prodigioussums. Its owner now does something still better; he makes observations in it. He has got thebest instruments of all kinds from Europe, necessary for the nicest observations, and he iscapable of making use of them. This astronomer, who is doubtless the richest of all the childrenof Urania, was charmed to see M. Verron. He desired he should pass the nights in his obser-vatory; unluckily, not a single one has been favourable to their purposes. M. Mohr has observed


the last transit of Venus [of 1761] and has communicated his observations to the society ofHarlem; they will serve to determine the longitude of Batavia with precision.37

De Bougainville’s favorable description of Batavia is noteworthy, as this Dutch settlementwas generally thought of as an insalubrious place and was much feared by soldiers andseamen, who knew it as the “graveyard of the Europeans.” The aforementioned JamesCook would not have disputed this bad reputation. His Batavia stop in Endeavour was toprove fatal to several crew members, though up to that point all had enjoyed reasonablygood health. One of the men who caught a fever during his stay at Batavia and died aftera few weeks at sea was the expedition’s astronomer, Charles Green (1735–1771). He hadassisted Maskelyne at Greenwich in observations of the Venus transit of 1761 and hadobserved the 1769 transit with Cook from King George’s Island (present-day Tahiti).Green’s sudden death, just a few weeks after he left Batavia, is probably the reason whywe are deprived of his views on Mohr’s observatory. From Cook’s journal we know thatsome members of his expedition visited the site, but unfortunately Cook (who was alsotaken ill) gives no particulars. However, a glimpse of Green’s visit is unveiled by ananonymous “letter from a gentleman on board the Endeavour,” printed in the LondonEvening Post, which reports that “great respect was paid here to Mr. Green by the principalpeople of Batavia, but no particular notice was taken of the rest of us by the Dutch.”38

According to Joseph Banks, the Endeavour’s botanist, the main reason for the somewhatlabored relations between the Dutch and the British during their stay in Batavia was thefact that “we could have no business with them.” Thus it was only after a long period ofnegotiation that he and his traveling companion, the Swedish scientist Dr. Solander, weregranted an audience with the governor-general, where they “had the honour of conversingfor a few minutes with his High Mightiness.” In his Endeavour journal Banks makes nomention of a visit to Mohr’s observatory. However, some particulars of Banks’s meetingwith Mohr can be inferred from the correspondence of the Dutch-born former VOC gov-ernor of Ceylon, Joan Gideon Loten, who in 1771 lived in London. By coincidence, Lotenwas a neighbor of Banks. In some letters to his younger brother in Utrecht, Loten vividlydescribed the enthusiasm with which Banks and Solander told him about their trip aroundthe world. These gentlemen also spoke about their meeting with Mohr in Batavia: “Theydon’t stop talking about the magnificent and well equipped Observatory in Batavia, builtby the reverend Mohr. . . . This is such a noble undertaking, especially under the admin-istration of a governor who is ignorant of all the sciences and hates everybody who triesto practise them.”39

37 L.-A. de Bougainville, Voyage autour du monde, par la fregate du roi La Boudeuse, et la flute L’Etoile: En1766, 1767, 1768 et 1769 (Paris, 1771), quoted from the English translation by John Reinhold Forster, publishedin 1772 (pp. 425–426). In the end, Le Veron was unable to observe the 1769 transit effectively because his shipwas at sea when it occurred; see Woolf, Transits of Venus (cit. n. 2), p. 156.

38 Regarding the insalubrious nature of Batavia see Peter H. van der Brug, Malaria en Malaise: De VOC inBatavia in de Achttiende Eeuw (Amsterdam: Bataafsche Leeuw, 1994). On illness among the Endeavour crewsee Edward Smith, The Life of Sir Joseph Banks (New York: Arno, 1975), pp. 19–20. Green’s death is noted inBeaglehole, ed., Journals of Captain James Cook (cit. n. 36), Vol. 1, p. 442, entry for 26 Dec. 1770. On theanonymous letter see Margaret Morris, “Man without a Face: Charles Green,” Cook’s Log, 1980, 3(4):92–99;the original date of publication in the London Evening Post is not given.

39 John C. Beaglehole, The Endeavour Journal of Joseph Banks, 1768–1771, 2 vols. (Sydney: Public Libraryof New South Wales, 1962) (online edition: South Seas Project, State Library of New South Wales, 2002), entryfor 20 Oct. 1770; and J. G. Loten, London, to Arnout Loten, Utrecht, 18 July 1771 (quotation), 30 June 1775,Archive of Utrecht, Collection Grothe, no. 1428. The reports on Mohr’s observatory made such an impressionon Arnout Loten that in 1771 he established his own astronomical observatory on the roof of his house in Utrecht.


THE SCIENTIFIC CLIMATE AT BATAVIA UNDER GOVERNOR-GENERAL VAN DE PARRA

The “governor” Loten referred to was Governor-General Paulus Albertus van de Parra(1714–1775), who had succeeded Jacob Mossel in 1761. The Ceylon-born parvenu Vande Parra never received a formal European education. Even his coat of arms was “bor-rowed” from the distinguished Dutch family Van de Perre, to which he was not related inany way. In a letter of 1775 Loten again vents anger about Van de Parra’s attitude towardthe sciences: “The present lord Governor [of Batavia] used to be a major enemy of thosestudies. I have no doubt at all that in his heart he still is.” From these and other remarksit becomes clear that Mohr (to whom Loten referred as “this happy son of Urania”) receivedlittle official support for his scientific undertakings. Indeed, the only support we know ofwas that the governor-general funded the printing of the last volume of Mohr’s Portuguesetranslation of the Bible. Jealousy may have been one of the reasons for this hostile climatefor the sciences. According to a letter from Friedrich Baron von Wurmb, a zoologist anda close friend of Mohr’s, the fortune that Mohr had invested in his observatory arousedenvy indeed. To free himself from the “hate and disdain” of those in Batavia who “triedto obstruct the undertakings of others which do not conform to their own taste and ap-proval,” Mohr sought the support of one of the highest-ranking members of the DutchVOC hierarchy. In 1768 he pleaded with Thomas Hope, one of the directors of the Am-sterdam chamber of the VOC, to be granted official status as astronomer of the VOC.Mohr complained that the only science heard of in Batavia was the practice of making alot of money very fast. Now that, driven by “love for the sciences,” Mohr had voluntarilyappointed himself astronomer of Batavia, he sought to secure this position by an officialletter of recommendation from the Dutch East India Company. The fact that Hope was atthe time the official representative of the Dutch stadholder at the VOC suggests that Mohrknew of the official appointment given to the Dutch astronomer Jan de Munck (1668–1768) twenty years earlier: in 1748 this self-made Dutch astronomer had received the title“Astronomus of the Stadholder” from Prince William IV of Orange.40 Mohr probably heardabout this gesture of princely protection from the Batavia official Jacob Cornelius MattheusRadermacher (1741–1783). It had been his father, Jacob Cornelis Radermacher (1700–1748), then treasurer-general to the prince, who was responsible for creating De Munck’sofficial title in 1748. Whether Mohr ever received an answer to his request is doubtful; weknow of no official appointment or any other pertinent document issued by VOC officials.

At about the same time, another local scientific enterprise failed. Sometime around 1770,J. C. M. Radermacher came forward with a plan to establish a learned society in the Eu-ropean style in Batavia. Radermacher was a member of a very influential Dutch family.Both his uncle and his nephew were members of the board of directors of the VOC. In

His London-based brother Johan Gideon was commissioned to buy instruments from several English instrument-makers such as Adams, Bird, Nairne, and Dollond. See J. G. Loten to A. Loten, 13 Sept. 1771, 24 Nov. 1771,17 Mar. 1772, 25 Aug. 1772, 20 Sept. 1773, 8 Oct. 1773, 11 Mar. 1774, 23 July 1774, 30 June 1775, CollectionGrothe, no. 1428.

40 J. G. Loten, London, to A. Loten, Utrecht, 30 June 1775, Collection Grothe, no. 1428. Regarding the fundingof Mohr’s translation see “Van de Parra,” in Nieuw Nederlandsch Biografisch Woordenboek, 10 vols. (1909–1935), Vol. 7, pp. 940–941. For Von Wurmb’s letter see Friedrich von Wurmb et al., Briefe des Herrn vonWurmb und des Herrn Baron von Wollzogen (cit. n. 29), pp. 104–135, esp. pp. 123–124. In 1778 Wurmb(d. 1782) would become the first secretary of the Bataviaasch Genootschap. For Mohr’s request see Mohr toHope, 2 Nov. 1768 (cit. n. 31). On De Munck’s appointment see Huib J. Zuidervaart, “Astronomische waar-nemingen en wetenschappelijke contacten van Jan de Munck (1687–1768), stadsarchitect van Middelburg,”Archief: Mededelingen van het Koninklijk Zeeuwsch Genootschap der Wetenschappen, 1987, pp. 103–170.


1757, at the age of sixteen, he had traveled to the Dutch Indonesian settlements as amerchant for the VOC. Following in the footsteps of his father, who in 1735 had been thefirst Freemasonic grand master in the Netherlands, the young Radermacher created a Free-masonic circle in Batavia in 1762, the first of its kind in Asia. A year later Radermacherreturned to the Netherlands, where he enrolled at the University of Harderwijk. Afterhaving completed his studies in law, he went back to Batavia in 1767. While in the Neth-erlands Radermacher had been inspired by the spirit of the Enlightenment. In those yearsseveral learned societies were established in the Netherlands, and so Radermacher cameforward with the proposal to found in Batavia “a Society with several members, who in ajoint effort would promote fine arts and crafts in the Dutch East Indies and in the otherDutch Asian settlements.”41 But Radermacher’s appeal (and similar proposals by others inthe Netherlands) was made in vain. He would have to wait until the death of both Van derParra and his successor Jeremias van Riemsdijk (governor-general of Batavia from 1775to 1777) before such an initiative met with success.42

MOHR’S DEATH AND THE FOUNDING OF THE BATAVIAASCH GENOOTSCHAP VAN

KUNSTEN EN WETENSCHAPPEN

In 1778, at long last, the Bataviaasch Genootschap van Kunsten en Wetenschappen (Ba-tavian Society of Arts and Sciences) was founded, this time with the official support ofthe newly appointed governor-general Reinier de Klerk (who governed from 1777 to 1780).The fact that De Klerk was the stepfather of Radermacher’s wife surely contributed to theeventual launching of this first learned society in Asia. In the early days of the BataviaaschGenootschap some meetings “devoted to the Arts and Sciences” were held on the porchof De Klerk’s house. Moreover, he encouraged all senior officials in Batavia to join thenewly founded society by sending out a circular announcing its formation and his accep-tance of the post of chief director. In the first year 103 Batavians enrolled, along with 77

41 “Voorbericht,” Verhandelingen van het Bataviaasch Genootschap der Konsten en Wetenschappen, 1779,1:3–4; on Radermacher’s role in Batavian Freemasonry see Paul W. van der Veur, Freemasonry in Indonesiafrom Radermacher to Soekanto, 1762–1961 (Athens: Ohio Univ. Center for International Studies, 1976). Afterthe establishment of the Hollandsche Maatschappij der Wetenschappen in 1752 more scientific societies emerged:in 1769 at Rotterdam (the Bataafsch Genootschap der Proefondervindelijke Wijsbegeerte), in 1769 at Flushing(the Zeeuwsch Genootschap der Wetenschappen), and in 1772 at Utrecht (the Provinciaal Utrechtsch Genoot-schap voor Kunsten en Wetenschappen). In 1777 the Oeconomische Tak came into being, an offspring of theHollandsche Maatschappij der Weetenschappen devoted to the promotion of commerce and industry. In thecourse of the founding of this society some suggested the establishment of a special branch in the East Indies.However, the founding of the Bataviaasch Genootschap brought this initiative to a standstill. See H. A. M.Snelders, “Het Bataviaasch Genootschap van Kunsten en Wetenschappen in de periode 1778 tot 1816,” Docu-mentatieblad Werkgroep Achttiende Eeuw, 1979, 41–42:62–90, esp. p. 68, and Snelders, “Professors, Amateurs,and Learned Societies: The Organisation of the Natural Sciences,” in The Dutch Republic in the EighteenthCentury: Decline, Enlightenment, and Revolution, ed. Margaret Jacob and Wijnand W. Mijnhardt (Ithaca, N.Y.:Cornell Univ. Press, 1992), pp. 308–323.

42 See Snelders, “Het Bataviaasch Genootschap van Kunsten en Wetenschappen”; and P. Bleeker, Overzigt derGeschiedenis van het Bataviaasch Genootschap der Kunsten en Wetenschappen, van 1778–1853 (Batavia, 1853).The fact that both Van de Parra and his successors Van Riemsdyk and De Klerk were appointed “director” ofthe Hollandsche Maatschappij der Weetenschappen (in 1768, 1775, and 1777, respectively) should not be seenas evidence of their scientific interests but points, rather, to the importance attached to these officials, whorepresented the highest authority in the Dutch East Indies. This status is also reflected in the fact that both Vande Parra and De Klerk were made “honorary members” of the Bataafsch Genootschap at Rotterdam (in 1770and 1778, respectively) and the Zeeuwsch Genootschap at Flushing (in 1774 and 1778, respectively). In theyears 1777–1779 J. C. M. Radermacher also was appointed “foreign director” of the three most important Dutchlearned societies.


additional participants who were residents of the other Dutch dependencies in Asia. Therewere a few “corresponding members” in the Netherlands as well.43

Mohr would not live to witness Radermacher’s success. As early as spring 1775 Mohrhad informed the Hollandsche Maatschappij der Weetenschappen in Haarlem that hishealth was deteriorating. As a consequence, he explained, he could no longer continue hisastronomical and meteorological measurements. According to Johan Splinter Stavorinus,a rear admiral for the VOC Chamber of Zeeland, Mohr had developed into an assiduousobserver over the years, especially in the field of meteorology. Although Mohr neverpublished any meteorological measurements, Stavorinus tells us that his daily barometerreadings showed little variation throughout the year.44

Mohr’s last scientific memoir, dating from 1773, gives a vivid description of the volcaniceruption and the subsequent collapse of the nearly 3,000-meter mountain Gunung Papan-dajan, located some 165 kilometers southeast of Batavia. According to his detailed report,based on dispatches sent to him by European and Javanese witnesses, on the night of 11–12 August 1772 an area of some 240 square kilometers was completely swallowed by theearth in the aftermath of the eruption, resulting in the destruction of forty villages and theloss of nearly three thousand lives.45

In October 1775 Mohr’s life came to an end, the result—according to the statement ofhis widow and stepson—of “a long loss of strength.” Strangely enough, the obituaryspeech, delivered by one of Mohr’s colleagues, said very little about his scientific under-takings.46 If Mohr had lived, he surely would have had a prominent place in the newlyfounded Bataviaasch Genootschap van Kunsten en Wetenschappen, for its mission state-ment echoed his own earlier recommendation. In 1764, in a letter to the HollandscheMaatschappij in Haarlem, Mohr had asked the society to appoint more members in theEast Indies, not only to promote astronomy but on behalf of the other sciences, such asphysics and natural history, as well. Although very few people in Batavia were workingin these fields, Mohr argued, it would be a huge step forward when useful observationscould be collected from the Indonesian islands.47

43 On De Klerk’s role see Jan Hooyman, De rechtvaerdige op zyn sterfbedde, . . . treur-rede, ter gedachtenissevan . . . Reynier de Klerk (Batavia, 1780), p. 27. This obituary, delivered as a speech before being published,was dedicated to De Klerk’s heirs, among them his son-in-law, J. C. M. Radermacher. On the society’s earlymembership see Taylor, Social World of Batavia (cit. n. 26), p. 86.

44 HMW Notulen, 2 Jan. 1776, mentioning the contents of a letter from Mohr, no longer extant, dated 16 May1775; and J. S. Stavorinus, Reize van Zeeland over de Kaap de Goede Hoop, naar Batavia, Bantam, Bengalen,enz. Gedaan in de jaaren MDCCLXVIII tot MDCCLXXI, door den heer J. S. Stavorinus, Schout bij Nacht bij deAdmiraliteit van Zeeland, 2 vols. (Leiden, 1793). According to Stavorinus, Mohr noted that the level of mercurynever deviated significantly from the average of 29 inches and 10 lines.

45 J. M. Mohr, “Bericht nopens het springen en instorten van een brandenden Zwavel-Berg, met het droeviggevolg van dien, op het eiland Java, in de Maand Augustus 1772 voorgevallen: Met bygevoegde aanmerkingennopens dit verschynsel,” Verhandel. Hollandsche Maatsch. Weetensch. Haarlem, 1773, 14(2):82–96. The manu-script and the accompanying letter have not been preserved in the HMW Archives; see HMW Notulen, 3 Aug.1773. Mohr’s memoir was excerpted in a geological survey of Java by the American army surgeon–naturalistThomas Horsfield (1773–1859). On-site investigations in 1837 by the German-Dutch naturalist Franz WilhelmJunghuhn (1809–1864), the “Von Humboldt of Java,” revealed that Mohr’s description of the catastrophe hadbeen much exaggerated.

46 The loss of strength is mentioned in two printed obituary letters, signed by Mohr’s widow Anna Elisabethvan ’t Hoff and his stepson Johannes Gabriel van Gehren, preserved with the correspondence for the year 1775in the HMW Archives. For the speech see Theodorus Vermeer, Lyk-reede op het afstervan van . . . Johan MauritsMohr, in deszelfs leeven oudsten evangelie-bedienaar in de Portugeeschen Gemeente te Batavia, printed togetherwith another obituary (on the Rev. Hermanus Teeringh) in Albertus van der Parra, in leeven gouverneur generaalvan Nederlands Indie ([Batavia, 1776]). This obituary was dedicated to the widow and (step-)children of Mohr.

47 Mohr to HMW, 30 Oct. 1764, in Van der Bilt, “De sterrewacht van J. M. Mohr” (cit. n. 21), p. 73. In thisletter Mohr presented the physician Christaan Rose as a candidate for membership. But it would be sixteen years,after his return to Utrecht, before Rose was elected a member of the society.


MOHR’S INSTRUMENTAL RESEARCH PROGRAM CONTINUED BY THE BATAVIAASCH

GENOOTSCHAP

From the very beginning, the Batavian society tried to put into effect the program outlinedby Mohr. Members even tried to extend some of the instrumental observations he hadstarted. Although Mohr’s observatory was no longer used after his death, his instrumentswere bought in 1776 by Johannes Hooijman (d. 1789), one of the most active membersof the Bataviaasch Genootschap. In a way he was a second Mohr. Like his famous pre-decessor, Hooijman was a clergyman: he had been minister of the Lutheran Church ofBatavia since 1764. Also, like Mohr, Hooijman had married a very wealthy Eurasianwidow: the heiress Elisabeth Odilia Weijerman, the Indian-born daughter of a Dutch com-mander at Malabar.48 Even more essential, Hooijman had a scholarly attitude and wascurious as to what his investigations would find. On his plantation “Pondok-Gedeh,” nearBuitenzorg, he conducted several agricultural studies and performed botanical experiments.At the request of the Bataviaasch Genootschap he investigated the growth of wheat im-ported from the African VOC colony at the Cape of Good Hope. In the first three volumesof the transactions of the society Hooijman published extensively on the state of agriculturein the Batavia region. It seems that initially he hoped to continue Mohr’s observations,especially—probably because of his agricultural interests—the daily meteorological mea-surements. However, the instruments recovered from Mohr’s observatory were in such badcondition that restorations were urgently needed. There was no instrument-maker in Ba-tavia capable of fixing these devices, so Hooijman decided to ship most of them to theNetherlands for repairs.49 The defects were not specified, but probably one of the com-plaints concerned the state of the telescopic mirrors. In general, oxidation of the reflectingmetal occurred much more readily in the tropics than in milder climatic regions. So in1776 the Amsterdam merchant Hendrik van Akker was commissioned to see that theinstruments were repaired. In the meantime, it was probably Hooijman who urged themembers of the Batavian society to continue and even extend Mohr’s meteorologicalobservations. And with success: in October 1778 the society decided to order four ther-mometers, four barometers, two hygrometers, two anemometers, and two rain gauges fromAmsterdam. Indeed, starting in 1779—and under the supervision of the Bataviaasch Gen-

48 See the laudatory remarks in remembrance of Mohr made in 1779 by Josua van Iperen, secretary of theBataviaasch Genootschap, in the opening speech of his philosophical lessons for fellow “lovers of the arts”(kunstgenoten) in the society and others interested in the sciences: Josua van Iperen, Inleidingsredenvoering totzyne openbare lessen, over de wysbegeerte en fraaije letteren (1779; 2nd ed., Amsterdam: Allart, 1780), pp. 82–83. The fact that Mohr’s observatory was not used after his death was noted by the Swedish doctor, later professorof medicine and botany at Uppsala, Karl Peter Thunberg (1743–1822) during his stay in Batavia from 1775 to1777 as master surgeon (opper-chirurgijn) of the VOC: K. P. Thunberg, Resa uti Europa, Africa, Asia forrattadaren 1770–1779, 4 vols. (Uppsala, 1788–1793); we have used the German edition (Berlin, 1792–1793), Vol. 1,p. 197. On Hooijman’s marriage see Taylor, Social World of Batavia (cit. n. 26), p. 87.

49 The 31⁄2-foot Dollond refractor that Mohr used for the observation of the Venus transit of 1769 appears tohave remained in Batavia. In 1843 Mohr’s first biographer, the naval officer Pieter Baron Melvill van Carnbee(1816–1856), found the telescope in the museum of the Bataviaasch Genootschap. It was reported to be inexcellent condition. He and his assistant F. A. A. Gregorij used the instrument for longitude observations. Tenyears later the geographical engineer Sjoerd Hendrik de Lange (1816–1855) used the telescope for the samepurpose. Around 1910 this instrument was removed from the museum; it has been missing ever since. SeeF. A. A. Gregorij, “Lengte-bepaling van den tijdbal te Batavia, geplaatst op den Uitkijk, door middel der waar-genome eclipsen van den 1ste en 2de satteliet van Jupiter in 1843,” Tijdschr. Neerland’s Indie, 1845, 1st Ser.7(1):397–401; S. H. de Lange, “Reis van de geografische ingenieurs S. H. de Lange en G. A. de Lange vanBatavia naar de residentie Manado en terug, van 23 January 1852 tot 20 Maart 1853,” Natuurkundig Tijdschriftvoor Nederlandsch Indie, 1853, 5 (�2nd Ser., 2): 1–66, esp. p. 27; and Van der Bilt, Venus tegen de Zonneschijf(cit. n. 13), p. 64.


ootschap—instrumental meteorological observations were carried out on a daily basis atBatavia, at the Cape of Good Hope, and at the Decima factory of the VOC in Japan.50

Furthermore, by funding some essay contests—organized in the name of the BataviaaschGenootschap by major scientific societies in the Netherlands, such as the Rotterdam-basedBataafsch Genootschap der Proefondervindelijke Wijsbegeerte (Batavian Society of Ex-perimental Philosophy)—the society tried to contribute to scientific, and sometimes eveninstrumental, research (see Figure 5). One of these competitions addressed the interpre-tation of meteorological observations.51

To place the society on a firm footing, Radermacher, its first president, arranged for abuilding to house its growing assets. Radermacher himself presented the society with eight“well filled” cases with books, manuscripts, instruments, and some specimens for the“Cabinet of Natural Curiosities.” He soon became even more ambitious. In order to guar-antee the ongoing investigations of the Bataviaasch Genootschap, Radermacher (whoplanned to return to Holland in 1783) sought to employ an educated scientist who wouldbe capable of making botanical, meteorological, and other observations on a regular basis.In September 1781 and again in December 1781, he wrote to the Swedish professor KarlPeter Thunberg (who had been in Batavia in 1775 and 1777), asking if he could send oneof his students to Java to be employed in the service of the society. Radermacher himselfwould guarantee the salary of this employee.52

At the end of 1782, then, one of Thunberg’s students, Klas Fredrik Hornstedt (1758–1809) from Finland, set out for Java. In August 1783 Radermacher could inform Thunbergthat Hornstedt had arrived, after a short delay in the African Cape colony. However, thearrangement did not last very long. In 1785 Hornstedt left Batavia, traveling back throughFrance to Sweden. But by 1786 there was a successor. Hooijman, who had continued thecorrespondence with Thunberg after Radermacher’s departure, informed the Swedish pro-fessor that Francisco Norona, a capable botanist from Manila, had taken over the super-vision of the society’s museum. In 1786 and 1787 Norona collected all kinds of naturalspecimens on Java and published reports on them in the transactions of the Bataviaasch

50 The new meteorological instruments were shipped to Batavia in 1780 after being inspected by members ofthe recently founded Dutch Meteorological Society, the Natuur- en Geneeskundige Correspondentie Societeit.See I. J. van den Bosch to Van Swinden, 30 Sept. 1780, University Library, Leiden, BPL 755. See also Huib J.Zuidervaart, “An Eighteenth-Century Meteorological Society in the Netherlands: An Investigation on EarlyInstrumentation, Organisation, and Quantification of the Science of Weather” (forthcoming). Regarding the dailymeasurements see “Bericht wegens de hoogte der barometer en thermometer: De gesteldheid van weer, wind,en hoogte van het water aan het zeehoofd, en in de rivieren in 1779, op Batavia en van weer en wind tot Caapde Goede hoop, en Nangazaki,” Verhandel. Bataviaasch Genootsch. Konst. Wetensch., 1784, 2:65–87.

51 The contest was organized in August 1785 by the Rotterdam-based Bataafsch Genootschap der Proefon-dervindelijke Wijsbegeerte. The question was, “First: what use can be made of the meteorological observationsthat are so eagerly taken nowadays? Second: what use can they be to Medicine and to Human Society as awhole?” In the end, no answers were published. See Verhandelingen van het Bataafsch Genootschap der Proe-fondervindelijke Wijsbegeerte, 1787, 8:xii; and M. J. van Lieburg, Het Bataafsch Genootschap der Proefonder-vindelijke Wijsbegeerte te Rotterdam 1769–1984: Een bibliografisch en documenterend overzicht (Amsterdam:Rodopi, 1985), p. 105 (prize essay 38).

52 Radermacher’s stakeholder in the Netherlands, Frans de Wilde, an accountant of the VOC at Amsterdam,was commissioned to pay any botanist that Thunberg would send. See J. C. M. Radermacher to K. P. Thunberg,1 Sept. 1781, 10 Dec. 1781, University Library, Uppsala), cited in D. O. Wijnands, “De relaties van de Zweedsebotanicus/naturalist Carl Petter Thunberg (1743–1828) met de Nederlandse genootschappen,” Teylers MuseumMagazijn, 1990, 8(3):11–16; see also Wijnands, “The Letters of Maarten Houttuyn to Carl Peter Thunberg(1780–1790),” Proceedings of the Koninklijke Nederlandse Akademie voor Wetenschappen, 93:77–95. Thunberghimself had made meteorological measurements during his stay in Japan in 1775 and 1776: C. P. Thun-berg, “Thermometrische waarnemingen in Japan gedaan in den jaaren 1775 en 1776,” Verhandel. HollandscheMaatsch. Weetensch. Haarlem, 1780, 19(3):123–137.

Figure 5. Gold prize medal (front and back) of the Bataviaasch Genootschap van Kunsten enWetenschappen, enlarged size. (Courtesy Teylers Museum, Haarlem.)


Genootschap. But in 1787, after serious arguments with his superiors at the society, he,too, left Java, setting off to the island of Mauritius, where he died shortly afterward.53

For a time the survival of the Bataviaasch Genootschap was in doubt. Hendrik NicolaasLacle, who had become the secretary in 1783 after the collective departure for the Neth-erlands of Radermacher, the society’s president, and the Reverend Metzlar, the secretary,initially failed to win sufficient support for the organization. The absence of an inspiringpresident with the zeal and stature of a Radermacher was sorely felt. Moreover, the mightypatron of the society, Governor-General De Klerk, had died, as had several other originalmembers. The continuous deaths and departures of “capable Europeans” led to severeproblems for the Bataviaasch Genootschap. In 1783 even the printing of the Verhandelin-gen, the transactions of the society, seemed to pose an insurmountable problem becausethe remaining compositors in the region (most of them of Portuguese descent) couldscarcely read Dutch. The manuscript of the fourth volume had to be sent to the Netherlandsfor publication. In 1789, on his departure as secretary of the Bataviaasch Genootschap,Lacle summed up the difficulties. In addition to the problems already mentioned, he notedthat the hot and harsh climate, “the enemy of a concentrated mind,” did not encourageintellectual activity of the kind a flourishing scientific society needed. The isolation of theEast Indies was also perceived as a problem. It took years for news of some of the intel-lectual accomplishments of the Western world to reach Asia. Most of the work done byforeign scholars remained unknown there. Contacts with other scientific societies werescarce. Intellectually, Batavia was indeed positioned on the outskirts of the literary andscientific world. A last factor that—according to Lacle—had hampered the flourishing ofthe society was the business obligations of most of its members. Spare time for sciencewas a luxury that only a handful could afford. Still, Lacle concluded, the BataviaaschGenootschap had not been founded to be a “shining exhibit of scholarship” but, rather, tomake itself useful by informing the inquiring world about these foreign territories.54

Despite these setbacks and difficulties, Hooijman wanted to maintain the original in-strumental research program of the Batavian Society. Over the years he had continued hisown investigations and meteorological measurements. In the spring of 1789 he wrote tothe Amsterdam professor Jan Hendrik van Swinden, noting that he had asked the Bata-viaasch Genootschap to order some additional meteorological instruments, including newlyinvented hair-hygrometers after the design of De la Saussure and two barometers after thedesign of De Luc. In the same letter Hooijman asked whether Van Swinden knew any

53 Hornstedt’s travel diary was published in P. J. Bladh, ed., Anteckningar under en resa till Ostindien aren1782–1786: Anteckningar under en ekonomisk resa till Tyskland, Nederlanderna och Paris aren 1799–1800(Hfors, 1888). See also L. C. Rookmaaker, “The Descriptiones animalium (1784) Prepared by C. F. Hornstedton a Journey to the East Indies,” Archives of Natural History, 1988, 15:289–309. One of Hornstedt’s lastcommissions for the Bataviaasch Genootschap was the arrangement of transport to the Netherlands of a live“Oerang Oetang,” caught in the woods of Borneo. However, the animal was lost at sea. See Zeeuws Archive,Middelburg, Arch. KZGW, no. 5, fol. 239, 30 Aug. 1785. On Norona see Susana Pinar, “The Scientific Voyagesof Francisco Norona (1748–1788) in Southeast Asia and the Indian Ocean,” Itinerario: European Journal ofOverseas History, 1995, 1:161–164; and Pinar, “Little-Known Travellers and Natural Systems: Francisco No-rona’s Exploratory Voyage through the Islands of the Indian Ocean (1784–1788),” Arch. Nat. Hist., 1997,24:127–144.

54 Regarding the printing of the Verhandelingen see Metzlar to Justus Tjeenk, secretary of the ZeeuwschGenootschap, 20 Oct. 1780, 31 Aug. 1783, Zeeuws Archive, Middelburg, Arch. KZGW, no. 62, fols. 266–267,376. For the difficulties faced by the society see H. N. Lacle to the Secretary of the Zeeuwsch Genootschap, 7Sept. 1789, Zeeuws Archive, Middelburg, Arch. KZGW, no. 59, fols. 370–371. The society survived theseproblems. It flourished in the nineteenth and early twentieth centuries, only to be dissolved when the Dutchcolonial rule came to an end.


Dutch scholar capable of taking over the scientific investigations on Java. As AdriaanMoens, the newly appointed president and temporary secretary of the Batavian society,was withholding the finances necessary to employ such a person, Hooijman himself wasprepared to pay the expenses. He was looking for “an able person, middle aged, knowingthe botanical system of Linnaeus very well.” The man in question could live on his estate,free of charge, and would receive a yearly income of 1,200 Dutch guilders. In return, hehad to be prepared to record the state of the atmosphere three times a day and, in “theempty hours” between recordings, go out into the field in search of unknown plants. Acontract for at least two years would be guaranteed to any person willing to come to Bataviaon these conditions.55

Hooijman further asked Van Swinden if he was willing to make inquiries as to the fateof Mohr’s astronomical instruments, sent to Amsterdam for repairs in 1776. Although themerchant Van Akker had promised to get them repaired, Hooijman had never received anadequate response from him. It was still the case that no one in Batavia was up to the job:recently Hooijman had again been forced to send astronomical instruments to Holland tobe fixed. They had been used by a naval officer named Wille who had tried to determinethe longitude of several places in the Indonesian archipelago.56

THE DEMISE OF INSTRUMENTAL SCIENCE AT BATAVIA

Hooijman would not live long enough to see his dreams fulfilled. Two months later, inJune 1789, he was gruesomely murdered on his estate. The new meteorological instrumentshe had just received, made by the English-born Amsterdam craftsman John Cuthbertson,were returned to the Bataviaasch Genootschap. They never worked properly. One of thebarometers was broken in transit and lost all its mercury. The other barometer, after DeLuc’s design, also failed to perform properly, despite Hooijman’s many attempts to get itrunning. The same thing had happened with the hygrometers: the human hair in the in-strument prepared in Holland appeared to be completely useless. Moens, as acting secretaryof the society, wrote to Van Swinden informing him of Hooijman’s death. He also com-plained that a hot, wet tropical climate was not suited to instrumental science. The factthat only a very few people in the East Indies knew how to use these kinds of instrumentsonly made matters worse. According to Moens, Hooijman had come to the same conclusionjust before his death, a verdict corroborated by the fact that all the scientific instrumentsrecovered from his estate appeared to be defective. At this point instrumental science inthe Dutch East Indies came to a standstill, not to be revived for several decades.57

THE FATE OF MOHR’S ASTRONOMICAL INSTRUMENTS

In the meantime, Van Swinden had located Mohr’s astronomical instruments, which hadbeen stored in the attic of the merchant Van Akker since their arrival in Amsterdam in1776. This rediscovery had been an easy job, for Van Akker and his business partnerHeineken had just started negotiations with the Amsterdam society Felix Meritis for theloan of these instruments. Oddly, they were behaving as though they owned the instru-

55 Johannes Hooijman to Van Swinden, 2 May 1789, University Library, Leiden, BPL 755.56 Ibid. The Dutch naval officer Wille had taken a “common astrolabium,” a small reflecting telescope of which

the mirror had became dull, and a large naval telescope to Holland for repairs.57 Adriaan Moens to Van Swinden, 7 Apr. 1789, 4 Nov. 1789, Univ. Library, Leiden, BPL 755. On the second

period of instrumental research on Indonesian soil see Pyenson, Empire of Reason (cit. n. 1).


ments, even though the rightful owner—Hooijman—was still alive. The MaatschappijFelix Meritis was founded in 1777 as an institute for promoting the arts and sciences. Toaccommodate its four departments (Commerce, Physics, Arts, and Literature) the societywas constructing a large, specially designed edifice on the Amsterdam Keizersgracht. Anastronomical observatory was planned for the roof, and during the years of its construction(1786–1788) the society was on the lookout for proper instruments. Having heard of theseambitious plans, the merchants Van Akker and Heineken came forward. Although Mohr’sinstruments were in bad shape, they were of an excellent design, and once repaired theywould be perfectly suited for use in the new observatory. In December 1786 the merchantsoffered the instruments for a period of twenty years, on the condition that Felix Meritiswould pay for the repairs. And so it was agreed. In 1787 the instrument-maker FransPasteur was commissioned by Felix Meritis to perform the work.58

Although Van Akker and Heineken had not revealed the provenance of the instruments,this soon became known. On 31 October 1789 Van Swinden, who was invited to give alecture at the official opening of the new building, praised both Mohr and the second lifenow granted his instruments:

I know that [Felix Meritis] has a wonderful collection of artefacts, made by the most famousEnglish artisans, first shipped at great costs to the East Indies, where they were used in Bataviaby the late Mr Mohr. They were returned to the Fatherland after his death and were relegatedto an attic as dead weight, being subjected to rust and decay . . . , but you have been able toretrieve them, and had them restored . . . with the intent of installing them in your observatory.59

Apparently Van Swinden, who had just received Hooijman’s letter asking him aboutMohr’s instruments, accepted their presence at Felix Meritis since 1786 as a fait accompli.

In 1791, however, having learned the year before of the sad fate of the legitimate ownerof the instruments, Van Swinden pleaded with the board of Felix Meritis to buy the in-struments from Van Akker and Heineken (who evidently were still acting as the legalowners). The inventory handed over on this occasion summarizes eleven astronomicalinstruments: (1) a large standing quadrant, made by John Bird [at London]; (2) a smallerone [2 feet in radius, also by Bird]; (3) a [wooden] sextant [with brass inlay], made byBird; (4) a sextant, made by [Samuel?] Gregory [at Dublin]; (5) an octant by [Daniel]Voster [at Cork?]; (6) a large [41⁄2 foot] Gregorian telescope [with a heliometer], made byDollond, [London]; (7) a smaller one [of 3 feet, by the same]; (8) an astronomical telescope[with accessories in a long wooden box] by Dollond; (9) a [41⁄2 foot] meridian [� transit]telescope [with a level and a lantern for illuminating the cross-wires at night] by Sisson;(10) a [3 foot achromatic] transit telescope by Dollond; and (11) a parallel telescope [withits stand, in a triangular box] by Paauw.60 These eleven instruments were offered for sale

58 On the loan agreement see Municipal Archive, Amsterdam, Archive of the Society “Felix Meritis” (AFM),no. 234 (meeting of 29 Dec. 1786). See also M. R. Hermans, E. Lievense-Pelser, and O. Vlessing, Inventarisvan de archieven van de Maatschappij Felix Meritis 1777–1889 (Amsterdam: Gemeentearchief, 1994). TheGeneva-born instrument-maker Bernard Francois Pasteur (1741–1801) worked in Amsterdam from 1767. In1791 he was appointed a member of Felix Meritis. In 1793 he left for Leiden, where he got a job as scientificinstrument-maker at the university.

59 J. H. van Swinden, Redevoering en aanspraak, ter inwijding van het gebouw der Maatschappij Felix Meritis(Amsterdam, 1789), p. 97. In 1788, in one of the first descriptions of Felix Meritis, the provenance of theinstruments was made public: Amsterdam in zyne opkomst, aanwas . . . beschreeven, ten vervolge op het werkvan Jan Wagenaar (Amsterdam, 1788), p. 506.

60 AFM, no. 235 (meeting of 8 Apr. 1791). Some details of the instruments are added from inventory lists inAFM, no. 235 (9 July 1794); AFM, no. 260 (1794–1795); AFM, no. 274 (short inventory ca. 1820), and AFM,no. 275 (inventory in 1835). See also [C. S. Roos], Historische Beschrijving van het Gebouw der Maatschappijevan Verdiensten, ten spreuke voerende: Felix Meritis (Amsterdam, 1800), pp. 94–95, 123.


for the total of 4,500 Dutch guilders. The board of Felix Meritis refused the offer, intendingto prolong the lending arrangement as before. But in 1794 Adriaan Gilles Heineken (1763–1824), representing the firm of Van Akker and Heineken, granted permission for lendingonly the instruments of minor importance. The most important instruments were takenback; as a result, the instruments numbered 1, 4, 5, 7, 8, and 10 disappeared from the FelixMeritis building, never to be heard of again. After the dissolution of Felix Meritis in 1889,all remaining scientific instruments were handed over to the physics laboratory of Am-sterdam University; most of them have since disappeared. The whereabouts of only twoparts of Mohr’s costly instruments can now be traced.61

THE DEMISE OF THE BATAVIA OBSERVATORY

Nor had fate smiled on Mohr’s observatory in Batavia. In 1780, only five years after itsfounder’s death, the building was severely damaged by a heavy earthquake. Two yearsafter that, in May 1782, Mohr’s widow, Anna Elizabeth van ’t Hoff, passed away. Just amonth later, in June 1782, the future owner was granted permission “to modify, lower ordemolish” the building, but no such plan was immediately carried out. In 1784 the sitewas purchased by Willem Vincent Helvetius van Riemsdijk (ca. 1752–1818), one of themany children of former Governor-General Jeremias van Riemsdijk. Apparently little wasdone to repair or maintain the observatory, and in August 1788 Van Riemsdijk gave per-mission to convert the deserted facility and the adjoining buildings into lodgings for thepoorly housed company clerks of Batavia’s Castle. From that time on the building wasknown as the “Scribbler’s Asylum” (Pennistengesticht).62

Evidence of the speed with which the observatory was falling to ruin is found in thecorrespondence of the young Francis Beaufort (1774–1857), who would later becomefamous as an admiral and hydrographer. Enrolled as a fifteen-year-old captain’s servant,he visited Batavia in the summer of 1789 and described the abandoned observatory builtby a certain “M. de More” in a letter to his parents:

Such an Observatory I never saw. There is but one room in the house calculated to observe in,which is at the top of the house, near one hundred feet from the ground, affording only themost awkward viewing and so built that if you just stamp in any one part of the house it shakesthe Observation room. Indeed we find that a person walking about on the stairs or in any . . .room of the house shakes the Horizon and makes the objects turn about in the EquatorialTelescopes. . . . In short, I never saw or heard of such a place in my life.

Nonetheless, Beaufort and his captain carried their instruments to the old observatory everyday during the three weeks of their stop in Batavia to check and improve on Mohr’slongitude and latitude determinations. Four years later George Staunton (1781–1859), a

61 On the transfer of the instruments to Amsterdam University see AFM, no. 59 (last meeting: 5 June 1889).The Bird sextant (listed under no. 3) is now in the Nederlands Scheepvaart Museum, Amsterdam (no. B 21 [1]/H.12). A heliometer objective, originally an accessory to Mohr’s 41⁄2-foot reflecting telescope made by Dollond(listed under no. 6), is now at the Museum Boerhaave, Leiden (no. 6130). The 3-foot achromatic telescope byDollond (listed as no. 10) is the only instrument claimed back in 1794 whose fate can be traced. Through theAmsterdam astronomer J. F. Keyser and his pupil, the Utrecht professor Gerrit Moll, it went to the UtrechtObservatory in 1838. It was handed over to the Utrecht University laboratory in 1892; it has since disappeared.

62 NA/VOC, no. 812, 18 June 1782; and NA/VOC, no. 820/821, printed in J. A. van der Chijs, ed., Nederlandsch-Indisch Plakaatboek, 1602–1811 (Batavia/The Hague, 1885–1900), Vol. 11, pp. 29–34.


member of a British mission to the Chinese court, noticed during his stopover in Bataviain March 1793 that “there was an observatory, but we found it to be in a ruinous state.”63

In August 1809 the Pennistengesticht was closed down by Herman Willem Daendels,governor-general from 1807 to 1811, and for some years the buildings served as armybarracks. According to J. M. van Beusechem, director of the “Scribbler’s Asylum” from1808 to 1810, the observatory was still standing in 1812, but in 1844 nothing remainedexcept its foundation. The memory of the imposing structure, however, would be keptalive locally for another century. Up until the last years of Dutch rule in Batavia, theparallel streets in the district of Klentong (Glodok), running westward from the Molen-vlietse dike (Jalan Gajah Mada) through the former entrance and the garden to the site,were marked on the city’s municipal maps as the “Gang Torong” (i.e., Tower Alley) andthe “Gang Kebon Totong” (Tower Garden Alley).64

CONCLUSIONS

Stimulated by a prediction made by Halley in 1716, the French astronomer Delisle pleadedin 1760 with the Dutch East India Company to ensure that observations of the 1761 transitof Venus were made at Batavia. This simple request triggered a long chain of events. Thelocal reverend Mohr, until then a man devoted only to the humanities, attended the 1761observations performed at Batavia by VOC officials. This event prompted Mohr to appointhimself the astronomer of Batavia. Between 1765 and 1768, using the funds of his wealthyEurasian wife, he built himself an astronomical observatory equipped with instruments ofa quality theretofore unheard of in the region. Though Mohr himself emphasized thephysico-theological incentive, enhancement of his social status appears to have been themajor motivation for him to build this luxurious observatory.65

Very different attitudes toward the sciences characterized Dutch colonial authorities andthe officials of other colonizing nations—such as France and Britain—in the eighteenthcentury. The government of the Dutch Republic failed to support pure scientific research.The few achievements made in the sciences in the Dutch colonies were the result of private

63 Beaufort is quoted in Alfred Friendly, Beaufort of the Admiralty: The Life of Sir Francis Beaufort (London:Hutchinson, 1977), p. 31. See also W. F. J. Morzer Bruyns, “Prime Meridians Used by Dutch Navigators: ASurvey of the Prime Meridians Used by the Dutch for Navigation and Hydrography, Prior to 1884,” Vistas inAstronomy, 1985, 28:33–39, esp. pp. 37–38. For the latitude, Beaufort worked out a value between 6� 8� and6� 8� 40� South—somewhat lower than Mohr’s estimates, which ranged between 6� 10� and 6� 12�. Beaufortprobably made some observations for the determination of the longitude of Batavia, as well but these measure-ments appear to have been lost in the shipwreck of his vessel near the southeastern coast of Sumatra a coupleof weeks later. For Staunton’s remark see George Staunton, Travels of Lord Macartney to China (London, 1799),pp. 2, 75–76.

64 On the closing of the Pennistengesticht see Van der Chijs, ed., Nederlandsch-Indisch Plakaatboek (cit. n. 62),Vol. 15, pp. 848–849. Van Beusechem is cited in Melvill van Carnbee, “lets over den Nederlandschen Sterre-kundige Johan Maurits Mohr” (cit. n. 21), p. 177. For “reminders” of Mohr’s observatory see the “Stadskaartvan de Gemeente Batavia” (revised in 1918, published in 1921), reproduced in B. Brommer and D. de Vries,Historische Plattegronden van Nederlandse Steden, Vol. 4: Batavia (Alphen aan de Rijn: Canaletto, 1992), no. 14.The two streets are marked on present-day municipal maps of Jakarta as the Jalan Kemurnian 8 and JalanKemurnian 9, behind a hotel and a shopping center.

65 In this respect, it is noteworthy that in the 1920s similar social reasons played a major role in the foundingof Indonesia’s second astronomical observatory: the Bosscha Observatory at Lembang. “Providing funds forpure research allowed [Karel] Bosscha, a failure at the Delft Institute of Technology, privileged access to thedrawing rooms of polite society and the antechambers of political power”: Pyenson, Empire of Reason (cit. n. 1),p. 183. Like Mohr before him, the plantation owner Bosscha was a colonial overlord who used pure science asa vehicle to raise his own status. Nevertheless, in spite of this more or less hidden social agenda, in both caseswell-equipped observatories were built and some relevant scientific results were obtained.


initiative and funding. One reason why the state was reluctant to support pure science maybe the fact that eighteenth-century Dutch society was completely dominated by the conceptof usefulness. We met this idea in the remark of the Dutch astronomer Klinkenberg that“the usefulness of astronomy to mankind was not sufficiently appreciated in Dutch soci-ety.” He was right, indeed! The concept of usefulness was a key factor in Dutch intellectualideology; all scholarly and scientific efforts were at the mercy of this utilitarian bias. Andwhile in the Netherlands the promotion of theology was also considered a useful goal, inthe colonies “commerce” trumped every other interest. Adriaan Moens, governor of Mal-abar, remarked on the founding of the Bataviaasch Genootschap in 1779 that he surelyhoped that “this scientific society would help to serve the sciences and the promotion ofthe Christan faith”; but he feared that this would be a difficult mission, for “it is a pitythat in the East Indies the aim of making money is the principle object of study.”66

The situation elsewhere in Europe was very different. In the 1950s, in his influentialstudy on the eighteenth-century transits of Venus, Harry Woolf outlined the massive effortsin support of scientific expeditions made in name of the crowned heads of Great Britain,France, Sweden, Russia, and other countries. More recently, in analyzing the French “co-lonial machine” of the ancien regime, James McClellan and Francois Regourd concludedthat the central government systematically engaged its elaborate scientific infrastructure inits colonizing efforts. They suggest that the chief motivation for such an effort appearedto be “the sheer glory and magnificence of a great empire,” which “was enough of a raisond’etre for the French state to underwrite costly colonial investments.”67 In short, the majestyof the great kings of Europe was not to be taken lightly.

Evidently the decentralized Dutch Republic, in which all the provinces were sovereignand which by nature lacked a royal court, was not similarly sensitive to imperial argumentsof glory and royal luster—with perhaps one small exception. In 1761 the Dutch Provinceof Friesland subsidized a local mathematician in making observations of the transit ofVenus. The provincial authorities of Friesland wanted to support the “royal art” of astron-omy. Unlike most other Dutch provinces, Friesland had not had a period without a stad-holder. While the other provinces had abandoned this function between 1702 and 1747,in Friesland and Groningen members of the House of Orange had stayed in office. Thusthe provincial capital of Leeuwarden could boast a continuous tradition of court cultureup to the death of the last Frisian Princess of Orange in 1765. Perhaps more than otherDutch authorities, then, the Frisian officials were aware that funding scientific projectsmight serve to reinforce their own “royal” status.68 However, Friesland did not have any

66 Moens to Tjeenk, secretary of the Zeeuws Genootschap der Wetenschappen, Flushing, 15 Dec. 1779, ZeeuwsArchive, Middelburg, Arch. KZGW, no. 62, fols. 68–69. On the hegemony of usefulness see Wijnand W.Mijnhardt, “The Dutch Enlightenment: Humanism, Nationalism, and Decline,” in Dutch Republic in the Eigh-teenth Century, ed. Jacob and Mijnhardt (cit. n. 41), pp. 197–223, esp. p. 217. See also H. F. Cohen, “Open andWide, Yet without Height or Depth,” Tractrix: Yearbook for the History of Science, Medicine, Technology, andMathematics, 1990, 2:159–165; Klaas van Berkel, “Over nationale stijl en wetenschappelijke cultuur in Ned-erland,” in Citaten uit het boek der natuur: Opstellen over Nederlandse wetenschapsgeschiedenis (Amsterdam:Bakker, 1998), pp. 11–23; and Bert Theunissen, Nut en nog eens nut: Wetenschapsbeelden van Nederlandsenatuuronderzoekers 1800–1900 (Hilversum: Verloren, 2000).

67 Woolf, Transits of Venus (cit. n. 2); and James E. McClellan III and Francois Regourd, “The ColonialMachine: French Science and Colonization in the Ancien Regime,” in Nature and Empire, ed. MacLeod (cit. n. 2),pp. 31–50, esp. pp. 31, 49.

68 Huib J. Zuidervaart, Speculatie, Wetenschap en Vernuft: Fysica en Astronomie volgens Wytze Foppes Dong-juma (1707–1778), instrumentmaker te Leeuwarden (Ljouwert/Leeuwarden: Fryske Akademy, 1995), pp. 59–76; and H. J. Zuidervaart, “Reflecting Popular Culture: The Introduction, Diffusion, and Construction of theReflecting Telescope in the Netherlands,” Ann. Sci. 2004, 60, pp. 1–41.


say in the board of the Dutch East India or West India Companies, and so the echo of“royal” state funding of pure science was not heard in the Dutch colonies. Nonetheless,as we saw with Mohr in Batavia, there were some wealthy Dutch individuals who cameclose to copying the royal behavior of the foreign sovereigns. So why did their work nothave the same effect, especially when these scientific efforts were institutionalized—aswas the case with the Bataviaasch Genootschap, one of the earliest scientific societies inAsia?

It was long believed that Mohr’s initiative was an isolated effort, the work of a singleperson that was not followed up. We have shown that this idea, first put forward by Frederikde Haan and repeated by many others, is wrong. Mohr’s initiative did contribute, around1770, to thoughts of starting a scientific movement among some Europeans living on Java.But even if the Dutch governments did not provide any money to advance the cause ofscience, their approval was a factor of major importance. Mohr himself sought to securehis position through an official letter of recommendation from the VOC. Science couldperhaps do without money from the state but surely required its authority and protection.Because support from the colonial authorities was not forthcoming sooner, the foundingof a scientific society in Batavia had to wait until 1778. Mohr did not live to see thisparticular fruit of his labors; nonetheless, the Bataviaasch Genootschap tried from its in-ception to put into effect the program he had outlined. Moreover, Mohr’s family contrib-uted wholeheartedly to the assets of the society. Over the years his son-in-law wouldbecome one of its most dedicated patrons, donating money and a costly collection ofmanuscripts, maps, and paintings.69 Originally the Bataviaasch Genootschap even wantedto continue the kind of instrumental measurements Mohr had started a decade before andbought his instruments from his widow for that purpose. However, furthering this instru-mental program proved to be more than the society could manage. The reasons for itsfailure can be summarized briefly. First, all scientific instruments had to be imported fromEurope, causing long delays. Once they arrived, only a few members of the BataviaaschGenootschap had the expertise needed to use and, especially, maintain them. Even a smalldefect meant the end of the useful life of an instrument. The tropical climate speeded upthe deterioration of almost every scientific instrument brought to Batavia—and there wasnot a single philosophical instrument-maker in the East Indies capable of making thenecessary repairs. As a consequence, most of Mohr’s astronomical instruments had to bereturned to the Netherlands for repair. Once sent, it was almost a decade before theyresurfaced—and in the end they were never sent back to the East Indies.

Frequent repatriation and the deaths of many important members of the BataviaaschGenootschap were likewise difficulties this small society had to cope with, bearing heavilyon the continuity of its scientific programs.70 Another setback was the short stay of thetwo botanists recruited to serve the society and maintain its work on a regular basis. Theescalating shortage of funds in the decade before the financial breakdown of the VOC in1799 eventually brought to an end this first period of instrumental and institutional sciencein the Indonesian Archipelago.

69 For the idea that Mohr’s initiative was an isolated effort see [Frederik de Haan], Oud-Batavia: Gedenkboekuitgegeven door het Bataviaasch Genootschap van Kunsten en Wetenschappen naar aanleiding van het driehon-derdjarig bestaan der stad in 1919, 3 vols. (Batavia: Kolff, 1922–1923), Vol. 2, p. 280; Klaas van Berkel, Albertvan Helden, and L. C. Palm, eds., A History of Science in The Netherlands: Survey, Themes, and Reference(Leiden: Brill, 1999), p. 215; and Taylor, Social World of Batavia (cit. n. 26), p. 88. On Mohr’s son-in-law’ssupport see ibid., p. 87 and App. 3.9.

70 Moens to Van Swinden, 4 Nov. 1789, University Library, Leiden, BPL 755: “ . . . because the continuousdying and repatriation of competent men sets us back here more than one in Holland would believe.”


On the whole, this eighteenth-century episode confirms Lewis Pyenson’s observations,made with regard to nineteenth-century Indonesia, that the scientific effort in this colonialsetting was an initiative taken by Europeans, modeled after European examples, and lean-ing on European-made instruments. Apart from the localized subjects of study, especiallyin natural history, the colonial setting had little influence on the science undertaken. Forthe scientists themselves, however, that setting was very influential indeed. Jean GelmanTaylor has pointed out that almost all the men active in the eighteenth-century BataviaaschGenootschap were European immigrants married to local “Mestizas,” women raised inAsia and often many years their juniors, who had no connection at all to European culture.The wives of Mohr, Radermacher, De Klerk, and Hooijman were all of Eurasian descent.Thus this small group of men, who tried to create Dutch or European institutions in asomewhat alien world, was firmly linked with the Indonesian homeland of their wives.Taylor even goes so far to attribute some of the relative lack of success of the BataviaaschGenootschap to such factors, suggesting that “in taking young Eurasian wives with whomthey shared no cultural affinity, nor language for weighty discourse, these men of theEnlightenment defeated their own purpose of promoting Dutch culture in Asia.” For what-ever reason, we must admit that, despite great efforts and costly investments in equipment,very little was achieved as far as the instrumental sciences are concerned. From that per-spective we agree indeed with James McClellan that the Bataviaasch Genootschap can beseen as a “bare outpost of learned [European] culture on the edge of the jungles of Java.”71

EPILOGUE

Some final remarks, then, can be made about the nature of scientific interest in Hollandand the Dutch colonies. First, it must be noted that in Batavia almost all scientific effortswent to the observational sciences: astronomy, meteorology, and natural history. Whereasin Holland local physical societies flourished from the middle of the eighteenth century,and often members had their own cabinets of scientific instruments, in the colonies veryfew of these konstgenoten (“fellows of the arts”)—as they called themselves—could befound. Physical instruments other than those necessary for observational purposes wereextremely rare. As far as we know, an air-pump was used only once at the BataviaaschGenootschap, when one of its medical members lectured on the properties of air. Howdifferent things were at the Cape colony, where in 1776 several “distinguished amateursof the sciences” could be found and even the local governor possessed “an air-pump,electrical instruments and other magnificent machines.”72 An instrument-maker could eas-ily make a living there; even so, however, his repeated orders for dozens of glass barometerand thermometer tubes from the Netherlands illustrates the fact that here too observational

71 Pyenson, Empire of Reason (cit. n. 1), pp. 176–178; Taylor, Social World of Batavia (cit. n. 26), p. 92(Taylor uses the word “Mestizas” in this unusual sense); and James E. McClellan III, Science Reorganized:Scientific Societies in the Eighteenth Century (New York: Columbia Univ. Press, 1985), p. 125. A short reviewof discussions on the subject of the European basis of Indonesian science is given in Roy MacLeod, “Intro-duction,” in Nature and Empire, ed. MacLeod (cit. n. 2), pp. 1–13, esp. p. 4.

72 Regarding the lecture on the properties of air see “Voorbericht,” Verhandel. Bataviaasch Genootsch. Konst.Wetensch., 1792, 6:17; and Snelders, “Het Bataviaasch Genootschap” (cit. n. 41), pp. 77, 88. On the situation atthe Cape colony see Brand, Cape colony, to Van Swinden, 28 Feb. 1776, 28 Feb. 1777, 6 Mar. 1777, 7 Apr.1777, 1 Apr. 1778, University Library, Leiden, BPL 755. Daniel Brand, who originated from the Frisian townof Sneek, had been one of Van Swinden’s students. In 1768 he enrolled at the Franeker University to studymedicine and philosophy. In 1774 he left Franeker for the Cape, where in addition to his work as a physicianhe constructed and repaired scientific instruments.


science was most common. It was the same in the Dutch West Indies. Regular observationalscience started in Surinam in 1743 with daily meteorological observations, the readingsof which were noted on preprinted tabular sheets. These sheets were prepared, distributed,and collected again by Nicolaas Duyn from Haarlem, a member of a very active localphysical and astronomical society. Why the other Dutch colonies did not participate in thismeteorological project is not known. The question of whether this might be attributed todifferent attitudes toward instrumental science in the Dutch West India Company and theVOC requires further investigation. At any rate, in the Dutch West Indies the “criticalmass” for science was also too small. An attempt, made in 1784, to found a “learnedsociety” in Surinam (a Societe pour l’Avancement de la Physique et l’Histoire Naturellede Paramaribo) never went beyond preliminary inquiries. And the few meteorologicalobservations that were carried out in those areas were organized from the Netherlands.73

In short, direct factors such as the availability of manpower, expertise, means, and money,together with indirect factors such as governmental support, high status, and spare time,appeared to be key in the success or failure of scientific practice in this Dutch colonialcontext as well.

73 The sheets are preserved in the Koninklijke Bibliotheek, The Hague, Van Swinden Collection, no. CCCII-B. See also Bert C. Sliggers, “Honderd jaar natuurkundige amateurs in Haarlem,” in Een Elektriserend Geleerde:Martinus van Marum, 1750–1837, ed. A. Wiechmann (Haarlem: Enschede, 1987), pp. 67–102, esp. pp. 71–75.Regarding the proposed Surinam society see J. Voegen van Engelen to Van Swinden, 7 Feb. 1784, UniversityLibrary, Leiden, BPL 755; on meteorological observations organized in the Netherlands see Van Swinden toJean Deutz, 5 Jan. 1784, University Library, Leiden, BPL 755.

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