Robert Grosseteste as an ObserverAuthor(s): E. G. R. TaylorSource: Isis, Vol. 55, No. 3 (Sep., 1964), p. 342Published by: The University of Chicago Press on behalf of The History of Science SocietyStable URL: http://www.jstor.org/stable/228576 .Accessed: 09/05/2014 17:46

Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at .http://www.jstor.org/page/info/about/policies/terms.jsp

.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range ofcontent in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new formsof scholarship. For more information about JSTOR, please contact support@jstor.org.

.

The University of Chicago Press and The History of Science Society are collaborating with JSTOR to digitize,preserve and extend access to Isis.

http://www.jstor.org

This content downloaded from 169.229.32.138 on Fri, 9 May 2014 17:46:25 PMAll use subject to JSTOR Terms and Conditions

342 JUNE GOODFIELD AND STEPHEN TOULMIN

visited was only a stone's throw away from this square. By this time, we were informed, the house and laboratory are completely deserted and the man in question is dead. It is nevertheless a curious fact that Holmyard never mentions having seen specimens of the qattdra. A Moroccan alchemist might have been expected to possess one: so far as we were able to determine, it is the only traditional piece of distilling apparatus in common use in the country. Certainly during the seven weeks we spent at Fez we found no evidence of any other type of still.

ROBERT GROSSETESTE AS AN OBSERVER

By E. G. R. Taylor *

In his article on Grosseteste's scien- tific works (Isis, 1961, 52: 381-402), Richard C. Dales, discussing the section De accessione et recessione maris, quotes Grosseteste as saying " ships in the sea are more elevated in the time of rise than of fall " and " experience also tells us that in the time of rise, the water is found to be hotter than in time of fall." These are said to be examples of " fla- grantly inaccurate observation" and Grosseteste is stigmatized as " evidently not a great observer." But the opposite is the case. Both statements were com- mon knowledge in the estuarine ports of Britain, particularly in the port of London. Salt water comes flooding in at high tide, and owing to its greater density the ship's displacement is re- duced. But at low water the fresh river water has replaced it, and the ship " rides lower." Moreover, every swim- mer knows that sea-water is normally

* Lon-don.

warmer than the water of a swift run- ning river, so that the temperature changes with the tides. Grosseteste, of course, knew only the facts, and not the explanations.

Roger Bacon also exemplifies the con- tention that medieval scholars had more practical knowledge than com- mentators usually realize. In Chapter V of Part III of the Opus Majts, when discussing the tides, he indicates clearly that he is aware of the " establishment of the port," which was three hours in the ports of the Atlantic margin of Europe as far north as South Britanny, "High tide NE-SW " as the sailors would say, using the rhumbs as a clock face: " Low tide SE-NW." Bacon, of course, cannot explain this correctly, but quotes Averroes on the similarity between opposite quarters of the celestial sphere.

This content downloaded from 169.229.32.138 on Fri, 9 May 2014 17:46:25 PMAll use subject to JSTOR Terms and Conditions

Article Contentsp. 342

Issue Table of ContentsIsis, Vol. 55, No. 3 (Sep., 1964), pp. 261-404Front Matter [pp. 261-263]Motion in the Void and the Principle of Inertia in the Middle Ages [pp. 265-292]Lamarck's Theory of the Earth: Hydrogologie [pp. 293-307]Contra-Equivalence a Defense of the Originality of Copernicus [pp. 308-325]The Fourth Dimension in Nineteenth-Century Physics [pp. 326-338]Notes & CorrespondenceThe Qara: A Primitive Distillation and Extraction Apparatus Still in Use [pp. 339-342]Robert Grosseteste as an Observer [p. 342]The Semantic Distinction between the Terms Astronomy and Astrology according to Al-Brn [pp. 343-349]The Growth of Scientific Physiology [pp. 349-351]Query 171 Darwin-Bates Correspondence [p. 352]

Documents and TranslationsA Fifteenth-Century Botanical Glossary [pp. 353-367]

News [pp. 368-369]Correction: News of the Profession [p. 369]Book ReviewsReview: Two Views of Maury... and a Third [pp. 370-372]History of ScienceReview: untitled [pp. 373-374]Review: untitled [pp. 374-375]

Social Relations of ScienceReview: untitled [pp. 375-376]

Physical SciencesReview: untitled [pp. 376-377]

Biological SciencesReview: untitled [pp. 377-379]

MedicineReview: untitled [p. 379]

TechnologyReview: untitled [pp. 380-382]Review: untitled [pp. 382-383]

Classical AntiquityReview: untitled [pp. 383-385]Review: untitled [pp. 385-386]

Middle AgesReview: untitled [pp. 386-388]

Renaissance and ReformationReview: untitled [pp. 388-389]Review: untitled [pp. 389-391]

Seventeenth and Eighteenth CenturiesReview: untitled [pp. 391-392]Review: untitled [pp. 392-394]Review: untitled [p. 394]Review: untitled [pp. 394-396]

Nineteenth and Twentieth CenturiesReview: untitled [p. 396]Review: untitled [p. 397]Review: untitled [pp. 398-399]

Contemporary SciencesReview: untitled [pp. 399-400]Review: untitled [pp. 400-401]

Back Matter [pp. 402-403]