THE ENG INEER D Ec. 14, 1917 - Hot Air Engines | Hot Air Engineshotairengines.org/patents/stirling-patents/THE ENGINEER... · 2020. 5. 31. · strating the adaptability of the principle
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516 THE CENTENARY OF THE HEAT REGENERA- TOR AND THE STIRLING AIR ENGINE. THE library of the P a. tont Offi c.e ha s rece ntly been the recipi en t of the o riginal spec ification in the hand- writing of the inven tor, the Rev. Robert St irling, D.D., of the H eat "R egene r ator ," and the St irling Air Engin e (Let t ers P atent No. 4081 of 1816 ). F or some reason, n ot d efin itely asce rtained , this specifica- tion, th ough dul y s ign ed , atte ste d an d s tamped, wa s n ot e nr olle d. He nce, it does n ot a pp ea r in the Offi cial Blue-book se ries , an d ha c; a.lwavs been as a lapse d application. I t is now pub- h she d tn extenso f or the first time, although it i:; kn own that copies of the Scotch specification were produced in e vi de nc e in the celebr ated trials of the Ne il son H ot- bl ast patent. I t is, we believe, estab- lis hed that the first application of th e regen er ative principle to iron smelting by J a.mes B air d in 1825 wa s due to the s ug gestion of Robe rt Stirling, who, it is stat ed, had in clud ed "iron sme l ting furn ace" in tho origina l d raft of hi s specification, but had st ruck out the words, and gave on ly one exampl e, se lect ing a. glass furn ace for the purpose . Thi s ?mission pr obably save d Neil son's p atent, while 1t accounts for the fact that Stirling was n ot ca lled to give evi d ence at the Edinburgh trial in sp i te of the pressure put upon him by the defendants. It sho uld be observed that the term " regene ra ti ve furnace" was not coined by Stir l ing, who elsewhere c; tat ed that he pref e rr C' d to desc ri be his inventi on as an " E conomiser," bu t the term coined by Eri csson was so firmly rooted in the language in Siemens' t ime tha t the latter acce pt ed it und er prot est (Pr oc. In st. C.E., vol. xji., 1852-3). Fur ther, it is worthy of n ote that n ea rl y all the applicati ons of the regenerative prin cipl e in h eat ing and cooling were fore see n by Stirling, and indi cate d by him in hi s specification. The prin ciple of the tirling Air Engine differs from 't hat of Sir Ceo rge Ca.yl ey ( 1807 ), in w hi ch the air is forced thr oug h the furna ce and exhauste d, wher eas in Stirling's e ngin e the a ir work s in a. closed c ir cuit. It wa s to it that the in ven tor d evote d most of his attention. A t wo hor se -power e ngine, built in 1818, for pumping water at an Ayrshire q uarry, continued to w ork for some time, until a care less attendant a ll owed the h eate r to become over heated. This experiment proved to the inventor that, owing to the low working pr essure o btainabl e, the engine could only be adap te d to sma ll powers for which there was at that time no d emand. Ilia yo un ger br ot he r, Ja . mes Stirling, O.E., suggeste d, in 1 824, using corn· pr essed air, and in 1843 built an e ngin e of 45 br ake hor se·p owe r, which successfully dr ove the machinery at the Dund ee F oun dry for severa l years, t hus demon- st rating the adaptability of the prin ciple to higher powers. It ma y be of int er est to note here that R obert Stirling was born at Cloa.g, Methvin, Per tbshi re, in 1790, a nd entere d the Chw- ch. At tho dat o of hi s in vent ion, 1816, he was twonty·six ycar 1:1 of age. , a nd had j w;t been o rdaine d t o hi s firbt pari sh. He l' l&S greatly es teemed as a 1ninil>ter, and was a. n ote d clas!'ica.l as well as a. scie ntist, and be fore he di ed, in 1878, was the Fa thor of the Ohm-eh of Scotland. Hi 1:1 grandfather , l\Iich.aol Stirling, of Glas & inge. l, Dumbl a.no, invented tho rotary thrashing machine in 17 56 (vide En cyclopredia Brit- t anica, thir d editi on- ThraHh.ing). B is broth er Ja.mes wa .; a. cel ebr ated Ci vil Engine er in Edinbur gh, and fo ur of h.i.s so ns wero e ngin eers, who all made their mark in the e ngin eering world. T wo of the m, Pa.trick and JameR, are well kn own in this count ry to l ocomotive engineers of the present generation. SPECIFICATION OF S TIRLI NG'S l ,A'l'EXT No. 40 I of 18 16. AU my I mprovements for diminishin g tbe cooswnption of fuel consist of the diffe rent forms or modifications of a New Method, Co ntrivance, or )l echanica l arrangement for heating and cooling L iquids, Airs or GUBCS, and other Bodies by the UBe of which Con trivance H oot is abstracted from one porti on of such liquids, a irs, and o th er bodies nod communica t ed to another portion with very little loss ; so t ha t in aU cases where a constant succession of heated liquids or other bodiea is r equired. the quantity of fuel ncceaaary to main tain or s upply it is by this contrivance greatly di mioished. - 'fhe First Modification of 86id Contr ivance or arrangem ent is describ ed as foll ows :-A B fig. l st is a pipc, chann e l, or passage, formed of Meta l, Stone, Br ieki< or other M ateriahl according to circwustances i.e. accordiug to tbo Che· mica! agencies of the bodies to bo or cooled and the degr ee of heat in said bodies. - 'I'he Hot liquid, gas , or body to be coo l ed is by any m ea ns rrulde to enter the passage at A and to pass nlong to its other ext r emity B. - In it11 progress it gives out its h eat to the si des of the passage or to any boclies conta i ned in it a nd issues at Bat nearly the or igina l temperature of the passage. - In this manner the ex tremity at A and a considerable po r tion of the passago is h eate d to nea rl y the temperature of th e H ot liquid whil e the ex tremity B stiJ I retains it s or iginal te m pera· turo uea rl y. Wh en the temper ature of the passage at B has boon raised a !ew d eg rees the motion of the fluid fr om A to B is stopped and a por tion of lluid whi ch is r eq uired to bo Heat ed and which is supposed to boa few degrees colde r than the e xtremity of the passage at B is made to tra.verse th e 86me passage in a cont r ary D irection i. e. fr om B to A; by which means it r ccet ves heat from the 10ides of the passage or other bodies contained in it and i!;ljue.'! at A at nea rly the same te mpe rature with the fluid to be cooled. When the temperature of the passage at A has thus been lower ed a few degrees, the procc88 ia again stopp<'d aud a portion ol tbo fluid to be coo l ed is made to pu ss from A to B uud tiO on tdter· nately. - Th e Second )lodifi ca ti on of my Raid Gootri, ·ance or arrange· ment co n a;illts in wterposing a thin plate of Met al or other materi a l'! , according to ctrcumstanccs, between two currents of liquid gas or vapo ur which are made to run in oppo11itc direc tion s. - A B fi g. 2nd represents s uch a plate aud c, d, h\ O passages betwetln wluch it is wterp osed.- Th e flwd to be cooled is made to traverse th e passage d fr om A to Band the fluid to be heated is mude to t ra verso the passage d from B to A .-The ext remity of Lhc plate at A is kept H ot by the current in d and the e xtremity THE EN G INEER B ia ke pt cold by the cur r ent in c.-The plate A, B abst racts the heat from the fluid in th e passage d and communicates it. to that in c with ve ry little loss.- The was te or eacape of heat fr om the pas86ges is pr evented by th e ir being sur r ou nded with Cha r coal powde r, wood, br icks or any substance that does not easily permit heM to pass through it, as is r ep res ented at c, d. e, 1. fig. l s t a nd 2nd. - In the construction of the passag es in both Modifications o£ my contr ivance for heati ng and cooling liquids a nd ot her bodi es I obse r ve the follo wing rules :- 1. Whetl the pa ss ages are made of me tal or any othe r su bstance t hat conducts or tran smi ts h eat easi ly I make th e metal or o t. her subs tance as thin as possible to prevent the h eat fr om being transmitted in this ma nner fr om the hot to the cold ex tremity of the passages. - 2. Liquids and airs being ve ry imperfect con· ductors of heat I make the passages very na rr ow (at leas t in one di r ec tion) in propo r tion to their length, for the purpose of heating and cooling more completely th e liquids or airs that pass t hrough them. - A transverse section of t he passages is given at A and B C fig. 3rd. - 3. \Vb en the passages canno t be made sufficien tly na rr ow I make t hei r sides jagged or rough by bodies pr ojecting fr om them as re pr esented at fig. 4 or I ad opt any similar method foe pr omoting the inte r nal mo tions of the fluids and the ready com mu nication o£ heat to them or to the pa ssage.- 4. \Vh en the width of th e passag e cann ot be sufficient ly diminished I enc rea se its length in order to at tain the same en d.- The form and cons tru ction of the tubes, pa ssagea and plates in both the modification s of my genera l Cont r ivance or Ar r angement may be va ried to cir cumstances: but the benefit to be derived from this contnvance arises from the fluids and o th er bodies to be heated and those to be cooled being made to move in oppoaite d irections and it is for the invention or impr ovement of this a rra ngement that I have applied for and obtained His Letters Patent. Hav ing thus d esc r ibed and a sce rt ained tbe nature of my Inv eo. tion I sh all now describe sever al of its numer oUB and ll8efuJ applications. - Th e First form or Modification of my general contrivance or arrang eme nt may be applied to dimiOJShiog the consumption of fuel in Glass house and o th er f urnaces wh e rever a degree of heat is r equired, and the nature of the processes earned on in these furnaces admits of th eir being accurately closed, nod this application i.s also capable of prod ucing a much more intense heat than can be r aise d by the ordinary methods. - A fig. 5 is a furn ace filled with fuel A, E (;and AD E (sic.) are two fl or passag es (a tran sverse sec ti on of which is r epre· sented at A fig. 6 ). B is a pa88age for introducing the fuel acc urately closed at G.-A ll othe r parts are likewise closed so that no air can pass through or have access to the fire but through said fluea.- The ai r which supports the combustion is alternately introduced at F an d G by blowing engines, bellows or any othe r means and thl' gases and vapours which arise £rom the fire pallS ofi in an opposite direction lea ving tbe greater part of their heat in th e flu es in the manner above described. - Titis beat is taken up by the air which suppo rts the fire and is again left in the opposi te flue along with the additional quantity produced by combustion. In tlti s manner the h ea t is accumulated in the furnace and the parts of tho flu es adjace nt to it. The bodies to be heated are placed at D and E and the openings by which they are intro· duced are accurately clo Red. The furnace and flues are con. structed o£ the beat firebricks or any material that may better r esis t the i11tenso heat, and the Ma son work, as in othe r furnaces, is made sufficien tly thick to pr event the waste of h eat.- Th e for m and management of the furnace and flues may be varied according to circWTIBtances ; but it m Wit be remembered that the narr ower and longe r the flues are and th e more frequently the dir ection o£ the atr is cha n ged the greater is the saving of fuel and the intensity of the heat produced. Th e Second fo rm or modification of my inv ention may be applied to the saving of fuel in Br eweries, Distilleri es, Dye W orks and other Manufactur es, by tran sfe rring heat from o ne po r tion of liquid, air, or vapour to o furt her directions seem to be neceaaary for these applications but this that the q uantity of fluids which is aJJowed to run through the r espective pa88ages mll8t be inversely proporti011al to the specific heat of the r espec· tive fluids which may be learned from books or from observing the d egree to which they are respectively heated or cooled in their pas.aage.- By either of the above desc r ibed Modific ati ons of my !laid Arrangement I couRtruct my l!:ng:iue, for moving Machine-ry and th e following ill a geueral description of the manner iu whi ch this is pcrfonned .- 1 c10ploy the Expansion and Gont raction (o r eithe r) of .. a1r or any of the permanent gases by heat. aud cold to comu1uuicate motion to a piston or othe r 1<i 1nilar coutri,·auce. - Iu order to produce this expansion and coutroction I eau&' th o air to JI0 88 fr om a cold to a hot part of thn ougiuo and th e coutrury cil her in the samo in the ut the explanation of fig. Ifit, or in diffe rent pab.\<ugc s as d(.'scribcd at fig. 2nd. - I app ly fire to the wa n nest pari o£ the engine, in order to supply the "as to of heat occasio n ed by its trana;mi.ssiou fr om the h ot to the cold parts by the radiating and conductiug power of the mate rials of which they are formed, by the change of capacity for heat which the air suffers from condensation and rarefaction , and by the im· possibility of transferring the whole o£ the heat from the air to the passagesandthe contrary and I apply a st r eam of cold ai r or water to the coldeat part of th e engine to carry off said waste heat. - Th e pru!8ages are of course li ot at the one extremity and Co ld at the ot her, and in passing through them the air is e.lternately h eate d and cooled or expanded and contracted. - The is a particular description of that fo rm of my e ngine which I consider as the best. - A A D D fig. 7 is a cylinder composed of three parts accurately joined toget her by ri ve ts or screws and r en de red airtight by hamme ring or so ldering th e joinings.-'fbc part A B is form ed of cast iron a11d accurately bored, th e part B C is made of sheet or cast iron as thin as p os.aib le (as one tenth of an inch). and the part CD is o£ Sheet or Cast ir on.- To this cylinder is fi t ted a piston E E which is made airtight in the usual way, and provided with rods I I for communicating its motion. - F F C G is a hollow cylinder also as thin as possible made of sheet iron covered with thin plat es of polished brnss or silver to prevent the wust<l fr om radiati on and di vid <>d into compartment s by plates/), /) , for the pucposo. - It is shut on all o.ud o.ir· tight, k ept at a smo.IJ distance fr om the o uter cylinder by whc c lK a, a, or any similar cont r ivance and furnished with a rod J:l working a stuffiug in the centre of th o piston, by tneans of which it is moved up and down.- Thi s inner cylinder 1 call th e Plunger. - T he part J3 D of the oute r cylinder is k ep t h ot by th e flame or heated airs of a fire C applied at D D made to descend on all side.s of the cylinde r to C and allowed to escape at e.-The part AB is k ep t cool by a s tream of air or of water directed up on it, and the part B C encroases in temperature f rom B to C.-The tcmperatuce of the plunger en creases fr om F to G and th e interval between t.ho cylinde r and pl u nge r is partially filled with v.ires wo u nd round th e latter and kept at a sma ll distance from it and fr om one nnothcr by wires laid along it. nt ri ght angles to the form e r, in o rder to heat and cool the air more completely. - This interval ill on each side about one fiftieth of th e whole di ameter of the cylinder.-Figures 7 and 8 are drawn to a scale of ono half web to a foot excep t th e thicknes.a of the meta l which is to no sca le. The space co ntain ed by the cy lmd er and p iston is filled with atmospheric air.- Figure is an olova t io n o£ th e engino.- A B C the cylindf' r DD pillars suppor tin g it, E Ea beam ce ntred at G to which tJv, rods I I o£ th o p1r.tou are con ncctcd hy a parallel Joint 1\ N ; I I un unn v. luch connec ts t.aid beam to th e crank g.--i o i a bent le,·cr jomted to said a nu at o and connec t ed to the fixed point A b) th e rod l, and t,o t ho oth<'r <'xtrcmity of t he beam F F t.y t he rod k.- T his beam is also cen tred at G aud moves bc•tw<'cn two or simila r beams of wh1ch the bt.>am E E is compot>rd. p a rod by ,,Jtich F F i8 councct cd to the rod of the plun g<·r M a t< hd t• r upon the rods of the pl kt on fixed to the rod of th e plunge r to r en der its mot1on steady and parall el.- h h h the fl y upon the !!amP axle with th e c rank. c d r t hP f urnace and flues. DE c. 14, 1917 The Operation o£ th e <'OF(ino i11 as foii 0\\8.- 'fh o pa rt of tho cylind<>r by the is heated to a tetn· peraturo of 480° higher than th o part A B.- In tlt e pollition at fig. 8 t be plunger is in contact with th e pibton. by which means the included air is brough t to th e warm pa rt of tl1 o cylin d er has its el asticity eocr eaae d and pr esses upon the piston with a force greater than that of 'the atmosphere. -The p iston is thUB forced downwards and the rod If and c rank g upwards till the pressure of the included nir and that of the atmos ph ere beco me equa L- T he impulso commu n ica t ed to the fl y ca rri es the en d of the cr ank towards q, an d the o.rm 11 and ben t lever i i are brought to such a position as to de pr ess the rod k and thUB to r aise the plunger fr om the piston. - The included air is t hWI to d escend be tween th e plunge r and cyli nder and brought to t he cold part ; it is coo led in its deacent, has its elasticit y diminished, and its pr ess ure b ecomes l ess than that of th e a t m o· sphe re, the p is t on iB forced upwards, an d the crank d ownwards.- T he r evolu t ion of the fl y and crank again bri ng the p lunger towards the p iston, the air a scends through th e same by which it desce nd ed, is heated in its ascent a nd forces th e pts t on downwa r ds and the cr an k upwar ds , and so on alternately. - In this manner a r otatory motion is produced which may be appli ed to the moving of machine r y. - The force of the engine is re gulated by allowing a po rtion of air to escape outwa r ds and inwards by a cock whic h is opened and shu t by a govern or as in Steam engines, and placed in the cold part of th e cylinder immediately above the highes t a scen t of th e pist on.- Th e di stance which the rod of the plunge r H fig. 7 moves through the pi ston I ca ll th e Stroke of the plu n ge r and 1 make it equal to that of the piston wh en the difference of tempe r ature in the bot and cold pa rt s of the cylinder is 4 80 °.- Wh eo the difference is less than 480° I make th e s troke of the plunge r proportionally greater th an that of the piston, and th e contr ary wh en the difference is greate r .- The l ength of th e arms of the bent leve r i o i and of the r od k which is n ecessa ry to make the p lun ger just to u ch t he piston on th e one band and the uppe r end of the cylinder on th e ot ht>r I dete rmine by expe r iment as being the most convenient method known to m e.- I do not answe r for the absolute co rr ec t ness of those in the plan. - 'l'he cylinder i.11 iuve r ted to prevent the oiJ UBed to make the piston airtight from getting to the bot part and wasting the h eat. In the { oregoing de scription, wh er eve r I hav e specified more than one Ma te r ial or more than one Method of perf orming the same thing, I have pla ce d that fi rst to which I give the pr efe r ence; But I r eserve to myself the p owe r of UBing any materials and applying my n ew contrivance for heating and cooling bodi es, to the purpose s to which it is applicable in an y form or manner which furth er experience may prove to be ad v an tageous and which is not inconsistent with the terms of his Majes t y's Lette rs Patent. In witne ss whereof I the 86id R ober t Stirling hav e here unto set my hand and seal this T wentieth day of January in th e year of o ur Lord one thousand eigh t hundred and seve nteen. sea led and delivered [ Seal of ] 1n pr esence of R.S . Ro bt . Stirling (R ob. Cameroo ) Accountant in Edinburgh, ( Fr ancis F. Cameron) Pr eache r of th e Gospel in Bdinburgh. BOMB NOTES ON RE C ENT GERMAN AERO- PLANES. THRoUGH the courtesy of the Air B oard we haYe be en afforded an opportunity of st.udyi ng and a.cqwrmg so me first -hand information r egarding cer tain typeR of r ecent ly con structE-d Ge rman aeroplanes and aer o·engines. Th o co ll ect ion is hou sed in a conveni ent ly situated building where it is, and has been for some time, open to the aero plane d es igners of this country for the ir inspect ion . It may be d escrib ed a s a. museum of ae r ial war relics, jor it compr ises exhibits of German ae ro pl anes and a.ero- engines that . ha.vo been brought d own by ihe Br iti sh for ces , or have ot he rwi Rc fa llen into o ur ha.ncl.R. poli cy of tho se djr ecting th e exhibit ion- if ,..,.e may use t hat word of a. co ll ection that i t> not op en to th e gene ral publi c-it> to cndea.vow- so far as po Rs ible to r econst rU<.: t a. machine or engine of ea.cd1 type from the undamage d part.s of man y of tho t;tuno cla.RH as ar e requirt..d to affo rd a co mplel o exa mple. Som et imes, of cow-se, a. pra ctica lly un damaged machine or engine will be ob t aine d. At othe r R, the damage m ay be so great that the p at ient co llec ti on of sepa rate de tail s from many different machines or engines is nec essa ry before a. complete e xample of the type ce.n be recons tructe d. In a ddi tion to s uch exhibi ts, a. d uplicate set of separ ate pa.rtR properly sect ion ed or ot he rwi se c ut up to r eveal the constructi on is shown for <'ach ae ro plane or A.ero-engine. The collection is naturally an expan ding one, a nd c:e rta.in ga p s--a ltho ugh th<'y are wond e rfully few- have yet to ba filled, even a mong the ex hibits a.lr ce dy s hown. Be ing int en ded to se r vE' a st ri< : tl y utilita r ian purpose, the f"xhibition d oes .Jot include Zeppcli11 relic. . For quite cm ot her r eason it is con w ed to a.er opla.ne t> and doe s not so fa r, a. Ringle or pa.rt of one. There wo uld be litt le excu xc f or us were we to <'ntC' r into a. long account of the mu ltifarious d eta ils of const r uction to be examine d at the e xhibition. It ma.y be taken for grant ed that whateve r of the se de tails are novel a.nd in&tructive have been duly noted already by those w ho will know how lo pr ofit by them. Fr om the gen e ral p oint of view, however, the re ar e se veral points pre ente d by the exhi bi ts that will , no d ou bt, be of inter es t to the ave r age engineer, and to th ese we will confine our attention. Among the engines , the most st riking f eature in our eyes is the s ign afforded by the e xhibition of the> Germa n's s tron g attachment to water cooling. Th E' F'okker machines , it is tru e, a.dop tl'd the Gnomfl r ota ry a.ir·cooled en gine or the Gn ome engin<" in a.ll but the na.me "' - but th e H a.lbers ta d t, the Albatro ss , th P. Av ia. t ilc, tho L .V. G., the Rtu n pl <> r, th e Gotll&, and o n, are all equi pp ed with either the Benz or the Mer ce des si.-x or seYen-cylindt>r wa.ter.coolPd engine of the motor ca r type. Thi !> ten de nc y, we s upp ose, is an illus tr at ion of Ge rman menta lity, for t. he fact is th at in th e GC'rma.n a. er o·engine compet iti on of l9 12-13t. a ir -cooled e ngin&s wer e comp lete ly out- • Th e Gnome engine 1n Ge rmany is known as the Oberucsel. t l:lee ToE ENGJl'EER for No,·ember and December 5th, 1913.
THE CENTENARY OF THE HEAT REGENERA-TOR AND THE STIRLING AIR
ENGINE.
THE library of the P a.tont Offic.e has recently been the r
ecipien t of the origina l specification in the hand -writing of
the inventor , the Rev. Robert Stirling, D.D. , of the Heat " R
egenerator," and the Stirling Air Engine (Letters Patent No. 4081
of 1816). F or some reason, not definitely ascertained , this
specifica-tion, th ough duly signed , attested and stamped, was n
ot enrolled. H ence, it does not appear in the Official Blue-book
series, and hac; a.lwavs been t~eated . as a lapsed application. I
t is now pub-hshed tn extenso for the first time, although it i:;
known that copies of the Scotch specification were produced in
evidence in the celebrated t rials of the Neilson H ot-blast
patent. I t is, we believe, estab-lished that the first application
of the regenerative principle to iron smelting by J a.mes Baird in
1825 was d ue to the suggestion of Robert Stirling, who, it is
stated, had included "iron smelting furnace" in tho original d raft
of his specification, but had struck out the words, and gave only
one example, selecting a. glass furnace for the purpose. This
?mission probably saved Neilson's patent, while 1t accounts for the
fact that Stirling was n ot called to give evidence at the
Edinburgh t rial in spite of the pressure put upon him by t he
defendant s. I t should be observed that the term " regenerative
furnace" was not coined by Stirling, who e lsewhere c;tated that he
preferrC'd to describe his inven tion as an " E conomiser," but the
term coined by Ericsson was so firmly rooted in the language in
Siemens' t ime that the latter accepted it under protest (Pr oc.
Inst. C.E., vol. xji., 1852-3). Further , it is worthy of n ote
that nearly a ll the applications of the regenerative principle in
heating and cooling were foreseen by Stirling, and indicated by him
in his specification.
The principle of the tirling Air Engine differs from 'that of
Sir Ceorge Ca.yley (1807), in which the air is forced through the
furnace and exhausted , whereas in Stirling's engine the air works
in a. closed circuit. I t was to it that t he inventor devoted most
of his attent ion. A t wo horse-power engine, built in 1818, for
pumping water at an Ayrshire quarry, continued to work for some
time, until a careless attendant a llowed the heater to become
overheated. This experiment proved to the inventor that, owing to
the low working pressure obtainable, the engine could only be
adapted to small powers for which there was at that time no demand.
Ilia younger brother, Ja.mes Stirling, O.E., suggested, in 1824,
using corn· pressed air, and in 1843 built an engine of 45 brake
horse·power, which successfully drove the machinery a t the Dundee
F oundry for several years, thus demon-strating the adaptability of
the principle to higher powers.
I t may be of interest to note here that R obert Stirling was
born at Cloa.g, Methvin, P ertbshire, in 1790, and entered the
Chw-ch. At tho dato of his invention, 1816, he was twonty·six
ycar1:1 of age., a nd had jw;t been ordained t o his firbt parish.
He l 'l&S greatly esteemed as a 1ninil>ter, and was a. noted
clas!'ica.l ~o~cho lar, as well as a. scientist, and befor e he
died , in 1878, was the Fathor of the Ohm-eh of Scotland. Hi1:1
grandfather , l\Iich.aol Stirling, of Glas&inge.l, Dumbla.no,
invented tho fir~;t rotary thrashing machine in 17 56 (vide
Encyclopredia Brit-tanica, third edition- ThraHh.ing). B is brother
Ja.mes wa.; a. celebrated Civil Engineer in Edinburgh, and four of
h.i.s sons wero engineers, who all made t heir mark in the
engineering world. Two of them, Pa.trick and J ameR, are well known
in this country to locomotive engineers of the present
generation.
SPECIFICATION OF STIRLING'S l,A'l'EXT No. 40 I of 1816.
AU my I mprovements for diminishing tbe cooswnption of fuel
consist of the different forms or modifications of a New Method,
Contrivance, or ) l echanical arrangement for heating and cooling
Liquids, Airs or GUBCS, and other Bodies by the UBe of which Con
trivance H oot is abstracted from one portion of such liquids, a
irs, and other bodies nod communicated to another portion with very
little loss ; so that in aU cases where a constant succession of
heated liquids or other bodiea is r equired. the quantity of fuel
ncceaaary to maintain or s upply it is by this contrivance greatly
dimioished.- 'fhe First Modification of 86id Contr ivance or
arrangement is described as follows :-A B fig. l st is a pipc,
channel, or passage, formed of Metal, Stone, Brieki< or other
Materiahl according to circwustances i.e. accordiug to tbo Che·
mica! agencies of the bodies t o bo heat~d or cooled and the degree
of heat in said bodies.- 'I'he H o t liquid, gas, or body to be
cooled is by any means rrulde to enter the passage at A and to pass
nlong to its other extremity B.- In it11 progress it gives out its
heat to the sides of the passage or to any boclies contained in it
a nd issues at Bat nearly the or iginal temperature of the passage.
- I n this manner the extremity at A and a considerable portion of
the passago is heated to nearly the temperature of the H ot liquid
while the extremity B stiJI retains its original tempera· turo
uearly. When the temperature of the passage at B has boon raised a
!ew d egrees the motion of the fluid from A to B is stopped and a
por tion of lluid which is required to bo Heated and which is
supposed to boa few degrees colder than the extremity of the
passage at B is made to tra.verse the 86me passage in a contrary D
irection i.e. from B to A; by which means it rccet ves heat from
the 10ides of the passage or other bodies contained in it and
i!;ljue.'! at A at nearly the same t emperature with the fluid to
be cooled. When the temperature of the passage at A has thus been
lowered a few degrees, the procc88 ia again stopp and does not
includ~>, so far, a. Ringle ~eapla.ne or pa.rt of one.
T here would be little excuxc for us were we to German's strong
attachment to water cooling. ThE' F'okker machines, it is true,
a.doptl'd the Gnomfl rotary a.ir·cooled engine or the Gnome
engin
•
• STIRLING'S RE G ENERA 1' 0 R AND H 0 T -A I R ENGINE 0 F 1 81
6
(For duc~tion •e• oppoliu page)
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Letters m square brackets are references tn the text of the
spec,hcat1on which do not ilppcar in the orl(;ioal drawtngs.
