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Show ELEMENTARY HEAT~ I'i) . h to Ii ht a bn.m fl:one ma t c· h .' and hence irt a mil on his anvil can make tt hot enough . ~duced to vitrify the parts thus firuckea NoTE VII. fl 'k·. flint and f1-ecl together heat enoug IS prl . r d by the new chemical com- un tng . ·11 off, the quantity of which heat IS ag::u prabab y mcrcat<:: . bt. natl. on. . ~ enomena of the elecnL n.C fl u1' d a nd o.f heat furmf11e.s I I. The analogy between the p 1 . {l f heat as a gravitating flUid. I. They ate another argument in ·fupport of the exl ~ncdebo dy 2 They arc propagated e::lllly or b f . cr on the eXCite 0 both accumulated y n ton bodies . w• ith e• afe by meta"ls, W.i t h Ie [:s e afe by with difficulty along the fame claffes obf ' filk air and glafs. Thus glafs canes d·n· It by refins ees-wax, ' ' . t f arr w:lter ; and with l lCU y , ' a blow· i pe or a candle witlun a quar er ~ or canes of fell ling-wax may be melted by. I t a~y inconvenient heat, while a pm or 'nc'h of the fingers which hold them, wtt 10u f . die fo readily conduCts the heat ~ls I r d the flame 0 :1 can h other rhetallic fubfl:ance app IC to cluthes of lilk keep the body warmer than ~lot es immediatc:ly to burn the fingers. H~n~e the heat upon the body. And hence pl:uns arc of linen of equal thicknef~, by con mng . b the greater denfity of the air con- I I ii nmits of mountams y . h . m fo much warmer t Jan t 1e ut Th both o-ive out light m t elr pa age fi . g the ac'quired heat upon them. 3• eyl b 4 They both of them 11111 • ir alfa e throug1 a vacuum. . . tluough air, perhaps not L·n .tl~e pf gl . leetrized if they are mechamcally ex- ! Bod1es a ter )emg e · · t of fufe or vitrify meta s. 5· . f I a icity as in Dr. Franklm's experunen tended wil'! receive a greater quantity o e e r . ' fipeet to heat as explained above. d h fame .feems .true In re d . the chain in fhe tanak a·r ·; t e . r r d fl:eam in the atr:-JOfphere by pro ucmg tnbute to 1L11pen 1 1 6o~ Both heat and ele nCI!y con . They 'both gravitate, when t 1ey lave increaflng the repulfion of its p~rttcl~sl:b}. ·n .I fi I theiTeqult lwm. f d I been accumulated, tl t 1ey m I mica! experiments which receive an ea y an e e-lf we add to the abov.e the many c 1e . h played in the works of Bergman , h ~ fed matter ot eat, as em II gant explanatiOn from t e uppo 1 ll f. ts exi!l:ence as an element, ocealiona y and Lavoifier' I think we may reafonab ya olwl o I·n:· g as a ffuid like the elec:tric fluid b -l" nd occafiona Y exl 111 ' fi combined with other Ot~les, a . b gated from the central res fl: h d that hence It may e propa h gravitating among t em, an 'b fcrve the mean heat of the eart ~ h h I nafs and contn lite to pre r If' n. of of the earth to t e w o e r ' b . ble from the greater or lets e eu · b It 4g degrees ut van a . r ~._ which in this country IS a ot 1 . d · Mr Kirwan's Treat11e on -tl·!l' •he fun's heat in different climates, fo well exp ame 111 d . ;.em_perature of different Latitudes. 1J'07· Elmily. Lon on. I ' ( I 7 ) NOTE VIIL-MEMNON·s LYRE. So to the .Jacrcd Sun in Memno11' s fa11e Spontalleous concords quired ihc matirt jh-ai1t. CANTO I. 1. I 8J. THE gigantic fiatuc of Memnon in his temple at Thebes had a lyre in his hands, -.vhich many credible writers afTi.tre us, founded when the riling fun £hone upon it. orne philofophers have f11ppofed that the fun's light polfeffes a mech~1ical impulfe, and that lhe founds above-mentioned might be thence produced. Mr. M1chel! confirueted a very ·tender horizontal balance, as related by Dr. Priefiley in his hifl:ory of light and colours, for this purpofe, but fomc experiments with this balance which I faw made by the late Dr. Powel, who threw the focus of a large reflector on one extremity of it, were not concluilve eitherway, as the copper leaf of the balance approached in one experiment a1 J receded in another. There are however ~nethods by which either a rotative or alternating motion may be produced by very moderate degrees of heat. If a firaight glafs tube, fuch as are ufed for 'b:uometers, be fufpended horizontally before a fire, like a roafiing fpit, it will revolve by intervals; for as glafs is a bad conduCtor of heat, t1Je fide next tl1e fire becomes heated fooncr than the oppofite fide, and the tube becomes bent into a bow with the exteon:ll part of the curve towards the fire, this curve then falls down and prodttces a fourth part of a revolution of the glafs tube, which thus revolves with intermediate paufe~. Another alternating motion I have feen produced by fufpending a glafs tube about eight inches long with bulbs at each end on a centre like a fcale beam. This curious machine is filled about one third part with pure£1 fpiJ it of wine, the other two thirds being a vacuum, and is called a pulfe-glafs, if it be placed in a box before the fire, fo ·that either bulb, as it.rifes, may become f11aded from the fire, and expofed to it when it dcf..:ends, all alternate libration of it is produced. For fpirit of wine in vacuo emits fieam by a very fm.11! Jegree of heat, and this ficam forces the fpirit'beneath it up into the upper bulb, which therefore defcends. It is probable fuch a machine on a larger fcalc might be of ufc to open the doors or windows of hot-houfes or melon-frames, when the air within them fhould become too much l1eated, or might be employed in more important mechanical purpofcs. On travelling through a hot fummcr's day in a chaife with a box covered with leather on the fore-axle-trc,e, I obferved, as the fun !hone upon the black leather, the box began to (Jpcn its lid, which at uoon rofe above a foot, and could not without grt:_at force be prelft.:d down ; and which gradually clofed again as the fun declined in the evening. This 1 fuppof(; might with flill greater facility be applied to the purpofe of opening melon- frames or the fafhcs of hot-houfes. ,1'he fiatue of 1\fernnoa was overthrown and fawed in two by Cambyfcs to difcover .its .internal firucture, and is faid flill to exifl.. See Savary's Letters on Egypt. The truncated fiatue is faid for mJ.ny ccuttuies to have fa!utcd the riling fun with chearfu! tones, :llld the f~:tting fun with mcluncholy ones. c |
