THERMOMETER. 



TJiermonWtfrs that arc dofired for meafuring great de- 

 jrrrM of hoat. require to bf fillfd with particular precau- 

 tions, which M. de Luc has minutely dcfcribcd. 



When the thermometer is filled and fealcd, nOthmg more 

 i» neceffary than to mark the two fixed points, graduate 

 ihf fcale, and attach it to a proper frame. See de Luc's 

 Recherches, «cc. vol. i. p. 39.^ &c. , • , r 



The frame may be made of any fubftance, or kmd of 

 wood, at pleafure : and the degrees may be marked on 

 metal or wood, or paper, or ivory, &c. ; but fuch fub- 

 flanees (hould he preferred for the feales of thermometers 

 as are not apt to be bent or (hortened, or otherwife altered 

 by the weather, efpecially if the inftrumcnts are not de- 

 fended by a glafs cafe, or by a box with a glafs face. 

 Thermometers for indicating the temperature of the atmo- 

 fphere need not have feales that are much extended ; if 

 they go as high as 120° it is fufficient. The lower degrees 

 may be carried down as low as may be neccffary for the cold 

 of any particular climate. The mercurial thermometer need 

 not be graduated lower than 40° below o, becaufe at about 

 that degree mercury ceafes to be fluid. The fpirit ther- 

 mometer mav be graduated lower, if necefiary. 



Thermometers ufed for obfervation, muft be fituated in 

 the open air out of the houfi-, and at the diftance of a foot 

 (at lead) from the wall, and where the light of the fun may 

 not fall direftly upon them. For chemical purpofes, the 

 bulbs and part of the tubes of the thermometers fhould 

 projeA fomo way below the fcaU s, that they may be dipped 

 in liquids, mixtures, &c. For other purpofes, as for bota- 

 nical obfervations, hot-houfes, brewing manufaftories, baths, 

 &c. the thermometers muft be m.ide longer or fhorter, or 

 narrower ; and particular dircftions may be given with re- 

 gard to the feales and other appendages. 



Great inconvenience has attended the ufe of various kinds 

 of thermometers with different graduations. Kirwan pro- 

 pofed to lay all thefe afide, and to conftruft a general one, 

 beginning at the congelation of mercury, and terminating at 

 the boiling of water, and divided into 250°. Mr. Murray of 

 Edinburgh has fmcc fuggefted, that it would be convenient 

 to form a fcale whofe extreme points fhould be the tem- 

 peratures of freezing and boiling mercury, both which are 

 now capable of being accurately afcertained, and to divide 

 this fcale into 1000^. 



Thermometers, Experiments with. We fliall here in- 

 fer! a table of fome obfervations made with the thermo- 

 meters of Fahrenheit, Reaumur, fir Ifaac Newton, and 

 Dr. Hales. 



Obferuatioru by Fahrenheit^i Thermometer. 



At 600 

 546 

 242 

 240 



212 



206 



Mercur\- boils 



Oil of vitriol boils 



Spirit of nitre boils 



Lixivium tartari boils 



Cow's milk boils 



Water boils. 



Frefh human urine boils. 



According to Muf- 

 chenbroeck, the ba- 

 rometer being at 29 

 Rhinland inches. 



From 



190 



174 

 176 

 ij6 

 146 

 108 

 107 



At 



to 103 



Brandy boils. 

 Alcohol boils. 



according to Mufchenbrceck. 



Serum of blood and v/hite of eggs hardens. 

 Killing heat for animals, in a few minutes. 

 A hen hatching eggs, but fcldom fo hot. 



}Heat of fl<in in ducks, geefe, hens, pigeons, 

 partridges and fwallows. 



106 Heat of 1km in a common ague and fever, 

 3 



Dcp. 

 From 1031 Heat of TkIu in dogs, cats, (hcep, oxen, fwine, 



to looj and other quadrupeds. 

 From 99I pj^^^ ^f jjjg ^y^^„ jj^i„ i„ hpj^h. 



to 92 J 

 At 97 Heat of a fwarm of bees. 



, f A perch died in three minutes, in water fo 

 9^ \ heated. 



f Heat of the air in the fliade, in very hot wea- 

 ^° \ ther. 



74 Butter begins to melt. 



, f Heat of the air in the fhade, in warm wea- 

 ^4 1 ther. 



48 Temperate air, in England and Holland. 

 43 Oil of olive begins to ftiflen and grow opaque. 

 f Water juft freezing, or fnow and ice jull 

 3 \ thawing. 

 30 Milk freezes. 



28 Urine and common vinegar freezes. 

 25 Blood out of the body freezes. 



fGood Burgundy, ftrong claret, and Madeira 

 \ freezes. 



f One part of fpirit of wine mixed with three 

 ' \ parts water freezes. 



fOreateft cold in Pennfylvania in 1731-2, 

 ^ 1 40° l3t. 

 4 Greateft cold at Utrecht, in 1728-9. 



A mixture of fnow and fait, which is able to 

 freeze oil of tartar per dcUquium, but not 

 brandy. 

 — 39 Mercury freezes. 



Martine's Effays, p. 284, &c. 

 Vv'e mull here obferve, that the heat of a hen hatching 

 chickens is placed, by this table, at 108° of Fahrenheit's 

 thermometer ; but it appears from M. Reaumur's experi- 

 ments, that eg-gs will hatch in a heat no greater than that 

 of the human Ikin. See Hatching. 



2. Olfer-uations by Reaumur's Thermometer. 



97t Anfwers to the heat of boiling water. 



80 Spirit of wine in Reaumur's thermometer boils. 



4 * 



At 



29 



, f Greateft height of the air in the (hade, ob- 

 " 1 



loi 



ferved at Paris in 1 706, 1707, 1724. 

 , f Conftant heat of the caves of the obfervatory 

 *■ I at Paris, 

 o Artificial congelation of water. 



, f Lower than (o) greateft cold at Paris, in 

 ^"^ I 1709. 



3. Obfervations byjir Ifaac Netvton's Thermometer. 



34 Water boils vehemently. 



28 /t- Heat between water boiling and wax melting. 



24 Heat of water on which floating wax melts. 



f Heat of water on which floating melted wax 

 20iV-j begins, by cooling, to lofe its fluidity and 

 (, tranfparency. 



f Heat of a bath fupportable to the hand at 

 I reft. 



f Heat of a bath fupportable to the hand in 

 , J motion. 

 '''^ » The heat of blood juft let out is almoft the 

 fame. 

 Heat of thermometer in contaft with a human 



body. 

 The heat of a bird hatching her eggs much 

 the fame. 



17 



1 I'-T , ' 



12 



