£4$ ^ N * HE TRA^SMrsSION OF HRA*< 



meter, (hewing that the fluid had been heated to this depths 

 The oil ftill covered the thermometer one quarter of an inch. 

 Exp. II. Repe- Experiment II. The experiment was repeated, the oil co- 

 t,ti °" w . lth * f vering the thermometer half an inch. The temperature was 

 oiL as formerly 32°, in three minutes the thermometer had rifen 



to 32£, in fix minutes to 32|, in eight minutes to 33, in 12, 

 to 34, in 15 minutes to 34y, at which it became ftatlonary. 

 Tn this experiment, therefore, the thermometer had rifen 2\ 

 degrees in 15 minutes : it defcended as flowly as in the pre- 

 ceding experiment. In a third experiment in which the ther- 

 mometer was covered three quarters of an inch with oil, it 

 rofe only If degree in the fame time. 

 Exp. in. Repe- The fame experiment was next repeated with quickfilver 

 tidonwhhjmr^ {n a fimikr cylinder of ipe> jft. The quickfilver covered tile 

 tranfmiffion of bulb of the thermometer one quarter of an inch. The fmall 

 heat. j ron CU p was no t fufpended, but allowed to float on its furface, 



and was filled with boiling water gently poured in. The ther- 

 mometer began to rife inftantly : in one minute it had rifen 

 from 32 Q to 36°, it remained at that temperature, or at leaft 

 with the increafe of half a degree, for another minute, and 

 then began to fall ; in three minutes it had fallen to 35, the 

 temperature of the water in the cup having fallen to 102. 

 The thermometer continued to defcend flowly, till it returned 

 to 32°. 

 Whether the In th" experiment there is a particular fource of fallacy, 



fubfidenceoftheagainft which it was found neceflary to guard. From the 

 ETof STice siting of the fides of the cylinder of ice at the upper part by 

 can affea the the contact of the heated fluid, the diameter of the cavity is 

 conclufion? enlarged, and therefore the column of mercury mu ft diroinifh 

 in height In the experiment with the oil this does not take 

 place, becaufe the water formed from the melting of the ice 

 being heavier, falls by the fides to the bottom, and fupports 

 the column of oil at its precife height, the one circumftance 

 counterbalancing the other, fince as much ice as is melted, as- 

 much water is produced, and very nearly the fame volume is 

 occupied by both. It was accordingly afcertained by exa& 

 measurement at the end of each experiment with the oil, that 

 it had not funk perceptibly ; in other werds, the bulb of the 

 thermometer remained covered with the fame height of fluid, 

 as at the commencement of the experiment. But with the 

 cuiicktilver the cafe is otherwife ; the water produced by the 



melting 



