jBSOO ON THE NATURE OF HEAT'. 



ture of the room, but the other was kept conftantly ice cold 

 by means of pounded ice and water contained in the dilh 

 beneath it. 



The two conical vefTels were now filled with boiling hot 



water, and every precaution was taken to prevent agitation in 



the air; the only means by which an afcent of cold fluid could 



be fufpected. The refult of the experiment was, that the 



vefTel fufpended over the ice-cold platter cooled from 509 to 



that of 40*^ ai>ove the temperature of the room, in 33 minutes 



and 42 feconds; whereas the other veflTel required 39 minutes 



and 15 feconds to cool through the fame interval. 



^xp. 30. Repc- Exp. 30. Upon repeating this experiment the next day, 



the times were 33 minutes 13 feconds and 39 minutes 30 



feconds. 



Velocity of cool- As the cooling of thefe veflTels is a complicated procefs which 



b^th^radiatki '"^^^^^^^5 the confideration of the heat that palfed through the 



from ice, in the covered fides, in thefe different times ; the Count enters into 



ratio of 5^0 4. ^ procefs of computation, founded on the principles made ufe 



of at page 61, by which he determines that the velocity with 



which the heat pafTed through the bottom of the vetfel expofed 



to the ice, was to that with which it pafied through the bottom 



of the other veffel as five to fpur nearly. 



Exp. 31. Pro- jE'jrp. 31. By the manner of defending the two conical vefiels 



heat abf^rbed b ^^^'^ ^^^ ^ circular band or hoop of the fine port paper which 



the air when a projeded half an inch below its bafe. It is evident that the air in 



current was al- this fpace could not pafs upwards, as it became heated by con, 



lowed to take ' t r > j 



place. It was ^^^> and confequenliy, that very little of the cooling efFcdl could 



then one twenty- i^ave been produced by the contact of an afccnding current. To 



whole lofs. afcertain what thisefFed might have been, the two velfels were 



fufpended as before; but one of them had its bafe inclined in 



an angle of 43®, while the other bafe continued horizontal. In 



this fituatron they were filled with boiling water, and fuf- 



fered 10 cool without the platter and fiands beneath them. 



Two effe6ls would follow from thefe arrangements : the veffel, 



which in the other experiment had been placed over a plalter 



at the temperature of the room, would now cool a very little 



fafier by the abfence of that platter, which no doubt mufi have 



liad its temperature a little raifed ; and the inclined veflel in 



the prefent experiment would be cooled fomewhat more fpee- 



dily, by the fucceffive contact of the afcending current of air 



which was at liberty to rife.- This velTel was found to cpol 



through the ftandard interval of 10^ in 37^ minutes, and the 



horizontaj 



