^0 KFFECTS OF CLOTHING, &C. 



the following law of cooling of hot bodies in a fluid, which be 

 found by experiment to be applicable without fenfible error in 

 the prefent cafe : It is that, if the equal portions of a right 

 line reprefent fucceffive intervals of time, and perpendiculars 

 be ereded upon the fame, to denote by their lengths the de- 

 grees of the excefs of temperature of the hot body beyond that 

 of the cold medium, at points denoting the correfponding in- 

 ftantsof time, the line joining the extremities of the perpen- 

 diculars will be the logarithmic curve. Whence if two tem- 

 peratures and the elapfed time be obferved, it will be eafy by 

 the help of a table of logarithms to determine the lime at which 

 any intermediate temperature took place. This is exemplied 

 by the Count, who then proceeds to relate his eyperiments. 

 Exp. T. Exp, 1. One of the veflels. No, 1. having its ends clothed 



t^tllncLh^^^ before defcribed, and its poliflied fides naked, was filled 

 the heat to with hot water. Another velfel. No. 2. alike in all refpedts, 



efcape much j^y^ having its fides clofely clothed with Irifh linen, fuch as 

 quicker than ./•,,. t i /-n i • ii 



from a bright IS fold m London at 45. per yard, was filled in like manner, 



metallic furfacc. and both were fimilarly expofed to cool. 



The naked inftrument employed 55 minutes in cooling, from 

 9^4-° to 84' Fahrenheit (the air of the room being at 45^.) — 

 But the clothed inftrument was cooled through the fame in- 

 terval in 36| minutes, confeqtently this clothing expedited the 

 emiflion of heat inftead of confining it. 



When both inftruments were cooled to 42** they were re- 

 moved into a warmer room at 62*^, and the clothed inftrument 

 was alfo found to acquire heat confiderably fafter than the 

 other. 



Whether the linen accelerated the cooling by affifting the 

 fucceflion of frelh particles of air, or by promoting the efcape 

 of heat by radiation, were points to be determined. 



Exp. 2. The Exp. 2. To decide this, the linen of No. 2. was removed, 



fame effeft from ^^^ ^j^^ ^^^j, ^g^g thinly coated with glue. In thefe circum- 

 a coating 01 glue. "^ 



fiances, while the ftandard or naked inftrument cooled through 



the interval in 55 minutes, the coated inftrument employed 

 only 43| minutes. 



In reafoning upon this experiment, the author concluded, 

 that if the glue operated only by preventing the air from at- 

 taching and fixing itfelf to the poliflied metallic fur face, and 

 confequently in that manner facilitated its circulation and the 

 cooling; it would be of no confequence, whether the fur face. 

 4 was 



