EFFECTS OF CtOTHlUG, &C. 59l> 



In each experiment two fimilar inftruments (fuppofe No. 1 Method of oper- 

 and No. 2, or No. 3 and ^o. 4) were ufed, one naked i^nd the ^j^^J^'^^^J,^ 

 oiUer covered; fo that in each experiment the naked inftrumpnt theeffcft of 

 ferved as the flandard of comparifon with the other. clothing. 



The experiments were made and regiftered in the following 

 manner: the two inftruments ufed in the experiment, placed 

 over their wooden ftands, being fet down on the floor, were 

 filled to within about J| inch of the tops of their cylhidrical 

 necks with boiling hot water; and a thermometer being put 

 into each of them, they were placed at the diftance of three 

 feet from each other, on a large table in a corner of a large 

 quiet room, 24- feet long, 19 feet wide and J 3 feet high, where 

 they were fufFered to cool undifturbed. Near them, on the 

 fame table, and at the fame height above the table, there was 

 placed another thermometer, fufpended In the air to the arm of 

 a ftand, toafcertain the temperature of the air. 



Every caution was ufed to prevent difturbance by currents 

 or agitation of the air, whether by partial heat or the intrufion 

 of any perfon during the progrefs of any experiment. 



By the refults of a great number of experiments, it Was Scale through 

 found that the fame inftrument cooled through any given ^^'*^^ '^*''^"'' 

 (fmall) number of degrees, for inftance 10^, in very nearly meafured. 

 the lame time, whatever was the temperature of the air of the 

 room; provided always that the point from which thefe 10 de- 

 grees commenced, was at fome conftant number of degrees 

 above the temperature of the air at the time being. The in- 

 terval chofen by the Count lay between the 501 h and the 40tfa 

 degrees above the temperature of the air in which the inflrtu 

 ment was expofed to cool; when for inftance, the air was 

 at 58«, the interval commenced at 108, and ended at 98**. — 

 When the air was at 64p it commenced at 114|° and ended 

 at I04f*>. 



The warmth of any covering, or its power to confine heat, 

 was eftimated by the time employed in cooling through that 

 interval. 



As it fometimes happened, though very feldom, in the Method of fup. 



courfe of an experiment (which commonly lafted feveral hours) P^y^"?5 byinter- 

 aii^xi ri/y r , . . polation the ex- 



that the moment ot the palTage ot the mercury through one or treme inftants of 



both of thefe extreme poinls was not obferved, it was of im- time elapfed, 



portance to determine the fame by interpolation from the other ^c obfcrved? 



points obferved. To do this, the author availed himfelf of 



the 



