and the Mode of its Communication. 31 



That the same instrument, exposed to cool in the 

 air, does in fact cool the same number of degrees in the 

 same time, very nearly, when the given interval of the 

 scale of the thermometer is reckoned from the same 

 height, or given number of degrees above the tempera- 

 ture of the air at the time when the experiment is made, 

 will appear from the following results of 1 1 different 

 experiments, made on different days, and when the air 

 in which the instrument was exposed to cool was at dif- 

 ferent degrees of temperature. 



The large cylindrical vessel, No. i, having its two 

 ends well covered up with eider-down, furs, &c., its 

 vertical sides being exposed naked to the air, in a large 

 quiet room, was found to cool 10 degrees, viz. from the 

 5Oth to the 4Oth degree above the temperature of the air 

 in which it was exposed, as follows : 



T ofTe r ar Degrees cooled. **$* 



O 00 



44 . . from 94 to 84 . . -55 minutes. 

 45i " 95i to 85i . . 



48 " 98 to 88 . . 



52 " 102 tO 92 . -55 " 



54 " i4 to 94 - 54i " 



44 . " 94 to 84 . . . 55$ " 



44 " 9 2 i to 8 2 | 55i " 



45 . . " 95 to 85 . . 56 



46 . " 96 to 86 . . 55 " 

 44 . " 94 to 84 . . 55$ " 



The fact which these experiments are here brought 

 to prove has likewise been confirmed by other experi- 

 ments, made with other instruments, and at times when 

 the temperature of the air has been as high as 64 ; but 

 I will not take up the time of the Society by giving a 

 particular account of them in this place. 



