and the Mode of its Communication. 37 



No. 2, which was clothed, acquired heat considerably 

 faster than the other, No. i, which was naked.* 



The discovery of these extraordinary facts surprised 

 me, and excited all my curiosity ; ' and I immediately 

 set about investigating their cause. 



As it is well known that air adheres with consider- 

 able obstinacy to the surfaces of some solid bodies, I 

 conceived it to be possible that the particles of air in 

 immediate contact with the surface of the cylindrical 

 vessel No. i, might in fact be so attached to the metal 

 as to adhere to it with some considerable force ; and, if 

 that were the case, as confined air is known to consti- 

 tute a very warm covering, it appeared to me to be 

 possible that the cooling of the vessel No. i might 

 have been retarded by such an invisible covering of 

 confined air; which covering, in the experiment with 

 the vessel No. 2, had been displaced and in a great 

 measure driven away by the colder covering of linen 

 by which the body of the instrument was closely em- 

 braced. 



I conceived that the linen must have accelerated the 

 cooling of the instrument, either by facilitating the 

 approach of a succession of fresh particles of cold air, 

 or by increasing the effects of radiation; and, with a 

 view to elucidate that important point, the following 

 experiments were made. 



Experiment No. 2. Removing the linen with which 

 the instrument No. 2 was clothed, I now covered the 

 sides of that instrument with a thin transparent coat- 

 ing of glue ; and, when it was quite dry and hard, 

 I again filled the two instruments (No. i and No. 2) 



* The details of this experiment (which was made on the nth of March, 1803) 

 may be seen on page 29. 



