Life of Count Rumford. 473 



experiments led him to a philosophical view of the 

 well-known facts as to the way in which we " catch 

 cold " or become afflicted with catarrhs ; why these 

 disorders prevail most in the cold autumnal rains and 

 upon the breaking up of the frost in the spring; whence 

 it is that sleeping in damp beds and inhabiting damp 

 houses is so very dangerous ; and why the evening air 

 is so pernicious in summer and in autumn, and why it 

 is not so during the hard frosts of winter. 



Finding a great difference between the conducting 

 powers of common air and of the Torricellian vacuum, 

 the Count continued his experiments by testing the con- 

 ducting powers of common air of different degrees of 

 density. He was surprised at the result of his experi- 

 ments, though he could not discover the cause of the 

 fact, nor account for it that there is so little difference 

 in the conducting powers of air of such very different 

 degrees of rarity, while there is so great a difference in 

 the conducting powers of air and of the Torricellian 

 vacuum. Obliged by the return of the Elector to 

 Munich to suspend the experiments which he had been 

 pursuing at Mannheim, he was privileged by his patron 

 in being allowed to take M. Artaria back with him to 

 the capital, to aid him in the construction of costly 

 apparatus for pursuing his investigations. 



In the second part of this Essay, which is substan- 

 tially the paper read, as sent by him, before the Royal 

 Society, January 19, 1792, he extends the inquiries he 

 had been making concerning the conducting powers of 

 fluids to those of solids, particularly such bodies as are 

 used for clothing. The especial object of his researches 

 was to ascertain the laws relative to the confining and 

 directing of heat. He constructed what he calls a pas- 



