in various Substances. 429 



thermometer, which prevented its cooling so fast as it 

 would otherwise have done. But when the weather be- 

 comes cold, I propose to repeat this experiment with 

 variations, in such a manner as to put the matter beyond 

 all doubt. In the mean time I cannot help observing, 

 with what infinite wisdom and goodness Divine Provi- 

 dence appears to have guarded us against the evil effects 

 of excessive Heat and Cold in the atmosphere; for if it 

 were possible for the air to be equally damp during the 

 severe cold of the winter months as it sometimes is in 

 summer, its conducting power, and consequently its ap- 

 parent coldness, when applied to our bodies, would be so 

 much increased, by such an additional degree of mois- 

 ture, that it would become quite intolerable ; but, hap- 

 pily for us, its power to hold water in solution is dimin- 

 ished, and with it its power to rob us of our animal 

 heat, in proportion as its coldness is increased. Every- 

 body knows how very disagreeable a very moderate de- 

 gree of cold is when the air is very damp; and from 

 hence it appears, why the thermometer is not always a 

 just measure of the apparent or sensible Heat of the 

 atmosphere. If colds or catarrhs are occasioned by our 

 bodies being robbed of our animal heat, the reason is 

 plain why those disorders prevail most during the cold 

 autumnal rains, and upon the breaking up of the frost 

 in the spring. It is likewise plain from 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. It has puzzled 

 many very able philosophers and physicians to account 

 for the manner in which the extraordinary degree or 

 rather quantity of Heat is generated which an animal 



