and the Hygrometer of Si Berzellus. rsl 



gine the vapour to be condensed by a refrigerating principle- 

 residing in the whale-bone. — What are the genuine inferences 

 from these facts ? 1st, That glass and other substances rob 

 the atmosphere of water by an attractive force ; and that a 

 loss of temperature does nothing more than prepace the air to 

 part with its moisture more abundantly : .2dly, That the at- 

 traction of the hvgrometer is resisted by a similar, but op*: 

 posite power, residing in the atmosphere itself : 3d!y, That 

 the phamomenaof the instrument are to be explained by the 

 mutual reaction of these contrary forces. 



There is one circumstance which renders the hygrometer 

 of little or no use to the advocates of the new hypothesis r 

 for, if I understand them tightly* a barometer will supply 

 the place of the other instrument in their opinion. The au- 

 thor of this-system maintains the joint pressure of the per- 

 manent gases to be 29*56 inches of mercury at all times and 

 places, I suppose on the level of the sea. This being ad- 

 mitted, it will follow, that the same join! presTurl may be" 

 found for any height; consequently, if this given quantity 

 be subtracted from an obsened elevation of the barometer, 

 the remainder will express the expansive force of the 

 aqueous atmosphere for the time and place. If this be what 

 they mean, it must convince every meteorologist that their 

 opinion cannot explain the changes that frequently take 

 place in the weight of the atmosphere. For instance, if the 

 hypothesis be true, the force of the aqueous atmosphere 

 ought to be greatest in summer, and the barometer to be 

 highest at the same season ; — but this is not the case. On 

 the contrary, the maximum of elevation commonly happens 

 after the winter solstice, and the minimum too ; for the 

 barometer frequently rises during January to 30*60 or higher; 

 i. e. the force of the atmospherical vapour is equivalent to 

 one inch of mercury or more. The preceding conclusion 

 cannot be reconciled both to observation and the hypothesis; 

 for the thermometer very seldom reaches 48°, at least in 

 Westmoreland, during the month of January; consequently 

 the force of the aqueous atmosphere is never equaj to -, l th ; 

 of an inch of mercury in this county at that season ; and 

 the hypothesis seems to confine the range of the baromae: 



M 3 to 



