152 THE WEATHER, AND WEATHER PROPHETS. 



paradoxical as it may appear, such ascensional move- 

 ments are the primary cause of this state of things ; in 

 consequence of the habitudes of air with respect to heat 

 when compressed or expanded, according to a mode of 

 action well understood by meteorologists, which we need 

 not stop here to explain, as the reader will readily collect 

 it for himself from what follows. 



(15.) As the air aloft is colder than below, so also is 

 it drier. Every one considers that he knows the dis- 

 tinction between damp and dry air ; but many are not 

 aware that all air contains some moisture, in the form of 

 transparent invisible vapour; or that in summer and 

 winter on two days, both which would in common par- 

 lance be pronounced dry ones, there is more than twice 

 as much moisture present in an equal bulk of air in the 

 summer, as in the winter day. In this state of invisible 

 vapour which water is always assuming (throwing itself 

 off in that form from its surface whenever exposed, and 

 the more copiously the warmer it is), the air is its general 

 recipient and distributor. The mechanism by which it 

 is enabled to do so on the great scale is exceedingly 

 curious. We shall endeavour to exhibit it, as it were in 

 action not so much with a view to affording a coup-d'ml 

 of the whole of meteorology, as with that of rendering 

 in some degree more intelligible than at present it seems 

 to be, that great phenomenon of the November storms, 

 with the mention of which we began this lecture, which 

 has never been satisfactorily explained. 



(16.) Looking at our globe as revolving under the 

 warming iiuluence of the sun, whose rays at noon fall on 



