316 Mr. Hinds on Climate in connexion 



12, 16 in favour of the old world; this however informs us 

 little. Dr. Mitchell during many years investigated this sub- 

 ject ; his results announce a difference in the mean tempera- 

 tures, which would require a compensation of 15° of latitude. 

 Nothing could display more completely the futility of com- 

 parisons ; it is only by a knowledge of local circumstances 

 combined with latitude that satisfactory information can be 

 attained useful for practical results. 



II. Humidity. 



On reviewing the processes continually going on in the 

 kingdoms of nature, we cannot fail to observe an apparent 

 vast consumption of material ; but this consumption is only 

 apparent. Following an element of a body in the state of de- 

 composition, we shall soon find it under a new shape, and 

 perhaps ere long again forming a constituent of a similar 

 substance to that it first started from. The various tribes of 

 quadrupeds, insects, and birds are constantly drawing large 

 quantities of food from the vegetable kingdom ; at first view 

 it seems to disappear, but it is only undergoing one of the 

 changes in the circle of its utility. Taking man as an in- 

 stance : a lai'ge portion of his food is soon cast off by the 

 respiration, by the skin, or in the excrement ; the small 

 quantity appropriated to the growth and support of the body 

 is only detained something longer in its course. In time even 

 his body has run its race, and when decomposition sets in, the 

 constituents, dissolved in air, hasten to new uses ; perhaps to 

 give beauty to the gem, or strength to the pride of the forest. 

 Again, the ore cast into the smelting furnace loses bulk and 

 weight ; escaping in an aerial torrent, and diffusing itself over 

 the habitations of men and their fields and gardens, it is greedily 

 seized on as the food of organized beings. Not a particle 

 escapes, every molecule has its use ; and we do not strain the 

 truth when we assert, that since the world was made habita- 

 ble for man and clothed with living things, not an atom has 

 been added to or taken from our globe. The chemist, assisted 

 by his noble science, can often produce surprising combina- 

 tions and disunions, but is as unable to destroy or generate 

 the smallest particle of matter, as the mechanic is to produce 

 power. 



Such reflections naturally arise on tracing Humidity through 

 the different conditions it is destined to occupy. Its changes 

 are developed in a circle, and wherever the investigation is 

 commenced it will ultimately lead us back to the starting-point. 

 It is first raised from the surface of the globe, both the aque- 

 ous and terrestrial portions, and occupies the atmosphere in 



