CLIMATE SANITARY RELATIONS. 465 



hour longer than that of its southern limit, supposing we are in the 

 northern hemisphere ; but, in etiology and therapeutics, the term is 

 used in a different sense, and simply expresses states of the atmo- 

 sphere. These states involve, or consist in varying quantities or 

 qualities of certain elements of the air itself its caloric, light, and 

 electricity ; its aqueous vapor, fogs, mists, and clouds ; its dews, rain, 

 hail, frost, and snow ; its weight and density ; its movements or 

 winds ; its factitious gases and mechanical impurities ; all of which 

 may be very different in different times or places of the same geo- 

 graphical climate, and nearly the same in different zones. 



"ELEMENTS OF CLIMATE ON THE GLOBE. The crust of the earth is 

 not uniform in chemical composition or surface ; it abounds in- moun- 

 tains, plains, and valleys, distributed in a very irregular manner ; 

 portions of it are densely overshadowed, while others are destitute 

 of forests ; the larger part is covered with oceans, lakes, rivers, and 

 swamps ; an elastic atmosphere rests upon the whole ; and every 

 part solid, fluid, or aeriform is permeated by electricity. Were the 

 earth, with this surface removed from the influence of the sun, the 

 phenomena of climate would be annihilated ; in that luminary, then, 

 reside the dynamics on which they depend ; and the rays of light 

 and heat are the efficient agents by which its quickening influence is 

 exerted on the earth. 



"THE ELEMENTS -OF CLIMATE NOT THE SAME IN DIFFERENT PARTS 

 OF THE EARTH. It results from what has been said, that the ele- 

 ments of climate are not precisely the same in any two regions of 

 the globe ; and, therefore, that the climate of every region, even in 

 the same latitude, must possess some peculiarities ; the causes of which 

 are to be sought in the physical geography and hydrography of the 

 region itself, and of those by which it is immediately surrounded."* 



This brings us to the therapeutics of climates, special and 

 general. . 



On climatic therapeutics we have the following univer- 

 sally-accredited statements and opinions of one* fully recog- 

 nized as uttering the voice of the science of the times : 



"The influence of climate over disease has long been established 

 as a matter of fact, and physicians have, from a very early period, 

 considered change of climate and change of air as remedial agents 

 of great efficacy. This opinion is supported both by reason and ex- 

 perience : it is reasonable, for example, to believe that a change of 



* Drake, "Diseases of the Interior Valley." 



f Sir James Clark, ' Sanative Influence of Climate." 



