270 MAN AND NATURE. 



that great and never-ceasing circuit of the waters of 

 the globe which is carried on by evaporation and by 

 rains. Though he has subjected the wonderful ele- 

 ment of electricity to wonderful uses, yet has he little 

 or no control over it in the wide compass of those 

 atmospheric and other changes in which it bears a part 

 so large, yet even now so little understood. The same 

 remark applies to the magnetic force as a mode of 

 electric action ; pervading, we have reason to believe, 

 the whole solar system, and concerned probably in 

 many more terrestrial phenomena than have yet been 

 assigned to this cause. Over gravitation, a force chiefly 

 strong in its concentration and by its fixed and un- 

 ceasing action over all matter, Man may seem to have 

 acquired more control ; but it is in every case gained 

 by the expenditure of some other energy, mechanical 

 or chemical, brought into momentary conflict with this 

 great motive-power of the universe. 



Such, briefly expressed, are the limits to human 

 power, in its relation to the elements, which in their 

 combination form the various climates of the earth. It 

 would require a volume, and one more ample and 

 complete than that now before us, to denote the ways 

 through which, directly or indirectly, man has sought 

 to extend these limits, and to gain a higher mastery 

 over the inorganic as well as the living world. Matter 

 and force being ever the same in absolute amount (a 

 modern doctrine repeating more explicitly one of 

 ancient date), his ability consists in setting in action 

 those changes and translations of which matter and 

 forces are susceptible, to fulfil purposes necessary or 



