FORCE PRODUCES THE WATER CIRCULATIONS. 237 



winds must, of necessity, cease. Similar currents are pro- 

 duced by the same cause in the waters of the sea. Their pow- 

 er may be inferred from the influence which in some cases 

 they exert upon climate. By them the warm water of the 

 Antilles is carried to the British Isles, and confers upon them 

 a mild, uniform warmth and rich moisture ; while, through 

 similar causes, the floating ice of the North Pole is carried to 

 the coast of Newfoundland, and produces cold. Further, by 

 the heat of the sun, a portion of the water is converted into 

 vapour which rises in the atmosphere, is condensed to clouds, 

 or falls in rain and snow upon the earth, collects in the form 

 of springs, brooks, and rivers, and finally reaches the sea 

 again, after having gnawed the rocks, carried away the light 

 earth, and thus performed its part in the geologic changes of 

 the earth ; perhaps, besides all this it has driven our water- 

 mill upon its way. If the heat of the sun were withdrawn, 

 there would remain only a single motion of water, namely, 

 the tides, which are produced by the attraction of the sun and 

 moon. 



How is it, now, with the motions and the work of organic 

 beings. To the builders of the automata of the last century, 

 men and animals appeared as clockwork which was never 

 wound up, and created the force which they exerted out of 

 nothing. They did not know how to establish a connection 

 between the nutriment consumed and the work generated. 

 Since, however, we have learned to discern in the steam-en- 

 gine this origin of mechanical force, we must inquire whether 

 something similar does not hold good with regard to men. In- 

 deed, the continuation of life is dependent on the consumption 

 of nutritive materials : these are combustible substances, which, 

 after digestion and being passed into the blood, actually under- 

 go a slow combustion, and finally enter into almost the same 

 combinations with the oxygen of the atmosphere that are pro- 

 duced in an open fire. As the quantity of heat generated by 

 combustion is independent of the duration of the combustion and 



