go 



THE ANIMAL AS A MACHINE. 



production of electricity ; and the minute insect that 

 flashes across his lawn on a summer evening, or the 

 worm that lights his path in the garden, exhibits a sys- 

 tem of illumination incomparably superior to his most 

 perfect electric lights. 



Nature in each of these cases converts the energy of 

 chemical union, probably of low-temperature oxidation, 

 into just that form of energy, whether mechanical or of 

 a certain exactly defined and required rate of ether- 

 vibration, that is best suited to the intended purpose, 

 and without waste in other force, utilizing even the 

 used-up tissue of muscle and nerve for the production 

 of the warmth required to retain the marvellous ma- 

 chine at the temperature of best efficiency, whatever 

 the environment, and exhaling the rejected resultant 

 carbonic-acid gas at the same low temperature. Here 

 is nature's challenge to man ! Man wastes one fourth 

 of all the heat of his fuel as utiHzed in his steam-boiler, 

 and often ninety per cent as used in his open fire- 

 places ; nature, in the animal system, utilizes substan- 

 tially all. He produces light by candle, oil-lamp, or 

 electricity, but submits to a loss of from one fifth to 

 more than nine tenths of all his stock of available 

 energy as heat ; she, in the glowworm and firefly, pro- 

 duces a lovelier light without waste measurable by our 

 most delicate instruments. He throws aside as loss 

 nine tenths of his potential energy when attempting to 

 develop mechanical power ; she is vastly more econom- 

 ical. But in all cases her methods are radically different 

 from his, though they are as yet obscure. Nature con- 

 verts available forms of energy into precisely those other 

 forms which are needed for her purposes, in exactly the 

 right quantity, and never wastes, as does invariably the 



