370 



SCIENCE. 



[N. S. Vol. I. No. 14. 



of the whole nervous system which inaugu- 

 rate and direct, automaticallj' or intelli- 

 gently, the currents of nerve-impulse and 

 set in operation and sustain the whole com- 

 plicated life-system. But how the mind 

 seizes upon these forces and compels these 

 energies to work its will, or how the spine, 

 and automatic mechanism, generally, is set 

 in communication with the mind on the 

 one side, and the organism of the machine 

 on the other, remains a mystery challen- 

 ging every resource of talent and the high- 

 est genius in the investigator. So far as a 

 judgment or even a surmise is permitted, 

 it may probahlj^ be assumed that, like all 

 other energies of the vital machine, those 

 of brain and spine and nervous system have 

 a definite, quantivalent relation with the 

 familiar physical energies, and fall within 

 the province of modern scientific research. 

 They demand, beyond a doubt, their pro- 

 portion of the potential energy supplied in 

 the daily ration. 



(7.) Observed phenomena and statistical data 

 upon which these deductions are founded may be 

 summarized as follotvs : 



Taking the human vital engine, in illus- 

 tration, the amount of potential energy sup- 

 plied the average individual may be taken at 

 2,500 or 3,000 calories when doing no exter- 

 nal muscular work, 4,000 calories when per- 

 forming a fall day's work as a laborer.* 

 This corresponds to 10,000 to 16,000 British 

 thermal units, to from 8,000,000 to 12,500,- 

 000, nearly, British dynamic units, foot- 

 pounds per individual per day, of which 

 supply a part is wasted by defective diges- 

 tion and assimilation and a portion by vari- 

 ous defects of the machine itself. Taking 

 the energy-supply of the vital machine as 

 8,000,000 foot-pounds for the man of seden- 

 tary habits and performing brain-work and 



*Pavy on Foods ; Mott's Manual ; Thurston's 

 Animal as a Prime Mover ; Year Book of the New 

 York State Reformatory, 1894 ; Reports of the Conn. 

 Agrioultural Station. 



10,000,000 for a steadj' and hard-working 

 laboring man, who does much muscular 

 labor and little thinking, we have the basis 

 of estimates which, though probably not 

 very precise, may yet answer present pur- 

 poses in giving general conclusions. 



Of tliis eight or ten millions of foot-pounds 

 of energy supplied the machine in potential 

 form, in the foods, not less than fifteen per 

 cent, must be reckoned for deficiency of 

 digestion and transformation into available 

 form in the chyme and chyle, the solutions 

 from which the sj'stem draws it for its vari- 

 ous special purposes. This seems the mini- 

 mum usual loss, and an excess is commonly 

 observed, which is furnished bj' larger food- 

 supply than the assumed figures as here 

 given. A good ' digestion coefficient ' is 85 

 per cent.* 



Of the 8,000,000 foot-pounds of energy 

 furnished in the food of the brain-worker, or 

 10,000,000 supplied the day laborerer, some- 

 thing like 7,000,000 in the one case, and 

 8,500,000 in the other, pass into the reser- 

 voirs of potential energy of the vital ma- 

 chine, and circulate in the blood through 

 all its organs ; giving up to each that pecu- 

 liar form of nutriment needed for its work 

 or for its own maintenance. The muscles 

 draw upon it for energy to be converted into 

 the work of external labor or of internal 

 operations essential to life; the various 

 glands elaborate from it those special com- 

 positions required for their purposes ; the 

 brain and nervous system absorb fi-om it the 

 material for consumption in the operations 

 directed by the mind or automaticallj' con- 

 ducted by the vital powers of the animal 

 system. Of the 8,500,000 foot-pounds of 

 energy thus furnished the mechanism of the 

 laboring man, in the best cases of applica- 

 tion, under most favorable conditions, about 

 2,000,000 are applied to the performance of 



•"Flint's Muscular Power ; Woods's Digestibility 

 of Feeding Stuffs, Awater's Studies of Dietaries, 

 Report of Conn. Ag. Experimental Station, 1893. 



