GENERAL CONCLUSIONS. 



345. Comparison of Various Motors.f 1 ) The human motor is 

 probably an " electro-capillary " engine in which nervous excita- 

 tion modifies the superficial tension and produces contraction 

 (Lippmann & D'Arsonval). The nature of the nervous agent 

 and the origin of human motive power are, however, veiled in 

 obscurity. 



The power of man, approximately ^ H.P., is very small compared 

 with other motors, but the efficiency is good. An input of 8 

 small calories produces about 1 kilogrammetre of work which is 

 an efficiency of 30% 



008 X 425. 



The human motor can develop, on the average, 300,000 kgm. 

 per diem. The equivalent dynamic expenditure is 300,000 X 

 ,008 = 2,400 great calories. Adding the expenditure when at 

 rest, 2,340 Calories, we get a total of 4740 Calories. 



A good steam engine would require about 1 kg. of fuel to do 

 the above work, about double the consumption of the human 

 motor. 



The life of the human motor is greater than that of any inani- 

 mate prime mover, which latter is at most 20 years, unless repairs 

 and renewals have been frequently effected. The human motor, 

 on the other hand, until old age sets in, is capable of continuous 

 self-repair. Also a suspension of nutrition does not cause an 

 immediate stoppage, for it can draw on its " alimentary reserves." 

 Further, within limits, it is capable of improvement, while the 

 efficiency of an inanimate machine is at its best when it is new. 



Experience and skill are factors capable of growth and im- 

 provement. 



Lastly, the control of the human motor is internal. It con- 

 forms to those unseen needs, generally organic, from which are 

 derived the principles of its conservation. Hence work under 

 natural conditions gives the greatest economy of effort making 

 good the wastage of energy by the more perfect adaptation of 

 bodily motion, which is capable of almost infinite flexibility. 



Inanimate motors cannot approach the human motor in this 

 latter quality. 



(*) Vide Reyer's interesting work Kraft, 2nd Edition, p. 251, Leipzig, 1909. 



