170 BULLETIN OF THE UNIVERSITY OF WISCONSIN. 



CHAPTER IX. 



THE CONSERVATION OF ENERGY. 



§1. Wasteful Muscular Tensions. — It is recognized in me- 

 chanics that a large part of the energy expended in the working 

 of a machine is wasted ; a relatively small amount, say 25$, in 

 the best machines is devoted to accomplishing the purposes for 

 which the machine exists. The more perfectly a machine can 

 be constructed so as to save this fruitless expenditure of force 

 the more efficient it becomes, of course ; and so it is of vital con- 

 sequence that friction and other avenues of waste be blocked up 

 as fully >as possible. !STow the human organism is a sort of ma- 

 chine ; it has work to accomplish and a given quota of energy 

 which may be drawn upon' for this purpose. It is a truism 

 that the greater the amount wasted the less can be expended 

 in profitable production. But if one should maintain that this 

 body of ours has been so carefully fashioned that there can be 

 no loss of vital force, that all parts run together so smoothly and 

 co-ordinate so perfectly that every item of expense is in lieu of 

 value received, he would doubtless have a show of reason on his 

 side. It would certainly be a fortunate arrangement if this 

 most intricate of all mechanisms could run of it&elf without su- 

 perintending and with no loss or unnecessary outlay of vital 

 force; but I think we shall see that with the majority of us 

 there are frictions which can be at least reduced by a little de- 

 liberate planning. 



The greatest source of waste of neural energy is found in 

 muscular tensions which are not at all essential to the accomp- 

 lishment of the piece of work in hand. This is seen to be true 

 in view of a simple physiological law, — that the exercise of a 

 muscle involves stimulation from nerve centers. This stimu- 

 lation implies a drain upon nerve cells, — an expenditure of en- 

 ergy, that is to say. When any task, as writing, is to be un- 



