258 BIOLOGICAL PROBLEMS 



rest does not completely restore his initial vigour. 

 Of these 12 units probably i unit is required by the 

 worker to enable him to get to his factory in the 

 morning, and for essential household duties, whilst 

 another unit is required for similar objects in the 

 evening. He therefore has 10 units of energy left, 

 which he can apply wholly to his work if he so desires. 

 Probably in peace times he does not utilize more than 

 7 units in such a way, and keeps the other 3 units for 

 his games, or for digging in his garden, or frequently 

 he does not utilize them at all, and ends the day in a 

 state of considerable unexhausted vigour; but we will 

 assume that in war time he desires to put every par- 

 ticle of energy possible into his work, and to expend 

 the whole of his 10 units in this way. How can he 

 use them to the best advantage? There can be no 

 doubt that a great deal of energy is expended if a man 

 stands idly all day in a factory without doing any 

 work whatever. The effects of the noise, the smell, 

 and the physical effort of standing for 10 hours would 

 probably account for quite 5 out of the 10 units, or 

 half a unit per hour. Hence there would be only 

 5 units left to put into active work. Supposing, on 

 the other hand, only 8 hours were worked instead of 

 10, then 6 units of energy would be available for active 

 work, and if 6 hours were worked, then 7 units would 

 be available. In other words, the shorter the hours 

 of labour the more the energy available for active and 

 useful work, and the less the energy wasted by mere 

 standing about. It might be supposed that in such 

 a case the shorter the hours worked the better; but 

 another factor which acts in the opposite direction has 

 to be considered. Supposing it needs i unit of energy 

 to produce i article in an hour, it does not need only 

 2 units to produce 2 articles in the hour, but distinctly 

 more than 2 units. The greater the speed of working, 



