26 THE ENGINES OF THE HUMAN BODY 



a short time if they may sit at ease after each spell. 

 Engineers tell us that we have to know a great deal 

 before we can manage a motor engine rightly, and when 

 you think about the human machine, I am sure you 

 will agree with me that it needs quite as much care and 

 understanding for its proper management as any engine 

 which man has invented. 



I have spent such a long time in counting over the 

 engines which are set working when the human machine 

 is made to walk or run, that there is danger of our for- 

 getting what 1 really am trying to prove to you. I want 

 to show that we can learn a great deal by comparing 

 together the motor cycle and the human body. Both 

 have the power of moving ; both are fitted out with 

 engines which act on the levers and compel the machine 

 to move forwards, backwards, or turn about. I have to 

 admit that the motor cycle is the more simple machine — 

 it has only one engine to drive it forward, whereas the 

 human machine needs about three hundred of them. But 

 we must also admit that if we were to collect all of these 

 engines from the body of a strong, fully grown man they 

 would not weigh more than 60 lbs., the same weight as 

 the single engine which is usually fitted to a motor cycle. 

 It is true that the single engine can make the motor cycle 

 travel four or five times the speed that the fastest sprinter 

 can attain, although his body is fitted out with hundreds 

 of motor engines. The motor cycle, too, can haul a load 

 which will tax the strength of twenty robust navvies. The 

 engine of the motor cycle has not only a greater brute 

 strength, but it never becomes really tired or needs a rest. 

 Why, then, was the human body not fitted with a single 

 engine and set on wheels ? As a matter of fact the 

 human body is fitted out on a wheel — a wheel of a peculiar 

 kind. It is a wheel with only two spokes, with a hub at 

 the hip-joint and felloes or rim at the feet. But because 

 these spokes are movable, first one swinging forwards then 

 the other, they are able to do the work of the twelve 

 spokes which are fixed together in a circle so that they 

 come in contact with the ground one after the other. A 



