MUSCLES RECIPROCAL ENGINES 41 



learning how to control the ringers in playing and the 

 voice in singing. The perfect singer or player is he or 

 she who, having been born with a gift for music, has 

 gained a control over the muscles of the voice and hand 

 so completely that they they can be timed in their action 

 to an infinitely small fraction of a second. In the 

 expert artist the will has become a perfect engine-driver. 

 Then there are the skilled pursuits of life — the expert 

 use of the chisel, the hammer, the saw, the brush, the 

 carving- and graving-tools — all the skilled arts and crafts 

 in which proficient workmen take a pride. Some become 

 masters of their engines more easily and more quickly 

 than others, but all have to serve an apprenticeship in the 

 great game of life — the game of setting our muscular 

 engines to work in the right order, with the right strength 

 and at exactly the right moment. 



Our lives would have been so much simpler and easier 

 if, like a motor cycle, we had been fitted out with only 

 one engine ! That would have been possible if we had 

 been content to do only one thing in life — namely, to 

 spin straight along a smooth road. That would not content 

 anyone for long. We should want to eat and drink, sing 

 and play, and do hundreds of other things ; therefore we 

 must have hundreds of muscular engines to do these 

 different things. And having hundreds of engines 

 introduces into our bodies a difficulty which I am now 

 to try to explain. Our muscles have to act as reciprocal 

 engines. I can make my meaning clear by taking an 

 instance from the arm. In fig. 7 all the muscles have 

 been stripped from the upper arm except two — the 

 anterior brachial and triceps. For you must understand 

 that muscular engines as well as railway engines are given 

 names. The forearm is the lever or crank on which both 

 of these muscles act ; the brachial bends or flexes the 

 elbow ; the triceps straightens or extends it. Each has to 

 give and take as the other takes or gives ; they have to act 

 as reciprocal or opposing engines. In fig. 8, which is set 

 side by side with fig. 7, these two muscles have been taken 

 away, and in their places have been fixed two internal- 



