14 THE ENGINES OF THE HUMAN BODY 



are covered by flesh or muscles, and secondly because the 

 flesh is covered by clothes. Of course if we had a dark 

 room and an X-ray machine we could make the clothes and 

 flesh quite transparent and see every bone of the body, 

 but as most of us have not got these things I have given 

 (Plate I.) 1 the picture of a skeleton — one drawn for a 

 famous anatomist in Holland a hundred and sixty years 

 ago. It is not only drawn very truthfully, but, fortunately 

 for us, it is shown walking — moving its legs just as I 

 supposed mine did when doing that uphill journey. I 

 need not name the pieces of the framework ; each bone is 

 shown with its name attached. There is one point about 

 the skeleton I must mention here ; we shall find it 

 corresponds not only to the framework of the motor 

 cycle but to the wheels as well. For a wheel is really a 

 number of legs so arranged and so fixed together as to 

 form a circle. 



Having run our eye over the framework of the human 

 machine we are now to glance at its muscles or engines. 

 The skeleton seen walking along so gaily in Plate I. appears 

 again in Plate II. fitted out with all its muscle-engines, 

 hundreds in number. The chief ones have had their 

 names attached, but in the meantime we are to concern 

 ourselves with only one of them — the one which makes 

 up the calf of the leg and in the drawing bears two names 

 — gastrocnemius and soleus — although it is but one engine. 

 You will notice that we give names to the engines of the 

 human body just as we do to railway engines. The muscle 

 of the calf of the leg is really a two-cylinder engine — a 

 kind which is often fitted to motor cycles. We can easily 

 see, by looking at Plate II., what the particular use of this 

 engine is. It will be seen to work on the heel ; the heel 

 is its crank-pin. It is the engine which suddenly lifts up 

 the heel as we take a step forward in walking. 



We are now to look at the manner in which the muscles 

 which move the heel are fixed to the framework of the 

 body. Engineers are very careful to fasten the engine of 

 a motor cycle very strongly and firmly to the framework 



1 The reader will find the plates inserted at the end of the book. 



