234 THE ENGINES OF THE HUMAN BODY 



moment, at the right rate, and stop at the right instant — . 

 in short, perform the carefully balanced movements which 

 an accomplished driver carries out almost automatically as 

 he passes a vehicle in a narrow road. 



These are merely a fraction of the parts of the mechan- 

 ism or brain with which an engineer must provide an 

 automaton driver. The movements of the optic cameras 

 must also be automatically regulated. Let us take an illus- 

 tration. We shall suppose a child runs across the road. 

 Its shadow will suddenly appear in the pictures registered 

 by the camera or eyes of the automaton. The cameras 

 must be switched at once on the child. There is no time 

 to call in the higher machinery of the brain ; a shorter 

 pathway must be used to get access to the machinery 

 controlling the muscles or engines which regulate the 

 movements of the camera, so that the danger may be 

 brought into full focus at once. Nature has provided the 

 eyes of her automaton drivers with such a machinery. 

 Then there are warning sounds which have to be registered, 

 deciphered, and acted on. Receiving, registering, and in- 

 terpreting of sound waves entail the elaborate machinery 

 of the ear, with communicating cables of nerves and 

 multitudes of exchange or brain centres. Sounds have to 

 be analysed and then compared with memories already 

 stored in the brain machinery of the automaton. The 

 automatic ear must be capable of detecting the slightest 

 change in the sounds emitted by the engine. A 

 contrivance for the detection and interpretation of smells 

 would certainly be useful. The automaton could certainly 

 be made to start or stop the engine at fixed times ; it 

 could be made to regulate the throttle valve according to 

 needs, to change gear and look after the supply of 

 lubricant. But what if a nut worked loose, or the engine 

 became heated, or the connecting-rod broke ? Or suppose 

 the automaton came to cross roads and had to ask its 

 way ? The fitting out of an automaton driver to answer 

 all these needs represents a problem so intricate and 

 difficult that no engineer would even dream of under- 

 taking it. He would regard it as a mad enterprise. Yet 



