14/2 



DESIGN FOR A BRAIN 



Our understanding has been greatly increased by the development 

 during recent years of the science of 4 cybernetics '. The word — 

 from KvfiepvrjTf]£, a steersman — was coined by Professor Wiener to 

 describe the science which, though really dating back to Watt 

 and his governor for steam-engines, has developed partly as a 

 result of the extraordinary properties of the thermionic vacuum 

 tube, and partly as a result of the urgent demands during the 

 last war for complex calculating and controlling machinery such 

 as predictors for gun- and bomb-sights, automatically controlled 

 searchlights, automatically controlled anti-aircraft guns, and 

 electronic computors. 



When a radar-installation passes information about the posi- 

 tion of an aeroplane to a predictor, and the predictor emits 

 instructions which determine, either manually or automatically, 

 the laying of an anti-aircraft gun, we can write simply enough : — 



Radar 

 set 



Predictor 



> Gun 



but what do the arrows mean ? what is transmitted from box 

 to box ? Energy ? No, says cybernetics — information. 



If we turn to simple machines for guidance, we will probably 

 be misled. When my finger strikes the key of a typewriter, 

 the movement of my finger determines the movement of the 

 type ; and the finger also supplies the energy necessary for the 

 type's movement. The diagram 



B 



would state, in this case, both that energy, measurable in ergs, 

 is transmitted from A to B, and also that the behaviour of B 

 is determined by, or predictable from, that of A. If, however, 

 power is freely available to B, the transmission of energy from 

 A to B becomes irrelevant to the question of the control exerted. 

 It is easy, in fact, to devise a mechanism in which the flow of 

 both energy and matter is from B to A and yet the control is 

 exerted by A over B. Thus, suppose B contains a compressor 

 which pumps air at a constant rate into a cylinder creating a 

 pressure that is shown on a dial. From the cylinder a pipe goes 

 to A, where there is a tap which can allow air to escape and 



154 



