14/2 AN INTRODUCTION TO CYBERNETICS 



// is the division into two stages that enables a power-amplifier to 

 be built in spite of the law of conservation of energy, the point being 

 that the energy suppHed to the input in stage 1 can be supplemented 

 to give the output in stage 2. 



Sometimes the proportionahty is important, as in the radio 

 amplifier. Then the machine has to be made so that the ratio 

 has the same value all along the scale. In other cases the exact 

 value of the ratio is of little importance, as in the crane, the essential 

 point in it being that the input values shall all be within some given 

 limit (that set by the strength of the crane driver's arm) and that the 

 output shall be supplemented generously, so that it much exceeds the 

 value of the input. 



Ex. : Design a " water-amplifier ", i.e. a device that, if water is pumped into 

 the input at x ml/sec will emit, from its output, water at IOOj: ml/sec. 



14/2. The process of amplification can thus be looked at from two 

 very different points of view, which are apt to lead to two very 

 diff'erent opinions about whether amplification does or does not 

 occur. 



On the one side stands the theoretician — a designer of cranes, 

 perhaps, who must understand the inner nature of the process if he 

 is to make the crane effective. To him there is no real amplification : 

 the power emitted does not exceed the (total) power supplied. He 

 knows that the operator at the control is successful simply because 

 the operator can, as it were, rob other sources of energy (coal, oil, 

 etc.) to achieve his end. Had Nature not provided the coal as a 

 generous source of supplementation, the operator would not be able 

 to lift the heavy load. The operator gets "amplification" simply 

 by caUing in King Coal to help him. So the basic type of amplifier 

 is the boy who can lift big weights — because his father is willing 

 to lift them for him! 



All this is true; yet on the other side stands the practical man who 

 wants to use the thing, the man who decides what machinery to 

 install at the quay-side, say. If he has access to an abundant 

 source of cheap power, then for him "amplification" becomes very 

 real and practical. It means the difference between the ships being 

 loaded quickly and easily by movements of a control handle, or 

 slowly and laboriously by hand. When the load is larger, a loco- 

 motive for instance, the non-availability of a power-amplifier might 

 mean that the job could not be done at all. Thus, to the practical 

 man the possibility of such an apparent amplification is of great 

 importance. 



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