THE MASTER CONTRIVANCE 235 



it is an enterprise which Nature has carried to a triumphant 

 issue. The human brain represents Nature's Master 

 Contrivance. 



This contrivance which we are now to look at can not 

 only drive machines ; it can invent and create them. It 

 was the machinery of the brain which discovered the uses 

 of fire and of iron ; found out the elements which compose 

 the earth, sun, and stars ; discovered the laws which 

 regulate the movements of planets. Shakespeare's plays 

 were conceived and written by such an instrument. The 

 brain machine has discovered how to bridge space and 

 time ; it balances and determines the fates of armies, fleets, 

 and nations. Nothing is too small and nothing too great 

 to fall within the compass of its machinery. It is such a 

 wonderfully contrived machine that, although the most 

 learned men have dissected and examined it for thousands 

 of years, they have done little more than cross the 

 threshold of its organisation. But every step forward 

 has made them more and more certain that its mechanism- 

 can be unravelled and that the only darkness about it is 

 the shadow cast on it by their own ignorance. 



The brain, then, is a great administrative, governing 

 machine, simple enough in outward appearance and only 

 imposing because of its bulk. In fig. 45, A, the right half 

 of the head has been removed to expose the greater part 

 of the central nerve machinery — the brain and spinal cord. 

 The brain itself is housed within the cavity of the head — 

 the bony-walled cranial chamber, which varies much in 

 size or capacity. A chamber which could hold between 

 50 and 52 oz. of water (1430— 1480 cubic centimetres) is 

 a common size amongst Englishmen ; in the English 

 woman the chamber, in conformity with her body, is of 

 smaller size — its capacity being in round numbers 12 per 

 cent, less than that of the male. In life the cranial 

 chamber is perfectly filled, the brain itself occupying 

 93 per cent, of its capacity, while the remaining space is 

 taken up by the coverings or wrapping of the brain, the 

 cerebro-spinal fluid which bathes it inside and out, and 

 the great capillary fields which permeate its coverings and 



