An Introduction to a Biology 



himself. And the first utilisation by man of ex- 

 traneous forces in industry, if we may enlarge the 

 scope of that term to include agriculture, was liter- 

 ally a harnessing ; when the burden of supplying 

 the labour required for tilling the soil was shifted 

 from the fore-arm of man on to the shoulder of 

 the ox. One of the greatest inventions ever made 

 by man was the wheel. Without it the impressing 

 of steam, electricity, and petrol into the service of 

 man would not have been possible. The wheel 

 bears the same relation to the extra-corporeal evolu- 

 tion of man as the feather does to the corporeal 

 evolution of birds. Machinery would be impossible 

 for man without the wheel ; flight impossible to 

 birds without the feather. And it is a fact that 

 the feather, an annually detached device, which 

 combined, in a manner hitherto undreamt of, the 

 minimum of weight with the maximum of resist- 

 ance to the air, was invented (or, if the mechanist 

 object, " was grown ") by an animal who was 

 much more reptile than bird, and who was dis- 

 covered fossilised at Solenhofen, and called 

 " Ancient wing " or Archseopteryx by another 

 animal (calling himself " man "), who was des- 

 tined, in a very few years, to learn to fly himself. 

 The wheel, by taking off the brake imposed by 

 friction and gravity, enabled man to take the burden 

 from his own shoulders and put it in a cart which 

 he or a beast of burden could draw. There seems 

 to be little doubt that the first use to which the 

 horse was put was to harness him to a cart. It 

 was not till a much later date that man learnt to 

 ride the horse. The chronological relation between 

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