636 ANNUAL. EEPOET SMITHSONIAN INSTITUTION, 1911. 



the movement of his limbs entails a certain amount of rising and 

 falling, as well as reciprocating motion and consequent loss which 

 occurs in running. 



Now, in theory, the wheel is perfect, and in the case of a perfectly 

 hard, circular wheel, rolling on a perfectly hard track, there should 

 be no resistance. This you can well imagine from the lantern model 

 which I now show in operation. In this there is no appreciable resis- 

 tance, but it is just in this direction that the wheel has defects 

 unknown to nature's methods, since men and animals move upon the 

 ankle joint in a quite superior way to the rolling of an ordinary wheel. 

 In passing I may remark that the more man improves the roads, and 

 the higher his standard of locomotion becomes, the more will he feel 

 the need of a mechanical walking machine (it will be a walking 

 machine, though possibly moving at 20 miles per hour) to progress 

 over parts of the earth where roads do not exist, or are still in an evil 

 condition. The better his mechanical appliances for producing such 

 a walking machine, the sooner will this come about, as this is really 

 a vital factor in the solution of the problem. No wheel, however, is 

 quite hard and round, and no road is quite hard and smooth, and there 

 is always an arc of contact, more or less appreciable, which causes a 

 loss, since rubbing takes place instead of true rolling, as shown in the 

 next lantern slide. The next lantern working model I show illustrates 

 the other effect, in which the wheel meets obstacles and is deflected 

 by them from its course, giving exactly the same kind of loss which I 

 showed you takes place with a man in walking, and which is made 

 apparent by making the car write its own record on a piece of smoked 

 glass, exactly as my assistant wrote his record of rise and fall on the 

 blackboard. 



Thus there are two ways in which the wheel can be improved : 



(1) By perfecting the wheel and hardening the track — and that is 

 the secret of the development of the railway system. 



(2) By causing the obstacle to be absorbed in the tire of the 

 wheel — that is the real secret of the success of the pneumatic tire. 



The working model now on the screen illustrates the latter point, 

 and shows at once how the three causes of resistance to animal loco- 

 motion are overcome. 



To-day we can replace the muscular energy of man by almost un- 

 limited mechanical power, and figure 3 is a comparative speed chart, 

 which I have prepared and which indicates the enormous advance in 

 the speed record which has been made over the best unaided muscular 

 efforts of any animal. It is curious to see that the highest speed ever 

 attained on a railway is' closely approached by that obtained with 

 motor vehicles. The records for the latter are as follows: 



The Darracq car of 200 horsepower has done 122^ miles an hour 

 for 2 miles. A Fiat car, driven by Nazarro at Brooklands, 126 miles 



