124 Professor H. S. Hele-Shmv [March ; 1, 



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 

 tvalking 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 produc- 

 ing 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) Is by perfecting the wheel and hardening the track — and that 

 is the secret of the development of the railway system. 



(2) The other is by causing the obstacle to be absorbed in the 

 tyre of the wheel — that is the real secret of the success of the pneu- 

 matic tyre. 



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

 and shows at once hoAV 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 Fig. 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 horse-power has done 122^ miles an hour 

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

 an hour. A Stanley steam car, 127 miles an hour, and a Benz car 

 has done 127^ miles an hour. 



