636 ANNUAL REPORT 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 Joco- 
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 1224 miles an hour 
for2 miles. A Fiat car, driven by Nazarro at Brooklands, 126 miles 
