TRANSACTIONS OF SCIENTIFIC SECTION. 147 
THE THEORY OF THE BICYCLE. 
We have all seen rope-walkers. Probably most of us 
have tried to walk on the top-rail of a fence, and havea 
vivid recollection of the incessant tossing of arms and 
legs to keep our balance, and how great assistance 
we got from a long stick, or even a stone held in our 
hands. 
But the bicyclist gets no help from stick or stone. 
His legs move only in the tread of the wheel, and his 
hands rest quietly on the ends of the cross-bar of his 
machine. Apparently there is entire repose, while the 
rope-walker keeps every muscle tense, and every limb in 
motion, or ready to move. 
No wonder when a tourist on his ’cycle spins for the 
first time, through a village here, or among the nomads 
of Asia, he is followed by wondering beholders till his 
machine carries him out of their sight. 
We involuntarily ask, how is it possible for one sup- 
ported on so narrow a base to keep his seat so securely, 
and apparently without effort ? 
For an answer to this question, I have searched some- 
what widely, and while I have found articles enough on, 
or about, the bicycle, I have found none that offers a 
reasonable explanation. This is my apology for present- 
ing the present paper, in which I shall state the theories 
which have been offered; the reasons why I consider 
them unsatisfactory, and then, give what I regard as the 
true rationale of the machine. 
The only formal paper I found, that claimed to explain 
_ the bicycle, was one by Mr. C. Vernon Boys, entitled 
‘‘The Bicycle and its Theory.’’ It was delivered before 
a meeting of Mechanical Engineers, and is reported at 
great lengthin WVature, Vol. 29, page478. Here, thought 
I, is probably something valuable and convincing. But, 
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