Fig. 117.

The Lever Arm.—To give motion to the mechanism a lever arm with a handle is frequently required ([Fig. 117]). It is bored 1" and has a key groove, and the hole is 1" long, so that the lever arm can be fixed on a stud socket like a wheel. By the aid of an adapter the lever arm is attached to a shaft. For the use of the handle see [Figs. 30] and [101]. There are however many other uses to which the lever arm is occasionally put. It can be used as a crank, and in linkage arrangements a pair of lever arms are very convenient. Studs A or C can replace the handle when necessary.

Such are the parts of the Willis apparatus which are adapted for our present purpose. It remains to add that the fits should be very easy, and the parts should be readily interchangeable.


INDEX.

THE END.

RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNGAY.

Footnotes: