Page:The Kinematics of Machinery.djvu/331

 DOUJJLE EXPANSION OF ELEMENTS. 301

We have therefore exhausted the praticable combinations of the pins 1, 2, and 3 in pairs. We may, however, go further, and make one of the pins include two others. 1 can be placed in 2, for in- stance, at the same time that 2 is lying in 3, so that we can place

1 within 2 within 3 and also 3 within 2 within 1.

FIG. 238.

FIG. 23 P.

These two arrangements are shown in Figs. 237 and 238 ; both being placed on the frame d ; both are turning slider-cranks,

The reader may perhaps think that this idea of pin-expansion, carried so far beyond practical limits, can have but little import- ance in Applied Kinematics. This, however, is not the case, as we shall now proceed to show.