The crank shaft carries a pinion which gears into a toothed wheel of a coarse pitch, carrying cutters at the ends of the teeth.

Fixed to the pinion were three cams, for high, low and mean tides.

245) a rack I, fixed to the carriage, caused a pinion H on the gun to revolve.

The wing of the bird, like that of the insect, is concavo-convex, and more or less twisted upon itself when extended, so that the anterior or thick margin of the pinion presents a different degree of curvature to that of the posterior or thin margin.

In this instance a very slight movement at the root of the pinion, or that end of the lever directed towards the body, 1 is followed by an immense sweep of the extremity of the wing, where its elevating and propelling power is greatest - this arrangement ensuring that the large quantity of air necessary for support and propulsion shall be compressed under the most favourable conditions.