Note 2 — Chapter II · THE ECCENTRIC A CRANK. SPECIAL MODEL TO GIVE QUANTITATIVE RESULTS.
Reading edition
The horizontal scales on the port-faces are obtained by projecting up equidistant circumferential marks from various circles having different valve-cranks for their radii. The scale (No. 1) is for the elementary form of valve, without lap; it serves also for link-motion in mid-gear; No. 2 is for a valve having outside lap; and No. 3 is for link-motion “linked up.” The student need not, unless he pleases, trouble himself to investigate the construction of the diagram, which is drawn to scale, so that if copied accurately it will serve to give him the demonstrations desired.