Note 53 — PART XI. THE VALVE-GEAR.
Reading edition
In order to get the engraving within the required limits, the diagram is drawn with a connecting-rod only 5¹⁄₂ instead of 7 feet. The latter is the length used in previous illustrations.
[54] This will be the case when the two arms of the rocker are of the same length, as they usually are. Sometimes, though rarely, they are of different lengths.