Page gauge

A gauge used by compositors for measuring the length of pages during the operation of making-up. When a new work has been commenced, the compositor who has set the first take of copy marks off a certain number of lines, according to the size of the page, adding the folio and while lines; he then places a piece of reglet down the side of the page, close up to the head of the galley, and cuts a notch into it at the point where the page terminates.