From the B&L Price list, 7th ed., 1882:

Bausch and Lomb Optical Co.'s Glass Stage and Slide- carrier.This (Fig. 128) is intended as a substitute for the mechanical stage to a certain extent. It consists of a polished plate of glass, incased in a brass ring, which clamps on the circular stage. The slide-carrier, which moves on it, consists of a light metallic plate, and has protruding from its lower surface four small points; at its two ends are prolongations, which are bent downward and inward, and, acting as springs, press against the lower surface of the glass. As the contact between glass stage and slide- carrier is only in these six points, friction is reduced to a minimum, and the action of the latter, although firm, is smooth and steady. It is claimed that it enables work to be done with far more facility than in the ordinary brass stage, where the entire surface of the slide bears on it, and that it is altogether more agreeable. The slide- carrier is provided at each end with small milled heads for manipulation, and has spring clips and a stop for Maltwood finder.