In the era before moving pictures, magic lantern slide shows were a relatively common form of public performance. Even when movies had come to dominate, the magic lantern slides could be used between often between reels to show advertisements. Illustrations, like this one of Noronic, were used to advertise company services, a service that might repay the extra work of tinting the slide.
Noronic: Canada Steamship Lines Ltd. on Great Lakes Canada Details
Keystone came to be the dominant company in the North American stereoview business. Many of their images were boxed in educational sets for schools and public libraries. Some of these were repurposed as magic lantern slides for the educational market. The numbers on the side referred to the set numbers, and the accompanying booklets.
Locks and Vessels in Ship Canal, Sault Ste. Marie, Michigan Details