M-261 Advertising Slide for 1920's Projector, to be shown in public movie theaters during intermission. This glass slide, by the Bellevue Herald, shows a "Harvesting in California with Mules". Original and Made by the National Slide Corp., Detroit, Mich. The slide is black and clear with sharp focus...and beautiful! The slide measures 4 inches by 3.25 inches. The photos I took don't do it justice!