Sound like good old lantern slides to me. This fore-runner of the present slide projector was a lantern used to throw an image on the side of a building outdoors, usually. Lantern slide or "illuminated presentations" were common during the Chautauqua period (1885-1920) for lectures to audiences. Frankly, until the arrival of electricity, many evening events for Chautauqua groups were these lantern slide programs. Many of the glass slides were black and white photos and then hand-colored. Such presentations included images of Yosemite, and others. We have a small group here as well. We also have a photographic collection of a local photographer; these are glass plate negatives (about 7,000) mostly 5 x 7 in size, but probably 1,000 are 8 x 10. ---Dean DeBolt, Special Collections, University of West Florida