Skip to content(44) STEREOPTICAN SLIDES used by Sutro to illustrate his lecture. Original photographic glass slides, English standard size 3¼ × 3¼ inches, in wood frames measuring about 7 × 4½ inches, about 126 of which 38 are hand colored photographs of drawings, mostly of scenes in the mines, 13 are black and white diagrams, 43 are photographs of executed sealed agreements between The Sutro Tunnel Company and the mines and 31 are hand colored original photographs of the Town of Sutro and the Sutro Tunnel | Collections | The Huntington