Scientific American 1912-10-26.jpg Scientific American 1899-11-04ThumbnailsScientific American 1899-11-04ThumbnailsScientific American 1899-11-04ThumbnailsScientific American 1899-11-04ThumbnailsScientific American 1899-11-04Thumbnails
A triple mirror for secret signaling. Signaling with one hand and watching the returning ray through the attached Zeiss prism monocular.



Source: Steve Kirch, collector, and creator of a great website about SCIENTIFIC AMERICAN in the past

Restoration by: magscanner