Scientific American 1912-10-26.jpg Scientific American 1912-10-19ThumbnailsScientific American 1912-11-02Scientific American 1912-10-19ThumbnailsScientific American 1912-11-02Scientific American 1912-10-19ThumbnailsScientific American 1912-11-02Scientific American 1912-10-19ThumbnailsScientific American 1912-11-02Scientific American 1912-10-19ThumbnailsScientific American 1912-11-02

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