Heliograph mirrors. The mirror facing the viewer catches the sun and reflects it to the second mirror, which in turn reflects the light to the shutter. When the operator was signaling toward the sun, only one mirror was used.
Heliograph shutter. By opening and closing the shutter, the sunbeam reflected by the heliograph mirrors was modulated into the dots and dashes of Morse Code for signaling. The six-bladed shutter was introduced in 1905, and replaced the two-bladed shutter of 1892, which, in turn, replaced the single-bladed shutter of 1888.
The heliograph is comprised of these two tripods and the hardware mounted thereon. The two wooden tripods had a 60 deg sector cross section for each legs, and the six legs of the two tripodsnested together in a circular cross-section for transport. The mirror tripod at left held the sun-reflecting mirrors on a mirror bar. The mirror bar had azimuth adjustment knobs, and the mirrors had elevation adjustment knobs. The shutter tripod at right had blades worked by a side lever.
