signal mirror:
US Signal Service Model 1892 "Kilbourne" Heliograph Shutter - Side A
signal mirror:
US Signal Service Heliograph Model 1892 Simplex
signal mirror:
US Signal Service Heliograph, from Gallup, 1893, p. 30
signal mirror:
US Heliograph Screen of 1892 - The Kilbourne Two-Blade Screen
signal mirror:
US Signal Service Model 1892 "Kilbourne" Heliograph Shutter - Side B
signal mirror:
US Signal Service Model 1892 "Kilbourne" Heliograph Shutter
signal mirror:
1892 Kilbourne Heliograph Screen HDR
signal mirror:
US Signal Service Model 1892 "Kilbourne" Heliograph Shutter - Base in Case
signal mirror:
US Signal Service Model 1892 "Kilbourne" Heliograph Shutter
signal mirror:
US Signal Service Model 1892 "Kilbourne" Heliograph Shutter
signal mirror:
1892 Kilbourne Heliograph Shutter Open