Lookout Show `n Tell #6: 1917 Osborne Fire-Finder

For a 3rd time in four years, Wm. B. Osborne again modified his fire-finding alidade instrument in 1917. Its weight was increased from 10 pounds to a hefty 70 pounds of cast iron. Its size went from 14" to the 24" circle that became the standard ever since.

Upright front and rear sights underwent a drastic change, from brass to iron. The front sight featured an endless thin brass tape that could be moved up and down freely with a gear-driven thumb screw; its pointer following the contour of the landscape that one sees in the distance. As you rotated the azimuth ring, while sighting with one eye through the rear sight, to the thin horse hair on the front sight, a pencil etched lines on a 24" paper circle, by sliding the pointer up or down as you followed the horizon and its closer peaks and valleys. The end result was a panoramic photo sketch of sorts, upon which the hills and valleys seen from the lookout could be labeled by name.

Leupold-Volpel Co. of Portland manufactured several hundred of them between 1917 and 1934.

1917 Osborne Fire Finder

1917 Osborne rear sight

1917 front sight assy.

1917 front sight & seen area marker

Next, the 1934 Osborne Firefinder.

Fire Lookout Museum