Lookout Snow `n Tell #5: 1914-1915
Osborne Fire-Finder
Wm. B. Osborne's first fire finder in 1913 was an
alidade with 360 degree bearings, like that of a compass, etched on
the outer rim of a circular iron map plate, with two brass upright sights
on a center pivot bar.
In 1914 he changed the front and rear pivot sights
to fit on an outer iron ring, which revolved around a cast iron base that fit
snugly on a sliding rail tabletop. This allowed the lookout to
see around obstacles such as corner posts in the building.
By 1915, a 0-power sighting tube resembling a
rifle scope was added between the front and rear brass upright sights. The
circular map disc remained 14" in diameter, and the instrument remained much the
same as in 1914. An azimuth reading on the base of a distant smoke could
be obtained, accurate to 1/60th of 1 degree on the compass. A
vertical angle reading could also be obtained, with accuracy to within 1/10th of
one degree above or below the zero elevation. About 300 were
made between 1915 and 1917 for state and federal forestry agencies in Portland,
Oregon by Leupold-Volpel & Co.
Next, the 1917 Osborne
Fire-Finder.
Ray Kresek
Fire Lookout Museum
Spokane,
Washington
