Osborne Fire Finder

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A USFS Fire Lookout using an Osborne Fire Finder while on duty at Vetter Mountain, California.

An Osborne Fire Finder device used in fire lookout towers.

The Osborne Fire Finder is a device used by fire lookouts in order to find a directional bearing (azimuth) to smoke in order to alert fire crews to a wildland fire.

The device was invented by William "W.B." Osborne, a United States Forest Service employee from Portland, Oregon, and has been in service since 1920. Mr. Osborne also designed the photo-recording transit for making panoramic records of forest conditions, as well as a collapsible water-bag knapsack for firefighting (U.S. patented in 1935). Many fire finders were manufactured from 1920 through 1935 but after 1975, the manufacturer Leupold & Steven, Inc. stopped production of replacement parts. With the resurgence and recovery of fire lookout towers, new Osborne devices were needed. The U.S. Forest Service, San Dimas Technology and Development Center (SDTDC) was contacted regarding the deteriorating condition of the Osborne Fire Finders housed in fire lookouts throughout the United States.

A pilot program to create new Osbornes was coordinated with manufacturer, Palmquist Tooling, Inc. and now Osborne Fire Finders are available again.

The system is comprised of a topographic map of the area oriented and centered on a horizontal table with a circular rim graduated in degrees (and fractions). Two sighting apertures are mounted above the map on opposite sides of the ring and slide around the arc.

The device is used by moving the sights until the observer can peek through the nearer sighting hole and view the cross hairs in the further sight aligned with the fire. The fire lookout notes the degrees on the graduated ring beneath the sight. A crude estimate of elevation and distance can also be made based upon the level and elevation of the table, with reference to the relevant map features and by measuring to the scale shown on the map. Sightings from multiple towers may be used to triangulate the location with more precision. Dispatchers at a central facility then use a compass rose centered on each reporting tower on a large map to quickly find where the reported bearings intersect.