The Osborne Fire Finder is a type of alidade used by fire lookouts to find a directional bearing (azimuth) to smoke in order to alert fire crews to a wildland fire.
The Osborne Fire Finder is a type of alidade used by fire lookouts to find a directional bearing (azimuth) to smoke in order to alert fire crews to a wildland fire.
The forerunner to the device was invented around 1840 by Sir Francis Ronalds to help combat fire in London – he also named his innovation the "Fire Finder". Ronalds's fire finder comprised a theodolite atop a watchtower. Bearings and vertical angles from the horizon to surrounding features were recorded either on a surrounding cylinder in the form of a panorama or on a circular table at the base of the instrument. The location of any fire could thus be pinpointed even in the dark. [1]
The modern version was created by William "W. B." Osborne, a United States Forest Service employee from Portland, Oregon, and has been in service since 1915. 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 (patented in the US in 1935). Many fire finders were manufactured from 1920 through 1935, but the manufacturer, Leupold & Stevens, Inc., stopped production of replacement parts after 1975.
In recent years[ when? ], 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[ when? ] Osborne Fire Finders are once again available.[ citation needed ]
The system is composed 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. Early Fire Finders were capable of a crude estimate of elevation based upon the level and elevation of the table, calculating distance and rough position of the fire by reference to any distinctive terrain features and by use of the scale shown on the map. However, in actual practice, fire distance and location were normally established using two or more Fire Finder-equipped towers, using the intersection method to fix the precise location of the fire. [2] [3] Dispatchers at a central facility used a compass rose to mark lines of position from each reporting tower onto a large map to quickly find where the reported bearings intersect.
Today, a more precise determination of a fire location can be made by the use of a single Fire Finder in conjunction with a digital elevation model (DEM). [4]
Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. These points are usually on the surface of the Earth, and they are often used to establish maps and boundaries for ownership, locations, such as the designated positions of structural components for construction or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales.
An alidade or a turning board is a device that allows one to sight a distant object and use the line of sight to perform a task. This task can be, for example, to triangulate a scale map on site using a plane table drawing of intersecting lines in the direction of the object from two or more points or to measure the angle and horizontal distance to the object from some reference point's polar measurement. Angles measured can be horizontal, vertical or in any chosen plane.
Parry Sound District is a census division of the Canadian province of Ontario. Its boundaries are District of Muskoka to the south, the Sudbury District to the north-northwest, the French River and Lake Nipissing in the north, Nipissing District and North Bay in the north and east and parts of Algonquin Park in the northeast.
Black Elk Peak, formerly known as Harney Peak, is the highest natural point in the U.S. state of South Dakota and the Midwestern United States. It lies in the Black Elk Wilderness area, in southern Pennington County, in the Black Hills National Forest. The peak lies 3.7 mi (6.0 km) west-southwest of Mount Rushmore. At 7,244 feet (2,208 m), it is the highest summit in the United States east of the Rocky Mountains. Though part of the North American Cordillera, it is generally considered to be geologically separate from the Rocky Mountains.
A fire lookout is a person assigned the duty to look for fire from atop a building known as a fire lookout tower. These towers are used in remote areas, normally on mountain tops with high elevation and a good view of the surrounding terrain, to spot smoke caused by a wildfire.
A fire lookout tower, fire tower, or lookout tower is a tower that provides housing and protection for a person known as a "fire lookout", whose duty it is to search for wildfires in the wilderness. It is a small building, usually on the summit of a mountain or other high vantage point to maximize viewing distance and range, known as view shed. From this vantage point the fire lookout can see smoke that may develop, determine the location by using a device known as an Osborne Fire Finder, and call for wildfire suppression crews. Lookouts also report weather changes and plot the location of lightning strikes during storms. The location of the strike is monitored for a period of days afterwards, in case of ignition.
The Angeles National Forest Fire Lookout Association ("ANFFLA") is a non-profit 501(c)(3) organization of citizen volunteers dedicated to the preservation, restoration and operation of the fire lookout towers in the Angeles National Forest, Los Angeles County, and other Southern California areas. The organization works in partnership with the federal, state, county and city agencies to meet these goals.
Base end stations were used by the United States Army Coast Artillery Corps as part of fire control systems for locating the positions of attacking ships and controlling the firing of seacoast guns, mortars, or mines to defend against them. A British equivalent was the position finding cell.
A fire control tower is a structure located near the coastline, used to detect and locate enemy vessels offshore, direct fire upon them from coastal batteries, or adjust the aim of guns by spotting shell splashes. Fire control towers came into general use in coastal defence systems in the late 19th century, as rapid development significantly increased the range of both naval guns and coastal artillery. This made fire control more complex. These towers were used in a number of countries' coastal defence systems through 1945, much later in a few cases such as Sweden. The Atlantic Wall in German-occupied Europe during World War II included fire control towers.
The Hickory Ridge Fire Tower is a Fire lookout tower located in the Charles C. Deam Wilderness Area. It is an Aermotors type lookout tower.
A plane table is a device used in surveying, site mapping, exploration mapping, coastal navigation mapping, and related disciplines to provide a solid and level surface on which to make field drawings, charts and maps. The early use of the name plain table reflected its simplicity and plainness rather than its flatness. "Plane" refers to the table being both flat and levelled (horizontal).
Black Mountain is a mountain located in Washington County, New York, of which its peak is the highest point. Isolated from the rest of the Adirondack Mountains by Lake George, Black Mtn. has the seventh highest topographic prominence of all the mountains in New York. Black Mountain also has the highest elevation of any of the peaks which surround Lake George and offers unobstructed views of the lake from its summit.
A hand compass is a compact magnetic compass capable of one-hand use and fitted with a sighting device to record a precise bearing or azimuth to a given target or to determine a location. Hand or sighting compasses include instruments with simple notch-and-post alignment ("gunsights"), prismatic sights, direct or lensatic sights, and mirror/vee (reflected-image) sights. With the additional precision offered by the sighting arrangement, and depending upon construction, sighting compasses provide increased accuracy when measuring precise bearings to an objective.
Position resection and intersection are methods for determining an unknown geographic position by measuring angles with respect to known positions. In resection, the one point with unknown coordinates is occupied and sightings are taken to the known points; in intersection, the two points with known coordinates are occupied and sightings are taken to the unknown point.
A lookout tree is a simple fire lookout tower created by attaching a ladder or a series of spikes to a tall straight tree with a view of the surrounding lands, allowing rangers or fire crews to conveniently climb the tree to survey their surroundings. The simplest kind consist only of a ladder to a suitable height: this kind was called a "ladder tree." Some ladder trees had platforms on the ground next to them for maps and a fire finder. A more elaborate version often created a platform on top of the tree trunk by cutting off approximately the last 10 feet (3.0 m) of the treetop and building a railed wooden platform on the resulting stump. These "platform trees" were often equipped with telephones, fire finder tables, seats and guy wires. Accommodation for the watcher was provided by a tent or shelter at the bottom of the tree.
The lookout trees in Kaibab National Forest are the survivors of a system of improvised fire lookout towers that used tall, straight trees as vantage points. The practice of using trees as lookouts was widespread in the western United States during the early 20th century, as there was no need to build a foundation or to pack and assemble a tower structure. Instead, a prominent tree could be selected, and a ladder or a series of spikes could be attached to the tree trunk. For transient use this could be all that was done, but for more permanent use the top 10 feet (3.0 m) of the tree could be lopped, and a platform constructed on the resulting stump. This railed platform was then outfitted with a seat and a platform for an Osborne Fire Finder.
The Salmon Mountain Lookout, on Salmon Mountain in the West Fork District of Bitterroot National Forest, near Darby, Idaho, was built in 1949. It was listed on the National Register of Historic Places in 2018.
Fairview Peak Lookout is a fire lookout tower located at the summit of Fairview Peak in Gunnison County, Colorado. The lookout lies within the Fossil Ridge Recreation Management Area of the Gunnison National Forest. At an elevation of 13,214 feet (4,028 m), the one-room stone structure with a second-story wooden cupola is the highest elevation fire lookout constructed in the United States.
A bearing compass, is a nautical instrument used to determine the bearing of observed objects.. Used in navigation to determine the angle between the direction of an object and the magnetic north or, indirectly relative to another reference point. Provides the absolute bearing, which is the clockwise angle between magnetic north or true north and the object. For example, an object to the east would have an absolute bearing of 90º, if it is relative to the magnetic north than it is called magnetic bearing. It is commonly used by geologists and surveyors to obtain precise bearings on the ground.
