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A level staff, also called levelling rod, is a graduated wooden or aluminium rod, used with a levelling instrument to determine the difference in height between points or heights of points above a vertical datum. When used for stadiametric rangefinding, the level staff is called a stadia rod.
It is still widely used in long-range military sniping, but in many professional applications it is being replaced with microwave, infrared, or laser rangefinding methods. Although much easier to use, electronic rangefinders can give away the shooter's position to a well-equipped adversary, and the need for accurate range estimation has existed ...
The level staff is placed with its foot on the point for which the level measurement is required. The telescope is rotated and focused until the level staff is plainly visible in the crosshairs. In the case of a tilting level, the fine level adjustment is made by an altitude screw, using a high accuracy bubble level fixed to the telescope.
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Diagram showing relationship between two level staff, or rods, shown as 1 and 3. The level line of sight is 2. The surveyor looks through the eyepiece of telescope while an assistant holds a vertical level staff which is graduated in inches or centimeters. The level staff is placed vertically using a level, with its foot on the point for which ...
A Philadelphia rod is a level staff used in surveying. The rod is used in levelling procedures to determine elevations and is read using a level. A Philadelphia rod consists of two sliding sections graduated in hundredths of a foot. On the front of the rod the graduation increasing from zero at the bottom.
Stadia marks on a crosshair while viewing a metric levelling rod.The top mark is at 1.500 m and the lower is at 1.345 m. The difference between the rod readings is 0.155 m, yielding a distance to the rod of 15.5 m.
In 1914 and 1915, the Forestry Quarterly published a series of articles on the use of the Abney level. [6] [7] [8] These tutorial articles remain useful today, but the primary reference for usage is the 1927 Abney Level Handbook. [3] The Abney level is typically used at the eye height of the surveyor, either hand-held or mounted on a staff at ...