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  2. Philadelphia rod - Wikipedia

    en.wikipedia.org/wiki/Philadelphia_rod

    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. On the back of the rod the graduation decrease from 13.09 ft at the bottom to 7 ft.

  3. Level staff - Wikipedia

    en.wikipedia.org/wiki/Level_staff

    The metric rod has major numbered graduations in meters and tenths of meters (e.g. 18 is 1.8 m - there is a tiny decimal point between the numbers). Between the major marks are either a pattern of squares and spaces in different colours or an E shape (or its mirror image) with horizontal components and spaces between of equal size.

  4. Stadia mark - Wikipedia

    en.wikipedia.org/wiki/Stadia_mark

    S is the difference between the rod readings at the two stadia marks For example, a typical stadia mark pair are set so that the ratio is 100. If one observes a vertical length on a stadia rod, rule or levelling rod with the telescope and sees that the rod spans 0.500 m between the marks (the stadia interval ), then the horizontal distance from ...

  5. Spirit level - Wikipedia

    en.wikipedia.org/wiki/Spirit_level

    The Fell All-Way precision level, one of the first successful American made bull's eye levels for machine tool use, was invented by William B. Fell of Rockford, Illinois in 1939. [2] The device was unique in that it could be placed on a machine bed and show tilt on the x-y axes simultaneously, eliminating the need to rotate the level 90 degrees.

  6. Grade (slope) - Wikipedia

    en.wikipedia.org/wiki/Grade_(slope)

    This is not the usual way to specify slope; this nonstandard expression follows the sine function rather than the tangent function, so it calls a 45 degree slope a 71 percent grade instead of a 100 percent. But in practice the usual way to calculate slope is to measure the distance along the slope and the vertical rise, and calculate the ...

  7. Rod (unit) - Wikipedia

    en.wikipedia.org/wiki/Rod_(unit)

    The rod, perch, or pole (sometimes also lug) is a surveyor's tool [1] and unit of length of various historical definitions. In British imperial and US customary units, it is defined as 16 + 1 ⁄ 2 feet, equal to exactly 1 ⁄ 320 of a mile, or 5 + 1 ⁄ 2 yards (a quarter of a surveyor's chain), and is exactly 5.0292 meters.

  8. Measuring rod - Wikipedia

    en.wikipedia.org/wiki/Measuring_rod

    A measuring rod is a tool used to physically measure lengths and survey areas of various sizes. Most measuring rods are round or square sectioned; however, they can also be flat boards. Some have markings at regular intervals. It is likely that the measuring rod was used before the line, chain or steel tapes used in modern measurement. [1]

  9. Degree (angle) - Wikipedia

    en.wikipedia.org/wiki/Degree_(angle)

    This was called grade (nouveau) or grad. Due to confusion with the existing term grad(e) in some northern European countries (meaning a standard degree, ⁠ 1 / 360 ⁠ of a turn), the new unit was called Neugrad in German (whereas the "old" degree was referred to as Altgrad ), likewise nygrad in Danish , Swedish and Norwegian (also gradian ...