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The term transit theodolite, or transit for short, refers to a type of theodolite where the telescope is short enough to rotate in a full circle on its horizontal axis as well as around its vertical axis. It features a vertical circle which is graduated through the full 360 degrees and a telescope that could "flip over" ("transit the scope").
A total station or total station theodolite is an electronic/optical instrument used for surveying and building construction. It is an electronic transit theodolite integrated with electronic distance measurement (EDM) to measure both vertical and horizontal angles and the slope distance from the instrument to a particular point, and an on ...
The permanent adjustments of theodolites are made to establish fixed relationship between the instrument's fundamental lines. The fundamental lines or axis of a transit theodolite include the following:- Vertical axis; Axis of plate levels; Axis of telescope; Line of collimation; Horizontal axis; Axis of altitude bubble and the vernier should ...
The initial setting operation includes fixing the theodolite on a tripod, along with approximate levelling and centering over the station mark.For setting up the instrument, the tripod is placed over the station with its legs widely spread so that the centre of the tripod head lies above the station point and its head approximately level (by eye estimation).
A transit level also has the ability to measure both the altitude and azimuth of a target object with respect to a reference in the horizontal plane. The instrument is rotated to sight the target, and the vertical and horizontal angles are read off calibrated scales [ 4 ]
The similar transit instrument, transit circle, or transit telescope is likewise mounted on a horizontal axis, but the axis need not be fixed in the east–west direction. For instance, a surveyor's theodolite can function as a transit instrument if its telescope is capable of a full revolution about the horizontal axis. Meridian circles are ...
Allow transit measurements in any direction . Theodolite (Describing a theodolite as a transit may refer to the ability to turn the telescope a full rotation on the horizontal axis, which provides a convenient way to reverse the direction of view, or to sight the same object with the yoke in opposite directions, which causes some instrumental errors to cancel.
A theodolite is used to measure the horizontal angle between indicators on the two ends of the subtense bar. The distance from the telescope to the subtense bar is the height of an isosceles triangle formed with the theodolite at the upper vertex and the subtense bar length at its base, determined by trigonometry .