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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").
Axis of altitude bubble and the vernier should read zero. These adjustments once made last for a long time. These are important for accuracy of observations taken from the instrument. The permanent adjustments in case of transit theodolite are:- Horizontal axis adjustment. The horizontal axis must be perpendicular to the vertical axis.
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).
Vernier theodolite; Total station; Transit (surveying) Tripod (surveying) Universal instrument (surveying) See also. Astronomical instrument; Measurement instrument ...
A retrograde vernier is similar to the direct vernier, except its graduations are at a slightly larger spacing than on the main scale. N graduations of the indicating scale cover N + 1 graduations of the data scale. The retrograde vernier also extends backwards along the data scale. Direct and retrograde verniers are read in the same manner.
The circles are read using a vernier scale, accurate to about 5 minutes of arc. [4] The design of his 1737 theodolite is the basis for modern instruments of this type. [17] The location of the boundary between the provinces of New York and New Jersey was long a source of violent disputes.
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Dividing engine at the Museo Galileo in Florence.. There has always been a need for accurate measuring instruments. Whether it is a linear device such as a ruler or vernier or a circular device such as a protractor, astrolabe, sextant, theodolite, or setting circles for astronomical telescopes, the desire for ever greater precision has always existed.