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 . They consist of a level mounted to a telescope fitted to a horizontal base graduated in degrees. The
assembly is mounted on a tripod which has a fitting for a plumb line is generally incorporated into the center of the base. They are used as a level when
locked into a horizontal position. Used in conjunction with a “leveling rod”, two people can do reasonably accurate layouts of level and horizontal angular
relationships over a significant distance. Degrees of elevation can be determined by elevating the telescope barrel which is fitted to a vertical axis scale
that is graduated in degrees. Accuracies of transits with the additional vernier scale on the horizontal are typically in the 1/4 degree range (15
minutes). Costs are in the $400 to $800 range.
Theodolites. 
While the transit is a very useful tool, what happens when an accuracy of 1/4 degree just isn’t good
enough. Enter the theodolite. The theodolite is to a transit as a micrometer is to a yard stick. Theodolites perform similar functions to transits but readings in
the 1 second range (1000 times finer than with a transit) are available for construction grade instruments.
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