Theodolite is one of the widely used instruments known for taking accurate measurements of horizontal and vertical angles. This instrument has other applications as well – helps to locate a point on a line, prolonging survey lines, finding elevation differences, ranging surveys, etc.
The primary classification of a theodolite are – transit and non-transit.
When telescope of a theodolite is transited, it is called a transit theodolite – takes a complete revolution around its horizontal axis in the vertical plane. On the other hand, a theodolite is said to be a non-transit when you are unable to transit it telescope. The non-transit theodolites have almost lost their use over the years, and that is why you won’t be able to see their application anywhere anymore in the world.