Carpentry/Survey/Transit

A transit level is composed of a sighting instrument usually a tripod that serves as a fixed point from which to sight readings taken usually from a stick with rule marks on it [usually in one inch, one foot, or one tenth of one foot and one foot increments, but also metric scales exist] that is usually held and moved by an assistant. The readings taken are also usually marked by wooden stakes placed at those points and the stakes will be driven to precise depths so as to serve as reference points with the end goal being to determine the deviation of various points in terms of height, elevation, or evenness differences. A chosen zero point indicates which other points will need to be lowered or raised in order to level and grade a given plot of land for example.