Hand levels (or sight levels) were standard issue for sanitarians, particularly those who worked in rural areas. Sanitarians use a sight level to get a rough idea of where the grading is on a particular site. This type of sight level is handy for doing preliminary land survey work and distance estimation of septic systems and drainage swales. They are an easy way to develop “cut and fill” plans for grading of a site. It is also used to easily determine if a specific area of land is generally level. Once the instrument is level (guided by the spirit level), the user looks through the telescope to compare different points against the same reference point.
Sight levels were first created around 1661, when Melchisédech Thévenot, a French scientist, attached a spirit level to a telescope. The one pictured above is an early tubular design from 1930.