Spirit level

Different types of spirit levels may be used by carpenters, stonemasons, bricklayers, other building trades workers, surveyors, millwrights and other metalworkers, and in some photographic or videographic work.

Within a year of this date the inventor circulated details of his invention to others, including Robert Hooke in London and Vincenzo Viviani in Florence.

It is occasionally argued that these "bubble levels" did not come into widespread use until the beginning of the 18th century — the earliest surviving examples being from that time — but Adrien Auzout had recommended that the Académie Royale des Sciences take "levels of the Thevenot type" on its expedition to Madagascar in 1666.

[2] The device was unique in that it could be placed on a machine bed and show tilt on the x-y axes simultaneously, eliminating the need to rotate the level 90 degrees.

Production of the level stopped around 1970, and was restarted in the 1980s by Thomas Butler Technology, also of Rockford, Illinois, but finally ended in the mid-1990s.

Early tubular spirit levels had very slightly curved glass vials with constant inner diameter at each viewing point.

These vials are filled, incompletely, with a liquid — usually a colored spirit or alcohol — leaving a bubble in the tube.

Alcohols also have a much wider liquid temperature range, and will not break the vial as water could due to ice expansion.

This reading indicates to what extent the surface is parallel to the horizontal plane, according to the level, which at this stage is of unknown accuracy.

The sensitivity of a level is given as the change of angle or gradient required to move the bubble by unit distance.

A traditional carpenter's spirit level looks like a short plank of wood and often has a wide body to ensure stability, and that the surface is being measured correctly.

Precise levelling is supposed to give the difference in elevation between two points one kilometer (0.62 miles) apart correct to within a few millimeters.

These modern electronic levels are capable of displaying precise numeric angles within 360° with 0.1° to 0.05° accuracy, can be read from a distance with clarity, and are affordably priced due to mass adoption.

Digital levels, embedded with angular MEMS technology effectively improve productivity and quality of many modern civil structures.