The Telescopic Alidade

KB alidade (1943), manufactured by the Geofizika factory · Source

The telescopic alidade (German kippregel, from kippen, “to tip”, and regel, “rule”) is a mechanical or optical surveying instrument for measuring differences in elevation, distances and vertical angles, and for constructing directions graphically and plotting them on a terrain plan.

Shiryayev KVSh-8 height-measuring alidade (1970) · Source

The alidade forms part of a plane-table surveying set — the plane table being a drawing table used in the field — for topographic surveys. An alidade usually includes:

• a supporting column;
• a telescope with stadia hairs, or a sight;
• a vertical circle, graduated in degrees, for determining angles of inclination;
• a tubular spirit level used for levelling;
• a graduated rule for plotting survey points on the plane-table board.

KA-2 automatic alidade (1973) on a plane table · Source

The alidade is used to sight survey points. The stadia hairs give the distance to a point. Its difference in elevation is determined from the vertical angle and distance. The rule is used to plot the line towards the point and its distance on the board.

Plane-table surveying with an alidade is used, for example, in railway surveys to prepare plans of bridge crossings and difficult terrain.

MOM MA-5 alidade (1970, Hungary) · Source

In our country, a nomographic alidade was also mass-produced in two versions from 1976 onwards.

Further reading