s of different metals, so arranged that the distance between the two points viewed by compensation microscopes remains constant under all changes of temperature.
For account of measurements of degrees of latitude, see odometer.
The method of triangulation in a great survey, by means of quadrilaterals, is purely American in its origin, having been first introduced by the late Professor Bache. — Prof. Peirce.
The measuringcom-pass was invented by Jost Bing of Hesse, in 1602.
See circumferentor; theodolite.
An instrument employed for establishing perpendicular lines in surveying.
It has four sights fixed at right angles upon a brass cross, which can be screwed to a tripod or single staff.
The instrument is adjusted so that one pair of sights coincide with a given or base line, when a line perpendicular to the former can be easily observed, traced, or set out by viewing through the other pair of sights