In triangulation, in order to control the accumulation of errors of length and azimuth subsidiary bases are selected. At certain stations, the astronomical observations for azimuth and longitude are also made. These stations are called

Laplace Station:  A Laplace station is defined as a triangulation or traverse station at which a geodetic (Laplace) azimuth is derived from an astronomic azimuth by use of the Laplace equation. The Laplace equation expresses the relationship between astronomic azimuth, geodetic azimuth, and the astronomic longitude and geodetic longitude. the astronomic latitude is normally observed at each Laplace station. In the orientation of this type, a correction is made at the origin (initial point) which in effect reduces the sum of the squares of the astro-geodetic deflections at all the Laplace stations to a minimum.

∴ The triangulation stations at which astronomical observations for azimuth are made are called Laplace station.

Bowditch stations: It is used to eliminate the error in latitude or Departure of a line and in bearings of an open or closed traverse.