Palestine grid
The Palestine grid was the geographic coordinate system used in Mandatory Palestine.
The system was chosen by the Survey Department of the Government of Palestine in 1922.[1] The projection used was the Cassini-Soldner projection. The central meridian (the line of longitude along which there is no local distortion) was chosen as that passing through a marker on the hill of Mar Elias Monastery south of Jerusalem.[1] The false origin (zero point) of the grid was placed 100 km to the south and west of the Ali el-Muntar hill that overlooks Gaza city.[1] The unit length for the grid was the kilometre; the British units were not even considered.[1]
At the time the grid was established, there was no intention of mapping the lower reaches of the Negev Desert, but this did not remain true.[1] The fact that those southern regions would have negative northern coordinate then became a source of confusion, which was solved by adding 1000 to the northern coordinate in that case.[1] For some military purposes, 1000 was added to all northern coordinates, so that it then ranged uniformly from about 900 to about 1300.[1]