Work on the National Grid maps stopped for the duration of the war. However, it had not become established when World War II broke out and the Cassini Grid continued in use throughout the war. The Ordnance Survey National Grid was introduced in 1938 and the intention was to replace the Cassini Grid system with this. However, it is frequently not necessary to explicitly give the grid square at all, this can be implied from context. This is because square qY is three 100 km squares East of square vV and five 100 km squares North of vV. For instance qY 985 613 (somewhere around Carlisle) can also be expressed as 3985 5613. To do this, square vV (the South-West corner of the grid out in the Atlantic) is taken as square zero and then the grid squares are counted from there to the location being referenced. Grid references can also be given in an all numeral notation. For instance, wQ 683 825 is a location in South London. The complete grid reference includes both the grid square letters and the numerical reference giving the location within the grid square. Greater precision can be obtained by using six, eight, or even more digits, but always an even number with the same precision on both coordinates. That is, it is two squares across and seven squares up (counting from zero) from the reference corner. For instance, the grid reference 25 76 refers to a 1 km square within the 10 km square 2 7. These squares are numbered according to eastings and northings, that is, counting from the south-west corner of the 100 km square. Įach 100 km square is subdivided into 10 km squares, and each of these is further subdivided into 1 km squares. For instance, the squares covering London are wL and wQ. The full designation for a grid square is the 500 km letter in lowercase followed by the 100 km letter in uppercase. The 100 km squares are also given letters (with I omitted). Each 500 km square is further divided into 25 100 km squares. Ireland is covered by square I, but the Irish grid is tilted slightly to the East relative to the English grid. The squares covering England are Q, R, V and W with an intersection somewhere between York and Thirsk. The map is divided into a grid of 500 km squares. Hong Kong, for instance, was surveyed in 1962 for a series of 1:10,000 and 1:25,000 maps of the territory. However, the Cassini Grid system continued to be used to map colonial possessions into the 1960s. Īfter the war, the Cassini Grid system was replaced with the Ordnance Survey National Grid (see § Transition to National Grid). It continued in use until some time after World War II. It may also be referred to as Military Grid, War Office Grid, or Purple Grid (due to the grid colour on some issues of maps). The Cassini Grid system is thus more properly called the Modified British System. It modified and replaced a grid coordinate system first deployed in 1919 known as the British System. It is so called from the use of Cassini map projection. The Cassini Grid system was introduced in 1927 for maps of the United Kingdom for the British military. The system has been superseded by the Ordnance Survey National Grid. For a period after the war, the maps were also used by the general public. The referencing consists of square grids drawn on a Cassini projection. The Cassini Grid was a grid coordinate system used on British military maps during the first half of the twentieth century, particularly during World War II. This tool is perfect for locating precise geographical details for any location within Great Britain.Coordinate system used on British military maps These details can be found below the map. These coordinates include the latitude and longitude (in decimal degrees), the Ordnance Survey (OS) six-figure grid reference, and the OS grid square letter reference. Upon clicking, a marker will appear on the clicked location, and the corresponding geographical coordinates will be displayed on the screen. To pinpoint a specific location and get its geographical information, simply click anywhere on the map. You can also navigate around the map by dragging it with your mouse. Once you've entered your desired location, the map will automatically zoom in to the area. Begin by searching for a postcode or place in the search bar located at the top right corner of the map. Welcome to our interactive map! This tool allows you to find specific geographical coordinates for any location within Great Britain, based on your input.
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