Nautical chart a Mercator's projection map, a square is a square no matter where you are on the chart, but a square on the Arctic Circle is much bigger than a square at the equator, even though both occupy the same number of degrees on the globe. The result of this is that scale in a nautical chart is dependent on latitude. In practical use, this is less of a problem than it sounds. One minute of latitude is, for practical purposes, a nautical mile. Distances in nautical miles can therefore be measured on the latitude gradations printed on the side of
The Nautical Almanac The Nautical Almanac The Nautical Almanac has been the familiar name for a series of official British almanacs published under various titles since the first issue of "The Nautical Almanac and Astronomical Ephemeris", for 1767: this was the first nautical almanac to contain data dedicated to the convenient determination of longitude at sea. It was originally published from the Royal Greenwich Observatory in England. A detailed account of how the publication was produced in its earliest years has been published by the National Maritime Museum. Since 1958 (with the issue for the year 1960), [[Her Majesty's Nautical Almanac Office]] and