Published online by Cambridge University Press: 18 January 2010
The method of finding the latitude of a ship at sea from an observation of the Sun or other body near the meridian is practised extensively in the Merchant Navy. The history of the method, which dates from the middle of the eighteenth century, is full of interest: and the ex-meridian problem is almost as celebrated in the history of nautical astronomy as the double altitude problem. Considerable attention was devoted to the ex-meridian problem during the last century—a period which was, in truth, the golden age of astronomical navigation. Many ingenious solutions were contrived and a diversity of ex-meridian tables were constructed, all aimed at facilitating the problem of finding latitude at sea.