Nautical mile latitude could be used as the basis for a unit of measurement for distance and proposed the nautical mile as one minute or one-sixtieth () of one degree of latitude. As one degree is of a circle, one minute of arc is of a circle (or, in radians, ). These sexagesimal (base 60) units originated in Babylonian astronomy. Gunter used Snell's circumference to define a nautical mile as 6,080 feet, the length of one minute of arc at 48 degrees latitude. Since the earth is not a perfect sphere but is an oblate spheroid with slightly flattened poles, a minute
Adlard Coles Nautical Adlard Coles Nautical Adlard Coles Nautical is a nautical publisher, with over 300 books in print. The company publishes books on topics of interest to sailors and motorboaters and also ‘landlubbers’ with an interest in the sea. Their list includes almanacs, cruising guides, pilot books and how-to instruction books, as well as large format photographic books, sailing narratives and sea-related reference, maritime history, humour and trivia books. Adlard Coles Nautical has been part of Bloomsbury Publishing since 2003. The company was founded by yachtsman Kaines Adlard Coles in 1947. He wrote many of the books, including pilots, sailing narratives and