Foul (nautical) Foul (nautical) Foul is a nautical term meaning to entangle or entwine, and more generally that something is wrong or difficult. The term dates back to usage with wind-driven sailing ships. It is usually applied to the state of an anchor, which has become hooked on some impediment on the seafloor, or has its cable wound round the stock or flukes. The term is generally utilized when speaking of items of historical value such as the US Navy chief petty officer emblem. The foul anchor is also the official seal of the Lord High Admiral of the United Kingdom, presently
Grade measurement Grade measurement Grade measurement is the geodetic determination of the local radius of curvature of the figure of the Earth by determining the difference in astronomical latitude between two locations on the same meridian, the metric distance between which is known. The first known grade measurement was performed by Eratosthenes (240 BC) between Alexandria and Syene in what is now Egypt, determining the radius of the Earth with remarkable correctness. The Dutch geodesist Snellius (~1620) repeated the experiment between Alkmaar and Bergen op Zoom using more modern geodetic instrumentation. Later grade measurements aimed at determining the flattening of the Earth