The forgotten nautical astronomical instruments

Astrology and meteorology have always had great importance for agriculture and navigation. This paper describes some measuring and forecasting instruments which, at their design epoch, had a moderate success in sailing a small sea like the Mediterranean, but then over time they were forgotten because they were supplanted by other more reliable instruments even in the largest seas. In particular, we refer to the instruments for astrology, starting with a device, the parapegma, made when meteorology was still a particular aspect of astrology. The second instrument is a calculator for determining the position of the stars; so some instruments are then described to establish, for example, the position of a ship with respect to the Sun or the North Pole, and others to determine direction and speed of ship. The short list ends with a return to meteorology with two storm forecasters, essential for quite sailing which, unfortunately, never worked as their inventors hoped.