Anemometrical Observations on Board Ship ¹

Abstract

IT is known that the determination of the velocity of the wind in the ocean has always been one of the desiderata of meteorological observations. Maury devoted much attention to this subject, and to determine, at least approximately, the velocity of trade-winds, he was compelled to work on a very unsafe basis—the velocity of ships during different parts of the year—and to put aside all observations made in accordance with the scale of Beaufort as unreliable. But it is obvious that the velocity of a ship depends on so many circumstances quite independent of the wind itself (such as the shape of the ship, the surface of its sails, the disposal of the cargo, and so on), that its velocity is but a very imperfect means of measuring the velocity of wind. Besides, the relation which exists between the force of the wind and the velocity of a ship, under different angles between the direction of both, is a new source of error, as this relation has not yet been established with accuracy, and can be established only by means of anemometric measurements. The necessity of trustworthy measurements of the velocity of wind at sea was so well understood in England that the Royal Society and the British Association established in 1859 two anemometers—one on the Bermuda Islands, and the other at Halifax. But it is known that the force of the wind is usually lessened on continents and islands.