AN IMPORTANT NAUTICAL DISCOVERY.

Inangahua Times, Volume IX, Issue 1392, 25 April 1884, Page 2

AN IMPORTANT NAUTICAL DISCOVERY.

A valuable instrument has been invented by Capt Holdich, of the ship British Envoy, for determining tlie exact position of a vessel by cross bearings without the aid of a compass. Its simplicity commends it at once, as it can immediately be seen that no error can arise. Captain Holdich, who has used it for three years, refuses to take advantage of his discovery by patenting the instrument, as he thinks his brother shipmasters should have the benefit of it, and there is 'no doubt that all vessels ought to be provided with one, -.is the work of obtaiaing an exact position can he done in a minute. Captain Holdich describes his invention as " an instrument for marking ship's position without compass bearing." A brass circle grandnated from nonius to 180 degrees right and left is affixed to a board about lOin square. On a centre pin four pointers or arms revolve, the lowest of which is marked, to prevent mistakes. To use it the arms are undamped, and the board taken to any part of the ship, even up aloft if more convenient, where bearings cao be obtained. The lower arm is then pointed to the most prominent landmark ; keeping the board steady, the other arms are pointed to any other landmarks, and the whole is then clamped -firmly. The board is next taken to the chartroom, where the clamped arms are taken off and placed on the chart, the lowest arm being kept over the observed most prominent landmark, and all are then moved together until the arms cover the other landmarks, when through a hole in the centre where the clamp is fixed a pencil or compass point is placed, and this marks the position oF the vessel on the chart within a few jyards. To get the position absolutely, a sextant has to be used to measure th« angles from tho leading land-

mark to the others, and the 1 arms on the graduated rim have to be fixed to the observed angles. The advantages claimed for the instrument are no liability to error of position from misapplying compass variation or deviation, a very common cause of mistake, and it can be used in all weathers and under any circumstances. For steamers on coasting voyages, where quick and reliable observations are a desideratum, the instiumeutwill answer all purposes, and an inexperienced man can get his position withiu a quarter of a mile, and one accustomed to it can limit thu error to witliin a yard. Were it not for the short time that the Bdtis'i Envoy wilt* now be iv port, Captain Holdich would have allowed the instrument to be exhibited in the Exchange, but most likely one will shortly be made here, when it will be shown.— Age, April 2.