Page:Royal Naval Biography Marshall v4p2.djvu/509

  the rank of lieutenant in Sept. 1815; and served as such on board the Dispatch sloop, Comm. William Clarke Jervoise, on the Mediterranean station. In 1830, being then a commander, he was appointed to superintend the instruction of officers and seamen in gunnery, on board the Excellent 58, at Portsmouth; and all inventions relating to this part of the equipment of a man-of-war, were referred for his opinion. He was promoted to the rank of captain “for improvements in gunnery,” April 13th, 1832.

This officer is the inventor of very superior sights for ships’ guns, and of a moveable target, at which the crews of H.M. ships are now generally practised, for the purpose of instructing them in the art of pointing the great guns. The target is thus spoken of in the Hampshire Telegraph:–

“As the advantage of dispart or top-sights is now generally acknowledged, the object is – first, to teach seamen the application of them, as simply and expeditiously as possible; and, secondly, how to fire when their ship is rolling, or when firing at a moving object. The principle of the invention is entirely novel, and its name does not convey an adequate idea of its nature and utility. The following may make it intelligible:– On one end of a wooden bar, or lever, about eight feet long, is hung a light frame, three feet square, filled with canvas; on one side a white cross is painted, on the other a circle, with a bull’s eye. The lever vibrates from the centre, on a pin attached to an octagon block of wood, eighteen inches in length, and eight in diameter, on which is the requisite machinery to allow it a vertical and lateral motion, either singly or together, and to stop them both at the same instant: the lever is balanced by a weight at the opposite end, the whole suspended by an iron bar, about three feet long, to cne of the foremost beams on the main deck, either object of the target facing aft. A gun, ascertained not to be loaded, is run in under the half deck, and the men taught the first principle of pointing, by being made to bring the sights and a fixed object directly in one, the target being stationary. The lever is then made to vibrate, which causes the object to pass and repass before a man’s eye, as he keeps the sights in one, so as to represent the effect of his ship when rolling; and by the simple application of a line (the main feature of the invention) rove through a fair leader at the ventfield, representing a lock lanyard, and carried along under the beams to a trigger in the machinery of the target, a man, who is made to stand with it at a 