The compartment _D_ was furnished with a hood, having slits 1/4 of an inch wide, all round, through which the steersman could see with sufficient distinctness to direct his course easily. Motion was communicated from the wheel to the tiller by means of steel wire ropes, which it was originally intended should be encased in wrought iron tubes. The possibility however of these tubes being bent by a shot, and so jamming the wire ropes, led to this arrangement being abandoned, and the ropes were simply run through eyes at intervals along the side. The armament consisted of a cylindro-conical shaped torpedo towed from the top of the funnel, round which a ring was fitted with two pulleys for the towing rope, the strain being taken off by means of two stays attached forward. The length of this torpedo was 13 feet and the diameter 9 inches, and with a speed of 11 knots it has diverged to about 40 degrees from the direction of the boat's motion when running in smooth water. The torpedo is worked by means of a small winch and brake fixed on the after part of the engine room skylight; davits are provided for dropping the torpedo overboard. The engines were compound, of the usual inverted double cylinder direct acting type, capable of developing about 90 indicated horse power, and were fitted with a surface condenser, so that the vessel could run in salt water, without danger of injuring her boiler. A small tank contained a supply of fresh water, to make good deficiencies arising through leakage, and from steam escaping at the safety valves, &c. The circulating, air, and feed pumps were driven by a separate engine. The boiler was of the locomotive type, the shell being made of Bessemer steel; the fire box and its stays of copper, and the tubes of solid drawn brass. On the official trial, which took place on the Thames on the 17th of October, 1873, the number of revolutions done in the hour was found to be 27,177, and the number required to do a mile in still water was 1578. The distance run in the hour was then, 27,177/1578 = 17·22, or very nearly 17-1/4 miles. The steam pressure during the trial averaged 85 lbs. per square inch, and the vacuum 25-1/2 inches. _Swedish and Danish Boats._--Boats of the same size and similar in all particulars to the foregoing one--excepting the engines, which are improved by driving the air pump, feed pump, and circulating pumps off the main engines, and abolishing the auxiliary engine, which performed these duties in the case of the Norwegian boat--were made for the Swedish and Danish governments. The result was an increase of speed to 17·27 miles in the case of the Swedish boat, and to 18·06 miles, or 15-5/8 knots, in the case of the Danish boat.