I have described already the general principles and features of this system. When it is applied to a floating beacon, and it is desired to save the oil dropping from the drip valve, a tank is fixed to the deck of the floating structure, and connected by a flexible pipe to the coupling at the bottom of the float cylinder. A universal joint is attached to the connection on the top of the tank to prevent the pipe being twisted by the swinging and swaying motion of the lamp on the gimbals. When the lamp is inspected, the oil may be pumped out of the tank, strained, and used time after time in the float cylinder. One of the most interesting of this type of floating boat-lights is to be seen in Queenstown harbour. The hull is 30 feet in length, and has a beam of 11 feet. On this, within a conical structure measuring 7½ feet high and 6½ feet in diameter at the deck, is mounted the lantern. Although the lamp is exposed to drenching seas and heavy storms, it has never yet failed, a fact which conclusively points to its efficiency. It rides well, and the lamp is kept much drier than the lights on ordinary buoys, according to the observations of the engineer responsible for its maintenance. In this case the focus of the light is brought 12 feet above the level of the sea. Probably the most compelling illustration of the utility of the automatic beacon is offered by the unattended lightship. The Otter Rock vessel is one of the most interesting examples of this development. It was designed by Messrs. D. and C. Stevenson, and comprises a substantial steel hull, the deck of which is covered so that the interior is absolutely water-tight. The craft is provided with a central and heavy bilge keels, so as to reduce rolling to the minimum. Two heavy steel bulkheads divide the craft into three water-tight compartments, in the centre of which two large welded-steel gas tanks are stowed. These are of sufficient capacity to feed the light for several months without replenishment. The light is mounted upon a steel tower placed amidships, which brings the focal plane 25 feet above the water. The gas is fed from the tanks to the lantern through the tower, a valve reducing the pressure, while a ladder enables the attendants to climb to the lantern gallery to adjust the burner and flame, and to clean the lenses, upon the occasion of their periodical visits.