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 happen and assistance be required. The room over the bedroom is called the watch or service room, and may be properly regarded as the office of the establishment, for it contains official books and papers (in bookcases and on shelves), electric machines, galvanometers, and barometer, as well as spare burners and spare glass for lantern, lamp cylinders, and various diagrams on the walls; around the room, deeply incised in the course of the ceiling, is the text from Psalm cxxvii., adopted by Smeaton for his tower: "Except the Lord build the house they labour in vain that build it." Considerable space is here devoted to the two pressure pumps for supplying oil to the lamps by means of weighted rams, which, being first raised by a pumping lever, descend gradually into the oil, forcing it up the pipes into the lamps. The chief work performed in the service room is at night, when the light is going and a keeper is on duty.

Surmounting the last flight of stairs we enter the most interesting compartment of all, namely, the lantern. It is 16ft. high, 14ft. in diameter, and cylindrical in form. The framings are made of steel, covered externally with gun-metal, and there is a very careful arrangement for thorough ventilation, having regard to the great heat thrown off by the lamps. But the lighting apparatus is clearly the most important feature, the present system being the outcome of many costly experiments in optical science. The special kind of lamp in use is known as a Douglass improved six-wick burner, that is, one having six tubes of wick of varying sizes, the larger encircling the smaller, which, when burning, produce a solid flame equal to the intensity of 722 standard sperm candles. Two such burners are fitted, one above the other, within the revolving drums (now to be described), so that in bad weather flashes of enormous intensity are sent forth, the combined illuminating power being equivalent to a quarter of a million candles, or about six thousand