The construction of the lantern is a point of importance; and one of the first order will cost about £1,260. On the level of the top of the lower glass a narrow gangway is usually built for the keeper to stand upon in order to clean the panes, an operation which in snowy weather may have to be frequently repeated during the night. At some of the lighthouses on the Mediterranean the lantern is at certain seasons so completely covered with moths as to obscure the light and to require the attendance of men with brooms. Mr. Tomlinson was informed by the keepers at the Eddystone that bees and other insects were much attracted by the light, and collected round the lantern in great numbers. Larks and other birds flew against it, and, becoming stunned with the blow, were picked up on the balcony and were cooked by the men for breakfast. The lantern is very liable to injury in high winds, or the glass may be broken by large sea-birds coming against it on a stormy night, or by small stones violently driven against it by the wind. Extra plates of glass are always kept to take the place of broken panes. The number of light-keepers employed varies, ranging from two to four, and in the latter case one is usually allowed to remain on shore, the men taking the privilege in turns. When the situation admits, it is usual to have the keeper’s rooms in a building outside the lighthouse to avoid dust, which is most injurious to the delicate apparatus of the light-room. Great cleanliness is enforced in all that belongs to a lighthouse, the reflectors and lenses being constantly burnished, polished, and cleansed. And so we have traced the history and progress of lighthouses, and it is hard to believe that any great change can be advantageously made in their construction, though their mode of illumination will doubtless be greatly improved. As we have seen, the electric light was used practically in a lighthouse long before it was in the streets of the great metropolis, and not in a merely experimental way, but with the most successful results. [Illustration: BREAKWATER AT VENICE.] CHAPTER XIII. THE BREAKWATER. Breakwaters, Ancient and Modern—Origin and History of that at Cherbourg—Stones Sunk in Wooden Cones—Partial Failure of the Plan—Millions of Tons dropped to the Bottom—The Breakwater Temporarily Abandoned—Completed by Napoleon III.—A Port Bristling with Guns—Rennie’s Plymouth Breakwater—Ingenious Mode of Depositing the Stones—Lessons of the Sea—The Waves the Best Workmen—Completion of the Work—Grand Double Breakwater at Portland—The English Cherbourg—A Magnificent Piece of Engineering—Utilisation of Otherwise Worthless Stone—900 Convicts at Work—The Great Fortifications—The Verne—Gibraltar at Home—A Gigantic Fosse—Portland almost Impregnable—Breakwaters Elsewhere.