The theory of coast lighting is that each coast shall be so set with towers that the rays from their lights shall meet and pass each other, so that a vessel on the coast shall never be out of sight of a light, and that there shall be no dark places between lights. This is the theory upon which the United States is proceeding, and it plants lights where they are most needed upon those lines. Hence from year to year the length of the dark spaces on its coasts is lessened or expunged entirely, and the day will come when all its coasts will be defined from end to end by a band of lights by night, and by well-marked beacons by day. In the first century of its existence the light-house establishment of the United States cost about ninety-three and a quarter millions of dollars. In 1791 the amount expended by the Government in support of its light-house establishment was $22,591.94. In 1890 the expenditures amounted to $3,503,994.12. The average yearly sum paid for maintaining an average light-station of each class is: For a first-order light-station $3,842.00 For a second-order light-station 2,711.12 For a third-order light-station 1,568.77 For a fourth-order light-station 1,107.83 For a fifth-order light-station 635.05 For a sixth-order light-station 552.17 For an outside light-ship of recent build 7,078.28 For an inside light-ship of old build 3,546.32 For an average fog-signal, operated by steam or hot air 2,260.59 For a steam tender of recent build 15,126.83 There are under the control of the light-house establishment the following named aids to navigation: Light-houses and beacon lights 1,423 Light-vessels in position 46 Light-vessels for relief 8 Gas-lighted buoys in position 130 Fog-signals operated by steam, caloric, or oil engines, about 197 Fog-signals operated by machinery, about 233 Post-lights, about 1,868 Day or unlighted beacons, about 668 Whistling buoys in position, about 88 Bell-buoys in position, about 139 Other buoys in position, including pile buoys and stakes in fifth district and buoys in Alaskan waters 5,088 In the construction, care, and maintenance of these aids to navigation there are employed: