438 



LIGHTHOUSE ESTABLISHMENT, THE UNITED STATES. 



and lighted in 1850, costing $53,817 for the 

 lighthouse, and $11,485 for the surrounding ice- 

 breaker. This was the first lighthouse built 

 in the United States on the Mitchell screw- 

 pile, which takes its name from the inventor of 

 its broad helicoidal flange, like an augur pod, 

 which, by merely turning, is bored into a sand, 

 mud, or other penetrable bottom, so as to 

 form a foundation with a broad bearing, on 

 which the weight of a columnar structure may 

 be safely diffused, and to which it is firmly 

 fastened. This structure has a light forty-six 

 feet above sea-level, and is independent of the 

 ice-breaker, which is a pier of thirty screw- 

 piles, each twenty-three feet long and five 

 inches through, connected at their heads, near 

 low water, by spider-web braces, by which a 

 shock on one pile is communicated to all. The 

 lighthouse is in good condition, as is its ice 

 pier, which has been reenforced. It was de- 

 signed and built by Major Hartman Bache, then 

 of the corps of Topographical Engineers of the 

 army. 



An iron-pile lighthouse was begun for Carys- 

 fort Reef, Florida, in 1848, and finished in 1852. 

 It stands on a coral reef in the Gulf Stream in 

 four and one half feet water, and is one hun- 

 dred and twelve feet high. It is founded on a 

 hard exterior coral crust, above a softer mass 

 of calcareous sand ; hence, screw-piles bored 

 through the crust would have an insufficient 

 bearing. On this account, large iron foot- 

 plates were used to diffuse the pressure over 

 the one hundred and thirty square feet of sur- 

 face crust, and the piles, passing through center- 

 eyes in the plates, were driven ten feet into the 

 sand, or until their under shoulders were lodged 

 on the bed-plates. Nine eight-inch piles con- 

 stitute the center and angles of an octagon, and 

 the aggregate column gets rigidity from a pe- 

 culiar system of cross-ties and braces. The 

 keepers live on the structure in an elevated 

 house. The whole was made, framed, tied to- 

 gether, and set up for trial in Philadelphia, so 

 as to obviate the necessity of fitting parts at 

 its isolated site. Its cost is stated at $105,- 

 069 for the entire structure. 



Sand Key lighthouse is built on a plan some- 

 what like that of Carysfort, but it stands in 

 deeper water, on screw-piles ; its focal plane is 

 one hundred and twenty-one feet above the 

 foundation; it cost $101,520, was completed 

 in 1853, and it has proved its complete stabil- 

 ity. It was built by the late Major-General 

 George G. Meade, then a lieutenant of Topo- 

 graphical Engineers, who also built an iron 

 screw-pile lighthouse on the flats in Key West 

 Harbor, and the important pile beacon on Re- 

 becca Shoals, since destroyed and rebuilt, and 

 several other lighthouses. 



But the most important lighthouse built by 

 General Meade was that on Coffin's Patches, or 

 Sombrero Key, on the Florida Reef, about fifty 

 miles east of Key West. It stands in eight feet 

 of water, and shows a light about one hun- 

 dred and forty feet above the sea, illuminating 



a range of over twenty statute miles. The 

 twelve-inch wrought-iron foundation-piles rest 

 centrally on cast-iron disks eight feet in diame- 

 ter, and go ten feet into the rock. They stand 

 at the angles and center of an octagon fifty-six 

 feet across, and are braced by horizontal radial 

 and periphery ties of five-inch round iron. The 

 frame rises from this foundation pyramidal in 

 shape, in six sections, with a diameter of fifty- 

 six feet at the bottom, tapering to fifteen feet 

 at the top. All the shafts, except those of the 

 lower series, are of hollow cast iron. The 

 keeper's dwelling, in the second section, is 

 thirty feet square, and of boiler-iron lined with 

 wood. A circular stairway ascends to the lan- 

 tern, in a cylinder of boiler-iron lined with 

 wood. The entire structure, illuminating ap- 

 paratus included, cost about $120,000, is still 

 standing, and is in excellent condition. 



There are now, principally in the Southern 

 waters, more than fifty iron-pile lighthouses; 

 some with and some without screws, and of 

 a variety of detail and size. The following 

 cut shows a specimen of the screw-pile river 

 or harbor lighthouse. It is a representation 



HARBOR BCREW-PTLE LIGHTHOUSE ON CEDAR POINT, PO- 

 TOMAC RIVER, VIRGINIA. 



of the lighthouse on Cedar Point, Potomac 

 River, Virginia. 



Fowey Rocks lighthouse was commenced in 

 1875, and finished and lighted on June 15, 

 1878. It is on the extreme northern point of 

 the Florida reefs. It is of iron, and rests on 

 nine piles driven about ten feet into the live 

 coral rock. The different parts were made by 

 three different contractors, but they were fit- 

 ted together and set up before the structure 

 was shipped to its site. 



The lower series of piles was put in place 

 in the summer of 1876. A working platform, 

 about eighty feet square, was erected on the 

 site, twelve feet above low water, on iron-shod 

 mangrove piles driven into the coral. The disk 

 for the central iron foundation-pile was then 



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