whose tenure of office is practically during good behavior, where transfers in location are made when the wishes of the keepers and the wants of the service coincide, and whose physical and mental welfare are carefully looked after, that they may be contented in their responsible and isolated situations.

The board has had the services of some of the brightest and most active minds in the American navy. The lighthouse service has, like the Coast Survey, come to be regarded as a training-school for young officers and as a field for the best efforts of those higher in rank. The roll of lighthouse inspectors contains the names of the flower of the navy; hence it is no source of wonder that a tour of lighthouse duty is sought by the more ambitious and studious of our naval officers, and that the service has its choice from among the best of them in times of peace.

The army has also been well represented in the lighthouse service. On the list of the lighthouse engineers will be found many of the names which have given our military establishment reputation if not fame, and such have been their victories in solving the problems of sub-aqueous structures, and in opposing successful resistance to the violent attacks of the elements under the most discouraging circumstances, that it is a question whether those names connected with the erection of certain lighthouses will not live when history has let die the memory of their brilliant military achievements.

The civil service has been well represented on the board itself, in connection with the army and the navy, by such men as Professors Bache, Peirce, Henry, and Morton, who have acted as the scientific advisers of the service, and whose names are identified with the solution of problems in physics which have been worked out under their direction in methods for guiding mariners by light at night, and by sound when light was unavailable. Something of the operations of the Lighthouse Board will be detailed in its proper place.

The lighthouses on the New England coast were constructed previous to 1810 in two forms, namely: conical towers of rubble stone masonry and wooden frame towers erected upon the roofs of the keepers' dwellings. The stone towers were built on the natural rock, from stone split from the adjacent ledges or from pieces collected on the beach, sometimes even from fragments of the cliffs rounded by attrition in the surf. The walls were usually three feet thick at the base, tapering to two feet at the top, and the towers varied in height from twenty to fifty feet. At the top of the tower and within the walling of rubble, a dome of brick was turned, with a square opening near the springing-line on one side, forming a scuttle entrance to the lantern. On this brick dome, a flat roof composed of slabs of stone four inches thick was laid, projecting over the walls of the tower from six to

twelve inches. The lanterns were attached to the towers by imbedding the lower ends of their iron angle-posts into the masonry of the walls some three or four feet, and the entire construction of the towers was rude in kind.

The wooden towers erected on the keepers' dwellings were framed into the roof of the house. The angle-posts rested on the attic floor-beams unsupported by studding; consequently the framing of the house-roof was distorted by the swaying lateral motion of the tower in storms, and there was necessarily some leakage.

In 1847 the construction of six difficult lighthouse structures was devolved by Congress on the topographical engineers of the army. They used the iron pile system, when applicable, and made numerous improvements in the combination of the framework, in making appropriate arrangement of elevated apartments for the keepers, in making disk pile foundations for coral or incrusted bottoms, and in improved devices for the foundations. Captain W. H. Swift, of this corps, rebuilt the Black Rock beacon in Long Island Sound, some four and a half miles from Bridgeport, Connecticut. Three successive stone beacons, costing together some $21,000, had, in the course of twelve years, been demolished. Captain Swift, at a cost of but $4,600, erected a pile beacon thirtyfour feet above low water, three feet higher than any of its predecessors, which is still standing. An artificial foundation was made by placing six twelve-ton stones partly in an excavation, and by bedding them in concrete, making a solid platform, and setting into it five wrought-iron periphery piles and one center pile, measuring from three to five and a half inches in diameter. They were sunk through holes drilled to receive them, rose in the form of a conic frustum, and were solidly joined together, and properly capped at the top.

A pile structure was also erected on Minot's Ledge, in the open sea, near Boston Bay, in 1847-'8, by Captain Swift, but it was destroyed by the storm of 1851, and the keepers lost their lives. It was based on the solid rock by drilling holes five feet deep, in which one center and eight periphery eight-inch wrought-iron foundation piles were wedged, and so placed as to form an octagon twenty-five feet in diameter at the bottom and fourteen feet at the top, which had an elevation of sixty feet. On this was placed the lantern, making the height of the whole edifice about seventy feet. The structure was stiffened by a complex system of diagonal bracing connecting the piles. Whatever may have caused the overthrow of the lighthouse-and that is still a mooted question

it does not appear to have been owing to any fault of the rock fastenings, as the piles were broken or twisted off, leaving stumps from four to six feet long in their original places.

Brandywine Shoal, in Delaware Bay, about eight miles from the ocean, was begun in 1848

and lighted in 1850, costing $53,317 for the lighthouse, and $11,485 for the surrounding icebreaker. This was the first lighthouse built in the United States on the Mitchell screwpile, 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 screwpiles, 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 reënforced. It was designed and built by Major Hartman Bache, then of the corps of Topographical Engineers of the

army.

An iron-pile lighthouse was begun for Carysfort 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 hundred 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 footplates were used to diffuse the pressure over the one hundred and thirty square feet of surface crust, and the piles, passing through centereyes 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 constitute the center and angles of an octagon, and the aggregate column gets rigidity from a peculiar system of cross-ties and braces. The keepers live on the structure in an elevated house. The whole was made, framed, tied together, 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 somewhat 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 stability. It was built by the late Major-General George G. Meade, then a lieutenant of Topographical Engineers, who also built an iron screw-pile lighthouse on the flats in Key West Harbor, and the important pile beacon on Rebecca 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 hundred 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 fiftysix 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 lantern, in a cylinder of boiler-iron lined with wood. The entire structure, illuminating apparatus 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 SCREW-PILE LIGHTHOUSE ON CEDAR POINT, POTOMAC 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 fitted 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

lowered to its place, and through this disk the first iron pile was driven. A perimeter disk was then located by a gauge, and then the first perimeter pile was driven through the center of this disk. After every blow of the piledriver, the pile was tested with a plummet, and the slightest deviation from the vertical was rectified. In locating the disk for the next perimeter pile, two gauges were used to get the proper distance from the center pile, and to maintain it from the perimeter pile just driven. The disks were dragged along the bottom until their outer edges just touched the free edges of the gauges. Each pile was then driven through the center of its disk. When all were driven, their tops were leveled by cutting off each to the line of the lowest. The piles were then capped with their respective sockets; the horizontal girders were inserted, the diagonal tension-rods were placed and screwed up, and the foundation series were completed. Two months were occupied in placing the wooden platform and this series. During this time they had a smooth sea, but after this time the main difficulty was the bad weather. Finally, that problem was solved

FOWEY ROCKS LIGHTHOUSE, FLORIDA REEF.

by pitching tents on the working platform, leaving a force of workmen there above the running sea, supplied with material, and with a small hoisting-engine to work their derrick and their shears which had been erected in the single day of good weather they had out of a

month. The material was stored at Soldier Key, four miles distant, and it was delivered by lighters towed by a steam-launch, which waited with steam up day and night to tow them out when the weather would permit. On March 16th the derrick and shears were set up, and a cargo of iron delivered; and in the course of the next sixteen days five more cargoes were landed on the platform, and the first series of columns, girders, sockets, and tensionrods was placed in position. On April 7th the skeleton of the second series and the cylinder to the top of the series was up; and in another week all the iron up to and including the service-room floor was on the platform. On April 30th the dwelling was finished; on May 25th the illuminating apparatus was in position, and on June 15th the work was completed and the light was exhibited. The whole structure was completed in good time, despite the trying circumstances accompanying its construction. The preceding is a representation of the lighthouse in question.

The use of iron plates for building lighthouses on dry foundations, though not uncommon abroad, met early with little favor in this country. But, in later years, when a greater knowledge of iron as a material for construction was obtained, it came into larger use. Among the more prominent of the iron towers are those at Cape Canaveral, Florida, designed in 1860 and built in 1868, 150 feet high; that at Bolivar Point, Texas, built in 1872, 120 feet high; that at Hunting Island, South Carolina, built in 1875, 130 feet high; and the tower now being erected at Cape Henry, Virginia, which is to be 165 feet high.

The following description of the tower at Hunting Island will show how these iron towers are put up, and this is a good specimen, as the necessity of taking it down to remove it further back, if the encroachments of the sea make it necessary, was considered at the time of its erection. The shell of the tower is composed of cast-iron panels of about twelve hundred pounds weight each, of exactly the same size, in each section, that they may each Occupy any position in the ring which they form when put together. These panels vary in thickness in the different sections, those of the lower section being an inch and a half thick and of the highest three quarters of an inch. They are provided with flanges so as to connect the several tiers of plates, and the plates of each tier with each other by bolts through them, and the flanges are made smooth, with true planed surfaces. The base of the first tier of panels consists of a flange three feet wide. This flange extends one foot four inches beyond the outside of the tower. It is strengthened by bosses and vertical knees extending upward to the top of the castings, which contain the holes for the foundation-bolts. The top flange is six inches by one and three quarter inches. The lower flange of the second section is one foot two inches wide.

The

top flange of this tier and the flanges of the third section are six inches by one and threequarter inches. The flanges of succeeding sections are similar. The side flanges correspond in size with the top flange of each panel. The horizontal flanges have strengthening knees. A nine-inch interior lining of brick is built between the lower flanges. The whole structure rests on an eight-inch concrete foundation, to which the lower iron section is secured by thirty-six anchor-bolts built into the concrete.

Iron skeleton-towers are used on land where the soil affords an inadequate support for a masonry foundation, and where great cheapness is required. That at the Southwest Pass of the Mississippi may be regarded as typical. Its foundation consists of a grillage of timber resting on piles and covered with concrete, on which are secured the iron socket disks from which start eight external and one central shaft of the skeleton. A two-story dwelling for the keepers was placed within the shafts, and a staircase was carried up to the lantern through a tube as in case of the similar lights on subaqueous foundations. These towers are found to meet the purpose for which they were intended, and are practicable where heavier structures would not answer, affording less resistance to the wind, and being much cheaper

structure of its kind in the history of lighthouse construction. The plan was born of necessity, as it was found that the appropriation made by Congress was insufficient to put up the kind of structure usual in such a position. The light exhibited is simply a locomotive head-light, which is a powerful parabolic reflector. It is claimed, however, that it is possible to use on it a lenticular apparatus. The tower is composed of columns, sockets, struts, and tension-rods, framed in the form of a triangular pyramid. It rests on six circular iron disks, anchored to a concrete foundation. The top sections of the side facing the channel, for which the tower is the guide, are provided with horizontal slats, to increase the visibility of the beacon by day. The light, which runs up and down in rails in the plane of the structure, is housed by day, and at night is hoisted to its place at the apex of the triangle by machinery worked in the oil-house. The large foundation-plates are about forty feet four inches apart. The focal plane of the light is one hundred and twenty feet above the sea level, but the top of the structure is one hundred and thirty-two feet from the ground. The cost of the iron work set up is $9,400, and that of the structure complete and lighted about $12,000.

Saint Augustine lighthouse was built of brick and iron, on Anastasia Island, on the

ST. AUGUSTINE LIGHTHOUSE, FLORIDA.

eastern coast of Florida. Its base is a frustum of an octagonal pyramid, on which rests the frustum of a cone. The interior of the tower

is lighted by five windows. Eight flights of spiral stairways furnish access to the watchroom, the first seven of which make half a revolution of a spiral, but the eighth a whole revolution. This arrangement does away with the incumbrance of a central shaft to support a winding stairway, and allows of a better lighted interior and of more room. The structure is 150 feet high from base to focal plane, and 165 feet above the level of the sea; shows a first-order light, and cost about $100,000. The spiral stripes shown in the cut are added to distinguish it, as a day-mark, from adjacent sea-lights.

Many brick lighthouses of this type have been built, among which are those at Cape Hatteras, Currituck Beach, and Body's Island, North Carolina; Morris Island, South Carolina; Sand Island, Alabama; Cape Foulweather, Point Arena, and Pigeon Point, on the Pacific coast.

Minot's Ledge lighthouse was almost the first, if not the first, important structure erected by the Lighthouse Board. According to General Barnard, himself an engineer of wide fame, "it ranks, by the engineering difficulties surrounding its erection, and by the skill and science shown in the details of its construction, among the chief of the great searock lighthouses of the world." [For an account of its erection, see Appletons' "Cyclopædia," article LIGHTHOUSE.] The board gave to the plan and its execution its freshest and best powers, and the combined energies of all its members. A careful survey of the rock was made by Major Ogden, of the Topographical Engineers, and then, after a full consideration of all the difficulties by the full board, the preparation of the plan was devolved on the chairman of its committee on engineering, General Totten, then Chief of the Engineers of the army, who planned the masonry tower for this difficult position, and so successfully that, with the exception of the lower stones of the foundation, which had to be studied out of the rock itself, and some details of the construction, the tower was built throughout by B. S. Alexander, then Lieutenant of Engineers, according to the plans of General Totten. The brief memoir left by Colonel Alexander, the only authentic record of the construction of the tower, brief and modest as it is, shows that the skill and ability of the builder equaled that of the designer, and the great tower stands as a monument to both and to the board that availed itself of their powers. The last stone was laid June 29, 1860, five years from the commencement, and the cost, including the keepers' houses on shore, was about $300,000. Spectacle Reef lighthouse, a similar structure, stands on a limestone reef at the northern end of Lake Huron, near the Straits of Mackinaw, which join it to Lake Michigan. The nearest land is ten and one half miles distant, but it is sixteen miles from Scammon's Harbor, where the work for it was prepared. The waves have

a fetch of one hundred and seventy miles to the southeastward, but the ice-fields, which are here moved by a current, and which are thousands of acres in area, and are often two feet thick, had to be specially provided against, as, when moving in mass, they have a force which is almost irresistible. But this is overcome by interposing a structure against which the ice is crushed, and then its motion is so impeded that it grounds on the shoal, on which there is but seven feet of water, and forms a barrier against other ice-fields. The tower (see cut) is in shape the frustum of a cone, thirtytwo feet in diameter at the base, and eighteen feet at the spring of the cornice, eighty feet above the base. The cornice is six and the parapet seven feet high. The focal plane is four feet three inches above the top of the parapet. The entire height of the masonry above the base is ninety-three feet, and of the focal plane ninety-seven feet three inches; the base is eleven feet below, and the focal plane eighty-six feet three inches above the water. For the first thirty-four feet, the tower is solid; from thence it is hollow, and in it are five rooms one above the other, each fourteen feet in diameter, with different heights, from nine feet two inches to seven feet eight inches. The walls of the hollow portion are five feet six inches at the bottom, and taper to eighteen inches at the spring of the cornice. The interior is lined with a four-inch brick wall, between which and the masonry is a two-inch air space.

The blocks of stone below the cornice are all two feet thick; those of. the solid portion of the tower were cut to form a lock on each other in each course, and the courses are fastened together with wrought-iron bolts two and a half inches thick and two feet long, while the lower course is bolted to the foundation-rock with bolts three feet long, which enter the bedrock twenty-one inches, the other courses receiving the bolts for nine inches. Each bolt is wedged at both ends, and the bolt-holes, which were made with the diamond drill after the stones were in place, are plugged with pure Portland cement which is now as hard as the stone itself. Hence the tower is in effect a monolith. The stones were cut, as were those of Minot's Ledge, at the depot, and fitted, course by course, on a platform of masonry, the work was so well done there that a course could be, under favorable circumstances, set, drilled, and bolted in three days. The main difficulty, however, lay, as in Minot's Ledge tower, in the preparation of the foundation. This was overcome by a pier of protection inclosing a coffer dam. The pier was a cribwork of twelve-inch timbers built upon ways at the depot, as a ship might have been, when it was launched, and towed by a number of steam. ers to the reef and grounded on its site. It was of wood, ninety-two feet square and twentyfour feet high, having an inside space fortyeight feet square, and was divided into compart

and