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vided the funds for that purpose. The
results blast on a light-ship more than twenty miles of these tests are given in its Annual Reports from land, so that they would not be puzzled for 1879 and for 1880.
by shore echoes, on which all the various pheNone of the various lighthouse establish- nomena that could be registered by the therments have as yet succeeded in producing a mometer, the liygroineter, and the anemomelight that can be identified as to kind, or lo- ter, were also to be noted, on charts previously cated as to site, at any considerable distance, prepared, and it was expected, when all this through a fog, or even through it snow-storm. field work had been plotted, to deduce soineBut earnest effort is made to guide the mariner thing of the law of these variations of audiby sound when sight will not avail, and fog- bility, and to show what allowance may be signals of various kinds have been applied to made for them. The death of Professor llenry this purpose.
caused the postponement rather than the abanIn the course of his researches as head of the donment of these experiments. Professor board's committee on experiments, Professor Morton, liis successor as the scientific adviser Henry developed two theories, stating thein to of the board, in doing that duty wbich laid be good working hypotheses: one relative to nearest his hand, has brought out the photothe effect of the wind on the direction of sound, phone, an instrument by which the mariner, and the other on the failure of sound to inake when puzzled as to the location of the fogitself heard at irregular intervals. The etect signal, which, when heard in snow-storm or in of the publication on the first has been to foc, seems to come from anywhere, may decause seamen, wishing to hear a fog-signal termine its direction to within a point of the against which the wind is blowing, to go aloft compass as they would to see a distant light, and to And at this time, although the board has go as near to the surface of the water as pos- not brought its fog-signal service up to its own sible to catch the sound, if the wind is watiing standard, it is of large service to commerce, the sound toward thein.
and has been made the subject of study by As to the interval in the audibility of a commissions sent bither by other countries, escontinuous sound, it is now accepted that a pecially by Brazil and Great Britain; and it is fog-signal may be in full blast and audible not too much to say that it is in advance of for a long distance, and inaudible at varying that of any other lighthouse establishment. points within that distance, and that the sound The principal fog-signals now used by the may shade off from andibility to inaudibility, board are the trurnpet, the siren, the steamand back to audibility, several times in pass- whistle, the whistling-buoy, the bell-boat, tho ing from the fog - signal to that point far- bell-buoy, and bells rung by machinery imthest distant from it where it is clearly heard. pelled by clock-work. Hence mariners understand that, though they The board, in 1854, employed Professor J. inay not hear it, still they may be within car II. Alexander, of the l'niversity of Maryland, shot of a fog-signal in operati'n. They also to make a series of researches as to the audifully realize the fact that they mily, while bility of sound in fog andl as to the action of sailing toward the sound already caught, lose tog-signals, and it published the Professor's reit, and that by continuing their course they port and circulated it among scientific mechanmay pick it up again. They also understand ics. During this time, Mr. C. L. Daboll, of that, while sailin: away from the fog-signal, Vew London, Connecticut, had been experithey may lose its sound and hear it again menting on his own account. t'nder the enseveral times before passing entirely beyond couragement of the board, he brought out his its range of audibility. Therefore, they now trumpet fog-signal. IIis plan was to employ a make illowances for the variations of the reed trumpet, made somewhat like a clarionet, sound of the fog-signal as thoy do for the va- and sounded by air condensed in a reservoir riations of the inriner's compass, although by machinery driven first by horse-power, and, the law of the variations of its sound has not later, by a hot-air engine. In it the trumpet yet been fully deduced or completely formu- is the resounding cavity, and the necessary lated. The board's annual reports show some- agitation of the air is procluced by the vibrathing of its gradual but effective labors to tion of the tongue-like reed. The trumpet is wrest from Nature her carefully guarded se vertical, curved at the upper part. A firstcrets, and to utilize the results of this work as class trumpet is 17 feet long, including the rapiilly as they are obtained.
curvature, has a Haring mouth 38 inches across, It was within its plans to have continued its while its throat is 34 inches in diameter. The researches into the laws of sound by a grand at reed is of steel, 10 inches long, 24 inches wide, tack with all its available forces. Professor 1 inch thick at the fised, and half that at the Henry was to have been assisted by several free end. It is driven by an Ericsson liot-air scientists, in addition to those officially con- engine, having a 32-inch cylinder with an air nected with the board, who were to be sta- chamber 4! feet across and 6 feet long, which, tioned in steamers and in captive balloons at a pressure of from 15 to 20 pounds, could above, at various heights, all to note simulta- make a five-second blast every minute. While neously the degree of audibility in numerical the trumpet is not as far-reaching as some scale of the sound of a powerful fug-signal in full other fog-signals, it has been preferred for
rock stations where there was a scarcity of ranged for that purpose. When the slits in the fresh water, and where fuel was difficult of revolving plate coincide with those in the fixed access. But it is now losing favor because of disk, as they must, say twelve times in each revits liability to accident and the difficulty of its olution, a jet of steam or air is forced through repair.
each opening under great pressure into the The siren, originally invented by Cagniard de trumpet, and the interruption of these jets La Tour, and used by physicists in comparing causes the song of the siren. The rotating sounds and in measuring the number of vibra- plate is directly connected with and supported tions in different musical notes, was largely by the shaft, which is so geared to a steam or changed by A. & F. Brown, of the New York hot-air engine as to make 2,400 revolutions per City Progress Works, under the direction of minute, and as each revolution allows the escape the Lighthouse Board, and adopted for use as and interruption of twelve jets through the a fog-signal. It can be sounded with either coinciding openings, there are 28,800 shrieks steam or compressed air driven through a fixed given, creating, as the vibrations are taken up flat disk, placed in the throat of a trumpet, to by the trumpet, a condensed beam of sound of which is attached the pipe conveying the mo- great intensity and of surpassing power. tive power. The disk has from eight to twelve The siren is used on shore, as shown in the radial slits. Back of the fixed disk is a revolv- following cut, and on light-ships, as shown in ing plate with a like number of similar open- the cut of Pollock Rip Light-Ship, on page 450. ings, which is rotated by power specially ar The first-class steam siren, when working
with a pressure of seventy-two pounds of llouse, to this country, headed by Sir Freder-
not requiring the greatest intensity and power springs throw the ball from the bell after each of sound. It is the ordinary locomotive whis- blow, permitting vibration, and causing the tle, of a varying diameter, from six to eighteen bell to give out the largest volume of sound inches, operated by steam from an ordinary possible under the circumstances.
This signal and often an upright boiler, with a pressure is never silent, but the heavier the sea the of from fifty to one hundred pounds to the louder is the sound. square inch. It can be made to produce any The automatic signal- or whistling-buoy incombination of shrieks, in a given time, so that vented by Mr. J. M. Courtenay, of New York, it can be identified by its published character- consisted originally of an iron, pear-shaped istic. These are produced and regulated auto- bulb, say twelve feet in diameter, with a tube, matically by an engine taking its steam from twenty inches across and forty feet lons, dethe same boiler, which, at arranged intervals, scending through its bottom. The water in opens and closes the valves, thus shutting off this tube acts by its own inertia as a piston to or letting on the steam. The machinery is draw in air through an orifice supplied with simple and the piston-pressure quite light; a retaining valve, and to expel it through a and, while it is not liable to get out of order, ten-inch whistle. The sound produced is only it requires no more attention than an ordinary comparable to itself in kind, and it is of a qualstationary engine.
ity which asserts itself over all others, and of A great number of experiments have been a power audible several miles even against the made with these three signals. From their wind. Its dimensions have been recently largeaverage it appears that the power of the first- ly but proportionately reduced without detractclass siren, the twelve-inch whistle, and the ing from its usefulness. As its action depends first-class Daboll trumpet may be thus ex on the undulation of the surface, and, as from pressed : siren, nine; whistle, seven; trumpet, its great draught it must be moored in deep wafour; and their relative expenditure of fuel is ter, it is only used in roadsteads or in the open recorded as, siren, nine; whistle, three; trump But it has proved so successful that it is et, one.
used at somo points where a light station The board had in operation on July 1, 1880, would otherwise be required, and, in one infifty-seven fog-signals operated by steam or stance, lias, satisfactorily to mariners, replaced hot air.
a light-ship. At the date of its last report, Bells are also largely used as fogsignals. When the board assumed charge of the establishment, tliey were rung by clock-work, rude in kind and wasteful of power, its weight constantly descending even during the silent intervals. This defect was remedied, under the suygestion of the board, by Mr. Stovens, of Boston, who introduced an escapement arrangement, somewhat like that of a clock, and moved by a sigall weight, the larger one operating only to strike the bell itself.
The large, unwieldy bell-boats of the early days of the establishment have mo-tly gone out of use.
The Brown bell-buoy, recently invented by the master of one of the lighthouse tenders, is a simple arrangement by which the bottom section of a first-class jron nun-buoy is decked over and fitted with a framework of three-inch angle iron, nine feet high, to which a bell is rigidly fixed. Under the bell, which, if of the first-class, weighs 300 pounds, a concentric grooved iron disk of chilled cast iron is fastened to the frame around the disk; opposite each groove July 1, 1880, the board had twenty-five of the a spring is fastened, and on the disk a heavy whistling-buoys in position. iron ball is allowed to roll. The swaying
The purpose of a light-ship is to do the work of the buoy, by the undulations of the sea, of a lighthouse in a place where one is necessary, causes the ball to roll from side to side but where it has not bern erected because of and to strike the bell with each roll. The the great difficulty, not to say expense, of plac
VOL. XX.-29 A
ing such a structure. But the light-ship should off the mouth of Cape Fear River, North Carhave the permanency and efficiency of a light- olina; another on Rattlesnake Shoal, off the house, and should give as good a light in clear entrance to Charleston, South Carolina ; anweather and sound as far-reaching a fog-signal other off Martin's Industry Shoal at the enin thick. To insure permanency of position is trance to Port Royal, South Carolina ; and a matter of great difficulty. When moorings the last light-ship built (1880) is on Trinity have been made too heavy to drag, chains bave Shoal, off the coast of Louisiana. This last is broken ; when they bave held, mooring-Vitts fitted with a twelve-inch steam-whistle foghave been torn out; when they have held, the signal, and is perhaps the strongest and bestship has foundered at her anchors, or the ca- equipped light-ship afloat. The light-ships on ble has been slipped, and the ship has sought Pollock Rip and at the mouth of Vineyard a harbor or gone to sea for safety. But under Sound have fog-signal sirens operated by botthe present rules of the board rigid inspection air engines, which are to be replaced by steamis frequently made of their riding-gear, and the engines, as it is found that hot air endangers absence of a light-ship from her moorings is the health of the crew and shortens the life of now quite unusual.
the ship. The board has thirty light-ships of various Each light-ship shows either one or two sizes on duty in the service. The smaller, lights. Each light has eight reflectors, each slighter built, and older vessels are moored in twelve inches in diameter, set upon a ring sounds and bays. The larger, stronger, and which encircles the mast, and can be lighted later built are anchored in the open ocean. and hoisted to the masthead by night and Among the latter is that on New South Shoals, lowered and housed by day. These reflectors some twenty-seven miles at sea, the nearest are illumined by a kind of Argand lamp, in land being Nantucket; Pollock Rip light- which the sperm-oil formerly burned was sucslip, moored at the eastern entrance to Nan- ceeded by lard-oil, and that is now supertucket Sound; another is moored at the west- seded by mineral-oil, burned in a lamp speern entrance to Vineyard Sound; two offcially adapted to the purpose. The lighting Sandy Hook entrance to New York Bay; an apparatus is inclosed in a lantern, with large other off the mouth of Delaware Bay; an panes of glass which protect the light from the other on Winter Quarter Shoal, off the coast wind. of Virginia ; another on Frying Pan Shoal, The light-ship shown in the accompanying
cut is that upon Pollock Rip Shoal, in the beam, twelve feet five inches hold, and is of four broken water at the eastern entrance to Nan- hundred and ten tons burden. She is schoontucket and Vineyard Sounds, Massachusetts. It er-rigged, with a lighting apparatus upon each was built in 1877, is about one hundred and mast supplied with eight burners and reflectwenty feet long, nearly twenty-seven feet tors. It has been found so difficult to keep
SPAR-BI'OYS, FIRST CLASS.
BLACK AND WHITE.
RED AND BLACK
this vessel from dragging her anchors that tern required to tell their allotted story, fitted she is now fitted with moorings as heavy as at the larger end with an iron sleeve, to which those of a frigate. In spite of her brilliant the stone or iron anchor can be attached by a lights and her powerful fog-signal, she has mooring chain, when they are packed in classes been repeatedly run into by passing vessels or sizes on skids to season, and finally to take and more or less damaged, as have most of the their tour of duty in the water to replace other light-ships in the service. She has a others wirich are to rest a while on shore, be master, å mate, two engineers, and a force of freed from acquired barnacles, take on a fresh six men. Hier cost was $50,000, and it requires suit of paint, and, by drying, recover their about $5,000 a year to maintain her exclusive buoyancy. Spar-buoys are classified first by of repairs—a larger sum than is needed for length and thickness, and then by acquired smaller ships, or for those without fog-signals. color; but they are interchangeable within It is estimated, however, that it costs $10,000 these conditions. The cuts represent sparper year to maintain and keep in repair each buoys and their appendages, much as they of the first class light-ships in the service, and appear in the water. this is urged as a reason for replacing thein as fast as possible with lighthouses.
The buoy is to the seaman by day what the light is at night, and what the fog-signal is in thick weather. It tells him by its size, forin, color, and nuinber how to avoid the rocks and shoals, and shows the way in and out of harbor.
The growth of the buoy service may be mcasured by its cost, which was for the five years preceding the organization of the board, in 1852, about $75,000 per year, and for the five years after about $82,000 per year.
In 1812 there were nearly 1,000 buoys in position; in 185.5 the board had 1,034; in 1860 it had 1,738; during the war it lost those on the southern coasts, but in 1867 it had so far replaced and added to them that it had 2,014; in 1875 it had 3,002; and on June 30, 1880, it had 3,140 buoys in the waters of the several districts. An appropriation of $325,000 was made for maintaining the buoyage of the United States coasts during the year ending June 30, 1882.
The buoy service has its own code of laws, state and national, a fleet of small tenders for its
Iron buoys are hollow, with air-tight commaintenance, besides a corps of contractors to attend to the buoyage of coves and inlets imprac. partments, and are made of three shapes, called ticable to the lighthouse tenders. It has its de- nun, can, and ice buoys. The nun-buoy is alpots for the storage of iron buoys, where they are painted and numbered, or repaired, and also where wooden buoys are made ready for service. It has its own directory printed yearly, in twelve volumes, distributed gratuitously for the benefit of commerce, in which each one of the more than 3,000 buoys is mentioned by name, located by station, and is described by size, shape, color, number, and vicinity. The problems connected with its improvement, as well as its inaintenance, are considered as of grave importance, and are made the subject of deep consideration by the best scientific aid at the disposition of the board.
Buoys are of wood or iron. The wooden buoys now in use are sticks from twelve to sixty feet long, of pine or spruce, but preferably of cedar. The board frequently contracts for the delivery at one of its depots of a cargo of logs, in the roughi, at from $10 to $15 each, where they are freed of their bark, smoothied most conical in form; the can-buoy is in shape of their protruding knots, painted to the pat- the frustum of a cone nearly approaching a