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ments, which were ballasted to make it firm. Thus a protected pond was formed for the coffer-dam, designed by General W. F. Raynolds, of the United States Engineers, and a landing wharf was afforded for material, as well as for the reception of quarters for the men, all twelve feet above water, and out of reach of ordinary waves. The coffer-dam was thirty-six feet across, and cylindrical in form. It was made of jointed staves fourteen feet long, four inches thick, and six inches wide, held in place by three iron hoops, like a tub, and braced and stayed inside against a center post, the axis of which coincided with the axis

SPECTACLE REEF LIGHTHOUSE, LAKE HURON.

of the cylindrical coffer. It was built at the surface of the water, and suspended exactly over the site of the tower. A loosely twisted inch and a half rope of oakum was tacked to the lower end of the staves, and then the cylinder was lowered to the bed-rock, which had such irregularities on its surface that some of them were three feet high. All these were compensated by driving the jointed staves home with a heavy top-maul, the oakum rope serving as calking; and this was made approximatively water-tight by an ingenious arrangement of a loosely twisted four-inch hay-rope and a canvas flap, which was attached in part to the outside of the lower edge of the cylinder, that lay in part flat on the rock, and which was forced into the angle by the outside pressure when the pumps commenced lowering the water in the dam. The work was commenced

in May, 1870, and the light was first exhibited from the finished structure in June, 1874; but the available working time spent on this lighthouse was but about twenty months. This tower, which cost, including the steamer and appliances of all kinds, about $375,000, is our best specimen of monolithic stone masonry. It was built by General O. M. Poe, of the United States Engineers, who was General Sherman's chief engineer in his march to the sea. Its strength has been thoroughly tested by the ice push already. When the keepers returned to the tower on May 15, 1874, they found the ice piled against it to a height of thirty feet, which is seven feet higher than the doorway, and they could not effect an entrance to the tower until they had cut through the iceberg, of which this lighthouse formed the core. The cut shows this lighthouse surrounded by an ice-floe.

The board is now building a stone tower in Lake Superior, on Stannard's Rock, twentyeight miles from shore, for which the steamer and the plant used in erecting the light on Spectacle Reef are being used. It will be, when finished, 101 feet in height, will cost about $300,000, and will show a light of the second order.

Tillamook (Oregon) lighthouse is placed on an isolated basalt rock high out of water, about one mile from the mainland, in fifteen fathoms of water, and about twenty miles south of the mouth of Columbia River. It is divided above low water into two unequal parts by a wide fissure, with vertical sides running east and west, standing one hundred feet above the sea, with a crest capable of such reduction as to accommodate a structure not larger than fifty feet square. A landing could with difficulty be made on the side next the shore during a smooth sea. The rugged character of the headland, the tendency of the sea face to landslides, and the great distance from Astoria, the nearest supply-point, made the execution of the work a task of labor, difficulty, danger, and expense. The drowning of the foreman on the landing of the first working-party tended to confirm the prejudices of the local public against the enterprise, and to increase the difficulty of obtaining the services of skilled workmen. On October 21, 1879, however, four workmen, with hammers, drills, bolts, provisions, fuel, a stove, and some canvas to protect them and their supplies from the weather, were landed, and, a few days later, five more men and a small derrick were got to the rock, from which time the commencement of the work may be dated. For the first nine days after reaching the rock, the nine quarrymen had no shelter from the rain and spray, except that of the canvas lashed to ringbolts. But during this time they cut a shallow niche in the north and east sides, in which they set up a strong timber shanty, which they bolted to the rock, covered with canvas, and secured to ringbolts. From this they secured safety, but got little comfort. After setting up the

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main derrick and cutting a pathway up the face of the rock, they opened a bench around it by suspending the workmen on staging supported by bolts let into the rock's crest. The bench once formed, the reduction was pushed to the center. The outer surface of the rock was easily removed with moderate charges of black powder, but the nucleus was hard and firm, and giant-powder was necessary to open the mass, when large charges of black powder acted satisfactorily. The working party, in spite of their rude, uncomfortable quarters, worked diligently through the winter with good results. But the work was much delayed by spells of weather so bad that little could be done. The coast was visited by a tornado in January, which caused the waves, reflected from the rock, to be carried by the wind over its crest, so that for many days continuously the receding floods poured over the eastern slope, making work impossible. On one such day this cataract carried away the supplyhouse, and even endangered the quarters of the working-party. For more than two weeks at this time it was impossible for the steamtender which supplied their wants to cross the

bar at the mouth of the Columbia River to go to their assistance; when, after sixteen days, communication was reopened, the party was found to be safe, but much in want of fresh provisions. These were supplied by an endless line running between the mast of the supplyvessel and a ringbolt driven into the top of the rock, in water-tight casks suspended by slings from a traveler, which was made to move along the line.

In May the top of the rock was leveled, and a foundation made about eighty-eight feet above the sea, and, on the 31st, three masons, four derricks, a sinal engine, and the appliances for laying the masonry, were landed. The stone, a fine-grained, compact basalt, quarried near Portland, and cut to dimensions by contract, was delivered at Astoria and shipped to the rock on the tender. The first cargo was landed on June 17th; on the 22d the cornerstone was laid, and then the rest of the material was shipped to the rock as the weather permitted.

The building is a square, one-story keeper's dwelling, with a rectangular extension for the duplicate siren fog-signal apparatus. From the

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center of the keeper's dwelling rises the tower, which is crowned by a gallery and a lantern containing a first-order lens apparatus. material used is stone, cut to dimensions on the shore, for the outer walls, and brick, iron, and wood for the interior. The light is fortyeight feet above the base of the tower and one hundred and thirty-six feet above mean sealevel, and it was shown for the first time on February 1, 1881. If it had been finished a month

earlier, it probably would have saved the English iron bark Lupata, of 1,039 tons burden, which was dashed to pieces on the main shore, not a mile from the lighthouse, with a loss of the vessel, its freight, and every one of the twenty persons on board. The bark came so near the rock that the creaking of the blocks and the voices of the officers giving orders were distinctly heard, but the night was so dark that nothing could be seen except her lights. The

local foreman had a bonfire built on the rock as soon as possible, but the vessel was lost probably before the signal could be seen. It was on this night that the working-party lost their supply-house, and came so near losing their quarters, if not their lives.

The illuminating apparatus used by the lighthouse establishment varied with the dates of its use. The beacon on Point Allerton, Massachusetts, was illumined in 1673 by "fier balls of pitch and ocum,' ," burned in open braziers. The lighthouse on Little Brewster Island, Boston Harbor, erected in 1715-'16, was first lighted by tallow candles. Then followed the spider lamp, burned in the lantern as it might have been in a window. In 1812 the Government bought of Mr. Winslow Lewis, for $20,000, the patent for his "magnifying and reflecting lantern." This is described as consisting of a lamp, a reflector, and what was called the magnifier. The reflector was of a thin sheet of copper, commonly segments of a sphere, plated over with a slight filin of silver, though the copper was so thin that its compression between the arms of its iron supports materially altered its form, and its silvered concave surface had much the grain and luster of tin ware, and would reflect no distinct image. The patentee, in 1812, made no pretension to a knowledge of optics as now understood, and his reflectors caine about as near to a true paraboloid as did a barber's basin. The lamp, roughly constructed on the principle of Argand's fountain-lamp, burning from thirty to forty gallons of oil per year, had a three-quarter inch burner, and was attached to a circular iron frame in front of the reflector. Before the lamp was a so-called lens, of bottle-green glass, shaped like the bull's-eye let into a ship's deck, from two and a half to four inches thick through the axis and nine inches in diameter, which was supposed to have some magnifying power. This apparatus was inclosed in a massive wrought-iron lantern, glazed with panes ten by twelve inches in size. The effect of the whole was characterized by one of the reporting inspectors as making a bad light worse. But its main merit seems to have been that of economy, as the patentee, who had fitted thirtyfour lighthouses with his apparatus, contracted in 1816 to maintain the lights on receiving one half the oil previously consumed, and again, in 1821, for one third of the old allowance.

This apparatus is spoken of more respectfully in a report to the House of Representatives in 1842, made by its committee on commerce, from which it appears that "the improvement in the character of the light and the economy in saving oil were subjects of high commendation by the Government." It also appears that the use of the magnifying bull's-eye was gradually abandoned, so that but few remained in 1838, and the last one was removed in 1840. The administration of the system was largely improved. The reflectors were made on true optical principles, approximating,

if not reaching, the paraboloid in form, and were heavily silvered and properly placed. The heavy lantern frames were replaced by lighter ones, the small panes of glass by larger ones, and the ventilation of the towers was so largely improved that obscuration by smoke was no longer unpreventable. The system, largely improved, was retained, but its administration was good only where it had faithful, intelligent, and honest administrators. Finally, the reflectors were so well made and so well placed that, in certain instances, it is now a question whether a better light was possible than was then furnished. Some of the old reflectors then used appear from recent examination to have an enormous candle power. But a poor light was the rule, and a good light the exception. War was made on the system of reflectors, and, when the lighthouse establishment was turned over to the Lighthouse Board in 1852, the reflectors were replaced by the Fresnel lenticular apparatus, found so successful in France, and more or less throughout the world. The adoption in this country of the lenticular apparatus made it possible for a light-keeper of average capacity to keep a good light, and impossible for him to keep a bad one, except by violation of plain rules and avoidance of routine duties. Besides this, the saving in oil effected by use of the lenses over reflectors was so great that the expense of exchanging the one for the other was saved in a few years, although the first cost of the lenses was quite large.

It was shown, in a report made to Congress in 1858, that the mean average cost of each lighthouse, for the five and a quarter years preceding the organization of the Lighthouse Board, was $1,302, with oil at an average of $1.13 per gallon, while, for the same period after the board took charge, it was but $1,286, with oil at $1.62 per gallon. Thus it appeared that under the board the average cost of maintaining each light was about $16 per year less than under the previous management, although oil was about fifty cents per gallon more; and it was broadly claimed by the board, and the claim does not appear to have been disputed, that by the change it furnished under the new system, "at least four times as much light for the benefit of the navigator as the best system of reflector lights which has been devised, and at the same time at a consumption of not more than one fourth of the quantity of oil, required for the best system of reflector lights."

A full description is given in Appletons' "Cyclopædia" of the reflectors, under the head LIGHTHOUSES, and of the lenticular apparatus under the name of AUGUSTIN FRESNEL, its inventor.

The illuminant of the lighthouse establishment has been changed whenever a better one has been found. The "fier-balls of pitch and ocum," used in the open brazier at Point Allerton in 1673, were succeeded by tallow candles at Little Brewster Island in 1716, which gave

way to fish-oil, burned in spider-lamps, with solid wicks, suspended by iron chains from the dome of Sandy Hook lighthouse as late as 1760; and this was in turn succeeded in 1812 by sperm-oil, burned in a sort of argand lamp in Winslow's "patent magnifying and reflecting lanterns"; and this illuminant was continued until the beginning of the latter half of the present century, when the reflector system, much as it was improved, was itself superseded by the Fresnel lenticular apparatus, now in use. When the Lighthouse Board came into power, one of the first subjects which received its best attention was that of obtaining a new illuminant of less cost than sperm-oil. The yearly diminution of the whale catch and the increased use of sperm-oil as a lubricant made it more and more expensive. The board, there fore, called in the aid of such scientists as Professors Morfit and Alexander, of the University of Maryland. Their analyses, quantitative and qualitative, chemical, photometric, etc., of sperin, whale, shark, fish, seal, colza, olive, lard, and mineral oils, of various grades and combinations, were published by the board in 1855, and these are still regarded by the trades as high authority on those subjects.

Oil for the year is usually purchased by contract in the autumn, after advertisements for proposals, and is made deliverable in large lots at different times and places, to suit the convenience of the establishment. When delivered, it is subjected to careful and exact test, to ascertain its purity; and its light-giving power, in lighthouse lamps, is ascertained by photometric measurement. The best oil of commerce is not always the best for lighthouse lamps, and the dealers have much difficulty in meeting the precise wants of the establishment; hence it is not unusual that some oil is rejected. Taking the oil purchased in open market, to meet sudden demands, which it is cheaper to meet by purchase than by transportation, together with that purchased by contract, the establishment bought on an average about 100,000 gallons of oil yearly. The highest price it has paid for sperm-oil was $2.43 per gallon, the lowest $1.09; the highest that it has paid for lard-oil was $2.27, and lowest 48 cents per gallon. The lard-oil used by the lighthouse establishment from 1867 to 1880, both inclusive.

1867.

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1870.

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91,000

1.2635

115,197 50

91,000

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1873.

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88,060 00

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167,575 00

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It was found from these examinations that colza, the oil expressed from the seed of several 1868.. plants, but especially from that of the wild cabbage (brassica oleracea) was largely used in France, and would comply with all the required 1872. conditions except that of being of home production. This difficulty the board overcame by stimulating the cultivation of the plant and the manufacture of the oil from its seed as a private industry.

In 1861 the board purchased and used over 5,000 gallons of colza-oil at $1.10 per gallon; in 1862, 2,000 gallons at $1 per gallon, and 10,000 more at $1.10 per gallon, and that, too, while sperm-oil was selling at $1.643 per gallon; and it speedily became evident that the country would soon supply all the colza-oil wanted for lighthouse consumption at $1 per gallon as a maximum price.

Meantime the board had experimented with lard-oil, and with such success that it appeared that this oil of a certain grade was a more desirable illuminant than colza, and it gave equally good results, was more certain in quantity and production, and was economical in price.

The principal manufacturer, who, after several attempts, had succeeded in making colzaoil, and who to do so had put up expensive machinery at the board's instance, finally informed it that the result of its experiments had convinced him that the Government could not afford to use colza-oil in preference to lardoil, and that he would abandon its further manufacture for lighthouse purposes, though he had demonstrated its success in all respects except competition with lard-oil, if the board would purchase from him the colza he then had on hand. This was done, and lard-oil became the established illuminant.

1881.

the "

67,000
44,000

The lighthouse establishment from its inception had a tendency to the use of petroleum. As early as 1807 there was a correspondence between Mr. Gallatin, then Secretary of the Treasury, and the owners of the good ship Corlomande, from Rangoon, in the kingdom of Ava, relative to five thousand gallons of earth-oil, which is commended as the "best article known for burning in lighthouses, making a very strong, clear, and bright flame, emitting at the same time a great volume of smoak." It may be that then, as often since, great volume of smoak" prevented the use of the earth-oil. In 1855 the board made some unsuccessful experiments with the various forms of petroleum. Meantime the price of lard-oil had so far increased that a cheaper illuminant became a necessity. It was only necessary, however, as a matter of economy, since lard-oil had proved itself acceptable in every other respect. The matter was approached with much caution, as the volatile, inflammable, explosive nature of mineral-oil was well known. The keeper of one of the lights on Lake Michigan had, in 1864, on his own motion, substituted for the usual lard-oil lamp one burning kerosene. Soon after commenc

ing its use, he attempted to extinguish the lamp by blowing down its chimney, when it exploded. He had scarcely reached the foot of the staircase, with his clothes on fire, when another explosion took place, which blew the whole lantern from the tower, and effectually destroyed the lenticular apparatus. But, as mineral-oil was, in one form or another, in successful use in European lighthouses, the board set about solving the problems connected with its uniform and economical combustion, its purchase in the large quantities needed, the tests as to purity, and the degrees of heat at which it should burn and flash, the degrees of cold at which it should remain limpid, methods for its transportation and storage, and the other questions connected with its safe and economical use.

The first difficulty was that of the lamp in which it should be burned. At the outset a claim was set up that mineral oil could not be burned in a lighthouse without infringing on a certain patent. The board, always ready to encourage inventive genius when applied to lighthouse matters, asked the necessary authority to deal with the patentee, when the Secretary of the Treasury, as the custom is, referred the legal questions involved to the Attorney-General. Thus a legal controversy arose which continued some three years, running through the Patent Office, and was finally adjudicated in the courts, where it was decided that mineral-oil could be burned in any lighthouse lamp except one without infringing any patent. Meantime, the board had, after much experimentation in its own laboratory and workshops, succeeded in producing a mineral-oil lamp capable of consuming all the carbon it set free, and introduced it into its lighthouses. The chairman of the board, the venerable Professor Henry, had been during this time dealing with other difficulties practically and personally in laboratory and workshop, and in them had more than once endangered his person, if not his life, and thus the board reached in advance certain determinate results. It fixed the flashing test of the mineral-oil that would be accepted for lighthouse use at 140° Fahr., the fire test at 154°, and the freezing test at which it should remain limpid at zero. Litmus paper immersed in it for five hours must, by remaining unchanged in color, show its freedom from acid; its specific gravity must not be less than 802°; and it is to be paid for by weight, at the rate of 6 pounds net weight to the gallon. The board has contracted for several lots deliverable at different periods at New York, Detroit, and San Francisco, amounting to 75,000 gallons in all, at an average price of 14 cents per gal lon. The difficulty of storing and transporting such quantities in bulk was conceded, but its danger was evaded by having the oil placed at once in fire-gallon cans, where it was to remain until transferred to the lighthouse burners for combustion. Mineral-oil is now used

throughout the lighthouse establishment, except in the seventy-three lights of the highest powers, in which this illuminant fails yet to burn to as good advantage as does lard-oil. It is claimed that five gallons of mineral-oil will give as much light as four gallons of lard-oil, while mineral-oil at the present writing costs about fourteen cents and lard oil about seventy-five cents per gallon. Thus it may be stated roughly that mineral oil, as compared with lard-oil, gives one fifth more light and costs four fifths less money.

The propriety of using gas as a lighthouse illuminant has several times been considered. An effort was made in 1844 to use a rosin gas at the Christiana light station, near Wilmington, Delaware, but, after something less than a year of trial, it was abandoned as impracticable. Another unsuccessful attempt was afterward made at the light station on Reedy Island, mouth of Delaware River.

From time to time, lighthouses near cities have been illumined with gas from the city gas-works: it is now used in but three stations, namely, Cleveland, Ohio, Alexandria, Virginia, and Newburyport, Massachusetts; and even at these three it has been found necessary to guard against the accident to gas-pipes, most likely to happen in the coldest weather, by keeping a set of oil-lamps ready to take the place of the gas-burners at a moment's notice. But, while the board has not found the use of gas practicable thus far, it keeps itself informed as to the progress made in its manufacture and its combustion.

The board is using compressed gas to light the ten lights at the northern entrance to Currituck Sound, North Carolina. This gas is made and compressed at its own gas-works, and it is carried to each of the beacons in tanks, built into a scow, which is towed by a steam-launch, manned by the keepers of these ten small lights, who reside on board. The gas in each will burn for ten days and nights, if need be. Though the action of this illuminant is not unsatisfactory, it can hardly be said that it has yet passed beyond the experimental stage.

The board has watched the experiments made in other countries with the electric light as a lighthouse illuminant, and, while it does not consider that this light can be seen farther than its own best lights-which are seen, located, and identified as far as the curvature of the earth will allow and while it is not convinced that the electric light can be located or identified better, or even seen in fog farther, than its oil lights, still, for purposes of practi cal experimentation, it has unsuccessfully, however-for several successive years, asked Congress for such an appropriation as would enable it to erect and put in operation an electric light by the side of and in competition with an oil light. Meantime it has tested every prominent American-built machine for making the electric light, that it might be ready to use the best when Congress had pro

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