This plan was the construction of huge truncated cones of timber, which, of the reduced size at which they were actually built, measured 36 feet in height, with a circumference of 472 feet at base, and 339 feet at top, the angle of the slope being 60°. This was strengthened by an interior concentric cone, 5 feet 10 inches within the outer one. The frame of each was made of 80 large upright timbers 24 feet long and 1 foot square. On these were erected 80 more of 14 feet in length, making, for the 2 exterior and 2 interior portions, 320 of these uprights. The machine was then planked, hooped, and firmly bolted together. The first cone was built and floated at Havre, then taken to pieces, transported to Cherbourg, and floated off and sunk on June 6, 1784; and the second on July 7 following, in the presence of 10,000 spectators; but before the cavity of this one could be filled with stones, its upper part was demolished in a storm of 5 days' continuance in August, and the stones it contained were spread over the bottom, interfering with the placing of the next cone. The original plan was to set 90 of these cones, of 150 feet diameter at base, 60 at top, and 65 feet height, in succession, and fill them with loose stones or masonry, and the spaces between them with a network of iron chains, to break the force of the waves. The number was afterward reduced to 64. After the 2d cone went to pieces, the government directed that the remainder should be set 192 feet apart. This distance, by a new order, was increased to 1,280 feet, the spaces to be filled in with loose stones. At last, when 18 cones had been sunk at enormous expense, and with serious damage to many of them, the plan was abandoned, the tops of those left standing were cut off down to low-water mark in 1789, and the system of construction by sinking rocks was recognized as the only process sure to succeed. The filling in of stone was continued till, at the end of the year 1790, the quantity sunk was estimated at 5,300,000 tons; and the total expenditure, by the estimate presented to the legislative assembly in 1792, was about 31,000,000 francs, or $5,800,000. The commission appointed by the departments of war, marine, and the interior, in 1792, reported, after careful examination of the dike and of the partial protection it already afforded at different stages of the tide, that its stability could not be depended upon except by the use of larger blocks of stone as a facing than had before been employed-these stones should be at least of 15 to 20 feet cube; and they recommended that the dike be raised 31 feet above the level of the lowest tide, which would make it about 9 feet above that of the highest tides. But the revolution succeeding, further work was interrupted. In 1802, by advice of a new commission appointed 2 years previously by a new government, it was determined to raise the central portion of the breakwater to the height before recommended, for 195 metres (640 feet) in length, and to give it a

breadth at top of 19.5 metres, in order to construct upon it a battery of 20 pieces of the heaviest artillery; and the 2 extremities it was proposed to finally complete in the same man ner. At that time the old work, which had originally been raised to low-water mark, was reduced by the action of the sea to 15 or 18 feet below it, and the profile imparted to it was regarded as that of greatest stability with least expenditure of material. The interior slope was one of equal height and base, 12.5 metres. The slope exposed to the sea had at bottom a height of 6.3 metres to a base of 9, succeeded by one of 6.2 to a base of 47.5; its original form was a uniform slope of 1 in height to 3 of base. The sea washing over the top tended to move the stones from the outside to the inside; and this action it was essential to oppose by raising the top above the surface of the water. In 1803, the central portion was completed to low-water mark, and a superstructure or parapet, of blocks of 60 to 80 cubic feet each, was raised along the south or inner side to the height of the highest tides, along which the smaller stones used in the construction, pressed upward by the great waves in the winter storms, collected and formed a solid and compact surface, at a new slope, of which the base was about quadruple the vertical height. It was observed that the lateral movement of the small stones by the storms, driving obliquely along the outer face of the dike, caused them to collect at each extremity in a conical mound of the precise configuration traced for the proposed terminal batteries; but to prevent their extending into and obstructing the passes, it was found indispensable to face the whole exterior with blocks large enough to resist these oblique impulsions. In May, 1805, the battery on the central portion was armed with 20 pieces of heavy ordnance. In February and May, 1807, occurred 2 great storms, the effects of which upon this portion, as also of the unprecedentedly severe storm of Feb. 12, 1808, are described in the “ Memoir upon the Dike of Cherbourg, compared with the Jetty or Breakwater at Plymouth," by the baron Cachin, inspector-general of roads and bridges. In the last-named storm the battery was submerged, the parapet was upset, and the barracks and garrison, with 60 men, were swept away. The large blocks of stone, with which the dike was faced, were by this storm arranged in new positions, and so closely stowed, that they appeared as if placed by the hand of man in positions of the most perfect stability. As thus arranged, the outer side presents 4 slopes. At the upper part, reached only by the tops of the waves, the height is to the base as 100 to 185. Benoath this is the space between the high and low-water marks, which is exposed at all times of tide to the most violent action of the sea. Its slope is the most inclined, the height being to the base as 100 to 540. Below the lowest spring tides is a space but little ex

posed to the action of the waves; the height of this slope to its base is as 100 to 302. The lowest part which is always submerged has a height of 100 to a base of 125. The slope on the inner side is of 45°. From the experience of these 2 breakwaters, incomparably the greatest of their sort which the mind of man has ever contemplated to undertake, M. Cachin concludes with the observation, that if man be strong enough to heap together rocks in the midst of the ocean, the action of the sea alone can dispose them in the manner most likely to insure their proper stability. This, it may be added, will necessarily vary in form with the specific gravity and size of the stones used. The length of the dike, as reported by M. Cachin, is 3,768 metres-24 miles; and the area of its transverse section 1,350 square metres. When complete, it is intended to extend from 3 to 4 miles, running nearly W. N. W. from the Isle Pilée toward Querqueville. In 1830 it was decided to raise the dike by building up a wall of rubble masonry faced with granite to the height of 6 feet above highest water. This is protected by a foreshore of great blocks of stone on the outer side, which extend in a slope of 120 feet to the depth of 21 feet below low-water mark. This nearly vertical wall (the slope of its sides being to 1) is 36 feet 3 inches wide at base, and 29 feet 3 inches wide at top. A parapet is raised to the height of 6 feet upon its outer edge, which is 8 feet 3 inches thick; at top 8 feet 6 inches wide. The altitude of the breakwater is given by the United States commission of engineers and naval officers, who examined it in 1829, at 72% feet, the base of its sea-slope being 2285 feet; and they state that similar proportions were adopted at the Plymouth breakwater, the altitude of which is 57 feet and base 180 feet. The inner slope of this, however, was built at an angle of 32°, although that of Cherbourg had stood perfectly well at 45°. The adoption of the general plan of this work by the English and American engineers, sufficiently proves the correctness of its principles, though by some English authorities the work is alluded to as a failure.-The breakwater at Plymouth, England, was commenced in 1812, and it was considered as completed in 1841. Its object was to protect the inner harbor from the heavy sea that is driven in by southerly storms. Its dimensions are only about those of the breakwater at Cherbourg, its total length being 1,700 yards, made up of a central portion of 1,000 yards, and a wing bending in from each end, at an angle of 120°, of 350 yards. Its profile is 993 square feet. It was designed to have a base of 210 feet, breadth at top 30 feet, and height in the middle 40 feet. Its actual height exceeds this, but it is only about 3 feet above the highest tides. It is built of large blocks of limestone, some exceeding 5 tons in weight, brought in vessels from the quarries at Catwater, about 2 miles up the harbor. The convenience of position

30

of these quarries for loading the vessels, the facilities of quarrying the stone, and the judicious arrangements introduced, made the work of comparatively light expense. After some experience was had, the stone was quarried by contract at 28. 5d. (58 cents) per ton, and transported for 34 cents; and the total cost of the stone laid, including land purchases, salaries, buildings, &c., was estimated in 1816 at about 88. 1d. per ton. In 1841, it was calculated that 3,369,261 tons of stone had been laid, at a cost of nearly a million and a half of pounds. In 1854 the expenditures had amounted to £1,528,639; the sum of £13,000 was appropriated for further expenses, and £21,000 more estimated as necessary to complete the work. The 15 vessels kept employed in transporting the stone were furnished with 2 railways laid along in the hold, upon which were run the loaded cars from the quarries, entering through 2 stern-ports. These could be tightly closed when the vessel was loaded. On each side were arranged 8 trucks of the extreme capacity of 5 tons each. In discharging, these were drawn out by a windlass on deck, and upset as they passed out of the ports, each one being drawn up on the deck and run forward to make room for those behind. At the quarries they left the deck, and the track on which they descended over the stern being raised up, the loaded cars were run under it, into the hold. The usual cargo of 45 to 65 tons could thus be discharged in less than an hour. On Jan. 19, 1817, the work was tried by one of the most severe storms ever known. The breakwater, though in an unfinished condition, caused perfect protection to the inner harbor, where without it the damage would have been immense. Previous gales had had no effect upon it; but this caused the upper stratum of the finished part, 200 yards in length and 30 in breadth, to be stripped, and the huge stones of 2 to 5 tons weight to be carried over from the outside, and deposited upon the northern side of the breakwater. The quantity thus removed was estimated at 8,000 tons. Since that time the outer slope has been "cased with regular courses of masonry, dowelled, joggled, dovetailed, and cramped together; the divingbell being brought into requisition for placing the lower courses, which were of granite, and were laid horizontally on their natural beds, and dovetailed, lewised, and bolted together." This work was reported by Mr. Stuart, the superintendent of the breakwater, to have been done on a slope of 5 to 1, as the sea had left it. The foot of the outer slope has also been extended further out with loose stones, to give protection to the courses of masonry.-In the plan of construction of the breakwater for a harbor of refuge at Dover in England in 1846, a proposition was favorably entertained by the commission, of building a vertical wall for a breakwater, braced at its base by sloping piles of stone; and this was recommended by many eminent men as an eco

nomical method, and one that might be depended upon for stability. By their reports it would seem they attached but little importance to the horizontal shock which a wave, driven by the winds and swaying backward and forward, gives by its inertia, when it impinges upon a vertical wall. Sir Howard Douglas, one of the commission, strongly dissented from their views in the able report he presented to the house of commons. He also strongly opposed the use of bricks cemented into blocks, as was recommended by some, or of any material but stone, in the forms already proved so advantageous at Cherbourg and Plymouth. The construction of an important breakwater was commenced at Portland on the southern coast of England, in 1849. It is to consist of an outer and inner mole, the total length of which is to be 2,500 yards. The area these will protect is about 2,107 acres of Portland bay, over which the depth of water is from 2 to 10 fathoms. The entrance is made available for the largest men-of-war and steamers. About 3,000,000 tons of stone had been deposited up to the early part of the year 1858, and the arrangements are so complete for running down the stone upon the several lines of railway laid from the quarries, that nearly 500,000 tons can be deposited annually. These quarries are of the oolitic limestone or Portland stone, the same which furnished the stone for St. Paul's cathedral, London, and for the bridges of Westminster and Blackfriars. They are upon summits of considerable elevation-one full 300 feet above the water, from which the wagons descend by gravity to the breakwater, the loaded cars drawing up the empty. Stone is quarried by convicts, of whom 923 are kept thus employed; and 396 other laborers are engaged in other work connected with the construction. The stone used is rubble, faced with large blocks, some of which are quarried and laid, weighing 5 to 6 tons. Although the work considerably exceeds in extent the breakwater at Plymouth, its estimated cost, from the economical arrangements and convenient supplies of stone, is less than one million pounds sterling.— In 1828, a commission appointed by the government of the United States, under act of congress of May 24, 1824, consisting of Commodore Rodgers of the navy, Brigadier-general Bernard of the engineer corps, and William Strickland, architect and engineer, recommended the construction of a breakwater in Delaware bay, just within Cape Henlopen. The work was required from the fact that, from New York harbor to the mouth of Chesapeake bay, there was no good place of shelter along the coast for vessels exposed to easterly gales. The entrance of Delaware bay on the south side was judged the most advantageous point for constructing a harbor of refuge, though it was exposed both to the most dangerous gales from the Atlantic between E. S. E. and N. E. by N., and those across the waters of Delaware bay from N. E. by N. around to the W. VOL. III.-42

The place is also exposed to the fields of ice that are brought down by the ebb tide in the winter, and urged on by the heavy northerly gales of this season. The plan of the breakwater was consequently designed to guard against dangers froin these different directions. It consisted, first, of a straight mole, 1,203 yards long, in water of 5 to 6 fathoms depth, the sea slope having a base of 105 feet to a height of 39 feet, and profiled after the curvilinear figure assumed by the breakwater at Cherbourg; the inner slope to be at an angle of 45°. The width at top was designed to be 22 feet (afterward increased to 30), and the entire width at base 1664 feet (afterward increased to 175 feet). Its position was in a line tangent to the seaward extremity of Cape Henlopen, extending E. S. E. and W. N. W., which is in the original course of the ebb tide; the shore of the cape is 1,000 yards distant from its eastern end on the course of the breakwater, but only 500 yards opposite toward the south. This mole protects the harbor behind it from the northern and eastern winds. The second mole, designated as the ice-breaker, is opposite the western end of the breakwater proper, and separated from it by a channel of 350 yards. It lies in an E. by N. and W. by S. direction, making an angle of 1461° with the course of the other. The area protected against all the most dangerous winds, with a depth of 3 to 6 fathoms, is estimated at 360 acres. The work was commenced in 1829, under direction of Mr. Strickland, and in 1834 it was so far advanced, that vessels found protection behind it. Blocks of rubble from the nearest quarries were thrown in to form their own slopes for a foundation. The outer covering to within 6 feet of low-water mark was of blocks from 2 to 3 tons weight; from this to low-water mark they were of 3 tons; thence to high-water mark, 3 to 4 tons, and above this, 4 to 5 tons, to a height of 4 feet 3 inches above highest water. The ordinary rise of tide is nearly 5 feet, equinoctial tides 7 feet, and extreme tides 10 feet. As the breakwater was built, its exterior slope for the first 16 feet from bottom was at an angle of 45°, thence to summit 28°, or 3 to 1. The inner slope was 45°. The surfaces of both slopes to the level of low water were paved with rough blocks set at right angles to the slope, and well wedged together, thus presenting as little surface as practicable to the action of the waves. The stone used in this work was obtained from a variety of sources, some trap rock from the Palisades on the Hudson river, greenstone from the northern part of Delaware, and gneiss from different quarries in Delaware. These rocks, though averaging a weight of 175 pounds to the cubic foot, and employed of the dimensions named, were insufficient to withstand the action of the sea in the course of the construction of the moles. During the winter season, those upon the surface of the work were more or less displaced, and a large piece of 7 tons weight was moved

in one storm 18 feet to the inner slope of the ice-breaker, down which it was lost. At the same time about 200 tons of other heavy stone, that had been thoroughly wedged and compacted together, was torn up and swept over to the inner side. The experience acquired by all these breakwaters, and by the action of the waves upon coasts exposed to their greatest violence, establishes the principle that blocks of stone of large dimensions only can be depended upon to retain their places; that though smaller ones may be dovetailed together, and present an apparently solid foundation, the heavy waves exert a hydrostatic pressure upward proportional to their height, while the horizontal movement of the wave is exerted to thrust the mass forward. Mr. James Walker, president of the British institution of civil engineers, advanced the opinion in 1841 that a partial vacuum is created by the action of the waves, and the atmospheric pressure being taken off for an instant, the mass of stone is the more readily influenced by the forces which at the same time solicit it. ("Civil Engineer and Architect's Journal," Sept. 1841.) If the whole atmospheric pressure were taken off the surface, it would be equivalent to the removal of a weight represented by a column of rock 111⁄2 feet deep, weighing 175 pounds to the cubic foot. Under such circumstances, and exposed to the action of a wave 20 feet high, which is capable of moving masses of rock 7 feet deep, stability would be insured only by the addition of this amount to the 11 feet. But as it is not probable that a large proportion of the atmospheric pressure is ever thus removed, and as 22 feet is regarded as the maximum height of waves, a depth of solid stone of 15 feet, used as a coping, would probably resist all action of the waves. The subject is ably treated in a paper "On the Force of the Wind and Sea," by Ellwood Morris, civil engineer, who was employed as an assistant in the construction of the Delaware breakwater, published in the "Journal of the Franklin Institute," 3d series, vol. iii., 1842. Mr. Morris proposes a new form of construction of breakwaters, of which a transverse section is figured in the article referred to. It consists essentially of a semi-cylindrical mass of stone at least 32 feet in diameter, formed within of rubble stone well set in cement mortar, and without of large blocks shaped and arranged as arched stones, and cemented and bonded together; the base of the arch to be upon a cemented floor sloping toward the sea with an inclination of about 6 feet base to 1 foot rise. The seaward side of the arch is to be protected by a foreshore of rough cubical blocks weighing above 10 tons each; this work to reach above the highest tides, and slope down at an angle of 2 or 3 to 1, and below low water 2 to 1. Thus built, the whole cylindrical mass would gravitate as one body; and the weight of the upper portion would be most advantageously distributed to bind together and hold down all parts of the

The

work. The construction and history of the principal breakwaters are fully treated in the great work of Sir John Rennie, president of the institution of civil engineers, upon British and foreign harbors, published in 1854, in 2 folio volumes.-Breakwaters of considerable magnitude have been constructed upon the great northern lakes for the protection of harbors, as at Buffalo and Cleveland on Lake Erie, and Chicago on Lake Michigan. first-named is a massive pier of stone-work. Piles driven in rows into the sand are sometimes employed for the construction of breakwaters; but they are of little service in exposed situations. Beaches are protected from the inroads of the sea by this method, by layers of brush kept down by stones, intended to hold the sand together and collect more, and also by triangular frames of timber, arranged closely together and kept in place by stones placed upon the projecting ends of the timbers which serve as the base of the frames.

BREAM (pomotis vulgaris, Cuv.), an acanthopterygian fish, of the family percide, of which several species are found in North America, and of which the above, called also sunfish, pondperch, and roach, is the most common. In this genus the borders of the preoperculum have a few denticulations; no teeth on the palative bones and tongue, but with minute teeth on the jaws, vomer, and pharyngeals; branchial rays 6; a membranous elongation at the angle of the operculum. This beautifully colored species is common in fresh ponds, and is an excellent edible fish; the length rarely exceeds 8 inches. The color above is greenish brown, with rusty blotches irregularly distributed, in some specimens arranged longitudinally; undulating deep blue lines, longitudinally across the gill covers; opercular membrane black, with a bright scarlet blotch at its posterior portion; abdomen whitish or yellowish; dorsal, anal, and caudal fins dark brown; ventrals and pectorals yellowish. The body is compressed; the back curves very gradually as far as the posterior extremity of the dorsal fin, and then abruptly gives place to the fleshy portion of the tail; the eyes are large and circular; nostrils double, the anterior tubular; mouth small and minute, teeth sharp; the lateral line assumes the curve of the back; the scales of the body are large, and dentated at the base, small at the base of the fins; the pectorals are long, and the caudal emarginate. The bream builds a circular nest along the shore, by removing the weeds and excavating the sand to a depth of a foot and an extent of 2 feet; sometimes 20 or 30 occur within the space of a few rods, and often in very shallow water; over the nest the fish hovers, protecting its eggs and young for weeks; it darts against other fishes which come near, and is so intent on its guard duty, that a spectator can approach very near, and even handle it. This species has a wide distribution, being found in New Brunswick, the Canadian lakes, the New England states, Ohio, Kentucky, &c. The name of bream is given in