Ship, a term applied in general to all vessels navigating the sea, and in particular to sailing vessels with at least three masts carrying square sails. The masts are known as fore, main, and mizzen. The mizzen is sometimes merely fore-and-aft rigged, carrying no yard; the vessel is then known as a bark. Brigs have two masts rigged with square sails, and are generally smaller than ships; they are convenient for handling with few men, and were formerly very popular, especially in the West India trade. Hermaphrodite brigs (partly brig and partly schooner) carry on the mainmast only fore-and-aft sails; they are usually of inferior size to full-rigged brigs. Schooners are two-masted and fore-and-aft rigged, carrying jib and flying jib), foresail and mainsail, with a gaff topsail over each of the latter, and a long square sail for the foremast, only brought out for use when the wind blows steadily from astern. The topsail schooner has a square topsail and sometimes a topgallant sail on the foremast, but the lower sail is the usual fore-and-aft foresail. These are light and easy to navigate, and excellent sea boats. Cutters used for revenue service were formerly topsail schooners; steamers have now taken their place.

When it is desired to increase the capacity of schooners without increasing their draught, they are considerably lengthened, and a third mast is added to them, when they are known as three-masted schooners. Pink stern schooners, or those with high-pointed sterns, were once favorites in the cod and mackerel fishery of New England; they carried no jib, but only a foresail and mainsail. Sloops are small, generally less than 125 tons, with one mast. They carry a jib and mainsail; the latter by the great length of the mast and boom is very large. They commonly have a gaff topsail, and sometimes a square topsail, and a long square sail occasionally set. They are adapted only for rivers and comparatively smooth waters. A vessel is sometimes seen in our harbors with three masts, the foremast rigged like that of a ship and the others schooner-rigged without topsails; this is known as a barkan-tine. - The nations of antiquity inhabiting the shores of the Mediterranean and Red seas, and foremost among them the Phoenicians, attained considerable skill in the construction of vessels, and made long voyages.

The Bible contains the description of an antediluvian vessel, Noah's ark; and it is remarkable that its proportions of length, breadth, and depth are almost precisely the same as those considered by our most eminent architects the best for combining the elements of strength, capacity, and stability. According to Gen. vi. 15, the ark was 300 cubits long, 50 cubits broad, and 30 cubits high; i. e., six times the breadth for the length, and three fifths of the breadth for the depth. The ships represented upon ancient Egyptian tombs were long galleys with one mast and a large square sail, which was sometimes of linen colored or white, and sometimes of papyrus with one, and in the later periods with two yards. These were of great size and length, so that men could walk out upon the lower one, holding on by the ropes by which it was suspended from the top. The vessels were made of planks of pine, fir, or cedar, each end rising up out of the water by a long slope, well adapted in shape for easy propulsion, and were furnished with oars, upon which the war vessels were wholly dependent when in action, and all of them indeed except when the wind was favorable.

The ships of war alone were decked wholly or in part, and upon the larger ones the deck was high, and in some instances covered with structures resembling houses. According to Pliny, the Thasians were the first to construct full decks. Merchant vessels were round-bottomed for the sake of capacity. The prow was furnished with an elaborately carved image, as a boar's head, dog's head, etc, which was the symbol after which the ship was named. This symbol was termed the insigne (whence our word ensign), and has descended to our own times as the figurehead. Upon the stern, which rose high out of water, like that of a Chinese junk, was the image of the tutelar god with other ornamental devices. A peculiar feature in the war vessels was a projecting beak, at first made above the water line, and afterward below it, armed with pointed irons or the head of a ram, the object of which was to pierce the sides of other vessels against which it was run. This was the only part built of oak or hard wood. From want of strength in the construction of ancient vessels, and the necessity in their voyages of avoiding exposure to rough seas, they were bound around the outside with broad and thick ropes.

During the gale which preceded its shipwreck the vessel which bore St. Paul, bearing the sign of Castor and Pollux, had to be "undergirded" (Acts xxvii. 17). The great ships of Ptolemy Philadelphus were provided with as many as 12 such bands, each of which was 900 ft. long. They were sometimes carried on board the vessels, to be put on when needed in rough weather. As the ships depended chiefly upon the use of oars, the arrangements for these were their most marked feature, and gave distinctive names to the several classes of vessels. (See Galley, and Navy.) A Roman ship of the time of Trajan, sunk in the lake of Riccia and raised after it had lain there more than 1,300 years, was described by Leo Baptista Albert in his book of "Architecture" (v. 12); it was built of planks of pine and cypress, daubed over with Greek pitch and calked with linen rags; the wood was in a good state of preservation; the outside was sheathed with sheet lead fastened with small copper nails. - In the middle ages navigation and ship building declined, and little is known of the vessels of that period. The expedition made by the Anglo-Saxons to England, A. D. 449, was in frail vessels, their sides made of wicker work and covered with skins.

Better vessels were undoubtedly used by the Northmen in their perilous voyages. For war purposes the long low galleys of the Mediterranean gradually replaced the ancient triremes. Alfred the Great adopted them in his wars with the Northmen, and he first made the English navy unequalled. In the latter part of the 14th century the best ships were of Norman construction; in the representations of their war vessels of this pe-riod the rudder is first seen as a substitute for the great steering oars always before in use. In southern Europe the credit of first building vessels to be propelled by sails alone has generally been conceded to the Genoese. In England many such vessels were employed as early as 1344. The use of cannon in naval warfare at the siege of Calais in the reign of Edward III. led to the enrolment of ships belonging to the crown. Ships of war had been numerous in the reign of John, but were owned by individuals; the government provided at that time for their accommodation the royal dockyards at Portsmouth. The ships of these periods were remarkable for the great height of their sides, their bulky rounded models, and the simplicity of their rig. They had no bowsprit, and seldom more than one mast; the sail was attached to a yard, which was let down to the deck when not used.

They were navigated by 17 to 20 sailors only. Henry V. added to the number of English ships. His vessels were of 100 to 600 tons each, some with three, others with two masts, with short topmasts and a forestage or forecastle built up to a considerable height for the soldiers. At the mast heads were topcastles, in which men were stationed during an engagement to annoy the enemy with darts and other missiles. In the middle of the 15th century William Can-ynge, a famous merchant of Bristol, built many large ships, one at least of 900 tons burden, and employed altogether not less than 2,850 tons of shipping and 800 mariners for eight years. The navies of the Netherlands, Venice, Spain, and Portugal attained great importance in that century. Many of the ships being so far improved as to sail upon a wind, and the compass and astrolabe having come into use, it was now possible to engage in longer voyages and prosecute explorations in unknown seas. The discovery of America and of the passage round the cape of Good Hope were early fruits of these improvements. The Portuguese employed small vessels in their voyages of discovery, as the best adapted for explorations along unknown coasts; but the Spaniards cultivated the art of building large ones, and long maintained a superiority in this respect.

The Great Harry, built in 1488, is considered to have been the first ship of the English navy as it is seen to-day, although a standing fleet was first formed under Henry VIII. She had four masts, carried courses, fore and main topsails, and topgallant sails, and had guns in broadside on two covered decks. (See Navy.) The vessels of this period, built up with high castellated structures at each end, seem intended rather for display than for actual service, and must have been far inferior sailers to the galleasses and galleons of the Mediterranean, which had succeeded the galleys. These were of moderate height above the water, and the first had overhanging bulwarks like the guards of modern steamboats, greatly adding to the width of the decks and affording room for the rowers. The galleons, on the contrary, which depended on sails alone, were drawn in at the top to such an extent as to contract their breadth from the water line fully one half; this feature has ever since prevailed in many European ships. Henry VIII. established the dockyards at Dept-ford and Chatham, and brought together from foreign countries, and especially from Italy, many skilful shipwrights and workmen.

In the reign of Elizabeth the superior management of the English ships over the much larger ones of the Spaniards, with their three tiers of guns, was fully established in the contests with these vessels; and great progress was made under the encouragement of the queen in increasing and perfecting the mercantile marine. The East India company was chartered in 1600, and the increasing traffic with the distant countries of Europe and America rapidly stimulated the demand for the best vessels and called forth the ingenuity of the ship builders. Sir Walter Raleigh gave much attention to the improvement of ships, and his publications entitled "Invention of Shipping" and "Concerning the Royal Navy and Sea Service" greatly added to the general interest in the subject. The shipwrights' company, established in 1605, was incorporated in 1612, and general charge was given to the association over ship building throughout the kingdom. The first master was Phineas Pett, of a family distinguished for the principal engineers it furnished to the royal navy from about the middle of the 15th century to the end of the reign of William III. He built the Royal Prince in 1610, a ship of 114 ft. keel, 44 ft. breadth, and 1,400 tons burden, introducing the great improvement of cutting off the long projection of the prow, hitherto universally adopted, and also much of the cumbersome top hamper of the older ships.

The first English three-decker was built by his son Peter Pett in 1637. She was called the Sovereign of the Seas, and had the reputation of being the best man-of-war in the world until she was accidentally burned in 1696. An account of her armament is given in Navy. She was 232 ft. in length over all, 128 ft. length of keel, 48 ft. in breadth, and of 1,637 tons. The drawings represent her as a full-rigged ship carrying square sails altogether, topgallant sails, and royals, but no jibs or staysails. Under the bowsprit was a square sail suspended from a yard, such as is now called the spritsail. The hull was somewhat lofty in the bow and stern compared with modern ships, but still greatly reduced from the older ones. A considerable portion of the additional length above water to that of the keel was from a long triangular beak. The Constant Warwick, also built by Peter Pett in 1646, and designated a frigate, was specially intended for fast sailing; she was light, with low decks, of 85 ft. keel, 26 ft. 5 in. breadth, 13 ft. 2 in. depth, and 315 tons burden; she carried 32 guns and a crew of 140 men, and soon acquired a high reputation for her conquests among the Dutch privateers.

But the Dutch ships at this time were quite equal to the English, and their navy was altogether the best in Europe, the result of their continual wars with Spain. The merchant vessels of England were superior in sea-going qualities to those of the royal navy, and during the wars with France and Spain they boldly continued their trading voyages, two or three of them usually sailing in company. During the 18th century the French attained a decided superiority in the size and models of their ships, and the Spaniards readily adopted the improvements of the French. Their largest vessels were two-deckers only until after 1763, and their largest armaments were of 84 guns. In this respect they were inferior to the English three-deckers carrying 100 guns; but in 1768 the French adopted the English system, and built ships of 110 and 120 guns, and of 196 ft. length by 50 ft. breadth and 25 ft. depth of hold, while the English in some instances copied the lines of the French ships that fell into their hands. But it is admitted even by the English themselves that their system of ship building received no aid from the applications of science, while the French availed themselves of the highest mathematical talent as well as of practical experience and skill.

To the latter and to the Spaniards also is due the credit of the important improvements made in ship building in modern times up to the present century; and yet in the United States, where the same course has been pursued as in England, of seeking aid only from experience and natural talent, the highest success has since been attained in designing 'the most perfect models for the special purposes required. The American ship builders were the first to entirely abandon the cherished features of the European models, as the high poop and inflected topside. Their frigates proved their superiority to all other vessels of war in actual service, and before the introduction of steam their Liverpool packet ships were the finest vessels afloat. Their fore-and-aft rigged vessels, less known abroad than the larger ships, were still more remarkable for originality and perfect success in their designs. The river sloops and coasting schooners were peculiarly American. The schooners of the Chesapeake were especially famous under the name of Baltimore clippers.

Broad of beam before the centre but above the water line, sharp in the bow, deep aft, long and low, they presented admirable forms for capacity, for stability to sustain a large amount of canvas, for great speed, and for holding their course on a wind with little drifting to leeward. The masts were long and slender, the sails unusually large for vessels of their size, and of so true cut and perfect set that no portion of the propelling effect of the breeze that reached them was wasted. Close-hauled, they drew well with the vessel running within 40° or 45° of the wind, while the best equipped frigate would be sharp set at 60°. The superior sailing qualities of these schooners were shown in their success as privateers and freedom from capture in the war of 1812, and were most conclusively established when the yacht America, built on the same principles, carried off the prize in 1851 in competition with the English yachts that had confidently challenged the world to a trial of speed. From these schooners the step was natural to the famous clipper ships by the adoption of the square rig for larger vessels of similar model.

They were called into existence by the increasing importance of the East India trade, in which speed and punctuality were more essential than mere stowage capacity, and still more by the sudden springing up of the California trade with its immense passenger traffic. In vessels of this class the voyage round Cape Horn lost its terrors, and the passage from New York to San Francisco was confidently calculated within a few days, and this at hardly half its former length. The clipper ship Great Republic, built by Donald McKay of East Boston, was an excellent type of this class, and was the largest, if not the fastest, merchantman ever constructed. Her capacity was about 4,000 tons, and her original dimensions were 325 ft. length, 53 ft. width, and 37 ft, depth. A peculiar feature in her model was the rising of her keel for 60 ft. forward, gradually curving into the arc of a circle as it blended with the stem. She had four masts, all provided with lightning rods. The after one, called the spanker mast, was fore-and-aft rigged, of a single spar; the others were built of hard pine, the parts dowelled together, bolted and hooped over all with iron. The main yard was 120 ft. long. A single suit of her sails consisted of 15,653 yards of canvas.

Even in 1851 the performances of some of the clipper ships on long voyages were far superior for days together to those of the steam vessels of that time, and on the whole run hardly inferior. In that year the Flying Cloud made the passage from New York to San Francisco in 89 days and 21 hours. Her greatest distance from noon to noon of any day was 374 knots (433 1/4 statute miles), which, allowing for difference of longitude, was made in 24 h. 19 m. 4 sec, or at the rate of 17.77 m. an hour. In 1852 the Comet arrived in New York from San Francisco in 83 days, and the Sovereign of the Seas from the Sandwich islands in 82 days. The greatest distance made by the latter from noon to noon in any day (in this case 23 h. 2. m. 4 sec.) was 362 knots (419 m.), or at the rate of 17.88 m. an hour. From March 9 to March 31, from lat. 48° S. in the Pacific to 36 S. in the Atlantic, the ship made 29° of latitude and 126° of longitude, equal to 6,245 statute miles, or a daily average of 283.9 m. During 11 of these days consecutively her daily average was 354 m., and during 4 consecutive days 398| m.

Her daily average for the whole distance of 17,597 m. was 222.7 statute miles, or at the rate of over 9 m. an hour for 1,896 consecutive hours. - The two prominent features that constitute the essential improvements of modern times are the shape of the bow and the increased length of the vessel. In place of the convex form noticed in the older ships in tracing the lines from the stem aft along and below the water, is now substituted a concave surface giving to the bow the shape of an elongated wedge slightly hollowed on the face, by which the waters are more easily parted and thrown aside. This wedge shape is extended even to beyond the centre of the ship, so that the broadest part, instead of being as formerly one third the distance from the bow, is now about the same proportional distance from the stern. Above the water line the old proportions may still be retained. This form of bow is not by any means altogether new, having been adopted by the Spaniards in past times and by various barbarous nations for their small craft; but its merits not being appreciated by other European nations, it was sacrificed for the sake of greater stowage, especially by the English, who were the more impelled to this course by reason of the old tonnage laws, in force up to 1836, as regards the method of measurement for regulating the dues, the increase of capacity gained in the bow not being reckoned in the estimate.

Thus the round swelling bow became the established form, in the correctness of which the builders felt confirmed by the similar shape in the head of the whale and of the codfish. The hollowed lines drawn from the stem back on each side the ship were designed by Mr. Scott Russell from his observations made as far back as 1832 upon the shape of the wave set in motion, as by the influx of water from the discharging of a lock of a canal, which travels at rates corresponding to the depth, as 8 m. an hour for 5 ft. depth, 10 m. for 7 ft., 15 m. for 15 ft., 18 for 20, 20 for 30, 25 for 40, and 30 for 50. Hence he designated them wave lines, and the form of the bow they produced he called the wave form. The lines for the stern he also established by study of the refilling or replacing or following wave, as necessarily falling in cycloidal curves. Definite lengths indicate definite rates with a given power, and it would be impossible to force a ship through the water at rates much exceeding those indicated as adapted to the length of her lines without an extravagant expenditure of power. Additional length of body inserted in the centre seems to have no effect, except as it presents an increased surface for adhesion of the water.

Thus the old idea that there must be a certain proportion between the length and breadth of a vessel, as that which for a long time was adopted in practice of one fourth the length for the breadth, proves to be entirely false. The speed does not appear to be affected by the shape of the vessel cross her middle or her midship section, nor by differences of depth to a considerable extent. The proportion between the speed for which a ship is to be designed and the length of entrance and run, Mr. Russell states to be three fifths of the whole length for fore body and two fifths for after body. For a speed of six statute miles an hour the length of entrance should be, according to his rule, 15.12 ft., length of run 10.8 ft.; for 8 m., 26.88 ft. for entrance and 19.2 for run; for 10 m., 42 and 30; for 15 m., 94.50 and 67.5; for 20 m., 168 and 120. The great experiments of the English in the construction of their largest steamers have been made on these principles. Before their adoption it was taught by the most experienced ship builders, and in this opinion Mr. Scott Russell was himself educated, that it was impossible to force steamboats through the water at a greater rate than 9 m. an hour.

He had even seen engines of 50 horse power taken out of one of the short bluff-bow steamboats, and replaced with others of 75 horse power, with the effect of increasing her speed only about a quarter of a knot an hour. With the increased power the resistance in front was much more than proportionally increased, keeping down the speed in this instance to about the same amount. This was in accordance with the mathematical deduction of the resistance in passing through water increasing as the squares of the velocities, or nearly so, and the power necessary to impart an increased velocity varying nearly as the cube of such increased velocity. It is not strange therefore that the opinion prevailed, that if a rate of 12 or 14 m. could ever be attained in sea-going steamers against the enormous resistance, increased as it must be by the tremendous shock of opposing waves, no vessel could be strong enough to complete a voyage. Yet in the United States the fallacy of these views had been practically demonstrated in the steamboats on the Hudson river for several years before the principles of their success were recognized by the English ship builders.

In 1827 these boats were making the trip from New York to Albany in 12 hours, the distance being about 145 statute miles, and the trip usually including 12 stoppings, at six of which the boats were brought to and fastened to the wharves. Several crossings of the river also added to the distance and the time over a trip direct. In 1829 the passage had been accomplished in 10 1/2 hours, in 1831 in 10 1/2 hours, and in 1832 in 9 h. 18 m. (See paper by William C. Redfield in "American Journal of Science," vol. xxiii., 1833.*) These boats were long and sharp, furnished with "cut-water bows," and of dimensions in some instances as follows: length 233 ft., breadth of hull at the water lines 28 ft., depth of hold 10 ft., draught of water 4 1/2 ft.; length 180 ft., breadth at the water line 28 ft.; length 220 ft., breadth 25 ft,; and length 145 ft., breadth 27 ft. In 1832 Mr. Russell demonstrated theoretically the principies upon which such speed was attainable, and in 1837 a river steamer called the Vesper, built on the lines he recommended, was actually run on the Thames at about 12 m. an hour. - The direction in which improvements in the construction of fast ships were to be made being thus determined by theory and practice both in England and the United States, an active rivalry sprang up between the two nations, each producing almost every year steamers of surpassing excellence.

But the American government refusing to pay subsidies to steamship lines, the scale turned in favor of the English, whose resources were greater in other respects than those of the Americans. This was especially apparent when in the course of the contest it was discovered that a limit was encountered to the required elongation of the ships, from the want of strength in wooden timbers, however large and well put together, to bear the increased strain; and that resort must be had to iron plates riveted together, the suitability of which for such use was fully established by the success of the Britannia bridge. In 1855 the Cunard iron steamer Persia was constructed, of 360 ft. length of hull, 45 ft. breadth, and 32 ft. depth, and of capacity exceeding by 1,200 tons the largest of the other ships of the same line. The next of these grand attempts was the construction of the Great Eastern, in which the principle was put to an extreme test upon a length of hull of 680 ft., a breadth of 82 1/2 ft., and a depth of 58 ft. Her lines were designed by Mr. Scott Russell in exact conformity with) his theoretical wave lines. Those of the bow are 330 ft. in length, and the length of the run is 226 ft., the filling in of parallel body to afford the capacity wanted being 120 ft.

This middle portion, as already remarked, is supposed to have no effect so long as the length in other respects is sufficient for attaining the required speed with the given power. In this case the power furnished could be expected to give only 15 m. an hour, and this she attained. For further account of the use of steam in navigation and the history of this application, see Steam Navigation. - The substitution of iron for wood in the construction of steam vessels was first made in 1830 and 1831 by William Fairbairn of Manchester, who then built three small iron steamers which made the voyage from Liverpool to Glasgow. Within the succeeding four years he constructed an iron vessel for the lake of Zürich, and two river steamers of about 170 tons for the navigation of the Humber. He then became associated with the Messrs. Laird of Birkenhead, and with them up to 1848 had constructed more than 100 first class ships. In France and in the United States iron has been partially introduced into wooden ships, bars of iron being employed to great advantage for a diagonal bracing covering the inner surface of the timbers with a complete network; horizontal stringers of plate iron are also fastened to the sides within at intervals from the deck to the keelson, which is also of iron.

The beams are also made of iron, shaped like those used in house architecture, and in various other parts this metal is substituted for wood, the advantage being greater strength with less weight and the occupation of less room. Iron frames are now used exclusively in the English navy. Ships constructed wholly of iron are lighter than those of the same tonnage made of wood, and consequently can carry larger freights. Their size moreover being capable of enlargement beyond the dimensions to which wooden vessels must be limited, they admit more than the latter of profiting by the principle, that the larger the capacity the less proportional part of it need be devoted to the transportation of the fuel required, and the more may be devoted to the cargo. Iron ships are built upon a frame of ribs and longitudinal pieces, upon which the outer plates are secured by bolts and rivets passing through their overlapping edges. Lloyd's rules for iron ships will be found in "Ship Building in Iron and Steel," by E. J. Reed, p. 491. In 1858 a steamer called the Rainbow, of 170 tons and 130 ft. length by 16 ft. beam, intended for the Niger expedition, was built with plates of steel.

These were rolled from lumps of crude steel which were exposed four hours in a close furnace to a temperature a little below the melting point; by this process the steel was made to assume a more homogeneous texture and uniform strength. Its advantage over ordinary iron plates is that equal strength to that of the latter is obtained with only half the weight. The boilers of the steamer were also made of it. - The recent important changes in ships intended for naval service are: 1, the introduction of light and swift vessels propelled by steam, carrying a few heavy guns, and able by their light draught to run into rivers and shoal waters; and 2, that of floating batteries, some account of which has been given in the article Ironclad Ships. Since 1858 the French and English governments have vied with each other in the construction of fighting ships in which the maximum powers of offence are afforded the utmost security from hostile shot consistent with buoyancy. The contest between offence and defence is in reality coeval with the history of ship building. In the earliest sea fights protection from the missiles of the enemy was sought by placing shields, interlaced, on what now would be called the "gunwale" of war galleys. During the middle ages the same expedient was resorted to.

At the siege of Tunis in 1535 the Santa Anna, one of the fleet of the renowned Andrea Doria, was plated with lead, and successfully resisted the artillery of the enemy. The light armaments of the last century often failed to penetrate the stout oak or teak sides of well built ships. Even so late as 70 years ago the ships of Nelson and Collingwood, so long under a concentrated fire as they bore down on the enemy's line at Trafalgar, would have been completely demolished had not the powers of attack and defence been so nearly equal. (See Iron-clad Ships.) - Composite ships are designed to combine the advantages of an iron frame or hull with those of a wooden bottom sheathed with copper or zinc. As the bottoms of iron sea-going ships get so foul by the adhesion of shell fish and sea weed as to materially reduce the speed, the protection of the iron becomes a very important consideration. The bottoms of wooden vessels are protected by a sheathing of copper, which by exfoliation sheds or sloughs off such adhesions. The chlorine contained in sea water has a strong affinity for copper, forming a green chloride of copper, which is dissolved by the water, and thus the copper is wasted away. This waste, which constitutes one chief value of copper as a sheathing, can readily be prevented.

Chlorine is electro-negative. If the copper sheathing were rendered electro-negative also, the chlorine would be repelled instead of attracted, and the metal would be protected from corrosion. Sir H. Davy proposed to do this by driving zinc nails into the copper. The zinc at once becomes electro-positive, attracts the chlorine to itself and generates an electrical current which is transferred to the copper; it thus becomes the generating plate of a battery, while the copper becomes the conducting plate. But while chlorine is repelled, lime and magnesia, electro-positives, are attracted to the copper, forming an earthy coating to which shell fish and sea weed readily and firmly adhere. This explanation shows why all the patent applications for the bottoms of iron ships fail to prevent fouling. No artificial coating possessed of the essential property of exfoliation has yet been devised. As any communication, through the medium of salt water, between copper sheathing and an iron hull would generate galvanic action highly destructive to the latter, it becomes necessary to insulate the iron by applying planking to the bottom and then sheathing that; hence we have what are now commonly known as composite ships.

With copper sheathing the iron must be perfectly insulated; with zinc this is not necessary, as it decomposes instead of the iron when they are in galvanic communication with each other. The English frigates Shah and Inconstant are composite. They have a double thickness of wood sheathing outside the iron skin, with copper over all, and brass stems and stern posts. A sheathing of three-inch teak is first laid fore and aft and bolted to the shell of the ship; next comes a layer of planking of the same thickness, but of lighter wood, secured with shifting butts and seams to the first by brass wood screws. The wood sheathing is calked, paid with pitch, and then coppered. The com-posite system will be adopted in the newmon-itors now (1875) in course of construction in this country. - Ship Building. Few if any mechanical operations demand such a variety of considerations as the building of a ship. A hollow shell is to be constructed in which lightness and stability are the first requisites. If the vessel be a man-of-war, it is a nice point to determine her displacement, or the entire weight of the structure itself with all that she carries of spars, armament, men, supplies, etc, that from this her depth in the water may be known, and the line of her lower ports be fixed so high as not to be washed into in time of action.

The form is to be specially suited for easy and rapid progress, and at the same time must be adapted to resist the severest strains, caused not merely by the weight of the structure and of its load, but by the shock of the waves, and their constantly varying figure, the effect of which is to continually change the places of support, and throw large portions of the weight first upon one point and then upon another. It has often been observed that after a vessel has left the stocks upon which she was put together, and lies upon still water, a line that had previously been drawn straight along her top side from stem to stern is deflected several inches by the settling of the ends, which is owing to a want pf precision and strength in the work to meet the inequality of the weights on the different transverse sections. The effect is to separate to some extent the planks and connecting pieces at the top, and compress those in the bottom of the structure. When the ship enters rough water, she is at one moment supported at the two extremities like a bridge, and the great weight bears down the middle, threatening to bend the whole structure and produce the effect called sagging; the next instant her bow and stern hang unsupported over the great wave which bears up the ship across her centre, and the two ends tend to droop; the latter change of form is called hogging.

If the ship was thus affected when first launched, it is obvious that the distortion must increase as she works in a heavy sea, and that her timbers and fastenings must be greatly weakened by the motion. In various other ways the strength of her framing is severely tried. Driven obliquely across the waves, she is lifted high upon their summits, and at any moment is dashed into the trough against the next coming swell, the force of which she receives upon her bow, side, or quarter, with a shock that quivers through every timber. When following too nearly the line of the waves, she is rolled violently from side to side, and the great weight and long purchase of the heavy yards and masts act with fearful power to strain the sides, to which they are fastened by the shrouds and stays. Again, when moving directly across the waves, each end is in turn elevated and depressed. In all these movements the force of the strain is told by the creaking of the timbers. The structure is put to still severer tests when the ship touches an uneven bottom, and the weight is supported by a few points upon a hard unyielding surface. Then, beaten by the waves, raised up and dashed down again by them, her frame is most perfect if she is not soon parted and broken up.

Indeed, the only vessels ever known to come off from a rocky exposed coast after remaining aground for a considerable time were iron ones, as the Great Britain, which lay a whole winter on the coast of Ireland, and the Vanguard, which was for several days on a rocky beach. The strength of ships, like that of roofs and bridges of long span, depends on the skilful arrangement and fitting of the timbers, so that they shall take the strains they are to meet to the best advantage, as well as on the bolts and fastenings by which they are held in their places. The keel is the foundation or backbone upon which the whole structure is built up. It receives the great upright timbers of the stem and stern, and those called floor timbers that support the ribs, which give form to the sides. The deck beams at different stages, securely fastened at their ends to opposite ribs, hold these together against any spread of the sides or lateral hogging, and also act as struts to prevent collapsing of the sides. Curvature on the length of the ship is guarded against by the planking on the ribs and that of the decks, the planks being laid longitudinally and strongly bolted down to the timbers.

In northern Europe since the middle of the last century a system of trussing has been introduced for greater security in this respect. Three parallel rows of pillars were set up extending from one end of the ship to the other, one row on the keelson, and one each side on timbers laid for the purpose and bolted to the ribs. On the top of the pillars of each row and directly under the lower deck was secured a longitudinal timber like an architrave; and diagonal braces extended from the top of one pillar to the foot of the next in the same row. By such arrangement the stiffness was materially increased, but at the expense of stowage room, and the trussing was not altogether secure of remaining in place in the violent movements of the ship. A much superior method was introduced in 1810 by Sir Robert Seppings, surveyor of the navy, which is known as the diagonal bracing. This was formed of a system of timbers crossing the ribs on the inside of the ship at angles of about 45°, and braced by diagonals or struts. This framing started below at the keelson or horizontal timbers at its side, to which it was strapped down, and terminated above under the horizontal shelf which supported the ends of the cross beams under the lower deck.

The shelf was thus braced up and supported; and in large ships the second horizontal shelf was likewise sustained by a continuation of the diagonal bracing above the lower deck. These shelves secured to the sides of the ship are always provided for the support of the deck beams, and serve themselves to stiffen the structure in their action like internal hoops. In place of this method iron plates or straps are now commonly employed in all important wooden ships for diagonal bracing. Diagonal braces are from 5/8 to 7/8 in. thick, and from 3 in. to 5 in. wide, laid at an angle of 45° with the keel. There are two tiers, which cross each other at right angles, and end on a belt of iron above the spar deck, called a head strap, somewhat larger than the diagonal straps. Straps are put either inside or outside of the frame in the merchant service; in the United States navy it is customary to put them inside. As wooden ves-sels now are not so deep in proportion to their length as in former years, the strength secured by this system of iron strapping is indispensable. - In designing a ship, the old plan, after deciding on her tonnage, is to determine the proper midship section for the proposed capacity, with due reference to the desired speed, degree of stability, etc.

The next thing is to plan the horizontal section called the load water section, and then prepare the drawing on a scale of a quarter of an inch to the foot. The three principal draughts are known as the sheer plan, the half breadth plan, and the body plan. The first is a vertical section extending the whole length of the ship, and presenting her full depth, the inclination of her stem and stern, her masts, ports, water lines, and generally whatever belongs to the side of the ship. The water lines are drawn straight and parallel, numbered from stem to stern. The half breadth plan is a horizontal section of half the ship divided lengthwise as seen from above. The several water lines, numbered as in the sheer plan, are dotted in, or drawn in blue ink, and designate the width and horizontal curves of the hull at the different levels. The body plan is a midship section, representing the height and breadth of this portion of the ship; it is divided vertically into halves, that to the left showing the curves and arrangement of the timbers toward the stern, and the other those toward the bow; the heights of the several water lines are also indicated.

Instead of these plans, the American ship builder has generally substituted a half model of the vessel built up of thin strips of wood laid horizontally upon each other. These strips represent the parallel water lines, and can be taken apart for any alteration of the plan, or for laying off from them the full size lines upon the floor of the moulding loft. This loft is a large room specially devoted to the preparation of the designs and patterns from which all the timbers are to be shaped. The designs being drawn upon the floor, the plank patterns or moulds are obtained from them, which are of the exact dimensions of one face of the timber, and are furnished with marks that designate the other dimensions. The ship yard is situated by the edge of the water, and sufficiently elevated to secure a proper slope for the completed vessel to slide down the ways. At a convenient distance out of the reach of the tide a row of blocks, 4 ft. or more apart and 3 ft. high, is set in the ground, extending back from the water the proposed length of the ship, and their flat upper surface sloping toward it about 3° from the horizontal. On these blocks the timbers which make the keel are laid, being nicely fitted together by scarfing and secured by bolts.

In Europe elm is preferred for the keel, being tough, holding the fastenings well, and long remaining sound under water; but in the United States live oak is commonly used. The latter is the most valuable native timber employed in ship building; but white oak of second growth obtained near the coast in New England is also excellent, and far superior to the same timber brought from the interior. Locust and cedar are strong and durable, and hackmatack is valuable for knees. Chestnut is employed to some extent, and white and yellow pine largely, the latter being the best for decks. It is recommended that the trees be killed by girdling in the beginning of the winter when the sap is down, and left to dry and harden before they are felled. After this the timber should be stored in a dry airy place to season. False keels or shoes are from 4 to 6 in. thick, and fastened to the lower side of the main keel with spikes or short bolts, after the frame bolts, which pass through the frame and the main keel, are clinched. The chief object of the false keel is to save the main keel from injury in case the ship should strike the bottom. Ships are generally built with the stern nearest the water, although sometimes it is more convenient to build and launch sidewise.

On the fore end of the keel is erected the stem, on the after end the stern post, with its lower end tenoned into the keel. The frames which cross the keel are formed of floor timbers and futtocks. They are put together while in a horizontal position, with the floor timbers lying across the keel. When all are calked and bolted together the whole frame is canted up by proper purchases, cross pawls preventing it from spreading. The frames thus crossing the keel are called square frames, as they are placed at right angles to the keel; forward and abaft of the square frames are the "cants" or cant frames, so called because they cant toward the round of the bow or stern. The keelson is a longitudinal timber parallel to the keel, and occupying a place on the inside of the frames corresponding to that of the keel on the outside. The spaces between the frames are generally filled in solid with white or live oak timber. The keelson is built in one or more pieces varying with the size of the vessel. After the frames are erected they are regulated so as to stand square with the keel longitudinally and level transversely. Heavy rib bands are attached to the frames on the outside, and secured by heavy shores.

The inside of the ship is then prepared for strapping, ceiling, placing and kneeing of beams, laying decks, etc. The outside of the frame is covered with plank nearly parallel in width and of various thicknesses; the plank or wales above water are the thickest, being in a large ship from 5 1/2 to 7 1/2 in., the bottom plank from 3 1/2 to 4 1/2 in. The lowest tier or strake of planks outside, known as the "garboard strake," meets the keel along an angular recess called a rabbet, which is cut into its side for the purpose of affording to these planks a tight fit along their lower edge. The keel is thus interlocked along its whole line between the planks each side of it. In large ships this lower tier is sometimes of timbers rather than of planks. The other planks are from 3 to 7 in. thick. To obtain the curves required for the planks to fit the bends, these are steamed in tanks, and then are brought into shape by bending them with screws and levers between fixed supports. The inner planking, known as the ceiling, begins near the keelson with what is called the limber strake, extending along the whole bottom of the hold, one on each side the keelson. The narrow space between is for a gutter to collect the drainage water, for delivering it to the pumps. Such a passage is called a limber.

The strakes over the heads and heels of the timbers are thicker than elsewhere, to give additional security against their ends being pressed in. As the planking is carried up, the projecting pieces called shelves are set in their places and strongly secured, the deck beams are laid upon them, and the ends of these are fastened with wooden or iron knees of great strength. Under the middle of the beams are placed pillars, starting from the keelson; these prevent the settling of the beams, which are arched upward, and their consequent thrusting outward of the sides instead of tying them to a fixed width. As in the rolling of the ship a powerful strain is exerted to lift the ends of the beams, this is also guarded against by another projecting timber set in the planking directly over the beams. This is called the waterway, and is secured by vertical bolts extending through the beam and shelf, and by horizontal bolts that pass through the frame and outer planking. The planks are fastened to the timbers with treenails (i. e., pins of locust) or with bolts or spikes. Treenails have sometimes been made with a thread cut round them and a square head by which they are seized and screwed into the holes.

For the decks yellow pine planks are commonly used, except along the sides of the ship, where a strake of hard wood thicker than the rest of the planks, called the binding strake, is laid for a waterway. In laying the deck planks attention should always be directed not merely to their use as a covering, but also to their action as longitudinal ties for the frame. In some instances decks have been laid diagonally from one side to the other, obviously involving a loss of strength; ships have also been built with three layers of planks for the decks and outer covering, two diagonal layers crossing each other, and a third upper layer running longitudinally. At the ends of the ship the shelf pieces, waterway planks, and strakes are secured to the beams, and crutches attached to the stern post and to the timbers called breast hooks, that spread out from the stem. The openings left in the deck for hatch and ladder ways necessarily weaken ii somewhat, though they are provided with stout framing secured to the beams. The holes for the masts are large enough to receive wedges all around of 3 to 6 in. thickness. For supporting the masts blocks called steps are fastened to the keelson, or for light masts to one of the beams, and into a cavity of these blocks the heel of the mast is set.

A great variety of work still remains for the ship carpenter to complete before he can give place to the calker, whose office it is to make the seams of the deck and outer planking water-tight. The bulwarks have to be finished, the pumps placed, the capstan or windlass for raising the anchor, the catheads for suspending it over the sides, etc. Calking consists in driving threads of oakum, rolled up in the hand, into the seams between the planks; and that it may reach to the bottom and make the seam perfectly tight, the planks should be bevelled on the outer edge to present an opening gradually closing toward the bottom. The width of the opening is sometimes increased by driving in an iron wedge-shaped tool, and the oakum is then crowded in with great force by the calking iron. When the seams are filled they are payed over with melted pitch; but a much better material sometimes used is the marine glue, prepared from shell lac and caoutchouc. (See Glue.) The rudder is sometimes hung before launching, but more frequently afterward. This is made of timbers as thick as the stern post, up and down which it extends, and to which it is suspended by pintals on the rudder fitting into braces on the stern post.

The head of the rudder passes up through the stern above the deck, and to this a handle called a tiller is fastened for turning the rudder. - The ship being ready for the launch, two parallel lines of heavy timbers are laid along her length, one on each side, and continued down into the water till sufficient depth is reached for the vessel to float. The fall of the water at low tide affords the opportunity for doing this. The slope of this track, or of the "ways," is about seven eighths of an inch to the foot for large vessels; small vessels require a little more inclination. The timbers are held together by others underneath crossing them, and the frame is kept down by being loaded with stones; this at least is the practice where the sliding ways are not permanent. The top of each timber is well covered with melted tallow, and upon this when cold is added soft soap or oil. On the top along the outer edge a ribbon of hard wood full 5 in. square is fastened down, and braced by a succession of shores extending back on each side against some solid support in the ground; the object of this ribbon is to prevent any outward deviation of the upper timbers that make the cradle in which the ship is held as the whole slides down together.

This second system is loosely piled up under the ship, the lowest portion being timbers smooth and well greased on the under side and laid directly on the ways. Between these timbers, called the bilge ways, and the bottom of the ship over them, the space is filled in partly with blocks of timber and planks, and toward the bow and stern by short shores, called poppets, set up from the bilgeways to the bottom of the ship, their steadiness being secured by stout planks temporarily fastened along the bottom against the heads of the poppets. Near the stem and stern chains are passed across to hold the cradle together. To the front of the timbers of the cradle are fastened ropes that are passed over the bow into the ship, and are intended to hold these when they float away from under the vessel. To bring the weight of the ship upon the cradle after this is fitted under it, long wedges are driven in over the bilgeways from one or both sides of each of them. The shores at the sides of the ship, which had heretofore aided to sustain her, and the blocks beneath the keel, which took the chief portion of the weight, may now be removed, with the exception of a few of the latter under the forward part of the vessel.

All this preparatory work is done on the rise of the tide; and when this is at about its height, and two short shores, called dog shores, have been placed, one on each side the vessel, to brace from the ways as a fixed point forward against the bilgeways, and thus hold the cradle with its load from sliding too soon, the fore blocks are split up with wedges and drawn out, letting the whole weight settle down on the ways. At an order the dog shores are knocked down, and the structure begins to move, at first slowly and then with rapidly increasing velocity. In rivers and contracted places the course of the vessel is checked by a hawser made fast on shore, or she is brought up by letting go an anchor. The French have long practised launching vessels without side ways, the weight being entirely supported upon a sliding plank fitted under the keel. A strip of timber is fastened along under the bilge on each side, and a few timbers are laid up in the usual place of the ways, reaching within about half an inch of these strips. It is not expected that they will come in contact except in case of the vessel heeling, when they will serve to prevent her falling over.

After the launch the vessel is conducted to the wharf to receive her spars, rigging, and machinery, if a steam vessel, and interior finish; or she may be taken into the dry dock to be sheathed. It is important to protect the bottom of a vessel with a metallic covering, as without this it soon collects an incrustation of marine vegetable and animal bodies, which seriously interferes with their progress through the water, and the timbers are liable to be attacked by the ship worm. Sheet lead was used in ancient times, and sheet copper was first applied to the ships of the royal navy in 1783. The great expense incurred in suits of copper, which need frequent replacing, is much reduced by the use of Muntz's yellow metal, a combination of copper and zinc described in the article Brass. The metallic sheets are of different thicknesses for surfaces more or less exposed, the weights being 32, 28, 18, and 16 oz. to the square foot. The thickest sheets are used for the bow and about the load water line.

The size of the sheets is 4 ft. by 14 in., and a 120-gun ship would require of them 4,444. They are fastened with copper nails, and are laid so that each sheet laps upon the edge of the next one to it behind and below. - Masts and Rigging. The spars include the masts, yards, booms, and gaffs, used to support the rigging and sails. The masts of the smaller vessels are single sticks of pine timber well rounded and with a gentle taper. For large ships it is necessary, on account of the size of the masts, to construct them of a central stick of a number of sides, with longitudinal pieces closely fitted and securely attached to them and then hooped with iron; these are called made masts, and are stronger than the single sticks of the same size. Hollow masts of plate iron are in use, particularly for iron vessels. Rules for the length of the mainmast of a ship have been half the sum of the length of the load water line and the main breadth of the vessel, and also twice the breadth added to the depth. About the head of each of the lower masts are framed timbers making a horizontal scaffolding or platform, which is known as the top. On large ships it is railed around, and on vessels of war it used to be the custom to station men in it during an engagement armed with muskets.

Upon the rounded front edge of the top stands the topmast, secured in part by passing above through a strong iron-bound flat block set horizontally upon the upper extremity of the lower mast and called a cap. The topmast is about three fifths the length of the lower mast; and above it succeed in like manner the topgallant mast and royal mast; and in seas where the prevailing winds are light and are felt more aloft, still another mast is added, called the skysail mast. At the head of the topmasts are cross trees in place of the top on the lower masts. Each of these masts carries its own yard, from which depends the square sail designated by the same name as the mast to which it belongs. Its lower corners are sheeted out to the extremities of the yard below, or, in case of the courses or lower sails, to the deck. The yards slide up and down their masts, the lower yards hanging in slings by their middle part, and most of them by lifts attached to the yard-arms, and passing thence through a block at the head of the mast. The foremast is about one tenth shorter than the mainmast, and is furnished with similar yards, rigging, and sails; those of the two masts are distinguished by the terms main and fore.

The mizzen mast of a ship carries no square sail hanging from the mizzen or, as it is commonly called, cross-jack yard, but a mizzen topsail, topgallant sail, and royal. In place of the lower square sail there is a fore-and-aft sail called a spanker, which extends aft from the mast over the taffrail, and is sheeted out to the end of a gaff above and to that of a boom below. This is of great service as a steering sail, acting as it pushes the stern off from the wind to bring the bow up as it is hauled in and kept flat. Similar sails are sometimes attached to the other masts and used for storm sails. The masts are supported by shrouds and stays. The former are strong ropes, each one 2 1/8 times as long as the mast, the head of which it encircles by its middle part. Several of these pairs are thus secured over the head of the mast, and the ends are brought down over the side, diverging as they descend. They terminate outside the ship in blocks called dead-eyes, which connect by a lanyard to others fastened on the outer edge of the channels or chain wales, which are heavy planking secured edgewise to the side of the vessel below the bulwarks. This edge is held down by iron braces bolted below to the futtocks.

Though the main object of the shrouds is to hold the masts steady, they also serve as ladders, small ropes called ratlines being hitched across from one to another for steps. The topmast shrouds are set up by dead-eyes secured to the outer edge of the top, and this edge is braced down by iron rods or chains called futtock shrouds attached below to the upper part of the lower mast. The futtock shrouds and those of the topmast have ratlines also, but those for the masts still higher have none. The stays are ropes which support the masts longitudinally, starting generally from their heads, and secured to the foot of the next mast in front, those for the foremast to the bowsprit. The back stays pass from the heads of the topmast directly down to the chain wales, somewhat aft of the foot of the mast to which they belong. The stays that pass from the several masts forward sometimes support triangular fore-and-aft sails, called stay sails. The main and mizzen masts stand nearest together, the former somewhat aft of the centre, and both of them usually are set raking or inclining aft. The foremast stands well forward and upright. The bowsprit extends forward over the bow, rising at an angle of 30° to 33°, its heel resting in a step on the first deck below close to the foremast.

A cap is fixed upon the head of it, presenting a round hole above the bowsprit, through which is passed the spar called the jib boom, which is the extension of the bowsprit. As the foremast is stayed forward to the bowsprit, and several fore-and-aft sails, called the foretop-mast stay sail, jib, and flying jib, are supported on the stays between them, it is essential that the bowsprit itself be well secured. This is done first by the bobstay, a very strong rope, sometimes double and triple, which connects the outer portion of the bowsprit with the stem; and by the bowsprit shrouds, which are ropes extending from the end of the bowsprit to the bows. The dolphin striker is a stiff brace or strut extending down from the outer end of the bowsprit; it is kept in place by the jib and flying-jib martingale stays and the back ropes. From the great angle which it forms with the head booms it amply counteracts the lifting effects of the jibs and the strain of the foretopgallant mast. The sails over the head booms are triangular. The rope by which their lower corners are made fast to the deck is called the sheet; this is also the name of the ropes by which the lower corners of the square sails are hauled out to the ends of the yards.

Of the courses or lower square sails the corners on the lee side, which in sailing on a wind are hauled aft, are secured by sheets; but the corners oh the windward side, which are hauled forward, are made fast to the deck by ropes called tacks. It is with reference to tending these, to shift them as the yard swings in going about, that the preparatory order is given of "Rise tacks and sheets," succeeded, as the evolution is completed, by "Let go and haul." The braces are the ropes by which the yards are swung round. The sail is made to lie still flatter by bowlines which are attached to the leach or edge of the square sails and lead forward. In sailing as close to the wind as possible, the weather bowline is hauled taut, whence the expression "to sail on a bowline," or "on a taut bowline," for lying up close to the wind. In running before the wind the yards are set at right angles to the line of the keel. The head sails are partially becalmed by the after ones, and the fore-and-aft sails over the head booms are of no service; the progress of the ship therefore is not so rapid as with the same wind on the quarter or abeam and filling all the sails.

In order to spread a greater surface of canvas when the winds are light and fair, provision is made for lengthening the yardarms by means of booms called studdingsail booms, which are run out through an iron ring on the end of the yard, and to the outer extremity of which are hauled the tacks of the studdingsails. With a side wind these sails are advantageously carried on the weather side. The assemblage of ropes upon a ship, many of which have already been named, are known as the rigging. Those which are fixed, as the shrouds, stays, etc., are called the standing rigging; and the rest, as the halyards, sheets, and tacks, are the running rigging. - Sails. The larger sails are made of the heaviest No. 1 flax canvas, while the smaller are formed of lighter varieties running to No. 8 of the same material, known as duck of different degrees of strength. The strips of cloth are sewed together with twine, usually with a double seam, and the patterns are skilfully cut for a smooth and even fit. The edges are bound around with a rope called a bolt rope to take the strain from the canvas, and in each corner an iron ring or thimble is inserted and held fast by a rope called a cringle, which goes round the outer concave surface of the ring, and is spliced each end into the bolt rope.

Through these rings are passed the ropes, called earings, by which the sail is stretched or bent to its place. The same contrivance is repeated at one or two places on the edge of the sail, that it may be shortened in single or double reefing; and on the line horizontally with these earings short lengths of cord, called reef points, are secured through the sail and hang loosely on each side, which are used when the sail is reefed to tie around the part which is taken in. Sails may be classed as square sails and as fore-and-aft sails. The former hang by the earings and rope bands from yards, and are drawn out by the lower corners or clews to the ends of the yards below. They are made to swing round with the yards so as to present their surface to a side wind; but the fore-and-aft sails are better designed for sailing on the wind, and the square sails for running with a free wind. Shoulder-of-mutton sails and gaff topsails are triangular fore-and-aft sails, the foot of which may be attached to a boom, or in the latter case to the gaff, and the top, by which they are hoisted, terminates in a point against the mast. Lateen sails, much used in the Mediterranean, are suspended from a very long yard, which is hoisted by the middle from the deck.

One end of the yard is brought down by a brace, and the other projects above the top of the mast, and rakes with it well aft. The sail serves very well as a fore-and-aft sail. The great superiority in the rig of American fore-and-aft vessels, by which they have been able to attain the highest speed of sailing craft, is in the great spread of their sails, their skilful cut, and perfect stretch, which causes them to keep full while their plane is more nearly in a line with the wind than could formerly be practised. - It belongs to the naval architect to determine the amount and disposition of sail which his ship is to carry. The former is proportioned to the immersed midship section, for every square foot of which a well designed ship may carry 35 or even 36 sq. ft. of plain sails, i. e., courses, topsails, topgallant sails, jib, and spanker. Yachts often carry as much as 100 to 1. In regard to the manner of disposing the various sails, it is important that their common centre of effort should be at such a point that the ship when in trim will carry, on a wind, a small weather helm.

It has been found that when the pressure of the wind on the sails forward of a perpendicular erected on the centre of load water line, is to the pressure on the sails abaft as 78 to 1, the ship will work well, all other conditions of a good ship being fulfilled. - The Theory of Working Ship. The principle upon which a vessel is made to advance against the wind may be explained as follows: Sustained in a state of equilibrium in the water, she is readily susceptible to any force applied to change her position. This involves a movement of the water to admit her passing through it. On the line of the keel this easily takes place from the wedge-like shape of the hull; but a movement sidewise is resisted by the great body of water pressing against the hull for its full length. Whenever therefore the sails are filled by a breeze blowing against them from behind, even if at a considerable angle with the length of the ship, it is easy to perceive that her motion must be forward on the line of the keel. As the wind draws further forward the sails are braced further round, so that they may still receive it upon their after side.

The wind of course strikes them to a greater disadvantage the nearer their plane approaches its direction; but so long as it impinges even obliquely upon their after surface, a portion of the force is exerted to press out the sails in a forward direction, while the remainder passes uselessly along the plain of the sails. The former portion tends to push the ship directly in a course at right angles with this plane; but the shape of the ship being opposed to this movement, this force also is resolved into two, one acting to propel the ship sidewise and the other forward. Thus this last result may prove effective even when the head of the ship is pointed obliquely toward the wind, as mentioned of fore-and-afters, at an angle of 40° or 45°, and in the case of ordinary sailing frigates at an angle of 60°. This may be shown by the annexed figure, where the sail A B, oblique to the line of the keel and to the wind V C, is impelled in the direction C D with a force expressed by the square of the sine of the angle of incidence A C V. If C D represent the force of the wind on the sail, as expressed by the square of the sine of incidence A V, we have only to construct G H to see that such a direction is composed of the two effects C H and C G with respect to the body E F on which it acts.

Now the sharper we brace the yard A B, the more acute becomes the angle A C E, the effect of which is to augment C H and diminish C G. For as ACE becomes more acute the angle D C H is lessened, so that C D perpendicular to the centre of the yard will approach more to C H perpendicular to the keel E F. Hence a portion of the force is applied in the direction C G, the length of the ship. When braced sharp up, ACE = about 20°. On the other hand, the larger the angle ACE the more the effect C G will increase, in the same proportion as the increase of the sine of that angle when the impulse of the wind upon the sail is the same; for the sines of the angle are in proportion to their opposite sides in the triangle C D G, of which the angle C D G is equal to the angle A C E. Though, when sailing thus partially toward the wind, but a small portion of its propelling effect is available, something is recovered by its greater force caused by running against it; while in sailing in the opposite direction its effect is diminished by running away from it.

If, after sailing for any time with the sails sharply braced, the head of the vessel can be brought round, so that the sails shall fill on the other side, the ship will proceed on the other tack on a line reaching further and further to the windward of that before passed over, and thus by a succession of zigzags progress is continually made against the course of the wind. This is called beating to windward, and the turning of the ship toward the wind and thence around is tacking. This is done as follows: The helmsman, having carefully kept the head of the ship as near the wind as practicable with the sails remaining full, at the order puts the helm gradually down, and soon after, at another order, "hard a-lee." As the head of the vessel is thus brought up toward the wind, the head sails are let fly by casting off their sheets, so that they shall present the least impediment in the way of this movement. The spanker on the contrary is hauled more toward the centre, that the wind continuing to strike it may push the stern round the other way. Soon the square sails on the foremast catch aback, or receive the wind on their forward side. This, while it checks the headway, also tends to throw the bow still further round.

The after yards are then swung for the wind to strike them on the other side, and the same is next done to the head yards. As the sails fill, the ship soon gathers headway on the new tack. Fore-and-aft rigged vessels are much better adapted for working to windward than those with square sails. Their sails keep full at a smaller angle with the wind, and in going about or tacking they do not lose headway, but even run some distance directly in the eye of the wind, which other vessels are prevented from doing by their great square sails catching aback. As a storm comes up at sea, the first precaution is to shorten sail. The lighter sails are taken in and furled, and the topsails are first single-reefed, and next double-reefed; mainsail is reefed; mizzen topsail close-reefed; next the fore and main topsail the same; mainsail is then furled, and the jib also. The foresail is then reefed and the mizzen topsail is furled. The main spencer may now be set, and the fore topsail furled unless the ship is too stiff. With close-reefed main topsail and reefed foresail, with the main spencer and stay sails, the ship is now under good sail for either running or lying to. With increasing wind and the ship lying to, the foresail may be taken in.

When the main topsail is taken in, the last resort is setting tarpaulins in the weather mizzen rigging of the ship. The practice is somewhat varied with different ships according to their manner of working. In case the vessel does not lie to well, she may in a favorable lull of the storm be put before the wind, and run off under bare poles. An expedient sometimes resorted to with good effect is the drag. This may be made of spare spars with an anchor attached to give it a hold on the water. A long stout hawser secured to this and brought in over the weather bow will enable a ship to "cathead" the sea, and, with all sails snugly furled, ride out the heaviest gale. With such resources, ships at sea in good trim with plenty of room usually escape in the severest storms, sometimes indeed with the sails torn, the topmasts carried away, and occasionally with a mizzen mast cut away to ease the vessel, or otherwise dismasted. The great danger is in proximity to land, especially a lee shore. - Cables are made of rope and of iron, the latter being used the most in recent times. They are worked by means of a capstan or kind of windlass which may have a vertical or horizontal axis, and may be turned by hand or by steam.

The method of making the different kinds of chain cables is given in the article Cable. A table showing the comparative sizes of chain cables and anchors which are used together according to the United States navy regulations will be found in the article Anchor. The following table gives the navy regulation for the number, size, and length of both hemp and chain cables for ships of the line, frigates, and sloops of the first class:

* Since the publication of the paper by Mr. Eedfield still increased rates of speed have been attained by these boats, till, in October, 1860, the steamboat Daniel Drew made the trip in 6 h. 50 m., including in this five landings and several crossings involved by them; these may fairly be considered as consuming 50 minutes, thus making the rate 24 m. an hour, the highest speed ever recorded upon the water.

Ship 1400384

SHIPS OF THE LINE.

NAMES OF CABLES.

THREE DECKS.

TWO DECKS.

First class.

Second class.

No.

In.

Fath.

No.

In.

Fath.

No.

In.

Fath.

Sheets, hemp....

2

25

120

2

24

120

2

23

120

Sheets, chain....

1

180

1

180

1

2⅛

180

Bowers, chain...

2

180

2

180

2

2⅛

180

Stream, hemp...

1

16

120

1

15

120

1

14

120

NAMES OF CABLES.

FRIGATES.

SLOOPS.

First class.

Second class.

First class.

No.

In.

Fath.

No.

In.

Fath.

No.

In.

Fath.

Sheets, hemp..

1

22

120

1

21

120

1

17

120

Sheets, chain..

1

115/16

165

1

113/16

165

1

111/16

150

Bowers, chain.

2

115/16

165

2

113/16

165

2

111/16

150

Stream, hemp.

1

13½

120

1

12

120

1

11

120