DOCK

Deck. An inclosed space for the reception of ships, either for their security or for the convenience of building or giving them repairs. This word has been derived by some, absurdly enough, from the Greek δοξααι, to receive. That we had it, along with almost the whole of our sea-terms, from the northern continental nations, is sufficiently obvious. Thus in Flemish it is dok; Teutonic, dock; Swedish, docka; Suio-Gothic, docka; perhaps originally from dekken, to cover, protect, secure, inclose. The dock for inclosing the prisoner in a court of justice is evidently from the same origin.

Docks for the reception of ships are of two kinds, wet and dry.

A wet dock may either have gates to retain the water in it, so that ships shall constantly remain afloat, or be left open for the tide to flow into and ebb out of it at pleasure, either leaving it dry at low water, or with a certain depth of water remaining in it, according to its construction and situation with regard to the low-water mark, and to the ebbing of the sea at spring or neap tides. A wet dock without gates is generally distinguished by the name of a basin, which, however, is sometimes indiscriminately applied to a wet dock whether with or without gates.

A dry dock either becomes dry by the ebbing of the tide when the gates are left open, or by shutting the gates at low water, and pumping out whatever water may remain in it at that time, by the power of men, horses, wind, or, which is now most commonly performed in the Queen's dock-yards, by the steam-engine.

A wet dock, therefore, may be defined to be "a basin of water, in which ships may be kept afloat at all times of the tide;" a dry dock, a "receptacle in which every part of a ship can be examined, and its defects repaired." Ships may also be conveniently built in dry docks, and floated out by opening the gates; though in all dock-yards there are places set apart for this purpose, under the name of slips. A wet dock is called by the French un basin; a dry dock, une forme; and a slip, une calle.

The digging out the earth, and building the surrounding walls of masonry to prevent the sides falling in, and the preparation of the mortar and puzzolana, in the construction of a wet dock, are attended with great labour and expense. The two wet docks or basins of Cherbourg (see BREAKWATER), which are among the finest specimens that exist in the world, are estimated to have cost three millions sterling. The labour of excavation may sometimes be spared, and a series of wet docks or basins conveniently made, by turning the course of a tide-river through an isthmus, and placing a pair of gates at each end of the old channel. In this way were the new docks of Bristol constructed out of the bed of the Avon.

Wet docks. Wet docks are an improvement in navigation and commerce of the utmost importance, but of very modern date in this country; indeed, they owe their introduction entirely to a spirit of individual enterprise in commercial speculation. Liverpool might still have remained a poor fishing village but for its convenient docks, which not only produce to the town and corporation a large revenue, but ensure to the merchant every possible facility in refitting, loading, and discharging his ships, whatever their burden or their cargo may be, without being exposed to the risk of losing both ship and cargo in a rapid tide-river; and, at all events, to an unavoidable delay, occasioned by distance, the weather, or the state of the tides.

Hull is also greatly indebted for the extension of its commerce to its docks. Its old wet dock contains an area of

ten acres nearly, and has accommodated at one time 130 sail of such vessels as frequent that port.

London, though unquestionably the first city in the world for its opulence, its commerce, and public spirit, and possessing within itself the powerful internal means of supporting docks, and all other conveniences that trade and shipping may require on the most extensive plans; London was the last to try the experiment of docks, except in the case of two spirited individuals, Mr Perry at Blackwall, and Mr Wells at Greenland Dock, both private ship-builders. Notwithstanding the total inadequacy of legal quays, which subjected the merchants to incalculable losses and delays, and in many cases proved absolutely ruinous; notwithstanding the effect of the heavy, expensive, and fatal embarrassments experienced regularly on the arrival of the West India fleets, and the annual losses, by plunder in the river, on West India produce, which alone were calculated to amount to £150,000 to the proprietor, and £50,000 to the revenue, and more than the double of those sums, including other branches of commerce; it was not till the year 1799 that prejudices and private interests were so far removed as to enable the merchants concerned in the West India trade to obtain an act of parliament to carry into execution a plan of docks, quays, and warehouses, for the convenience of that trade on the Isle of Dogs. Since that time the London Docks, St Katharine Docks, and various others, have been completed, to the incalculable benefit of the shipping interest and the commerce of the metropolis.

The docks of Liverpool were the first of the kind that were constructed in this kingdom, by virtue of an act of parliament passed in 1708; and from that period the town of Liverpool has rapidly raised itself from a poor fishing village, and a port for coasting vessels, to be the second commercial town and port in the empire; and the improvements carried out for the enlargement and better arrangement of the docks rendered it, for convenience and appearance, in this respect the very first, not even London excepted.

It appears from a statement, apparently authentic, that in the ten years ending with 1808 the number of ships which entered these docks was 48,497, tonnage 4,954,204; and the dock duties received £329,666; and that in the following ten years ending in 1818 the number of ships was 60,200, the tonnage 6,375,560, and the amount of duties £666,439; while for a single year (ending June 1853), no less than 20,490 vessels entered the docks, the tonnage of which was 3,889,981, and the amount of duties £256,702—the largest amount yet received—the following being the return for the last ten years:—

It may also be observed, that this extraordinary increase has taken place since the abolition of the slave trade, which, it was formerly asserted, would be the ruin of Liverpool.

For a more detailed account of these docks, see the articles BIRKENHEAD and LIVERPOOL.

Dock. The West India Docks on the river Thames were commenced in February 1800, and opened in August 1802. They consist of an outward and a homeward bound dock, and communicate by means of locks with a basin of five or six acres on the end next to Blackwall, and with another of more than two acres at the end next to Limehouse, both of which basins communicate with the Thames. The outward-bound dock is about 870 yards in length, by 135 in width, containing consequently an area of more than 24 acres; the homeward-bound dock is of the same length, and 166 yards in width, its area being little short of 30 acres; and the two together will contain with ease at least 500 vessels of from 250 to 500 tons. The whole are surrounded with a high wall, and, as a security against fire, the moment that a ship enters the dock the crews are discharged, and no person whatever is allowed to remain on board, or within the premises, the gates of which are closed at a certain hour. They are surrounded by immense warehouses, which are estimated to contain nearly 10,000 hogsheads of sugar, and an immense quantity of rum. The sum authorized by parliament to be raised for completing these docks and warehouses was £1,200,000, and the total expense was probably not far short of one million and a half; yet on this capital the subscribers have been receiving from a very short period after their opening ten per cent., which, by the terms of the act, is not to be exceeded, and the term granted is limited to 21 years; but, like most other property, these docks have been greatly depreciated in value, and at present barely pay 8 per cent.

The next set of docks that were undertaken for the advantage of the trade of the capital was the London Docks. These docks are situated in Wapping, and are appropriated for the reception of all ships arriving in the port of London with wine, spirits, tobacco, and rice on board, but not exclusively, ships having on board other cargoes being admitted on the payment of certain fees. The act of parliament for incorporating the dock company was passed in 1800, authorizing them to raise a capital of £1,200,000; but such was the number of houses to be purchased (we believe not less than 1200) occupying the site of the dock, that this capital by subsequent acts was extended to £2,200,000, the dividends on which are limited, as in the West India Docks, to ten per cent. The great dock is 420 yards in length, and 230 yards in width, covering an area of twenty acres. A basin of three acres nearly connects it with the river. The warehouses are very magnificent; and the tobacco warehouse is the grandest and most spacious building of its kind in the world, being capable of containing 25,000 hogsheads of tobacco, and the vaults underneath as many pipes of wine. This single building, under one roof, is said to occupy upwards of four acres of ground. These docks were opened in February 1805.

The East India Docks, for the exclusive reception and accommodation of the East India ships, were the last in succession. The act for the incorporation of the company was passed in July 1803, authorizing them to raise a capital of £200,000, which was afterwards increased to £600,000, the dividend, as in the case of the two others, to be limited to ten per cent. These docks are situated at Blackwall. That for the reception of homeward-bound ships is 470 yards in length by 187 in width, containing a surface of rather more than 18 acres; the outward-bound dock is 260 by 173 yards, and is consequently something more than nine acres. An entrance basin of three acres nearly, and a spacious lock, connect them with the Thames.

Besides these there are the London Docks, the St Katharine's Docks, and the Victoria Docks in course of construction; of these, detailed accounts will be found under the article LONDON.

Hull has five docks, occupying with their basins a water area of 49½ acres. A timber pond of 9 acres was con-

structed in 1853. The tonnage of shipping in 1852 was 799,866 sailing vessels, and 305,021 steam-vessels; the amount of dock dues £433,755.

Southampton, the station for the West India mail and Lisbon and Alexandria steamers, is now constructing extensive docks and quays to accommodate their great and increasing traffic.

Grimshy Harbour has lately been greatly improved. Wet and dry docks have been constructed on the most approved principles, at an expense of £250,000, and a canal cut into the Humber calculated to admit vessels of 1000 tons burden.

Hartlepool has also been of late years greatly enlarging its harbour and dock accommodation.

Sunderland has new docks of 18 acres extent, which were opened in 1850, and which can accommodate 300 sail.

Dundee has lately immensely improved her harbour and docks; besides two smaller docks, the wet dock now constructing will occupy 14½ acres, the lock of which will be 60 feet broad.

Aberdeen has a wet dock, where the largest vessels may float in safety; it covers nearly 40 acres, with quay room of about 9000 feet.

Leith, the port of Edinburgh, has three wet docks, containing about 15 acres of water room. Detailed accounts of these docks will be given under the names of the respective ports.

The naval dry docks of the United States are among the most stupendous mechanical enterprises of that country; they are constructed at the navy-yards of New York, Philadelphia, Boston, Portsmouth, Norfolk, Pensacola, and San Francisco. By far the most extensive and magnificent of these structures is the granite dry dock of New York; 80,000 tons of stone have been used in its construction; the masonry foundations are 400 feet in length, and 120 in breadth. The main chamber is 286 feet long, and 30 feet broad on the bottom; 307 feet long, and 98 feet broad at the top within the folding gates; the height of the wall is 36 feet. The work was commenced in 1841, and took ten years to complete it; the aggregate expenditure was above £430,000. For the docks at Cherbourg, see BREAKWATER.

A dry dock, requiring to be perfectly water-tight, demands the greatest care in its construction. It is sometimes lined all round with wood, but more generally with masonry, mostly of hewn granite. The expense is very considerable, as the foundation, by means of piles or otherwise, must be well secured, all leakage prevented, and the culvers or drains properly constructed, to let in and carry off the water without its undermining the quays or piers. The cost of a complete dry dock will vary probably from £20,000 to £100,000, according to the size of the ships it is intended to admit, and the nature of the ground on which it is to be constructed. A dry dock may be single, or made to contain only one ship; or double, to contain two ships; but the former is the most common, because most convenient.

As it is of the utmost importance to preserve the water in a wet dock, and to keep it out of a dry dock, it may be proper to describe the different kinds of gates which are in use for this purpose.

The most common, and on the whole perhaps the best and most convenient, are swinging gates, which open in the middle, and lie flat, one part against each wharf or side-wall of the passage leading into the dock or basin. The elevation of this kind of gate is represented in Plate CCVI, fig. 3. This kind of dock-gate requires to be made of great strength, with sound timber and good iron, and the gudgeons on which the hinges turn to be well secured into the stone abutments. Care also must be taken to make the bottom of the passage and the bottom of the gates perfectly plane and parallel, to prevent leakage, and give facility to their opening and shutting, which is usually assisted by rollers

fixed in a groove, and performed by means of a small capstern on each pier. Attached to the top of the gates is usually a foot bridge with railing, which, separating in the middle, opens and shuts with the gates.

The most simple but by no means the most effective contrivance for keeping out the water, is the wicket-gate, of which the plan and elevation are represented in Plate CCVI. figs. 5 and 6. It consists of three parts, which when opened are removed separately. This gate is rarely made use of unless where the abutments are not sufficiently strong, or their foundation sufficiently secure, to bear the weight of a pair of swinging gates.

A third kind of gate consists of a floating dam or caisson, first introduced into this country by General Bentham, and first applied to the great new basin in Portsmouth dock-yard. They are built somewhat in the shape of a Greenland fishing-boat, sharp at the two ends, narrow, and deep in proportion to the depth of water at the entrance of the dock. The keel fits into a groove at the bottom of the passage, and the two slanting ends rise and fall in corresponding grooves cut into the two abutments. Of this kind of gate, figs. 1 and 2, Plate CCVI. represent the plan and elevation. By letting in the water, the caisson sinks in the grooves, and acts as a closed gate; and by pumping out the water, or letting it out to a certain depth, the dam floats as the tide rises, and the narrow part, rising to the top, is readily disengaged from the grooves, and easily floated away as a boat. The advantages of these floating dams, as stated by General Bentham, are, that they are cheaper of construction than the gates heretofore in use for closing docks or basins; that they occupy less space, are more easily repaired, and one and the same dam is capable of being used, as need may require, in different places at different times. These caissons have also the advantage of serving as bridges of communication for loaded carriages across the entrances they close, and they require much less labour than gates in opening or shutting up passages into docks or basins, since their occasional buoyancy may be obtained without pumping water or unloading ballast.

Fig. 7 represents a plan, and fig. 4 a sectional elevation, of a dry or graving dock, into which ships are taken to have their defects examined and repaired, coppered, &c., and in which, if necessary, as already observed, ships may be built.

When a ship is brought into a dry or graving dock, she gradually subsides as the water flows out, till her keel rests upon the line of square blocks which are placed to receive it along the middle for the whole length; and on these blocks she is kept steady and upright by a number of shores or poles on each side, one of their ends being placed on the altars or steps of the dock, the other under the ship's bends and bottom. As a ship under repair generally requires something to be done to the main or false keel, or at any rate these parts require to be inspected, sometimes to shift the main keel, or to add to the whole length of the false keel, it was always found necessary in such cases to remove the blocks, in order to get at the bottom of the ship; but this operation could not be performed without the more serious one of first lifting bodily the ship clear of all the blocks, and suspending her as it were in the air. This process was performed by driving wedges simultaneously under the ends of all the shores that supported the ship; an operation that required from four to five hundred men to enable them to suspend a ship of the first rate. When the San Josef, a large three-decker, required her bottom to be examined in 1800, the assistance of almost every artificer in the dock-yard was found necessary to perform this process of lifting her; nor was this the only inconvenience; the ship, thus suspended, suffered very material injury by the pressure of her own enormous weight against the ends of the shores that supported her, such as forcing in her sides,

straining the knees and all her fastenings, breaking the treenails, &c.

To remedy these glaring inconveniences and very serious injuries that ships thus placed were apt to sustain, and to effect a saving of time and expense in the operation, Mr (afterwards Sir Robert) Seppings, then master shipwright, and afterwards surveyor of the navy, contrived, several years ago, an improvement, as ingenious as it is simple, by which twenty men will suspend the largest ship in the navy, or rather, which amounts to the same thing, will disengage any one block that may be required, in the space of two or three minutes, without the necessity of suspending her at all; and, as a first rate in dock sits upon about fifty blocks, these twenty men will clear her of the whole of these blocks in about two hours; and as the saving of a day in completing the repairs of a ship is frequently the saving of a whole spring tide, the docking and undocking of a ship may make, and frequently has made, by this new method, the difference of a fortnight in the time of equipping her for sea.

The block of Mr Seppings, instead of being one solid piece, consisted of three wedges, or, more properly speaking, of one obtuse wedge and two inclined planes, which, when put together and placed under the ship's keel, appear as under, when viewed in the direction or line of the keel,

where G is the wedge on which the keel rests, having its obtuse angle equal to $170^\backslash circ$, and HH are the two inclined planes, each having an acute angle of $5^\backslash circ$. The wedge is of hard wood, having its two sides lined with iron; the two inclined planes are of cast iron. When one of these blocks is to be disengaged from under a ship's bottom, nothing more is required than a few smart blows alternately on the two sides of the two inclined planes, when they fly out, and the middle part or wedge drops; and the facility of thus disengaging any of the blocks is in proportion to the quantity of pressure upon that block. The strokes are usually given by a kind of catapult or battering-ram, being a thick spar or pole moving on a pair of wheels, as KK.

This simple contrivance to get at any part of a ship's bottom by removing in succession all the blocks, without the necessity of lifting the ship, which the removal of any one block required to be done by the old method, is now universally adopted in all the dock-yards; and the Lords of the Admiralty marked their sense of the great utility of the improvement, by bestowing on Mr Seppings a reward of £1,000 for the invention.

Another very material improvement introduced into her Majesty's dock-yards, is that of covering the dry docks and the docks building slips with roofs. The rapid decay of our ships of war by that species of disease known by the name of the dry rot, attracted very general attention; its effects were well known, but a variety of opinions were entertained as

to its causes and its cure. It was quite obvious, however, that exclusion of air and moisture were the two great operating causes in giving activity to the progress of the disease (see Dry Rot); and that a ship in dock, stripped of her planking, and open to the weather in every part, alternately exposed to frost, rain, wind, and sunshine, must at least have her timbers differently affected, some swelled and water-soaked, others shrunk with heat, and others rifted with the wind and frost; and, if closed up with planking in this state, might be expected, at no great distance of time, to exhibit symptoms of decay. The workmen, too, in the open docks or slips, suffered from the vicissitudes of the weather no less than the ships, and their labour was frequently suspended, to the great detriment of the naval service. The measure of roofing over the docks and slips had long and repeatedly been suggested, but, either from prejudice or a false economy, it was only of late years carried into practice, but is now universal in all the yards. These roofs are generally constructed so as to be capable of having the sides and ends occasionally closed, according to the quarter from which the wind may blow; and by this contrivance the timber is prevented from rifting, as it is liable to do, by the action of a thorough draught of wind, and the health of the artificer is prevented from injury. The light is admitted through numerous windows placed in the roof. These roofs are in general supported on a row of pillars, and covered with plates of iron. Plate CCVI. fig. 8, exhibits the transverse section of a roof thrown over the head of the dock at Plymouth; its span, from A to A, being 95 feet 4 inches, and the extreme width, from B to B, 125 feet 4 inches, supported, on the principle of trussing, without a single beam. Another of the same kind was built at Chatham, whose span was 100 feet, and the extreme width 150 feet. These immense roofs, of which there are now some larger, were constructed after a plan of Mr Seppings. The cost of one of the dimensions above mentioned was from £6000 to £7000, which, great as it may appear, must be amply repaid by the superior quality and durability of the ships built under it; but the same roof, with little or no repair, serves as a covering for eight or ten different ships in succession. General Bentham, who, in his statement of Services rendered in the Civil Department of the Navy, seems to claim to himself all the inventions and improvements which have been introduced into the dockyards for the last forty years, carries his invention beyond a mere covering, and proposes to house over the docks and slips so completely as to afford "means of heating, warming, ventilating, and artificially lighting the interior at pleasure; the introduction of boilers or steam-kilns for bending the planks within the inclosure; the introduction of machinery for assisting in various operations, particularly the more laborious ones; the providing room for carrying on all the shipwright's work within the building; besides a variety of lesser works, such as it is found very inconvenient during the building or repairing of a ship to have executed, for example, in a smith's or carpenter's shop at a distance." Such buildings would not only be enormously expensive, but, in the present crowded state of the dock-yards, utterly impracticable. With regard to the invention of covered docks and slips, they have been used in Venice from time immemorial; and it appeared, from the evidence given by Mr Strange, the consul at that port in the year 1792, before the commissioners of land revenue, that two-and-twenty large ships had been under covered slips, some of them for sixty years nearly. At Carlsrona, also, there are several covered docks, and both Mr Nicholls and Mr Snodgrass strongly recommended the building of ships under cover nearly fifty years ago.

Among other experiments which were made in the dock-yards for facilitating and expediting the repairs of ships, one may be mentioned, of which many persons were sanguine enough to think that the successful result was likely

to be attended with most important benefits to the naval service. It was that of hauling up ships of war, of any dimensions, on building slips, instead of taking them into docks. It is no uncommon practice, at various ports of this kingdom, where there are neither artificial basins nor natural harbours, to haul vessels of the burden of fifty to two hundred tons, or probably larger, upon the beach, by means of capstans, to give them repairs; in like manner, most of the large fishing smacks are hauled up for security in tempestuous weather; but the practicability of hauling up ships of war, especially of the larger classes, was a matter of some doubt. Several frigates had, at various times, been hauled upon slips, when the docks were all occupied; and the ease with which the operation was performed induced the officers of the dock-yard to propose the hauling up of a line-of-battle ship. The Kent of 74 guns, was selected for this purpose. It was necessary, in the first place, to take her into a dock, to have proper bilgeways prepared, and to be stripped, so as to be made as light as possible; her weight being, according to a calculation made from the water she displaced when afloat, about fourteen hundred tons. To heave up this weight fourteen capstans were employed, and the number of men to work these were as under:

Total of men employed.....2116

The time occupied in hauling her up, after all the purchases were brought to bear, was forty minutes. The expense of preparing her, and the loss and wear and tear of the materials, was estimated at somewhere about £2000.

The advantages which slips are supposed to possess over dry docks are many and important. They can be constructed at one-twentieth part of the expense; they occupy less space; they can be constructed on a steep or a shelving shore; and ships can be hauled upon them either in spring or neap tides; whereas a dry dock can only be made in particular situations, and, when made, ships can only be docked and undocked in certain states of the tides; from which circumstance a considerable delay and inconvenience are frequently experienced. It should be recollected, however, that a large ship must necessarily go into a dock preparatory to her being hauled up on a slip.

It has been considered as not at all impossible, as was suggested some time ago by Mr Perring, then the ingenious clerk of the check in Plymouth dock-yard, that the whole ordinary might hereafter be laid up on slips, which, if housed over, would unquestionably be the best means of increasing their durability, and preserving them from partial decay. Nor is it certain that in the end it would not be the most economical mode of preserving them. The expense, as appears from the Estimates of the Ordinary of the Navy for the year 1817, is £187,000 for harbour victuals, harbour moorings and riggings, &c., besides £135,000 for wages; the chief part of both which sums is on account of slips of war laid up in ordinary, none of which would be required by placing them on slips. It would indeed form a singular revolution in naval management, if ships hereafter should be laid up in ordinary on dry land, whilst the timber of which they are built was considered to be the best preserved under salt water; a process which, from some experiments recently made, promises fair to be the most effectual prevention of, and a probable cure for, the dry rot. (See Dry Rot.) This method of preserving timber has long been practised at Brest, Carthagenia, and several other places on the Continent; and the only objection to it in some of our ports appears to be the attack of the worm known to naturalists by the name of Teredo navalis, whose bite is almost as destructive as the dry rot.