and owing to the large volume of water, generally more or less turbid, which enters at every tide, they are much more liable to silt up than are wet docks. For removing muddy or soft deposits the plan is sometimes resorted to of releasing a reserve of water with a sudden gush from an inclosure at the inner end of the dock. This scouring action is usually confined to clearing small docks or basins and their approach channels, and the method is of most effect when carried out about the period of three-quarters ebb of the tide.

Dry docks or graving docks are used for the purpose of laying vessels dry for examination or repairs. The earliest graving dock was a bed or grave' dug on the shore for receiving a vessel at high-water or spring-tides, the excavations being then protected from ingress of water by an artificial bank thrown up at time of low-water. As ships increased in size, dry docks became essential works, and all modern ports, dockyards, and ship-repairing establishments are equipped with a generous supply of dry docks. A dry dock, however, rarely earns any reasonable interest on its cost. It is remarkable that the first principles involved in early dock construction still obtain, development being confined to larger dimensions, details of construction, and elaboration of equipment.

Dry docks may have their entrance either from

may be made long enough to hold several vessels at one time, being divided longitudinally, but it is a more economical arrangement to have a system of several docks of different dimensions. The same pumping-machinery and other equipment, such as an unusually large crane, can be made to serve two docks if they are built close together in parallel. A dry dock is now frequently designed so as to allow for future extension, and in several British docks the caisson at the entrance is arranged to give additional length for accommodating a particularly long vessel.

In addition to adequate pumping-machinery, dry docks are equipped with cranes of various outreach and power, capstans to assist in making the entrance, and entrance gate-opening machinery. The operating power is hydraulic or electric, and a supply of water, light, steam, and power for riveting, &c., is available all over the dock area. The workshops should be arranged close to the dock. The following table gives the dimensions in feet of various large British dry docks with depth over the sill at high-water of spring-tides :

Thaines-Tilbury...

"

-King George V..

Fig. 3.-Section showing principle of Dry Dock.

a wet dock or from a tidal harbour or sea or river, but the former is usually the more convenient arrangement, as it admits of vessels being docked or taken out independently of the state of tide and free from the disturbance of currents, and gives more economical design of entrance and gates. These dry docks are built of good water-tight masonry or of concrete. The entrance is closed by means of a Caisson (q.v.) or by a pair of folding gates, pointing outwards to exclude the water. When the tidal range is great, the bottom of the dock may be placed above low-water level so that the dock can be run dry without pumping, but generally, when the rise of the tide is small, the bottom is well below that level, in which case pumping is required for emptying the dock in about three hours. The floor may be level or may slope slightly for drainage purposes towards the sides and entrance. The keel of the vessel to be docked rests on wooden blocks fastened down to prevent them floating, and built up to such a height, about 5 feet, as to admit of the shipyard workers getting under the vessel's bottom. Side-shores are put in to keep the vessel in an upright position, and blocks are fitted under the bilges as soon as possible after the water-level has been lowered. The sides generally consist of stone steps, called altars, the purpose of which is to fix the lower ends of the shores and also for the convenience of supporting the workmen's scaffolds. Dock sides are now usually steeper than shown in fig. 3, the use of altars being modified, and the lower part of the wall being vertical. Dry docks

At the Port of Liverpool there are twelve dry docks that can hold vessels over 500 feet long. At Rosyth Naval Dockyard four dry docks can accommodate vessels over 830 feet long. One of the largest dry docks is at Taranto, in Italy. Its length of 820 feet can be lengthened to 1150 feet, its breadth at entrance is 134 feet, and depth 40 feet. At Havre a dry dock is 1030 feet long, 125 feet in breadth, and 28 feet deep at low-water spring-tides.

The use of the graving dock is frequently superseded in the case of small harbours by that of an inclined Slip (q.v.). These slips are also a useful adjunct to a general dock system, but they are seldom designed to accommodate vessels over 1500 tons.

Floating docks were originally built of timber and of small size, and are a development of the gridiron formerly used at several tidal ports. This consisted of a frame of timber, over which vessels. were floated at times of high-water, and grounded upon it during the ebb tide. A partial examination was then made at low-water, prior to dry docking of the vessel for repairs, if seen to be necessary. The earliest floating docks took the form of a large timber box, with a flap door falling down at one end, which was closed after entrance of a vessel, and the water was pumped out. On account of their lack of stability, and from the fact that they could be used only in shallow water, the use of the timber dock was limited, but the introduction of iron for shipbuilding rendered practicable the construction of floating docks of large dimensions, and capable of working in deep water.

The early history of floating docks is marked by the numerous accidents which accompanied their development. Some were wholly lost by storm or capsizing, or proved unmanageable when completed. Even at the present day the slow process of towing a floating dock in the open sea, as frequently has to be done, from its place of construction to its destination, is attended with great difficulty and

Dockisation, or the conversion of tidal rivers into wet docks, may sometimes be carried out with advantage in suitable conditions. The water-level at the quays is held up by the construction across the river of a barrage with entrance-locks. Where more depth at low-water is required at the river quays, dockisation may render unnecessary extensive dredging, thus exposing existing quays to less risk than would be the case if dredging were resorted to, possibly below the levels for which they were designed. The enormous expense of wholesale reconstruction of quayage is thereby avoided, but the advantages or otherwise of the dockisation of British tidal rivers is one of the subjects on which, in recent years, there has been shown to be much difference of opinion among engineers. Cost of docks, as already stated, varies greatly with additional depth of foundation of the quay. walls, and has even been estimated as varying as the cube of the depth available for shipping. The problem of providing facilities at a port for larger ships has frequently to be faced, and it is a serious one for dock authorities, as the necessary works are usually clearly unremunerative, and, as the largest vessels trading to any port are few in number as compared with the average-sized vessels trading, the cost will fall to be met by the smaller trading vessels. The two large commercial vessels, the Majestic and the Leviathan, the former being 915 feet long, 100 feet beam, and 39 feet draft loaded, can be accommodated at only one British graving dock-the Gladstone Dock at Liverpool. But ports intending to attract in the near future the largest vessels are looking to having to provide docks and facilities for ships of 40 or even 45 feet draft.

The cost of dock construction varies greatly at different ports, the depth and nature of the foundation for the quay-walls being the main items governing the "cost. On the Clyde, quay-walls have cost about £40 per lineal foot of length for 60 feet depth of wall, and this cost is half that of a quay-wall of approximately similar depth at Antwerp. The cost of a quay-wall of over 70 feet deep constructed at Southampton, where unusual engineering difficulties of construction had to be faced, has been calculated at about £150 per lineal foot of length of wall when completely equipped.

Dock equipment is of extreme importance to shipping, and its adequacy is essential at a large modern port. The requirements of shipping, so far as docks are concerned, are: ease of access from sea to ample sheltered quayage, speedy facilities for loading and discharging cargoes, for transport to and from the quays, and for bunkering, provisioning, and repairs. The enormous expense of dock extensions can frequently be avoided by improved facilities in equip.

The method of dealing with cargoes differs at the various ports. It can be discharged straight on to the quays, as at Liverpool, being delivered directly into railway waggons or other vehicles for land transport. It can be dealt with by water transport, the vessel discharging into lighters alongside, as is the procedure with a large proportion of cargoes at London. In the case of the extended Albert Dock, the system of discharge is a combination of both methods, the ship's gear discharging into lighters and the dock gear discharging ashore. A usual manner of dealing with general cargoes is with quay cranes of under 3 tons capacity with net slings-one crane opposite each hatch. The average weight of most packages is under 30 cwts., and larger loads can best be taken by floating cranes of from 3 to 20 tons capacity. At Liverpool, self-propelling floating cranes have been provided for lifts up to 200 tons. 2000 tons a day is a good rate of discharge for general cargoes..

Particular bulk cargoes where the quantities are large, goods about the same dimensions, and traffic is regular, are best dealt with by special appliances. Grain can be dealt with by conveyor belts, or probably best by pneumatic suction. For discharge the grain can be sucked from hold, automatically weighed, and delivered loose into barges or directly into sacks. At Montreal, grain elevators can deliver 80,000 bushels per hour, and a vessel can be loaded up under twenty-four hours with a full cargo of, say, a quarter of a million bushels. At Sydney, the grain silos have a capacity of 6 million bushels. Frozen meat is dealt with by conveyor belt between ship and special storage sheds. Coal is dealt with by grabs or by raising and tipping the railway waggons. In discharging oil a pipe line can be laid under water and the oil can be pumped ashore, the vessel anchoring at a dolphin at the end of the pipe line. Other bulk cargoes frequently handled by special means are ore and timber. Cargoes of bananas from the West Indies are handled by special arrangements at Avonmouth.

Most dock appliances are best operated by electricity, which gives power usually always ready, and affords greater flexibility of movement for cranes and greater economy when operating at loads less than the maximum.

See Proceedings of the Institution of Civil Engineers.

Docket (from the same root as dock, to cut off or clip'), a small piece of paper or parchment, containing a brief or summary of a large writing. All attestations or declarations annexed to written. instruments are called dockets, more particularly those that are done by a Notary (q.v.).

Dock Warrants are orders or authorities for the removal of goods and merchandise warehoused in the various docks. The orders are granted by the proper officer at the docks, on application of the importer, in favour of any one whom the latter shall name. Careful rules as to obtaining warrants are laid down by the East and West India Dock and the London Dock Companies. These rules are, in a great measure, followed by the other dock companies in the kingdom. Unless the rules are complied with, goods will not be delivered from the docks. Warrants may be obtained for either the whole or a part of a cargo consigned. A warrant may be assigned by the holder. A single warrant may also, at the desire of the holder, be

divided into smaller warrants, and these also may be assigned. In case a warrant is lost, a new warrant will not be issued till the loss has been advertised, and the holder furnish the company with an engagement to indemnify them for any loss which may arise.

Dockwra, or DOCKWRAY, WILLIAM, a merchant who in 1683 devised a new penny postal system in London, was alternately favoured and persecuted by the authorities, and died in poverty

about 1702. See POST-OFFICE.

Dockyards. Under the names of the several towns where the royal dockyards are situated those establishments are briefly noticed.

of war.

The great naval centres of France are Cherbourg, Brest, Lorient, Rochefort, and Toulon. Germany had till 1919 three ports of war-Kiel, Danzig, and Wilhelmshafen. Of these, Danzig was made a free town under the League of Nations. Trieste and Pola were the Austro-Hungarian naval harbours. These became Italian in 1919. Russia has Cronstadt and Nikolaieff at home, and Vladivostok in Siberia. Italy has Spezia, Naples, Venice, Taranto, Castellamare, and Pola; Spain, Ferrol, Cartagena, and Cadiz. Japan has Yokosuka (destroyed by earthquake, 1923), Kure, and Sasebo. See ARSENAL.

;

A large number of men-of-war are built by the government at one or other of the dockyards at Portsmouth, Plymouth, Sheerness, Chatham, and Pembroke; but Rosyth dockyard is principally used for repairs. Each of these establishments comprises slips on which the ships are built, docks in which they are kept, and all the appliances for fitting them out for sea. Boat-building and mast-making are also carried on; and in some, though not all of the yards, rope-making, sail-making, anchor- forging, block-making, and other manufacturing operations connected with the finishing and furnishing of ships. There are also arrangements connected with the storing of guns, torpedoes, and other munitions At Plymouth, Gosport, and Deptford are large establishments for victualling the navy; while machinery is repaired and constructed in the dockyards proper. To enable ships to be repaired and refitted abroad, there are royal dockyards at Gibraltar, Malta, Bermuda, the Cape of Good Hope, and Hong-kong. yards are maintained by the various Dominion authorities at Sydney, Halifax, Esquimalt, and Bonbay. Haulbowline is now maintained by the Irish Free State authorities. Since the creation of a steam-navy, and the large substitution of iron for wood in shipbuilding, an increasing proportion of the royal ships are built in private yards. All the royal dockyards are under the Admiralty, and each is governed by a distinct set of officers responsible only to that department. The chief officer, called the superintendent, is always a naval officer an admiral at the larger yards, a captain at Sheerness and Pembroke. The superintendent controls all the other officers, and all the artificers and labourers employed; examines the accounts, authorises the payments, and is responsible for the stores. When a new ship is to be built, or other work executed, the superintendent receives general instructions from the Admiralty, while special instructions are conveyed to other officers more immediately concerned with the actual working. Engineers and electricians form an important part of the establishment. The artisans of the dockyards comprise shipwrights, platers, blacksmiths, caulkers, joiners, smiths, millwrights, block-makers, sail-makers, rope-makers, &c.; while under these is a large body of labourers.

The general direction of the royal dockyards is under the superintendence of the Controller of the Navy, under whom are many professional and

technical officers. See also COALING STATIONS. In the United States there are navy yards' and naval stations. Navy yards are Boston, Mass.; Charleston, S.C.; Mare Ísland, Calif.; New York, N.Y.; Norfolk, Va.; Philadelphia, Pa.; Ports mouth, N.H.; Puget Sound, Wash.; Washington, D.C. Naval stations are Cavite (Philippines); Culebra (Porto Rico); Guam ; Guantánamo (Cuba); Key West, Fla.; New Orleans, La. ; Newport, RI.; Pearl Harbour (Hawaii); St Thomas (Virgin Islands); and Tutuila (Samoa).

The university of Paris almost immediately followed in the footsteps of Bologna. In England the doctorate was not introduced till which is more modern than those of bachelor and the following century. Originally the degree, master, was granted only in law and divinity; in in philosophy, science, literature, and music, only medicine it was not granted till the 14th century; either on examination, and after the ancient form, quite recently. The doctor's degree is granted at least, of publicly defending a learned thesis in Latin has been observed, or else it is an honorary degree, conferred in consideration of the general reputation of the recipient for eminence in some science. The doctorate of laws (whether in the particular branch of learning, philosophy, or form of LL.D., Legum Doctor; D.C.L., Doctor of Civil Law; or J.U.D., Doctor Utriusque Juris, Doctor both of Civil and Canon Law) is especially wont to be conferred on eminent men honoris causa tantum; the D.D. is often distinguished rather as a pastor or public man than as a divine; the doctorates of medicine, science, and music are usually for ascertained professional attainment. In Germany, learned ladies occasionally shared the honours of the doctorate; and now universities generally, there and elsewhere, give women doctors' degrees. It was a special honour to Cardinal Cullen that, before he was ordained priest, the pope conferred the doctor's hat on him with his own hand. See DEGREE, UNIVERSITY, WOMEN.

Doctors' Commons, formerly the college of the doctors of civil law in London, situated in St Bennet's Hill, St Paul's Churchyard. It was founded by Dr Henry Harvey, Dean of the Arches, in 1568, previous to which time the doctors had lived in Paternoster Row. The original building was burned in the great fire in 1666, when the doctors removed for a time to Exeter House. In 1672 the Commons was rebuilt, and the doctors returned to their former quarters. The college was incorporated by royal charter in 1768. The persons practising

in Doctors' Commons were the doctors, called in the ecclesiastical courts advocates, and the proctors, whose duties were analogous to those of solicitors. Both doctors and proctors were admitted by fiat of the Archbishop, and introduced to the Dean of Arches in court by two persons of their own degree, in their robes. The robe of the doctors was scarlet, with a hood trimmed with taffeta or white miniver. In 1857, on the establishment of the Divorce Court and Probate Court, the charter of Doctors' Commons was surrendered, and the corporation was dissolved, the advocates being merged in the general body of the bar, and the proctors becoming solicitors; the last-surviving advocate died in 1912. The courts which sat at Doctors' Commons were the Court of Admiralty (q.v.); the Prerogative Court, whose powers were transferred to the Probate Court; the Court of Delegates, whose powers are now exercised by the judicial committee of the Privy-council; and two other ecclesiastical tribunals, the Faculty Court and the Archdeacon's Court. The Court of Arches also sat in the same place. The buildings of the College of Advocates were demolished in 1867; and in 1874 the Doctors' Commons Will Office was removed to Somerset House.

Doctrinaire, a term used of pedantic and unpractical views, as opposed to a policy based on precedent, prudence, laissez faire, or expediency. It was applied in France, in 1816, by the reactionary court-party to those who supported scientific doctrines of constitutional liberty against the arbitrary will of the monarch. This party, which had its rallying-point in the salon of the Duc de Broglie, was led in the Chamber_by_Royer-Collard, and supported in the press by De Barante, Guizot, and Villemain. At the Revolution of 1830 they became the advisers of Louis-Philippe.

Doctrine. See DOGMA.

Dodabetta. See GHATS.

Dodd, WILLIAM, clergyman and forger, was born, 29th May 1729, at Bourn in Lincolnshire; entered Clare College, Cambridge, as a sizar, in 1746, and graduated as fifteenth in the mathematical tripos, 1749-50. Shortly after, he removed to London, married, took orders, and ere long became a popular preacher. His sermons in behalf of public charities were particularly successful ; those preached as chaplain of the Magdalen Hospital attracted all the fashionable ladies of London. Dodd next published a series of edifying books, edited the Christian Magazine, and became in 1763 one of the king's chaplains, and soon after LL.D., and tutor to Philip Stanhope, nephew to Lord Chesterfield. His habits had always been very expensive, and his large income as a successful preacher and writer did not save him from drifting hopelessly into debt. He purchased Charlotte Chapel in Pimlico, and had all his wonted success, but an anonymous letter of his wife to the Lord Chancellor's wife, offering a large sum for the rich living of St George's, Hanover Square, led to Dr Dodd's name being struck off the list of chaplains (1774), and his wife's being taken off by Foote in a farce as Mrs Simony.' Dodd left England for a time, and was well received by his pupil, now Lord Chesterfield, at Geneva, and presented to the living of Wing in Buckinghamshire. After his return he sunk deeper and deeper into financial difficulties. He sold his chapel in 1776, and in the February of the following year offered a stockbroker a bond for £4200 signed by Lord Chesterfield. It was discovered that the signature was a forgery, and Dr Dodd was at once arrested. He refunded great part of the money, but was nevertheless sent to trial, convicted, and sentenced to death. Extraordinary efforts were made to secure a pardon; petitions and

pamphlets appeared in profusion, and even Dr Johnson, the most rigid of moralists, if the kindest of men, lent the unhappy man the great influence of his support. The sermon preached to his fellowprisoners in Newgate and his final appeal to the king were both composed by Johnson, whose final letter to Dr Dodd, when his awful doom was certain, thrills throughout its grave phrases with profoundest pity. The king refused to pardon his former chaplain, and Dr Dodd was hanged, 27th July 1777. Of his numerous writings the Beauties of Shakespeare (1752) was long popular, and Thoughts in Prison is still interesting. See A Famous Forgery, by Percy Fitzgerald (1865). Dodder (Cuscuta), a widely distributed genus of phanerogamous parasites, usually regarded as degenerate Convolvulaceæ, and forming the type of a small sub-order Cuscutacea. Being entirely parasitic, they have lost all trace of leaves, even the cotyledons of the embryo being no longer distinguishable, while chlorophyll is almost completely absent. The seed germinates very late in spring, and as the seedling rises from the ground its tip soon begins to show the sweeping movements of circumnutation of a climbing plant. If no host be

Dodder, attached to a Geranium and Ivy-plant.

in the neighbourhood for it to take up its quarters on, it falls to the ground, but retains its vitality for some weeks, by which time a victim may probably have germinated. As soon as it touches a living plant it twines firmly round it, and a series of small wart-like adventitious roots are developed, from the centre of each of which a bundle of suctorial cells force their way through the epidermis and cellular envelope into the bast, and press against the woody tissue of the host. The portion of the dodder stem below this attachment now dies off, and there is then no longer any connection with the ground. The growing point again circumnutates until it finds a new base of attachment upon the same or a different stem of the host, there to repeat the formation of suckers. In this way a tangled skein of threads is formed over which, late in the season, the flowers develop in dense clusters, and the ripened seeds are shaken out of the capsule by the wind, or gathered with the crop. This parasite is often very injurious, particularly in Germany, where the fields of flax, clover, and lucerne sometimes show well-marked