Three methods are commonly made use of in preparing drawings. (1) Orthographic, which represents the subject under consideration in one plane only, and from which dimensions may be scaled off, and which is the normal method of preparing an engineering drawing. (2) Perspective or radial projection is made use of by an architect for displaying the elevations of a building, and gives a truer appreciation of the actual appearance of the building than can be obtained by orthographic projection. (3) Isometric projection enables one to show the length, breadth, and thickness of an object drawn to scale on the one drawing. Such a drawing is really composed of three sets of parallel straight lines, and is not strictly a true representation of the object as it would appear to the eye. It has the great advantage, however, that measurements may be directly scaled from it, and lines which are parallel in the object are also parallel in the drawing.
Drayton, Michael, an English poet, born in 1563, is said to have studied at Oxford, and afterwards held a commission in the army. The poem by which his name is chiefly remembered is his Polyolbion (1622, reprinted in 1890), a sort of topographical description of England. It is generally extremely accurate in its details, with, at the same time, many passages of true poetic fire and beauty. Other works are his Nymphidia, the Court of Fairy; The Barons' Wars; The Legend of Great Cromwell; The Battle of Agincourt; besides numerous legends, sonnets, and other pieces. He died in 1631, and was buried in Westminster Abbey.—Cf. O. Elton, Michael Drayton: a Critical Study.
Drayton, Market, or Drayton-in-Hales, a town, England, county Salop, 18 miles northeast of Shrewsbury. It has a church, supposed to have been erected, with exception of the steeple, in the reign of William I. There are paper and hair-cloth manufactories. Pop. 5167.
Dreams, trains of ideas which present themselves to the mind during sleep. The principal feature of the state of dreaming is the absence of conscious control over the current of thought, so that all kinds of fantastic notions, which in the waking state would at once be put aside, are woven into the texture of the dream. The usual content of dreams consists of aspirations or dreads, which the dreamer had recently entertained or experienced, mixed up with incidents which excited intense emotion at some earlier period of the individual's history, and especially in early childhood. The memory of unpleasant experiences, such, for example, as the horrors of trench warfare, which is repressed in the waking state, tends to force itself on the individual's attention when the conscious control is relaxed in sleep, and to give rise to disturbing dreams which may become so intense as to interfere with sleep and cause insomnia. The only rational remedy for this distressing trouble is to discover the painful incident and persuade the patient frankly to face it and not 'try to forget'. In recent years S. Freud has placed the study of dreams upon a scientific basis. He maintains that dreams represent the fulfilment of wishes. There is usually an utter want of coherency in the images that appear before the mental eye, but this excites no surprise in the dreamer. Occasionally, however, intellectual efforts are made during sleep which would be difficult to surpass in the waking state. It is said that Condillac often brought to a conclusion in his dreams reasonings on which he had been employed during the day; and that Franklin believed that he had been often instructed in his dreams concerning the issue of events which at that time occupied his mind. Coleridge composed from 200 to 300 lines during a dream: the beautiful fragment of Kubla Khan, which was all he was able to commit to paper when he awoke, remains a specimen of that dream-poem. Dreams are subjective phenomena dependent on natural causes. They are retrospective and resultant instead of being prospective or prophetic. The latter opinion has, however, prevailed in all ages and among all nations; and hence the common practice of divination or prophesying by dreams, that is, interpreting them as presages of coming events. Some authorities declare that all our dreams take place when we are in process of going to sleep or becoming awake, and that during deep sleep the mind is totally inactive. This is denied by the majority of philosophers,
and with apparent reason.—Bibliography: Havelock Ellis, The World of Dreams; S. Freud, The Interpretation of Dreams; W. H. R. Rivers, Instinct and the Unconscious.
A, Shoot. B, Hoist-gear. C, Hopper. D, Sand-pump and its engines. E, Engines. F, Overboard shoot. G, Suction-pipe. H, Bucket-well. J, Overboard discharge.
Dredging, a term applied to the operation of removing mud, silt, and other deposits from the bottom of harbours, canals, rivers, docks, &c. The most simple dredging apparatus is the spoon apparatus, which consists of a strong iron ring or hoop, properly formed for making an impression upon the soft matter at the bottom, so as to scoop it into a large leather bag attached to the ring and perforated with a number of small holes. The means for working it is a long handle, a suspending rope, and a crane or sweep-pole planted in a boat. Much more effective is the steam dredging-machine now in common use. It has a succession of strong iron buckets on an endless chain, which travels on a frame whose lower end is vertically adjustable so as to regulate the depth at which it works. It is worked by steam, and the buckets tear up the matter at the bottom, raise it, and discharge it into punts or hoppers close to the dredging vessel. Various forms of steam-pump dredgers, in which suction-pipes are the chief features, are also used. The River Clyde, from being a shallow stream, has been converted, mainly by dredging, into a waterway carrying large vessels up to Glasgow. Dredging rivers for gold is now largely carried on; and the gold-dredge may even be floated in water artificially supplied. The operation of dragging the bottom of the sea for molluscs, plants, and other objects, usually for scientific observation, is also called dredging. The oyster-dredge is a light iron frame with a scraper like a narrow hoe on one side, and a bag attached to receive the oysters. The dredges used by naturalists are mostly modifications of or somewhat similar to the oyster-dredge. Scientific dredging has of late assumed great importance as making us acquainted with the life of deep-sea areas.