Abrasion is a form of sexual activity involving the stimulation of the surface of the body with abrasive materials, such as rough silk, chamoisleather, fine sandpaper, brushes or wire wool. Research Abrasion
Grinding is a mechanical process in which certain effects are produced by attrition. This process prevails in various mechanical arts, as in grinding corn, etc, the object of which is to reduce the materials to a fine powder; or in grinding metals for the purpose of giving them a certain figure, polish, or edge. In the first case the grinding or crushing is effected by rough stones, or, as in crushing ores, between heavy metal cylinders, or by a heavy stone or iron cylinder revolving upon a smooth plate. The grinding of cutlery is effected by means of the grindstone; emery powder grinds glass lenses and specula. Ornamental glass is ground into facets by stones and lap-wheels. Diamonds and other precious stones are ground with diamond dust.
What is called dry grinding is the grinding of steel with dry grindstones. The points of needles are produced by this means, also the finishing of steel pens. Sand-jet grinding is a process in which abrasion is effected by the percussion of small hard particles on a plain surface, sharp siliceous sand being impelled by a blast artificially produced of steam or of air. By the use of flexible jointed connecting tubes the jet can be turned in any direction. Research Grinding
A grindstone is a cylindrical stone, on which sharpening, cutting, and abrasion are effected by the convex surface while the stone is revolving on its axis. They are made of sandstone, or sandstone grit of various degrees of fineness. Good stones are obtained in various parts of England, especially from the coal districts of Northumberland, Newcastle grindntones being especially famous. The Sheffield grindstone, traditionally used for grinding files and the like, is obtained from Hardsley, about 14 miles north of Sheffield. Artificial grindstones have also been successfully used. Research Grindstone
Jade carving is the process by which the surface of jade stone is embellished through abrasion. The earliest known carved jades were made in China during the New Stone Age, or Neolithic period. Neolithic jades were usually fashioned as blades, although it is unclear whether they served a utilitarian or ceremonial function.
Excavations conducted at sites settled during the Shang dynasty have yielded a number of carved jades in a variety of forms. Certain shapes predominate, such as the round disk (pi), the ax (kuei), and a cylindrical tube (tsung). These objects probably served a ritual function, either as symbols of rank or as grave furnishings. The most beautiful examples of Shang jade carving, however, are small sculptures and plaques. The discovery, in 1975, of an undisturbed tomb from the Anyang era of the Shang dynasty has yielded the richest group of jade carvings to date. The excavation revealed plaques depicting dragons and various birds, along with near-miniature sculptures of human figures, mythical creatures, and recognisable animals, including an elephant.
The achievements of the Shang jade carvers were adopted and ultimately surpassed by artists of the Chou dynasty. Surface decoration became increasingly sophisticated, with open- work featuring birds and dragons, as well as tiny, individually carved curls. The development of the iron drill is probably responsible for the technical advancements seen in the carvings of this period. Elaborate jade carving continued in popularity during the Han dynasty; in addition, a most notable jade artefact was the so-called funerary suit. Various excavations have yielded corpses encased in a jade form made of thousands of rectangular pieces of jade, sewn together with gold thread, and fitted to the body. Other small jades, previously objects for burial, were now fashioned for the uses of the living. Toilet boxes, drinking vessels, and delightful adornments for the scholar's desk have been preserved from the Han period.
The dating of jade carvings from after the Han dynasty through the Ch'ing dynasty has been highly problematic, as the archaeological evidence is often incomplete. Throughout this period, however, small decorative forms of jade, often depicting animals, flowers, or children, continued in popularity. T'ang and Sung carvers favoured small figures. Drinking and desk vessels, and jadejewellery as well, were widely produced in the Yuan and Ming epochs. During the Ch'ing period, particularly in the 18th century, large jade carvings attained great favour with the emperors and royal officials. Forms were often taken from ancient bronze vessels, reflecting the continuing interest in early art. Landscapes, often paralleling those found on carved bamboo or in paintings, were carefully transcribed onto the surface of enormous jade slabs. Much of this intricacy is still found in Chinese jade work today; traditional design motifs and carving styles also have been retained. China's continuous interest in jade carving was never found in other Asian nations.
The Indians practised a degree of jade work, most notably the Islamic Mughals, who favoured ceremonial weapons with highly decorative jade blades. The most important centre of jade carving outside the Orient was pre-Columbian Mexico and Central America under the Olmec, Aztec, and Mayan rulers. Splendid ceremonial objects-axes, knives, masks, and large animal figures-were produced; the objects are sophisticated in style and highly advanced in technique. Research Jade Carving
An abrasion (graze) is a type of wound characterised as a sore place on the skin caused by rubbing or scraping. Often superficial, abrasions can be very painful and be disturbing in appearance. The risk from an abrasion is that infection may enter the wound, and it is important that the wound is cleaned. Research Abrasion
Blood may escape from the blood vessels as a result of injury. Capillaries are fractured by simple abrasion, veins with their very fragile walls are easily torn, while arteries are usually injured by a cut, either accidental or intentional. Infective or malignant disease, as it eats its way through tissues, may invade the wall of a blood vessel which subsequently gives way allowing free escape of blood. In the case of capillaries and veins, the inflammatory process involving the vessel usually sets up thrombosis so that haemorrhage does not occur. With arteries, while thrombosis may sometimes occur as the result of the inflammation, severe haemorrhage frequently follows erosion.
Perhaps the most common site of such arterial haemorrhage is in the base of a gastric ulcer. Because of the inflammation in the walls of the artery which may be coursing through the base of the ulcer, the vessel is prevented from contracting, and when it bursts the hole is held rigidly open with resultant severe and sometimes fatal haematemesis (vomiting of blood). High blood pressure is frequently associated with disease of the walls of the arteries, which lose their elasticity. In most parts of the body, the arteries are surrounded by fairly firm tissues which tend to support them, but this is not the case in the brain which is the most common site for the rupture of small arteries. Such cerebral haemorrhage is responsible for one form of apoplexy. The wall of an artery may be weak from injury, from congenital defect or from disease, and instead of it bursting it develops a large bulge which continues to increase in size as the years go by. The surrounding tissues become eroded by the continuous beating of the artery and eventually the stretched-out thin-walled sac bursts. This arterial bulge is known as aneurism. A congenital form occurs near the base of the brain. Aneurism follows gun-shot wounds in the region of arteries and the aorta undergoes a similar change as the result of arterio-sclerosis or syphilis. Research The Cause of Bleeding
Lycra is a synthetic fibre introduced in 1958 by Du Pont of Delaware, USA. Lycra is elastic, abrasion resistant and has stretch and recovery powers. It is extensively used in the clothing industry. Research Lycra
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Abrasion
