JIDDA, on the Arabian coast of the Red sea 21° 28' N., 39° I?' E., chief sea-port of Hijaz and principal landing place for pilgrims to Mecca, about 46 m. away: it contains about 30,000 permanent inhabitants of numerous different stocks—Arab, Per sian, Indian, negro, etc.,—and is surrounded by a wall dotted at intervals with bastions and pierced by 3 gates (Bab Madina on N., Bab Mecca on E., and Bab Sharif on S.) ; besides these there are 3 subsidiary gates connecting with Customs warehouses and wharves outside town. The main Suq (bazaar) runs N. and S. for about a the length of the town, and an important secondary Suq runs up from the Customs gate across the main bazaar to the Mecca gate ; this is partly roofed over with corrugated iron. Much of the W. part of Jidda has been built on land reclaimed from the sea and, the subsoil water being briny or brackish, the town depends for its drinking-water on sea-water condensed by two plants capable together of producing 200 tons a day. For merly there was a piped supply from wells about 7 m. distant, but this ceased when the sources dried up. A further source of supply lies in the subterranean cisterns (Sahrij) which catch and store the flood-water in the rainy season (Nov. to Feb.). The N. quarter is most favoured for residential purposes and here reside all the consuls and agents of various states—Great Britain, France, Italy, Holland, U.S.S.R., Turkey, Egypt and Persia. Five Euro pean commercial firms (2 British, 2 Dutch and i Italian) are established at Jidda, whose European population, including con suls, is about 5o souls. The houses are mostly built of coral-rock with much picturesque woodwork which Lawrence described as "gimcrack Elizabethan." The chief public buildings are the cus tom-house, the municipal offices, the condensers, the Government offices and, outside the N. gate, the barracks and aeroplane hangar. The tomb of Eve, formerly a favourite pilgrim resort especially for women, was demolished by the Wahhabi government in 1927; it had no claim to authenticity or even to great age. At varying distances outside Jidda are scattered villages occupied by Arab fisher-folk or African negroes and formerly notorious as active slave-marts; these are Ruwais and Bani Malik to N., Nuzla Ya maniya to E. and Nuzla Takarina close to S.E. corner of town.
Jidda has a governor (Qaim-maqam) at the head of the general administration and a municipal committee under a president for purely domestic administration. The old site of the town appears to have been at Ras al Aswad about i2 M. S. and the present loca
tion of Jidda does not date back more than 30o years. The original settlement is attributed to Persian merchants during the Califate of tUthman, but its commercial importance dates from the i 5th century when it was apparently a trade-centre between India and Egypt ; the general introduction of steamers rapidly deprived Jidda of its position as an emporium though this loss was made good by its increasing importance as a pilgrim-port. Jidda successfully resisted the Wahhabi attacks of early 19th cent. and remained in the Ottoman Empire till June 1916, when the Turks surrendered to a British naval bombardment and the town became part of the new Hijaz kingdom. During the World War it was important as the political centre of the Hijaz operations. From Nov. 1924 to Dec. 1925 it was besieged by the Wahhabis and on Dec. 23rd it surrendered to Ibn Saud after the abdication and withdrawal of King 'Ali. Since then its prosperity has rapidly increased and in 1927 there was a record overseas pilgrimage of 130,000 as against a pre-war average of 70,000 to 8o,000. Its trade statistics are not available in any reliable form but its imports (LI,400,000 in 1904) now probably exceed L5,000,000 p.a. Exports (mainly hides and sarnan) are small and the adverse balance is met from the cash proceeds of the annual pilgrimage. (H. ST. J. B. P.) JIG is a device used for accurately locating a piece of work for machining. When a casting or forging has to be ma chined to shape and size it must be held firmly in the lathe, or the drilling, boring, planing, milling or other machine, a chuck, vice or bolts and clamps being used for the purpose. Careful setting is necessary, which sometimes takes a considerable time. In mass production, or even in dealing with a moderate number of pieces, this setting can be reduced considerably by providing a jig or a fixture which is constructed with means for accurately locating the article by certain surfaces, and of then clamping it with total absence of slip. A fixture holds without exercising any other function, while a jig holds and also has means for guiding the tool exactly to position, a necessity in most drilling, reaming and boring. The guide or guides take the form of top or side plates, with holes of suitable size to receive the tools as they pass down on to the work, and usually the holes are filled each with a hardened steel bush of long wearing qualities.