Jidda is said to have been founded by Persian merchants in the caliphate of Othman, but its great commercial prosperity dates from the beginning of the 15th century when it became the centre of trade between Egypt and India. Down to the time of Burckhardt (1815) the Suez ships went no farther than Jidda, where they were met by Indian vessels. The introduction of steamers deprived Jidda of its place as an emporium, not only for Indian goods but for the products of the Red Sea, which formerly were collected here, but are now largely exported direct by steamer from Hodeda, Suakin, Jibuti and Aden. At the same time it gave a great impulse to the pilgrim traffic which is now regarded as the annual harvest of Jidda. The average number of pilgrims arriving by sea exceeds 50,000, and in 1903-1904 the total came to 74,600. The changed status of the port is shown in its trade returns, for while its exports decreased from £250,000 in 1880 to £25,000 in 1904, its imports in the latter year amounted to over £1,400,000. The adverse balance of trade is paid by a very large export of specie, collected from the pilgrims during their stay in the country. JIG, a brisk lively dance, the quick and irregular steps of which have varied at different times and in the various countries in which it has been danced (see DANCE). The music of the "jig," or such as is written in its rhythm, is in various times and has been used frequently to finish a suite, e.g. by Bach and Handel. The word has usually been derived from or connected with Fr. _gigue_, Ital. _giga_, Ger. _Geige_, a fiddle. The French and Italian words are now chiefly used of the dance or dance rhythm, and in this sense have been taken by etymologists as adapted from the English "jig," which may have been originally an onomatopoeic word. The idea of jumping, jerking movement has given rise to many applications of "jig" and its derivative "jigger" to mechanical and other devices, such as the machine used for separating the heavier metal-bearing portions from the lighter parts in ore-dressing, or a tackle consisting of a double and single block and fall, &c. The word "jigger," a corruption of the West Indian _chigoe_, is also used as the name of a species of flea, the _Sarcopsylla penetrans_, which burrows and lays its eggs in the human foot, generally under the toe nails, and causes great swelling and irritation (see FLEA).