are neither so fierce nor of so fine a physique as these latter. They are lithe and well built, but small: the average height is little more than 5 ft., except in the sheikh clan, who are obviously of Arab origin. Their complexion is more red than black, their features angular, noses straight and hair luxuriant. They bear the character of being treacherous and faithless, being bound by no oath, but they appear to be honest in money matters and hospitable, and, however poor, never beg. Formerly very poor, the Ababda became wealthy after the British occupation of Egypt. The chief settlements are in Nubia, where they live in villages and employ themselves in agriculture. Others of them fish in the Red Sea and then hawk the salt fish in the interior. Others are pedlars, while charcoal burning, wood-gathering and trading in gums and drugs, especially in senna leaves, occupy many. Unlike the true Arab, the Ababda do not live in tents, but build huts with hurdles and mats, or live in natural caves, as did their ancestors in classic times. They have few horses, using the camel as beast of burden or their ``mount'' in war. They live chiefly on milk and durra, the latter eaten either raw or roasted. They are very superstitious, believing, for example, that evil would overtake a family if a girl member should, after her marriage, ever set eyes on her mother: hence the Ababda husband has to make his home far from his wife's village. In the Mahdist troubles (1882-1898) many ``friendlies'' were recruited from the tribe.

For their earlier history see BEJA; see also BISHARIN,
HADENDOA, KABBABish; and the following authorities:—-Sir
F. R. Wingate, Mahdism and the Egyptian Sudan (Lond.
1891); Giuseppe Sergi, Africa: Antropologia della Stirpe
Camitica (Turin, 1897); A. H. Keane, Ethnology of Egyptian
Sudan (Lond. 1884); Anglo-Egyptian Sudan, edited by
Count Gleichen (Lond. 1905); Joseph von Russegger, Die
Reisen in Afrika (Stuttgart, 1841-1850). (T. A. J.)

ABACA, or ABAKA, a native name for the plant Musa textilis, which produces the fibre called Manila Hemp (q.v.). .

ABACUS (Gr. abax, a slab Fr. abaque, tailloir), in architecture, the upper member of the capital of a column. Its chief function is to provide a larger supporting surface for the architrave or arch it has to carry. In the Greek Doric order the abacus is a plain square slab. In the Roman and Renaissance Doric orders it is crowned by a moulding. In the Archaic-Greek Ionic order, owing to the greater width of the capital, the abacus is rectangular in plan, and consists of a carved ovolo moulding. In later examples the abacus is square, except where there are angle volutes, when it is slightly curved over the same. In the Roman and Renaissance Ionic capital, the abacus is square with a fillet On the top of an ogee moulding, but curved over angle volutes. In the Greek Corinthian order the abacus is moulded, its sides are concave and its angles canted (except in one or two exceptional Greek capitals, where it is brought to a sharp angle); and the same shape is adopted in the Roman and Renaissance Corinthian and Composite capitals, in some cases with the ovolo moulding carved. In Romanesque architecture the abacus is square with the lower edge splayed off and moulded or carved, and the same was retained in France during the medieval period; but in England,in Early English work, a circular deeply moulded abacus was introduced, which in the 14th and 15th centuries was transformed into an octagonal one. The diminutive of Abacus, ABACISCUS, is applied in architecture to the chequers or squares of a tessellated pavement . ``Abacus'' is also the name of an instrument employed by the ancients for arithmetical calculations; pebbles, hits of bone or coins being used as counters. Fig. 1 shows a Roman abacus taken from an ancient monument. It contains seven long and seven shorter rods or bars, the former having four perforated beads running on them and the latter one. The bar marked 1 indicates units, X tens, and so on up to millions. The beads on the shorter bars denote fives,—five units, five tens, &c. The rod O and corresponding short rod are for marking ounces; and the short quarter rods for fractions of an ounce.

The Swan-Pan of the Chinese (fig. 2) closely resembles the Roman abacus in its construction and use. Computations are made with it by means of balls of bone or ivory running on slender bamboo rods, similar to the simpler board, fitted up with beads strung on wires, which is employed in teaching the rudiments of arithmetic in English schools.

FIG. 2.—Chinese Swan-Pan. The name of ``abacus'' is also given, in logic, to an instrument, often called the ``logical machine,'' analogous to the mathematical abacus. It is constructed to show all the possible combinations of a set of logical terms with their negatives, and, further, the way in which these combinations are affected by the addition of attributes or other limiting words, i.e. to simplify mechanically the solution of logical problems. These instruments are all more or less elaborate developments of the ``logical slate,'' on which were written in vertical columns all the combinations of symbols or letters which could be made logically out of a definite number of terms. These were compared with any given premises, and those which were incompatible were crossed off. In the abacus the combinations are inscribed each on a single slip of wood or similar substance, which is moved by a key; incompatible combinations can thus be mechanically removed at will, in accordance with any given series of premises. The principal examples of such machines are those of W. S. Jevons (Element. Lessons in Logic, C. xxiii.), John Venn (see his Symbolic Logic, 2nd ed., 1894, p. 135), and Allan Marquand (see American Academy of Arts and Sciences, 1885, pp. 303-7, and Johns Hopkins University Studies in Logic, 1883).

ABADDON, a Hebrew word meaning ``destruction.'' In poetry it comes to mean ``place of destruction,'' and so the underworld or Sheol (cf. Job xxvi. 6; Prov. xv. 11). In Rev. ix. 11 Abaddon ((Abaddon) is used of hell personified, the prince of the underworld. The term is here explained as Apollyon (q.v.), the ``destroyer.', W. Baudissin (Herzog-Hauck, Realencyklo padie) notes that Hades and Abaddon in Rabbinic writings are employed as personal names, just as shemayya in Dan. iv. 23, shamayim (``heaven''), and makom (``place'') among the Rabbins, are used of God.

ABADEH, a small walled town of Persia, in the province of Fars, situated at an elevation of 6200 ft. in a fertile plain on the high road between Isfahan and Shiraz, 140 m. from the former and 170 m. from the latter place. Pop. 4000. It is the chief place of the Abadeh-Iklid district, which has 30 villages; it has telegraph and post offices, and is famed for its carved wood-work, small boxes, trays, sherbet spoons, &c., made of the wood of pear and box trees.

ABAE (rabai), a town in the N.E. corner of Phocis, in Greece, famous in early times for its oracle of Apollo, one of those consulted by Croesus (Herod. i. 46). It was rich in treasures (Herod. viii. 33), but was sacked by the Persians, and the temple remained in a ruined state. The oracle was, however, still consulted, e.g. by the Thebans before Leuctra (Paus. iv. 32. 5). The temple seems to have been burnt again during the Sacred War, and was in a very dilapidated state when seen by Pausanias (x. 35), though some restoration, as well as the building of a new temple, was undertaken by Hadrian. The sanctity of the shrine ensured certain privileges to the people of Abac (Bull. Corresp. Hell. vi. 171), and these were confirmed by the Romans. The polygonal wabs of the acropolis may still be seen in a fair state of preservation on a circular hill standing about 500 ft. above the little plain of Exarcho; one gateway remains, and there are also traces of town walls below. The temple site