AFRICA, BRITISH Coast Zone and Eastern Plateaux.—The first of the connecting Australia with the outer world were simultaneously broken, the sudden isolation was regarded as a parallel zones—the coast plain or “ Temborari ”—is generpossible operation of wTar, and the colonists called out their ally of insignificant' width, varying from 2 to 10 miles, naval and military reserves. Records of earthquakes except in the valleys of the main rivers. It consists originating at great distances have also frequently enabled largely of coral rock partially covered with deposits of us to anticipate, to correct, to extend, or to disprove tele- alluvium or sand, the latter forming ridges sometimes 400 graphic accounts of the disasters. Whatever information feet high. The shore line is broken by bays and branching a seismogram may give is certain, whilst the information creeks, often cutting off islands from the mainland. Such gathered from telegrams may in the process of transit are Mvita or Mombasa in 4° 5' S., and the larger islands of become exaggerated or minimized. Otherwise unaccount- Lamu, Manda, and Patta, between 20° 20' and 2°. Farther able disturbances in records from magnetographs, baro- north the coast becomes straighter, with the one indentation graphs, and other instruments employed in observatories, of Port Durnford in 1° 10' S., but skirted seawards by a are frequently explained by reference to the traces yielded row of small islands. The northern interior east of the riftby seismometers. Perhaps the greatest triumph in seis- valley is still little known, and a detailed description must mological investigation has been the determination of the therefore be confined to the more southern parts. Beyond varying rates at which motion is propagated through the the coast plain the country rises in a generally well-defined world. These measurements have already thrown new step or steps to an altitude of some 800 feet, forming the light upon its effective rigidity, and if we assume that the wide level plain of the “ Nyika ” (uplands), largely comdensity of the earth increases uniformly from its surface posed of quartz. In the south this zone has a width of towards its centre, so that its mean density is 5-5, then, some 80 miles, but it widens out northwards, and seems to according to Knott, the coefficient of elasticity which occupy a large part of the northern interior. The next governs the transmission of preliminary tremors of an stage in the ascent is marked by an intermittent line earthquake increases at a rate of nearly 1'2 per cent, per of mountains—gneissose or schistose—running generally mile of descent. These, then, are a few of the results which north-north-west, sometimes in parallel chains, and represeismologists have attained, and considering how much has senting the primitive axis of the continent. Their height been accomplished during the last few years, we may surely varies from 5000 to 8000 feet. The principal units are claim for the study of the changes in progress within the the Bura Mountains in 3^° to 3^° S., the Julu or Dyulu and 2f° S., the Iveti Mountains in planet on which we live as much attention as is devoted range between ] l° S., and various ranges in the districts of Kikuyu and to the study of the ocean, the atmosphere, and the stars. Ukamba. East of the latter the plateau itself seems to Authorities.—J. Milne. Seismology. London, 1898 ; Earth- consist of a wide extent of grass. Farther inland wide quakes. London, 1898.—Transactions of the Seismological Society uplands, largely grass-covered, and known to the inhabitants of Japan, vols. i.-xvi. ; Seismological Journal, vols. i.-iv. Yokohama, 1880-95.—Bollettino della Societd Sismologica Italiana, as Rangatan, extend to the eastern edge of the rift-valley, vols. i.-v. Rome, 1895.—Ewing. Memoir on Earthquake though varied with cultivated ground and forest, the former Measurement. Tokio, 1883.—Reports of the British Association, especially in Kikuyu, the latter between 0° and 0° 40' S'. 1881-1902.—E. von Rebeur-Paschwitz. Das Horizontalpendel. The most extensive grassy plains are those of Kapte or Halle, 1892. (j. Mi.) Kapote and Athi, between 1° and 2° S. The general altiEast Africa, British.—British East Africa, in tude of these uplands, the surface of which is largely its widest sense, includes all the territory placed under composed of lava, varies from 5000 to 8000 feet, the British influence on the eastern side of the continent highest portion occurring on or near the equator, beyond between the latitudes, roughly speaking, of 6|° S. and which the high Laikipia plateau falls gradually to the 10° 1ST. It is bounded on the S. by German East Africa, north. This zone contains the highest elevations in British on the W. by the Congo State, and on the 1ST., where its East Africa, including the volcanic pile of Kenya limits are still in part undefined, by the Egyptian Sudan, (17,200 feet), Settima (13,400 feet), and Nandarua Abyssinia, and Italian Somaliland. The total area is (12,900 feet). To the west the fall to the rift-valley is estimated at about 670,000 square miles. Administratively marked by a line of cliffs, of which the best defined portions it comprises the protectorates of Zanzibar (consisting of are the Kikuyu escarpment (800 feet), just south of 1 S.; the islands of Zanzibar and Pemba), British East Africa, the Kinangop escarpment, a little north of the same and Uganda. Apart from a narrow belt of lowlands parallel; the Laikipia escarpment, on the equator ; and the along the coast, the mainland area, which extends from the cliffs of Morongop, a little south of 1° N. In the intervals Umba river in the south to the Juba in the north, belongs the descent is often much more gradual. Rivers of the East Coast.—One of the main watersheds almost entirely to the great lake plateau of East Africa, rarely falling below an elevation of 2000 feet, while exten- of East Africa runs in close proximity to this eastern wall sive sections rise to a height of 6000-8000 feet. The of the rift-valley, separating the basins of inlandr drainage primary surface features run generally in zones from north from the rivers of the east coast, of which the tw o largest, to south. From the coast lowlands a series of steps with wholly within British East Africa, are the Sabaki and intervening plateaux leads to a broad zone of high ground Tana. The Sabaki rises (as the Athi) in 1 42 S., and after remarkable for the abundant traces of volcanic action. flowing north-east for 70 miles across the Kapote and Athi This broad upland is furrowed by the great East African plains, turns south-south-east under the wooded slopes of “ rift-valley,” formed by the subsidence of its floor, and the Yatta ridge, which shuts in its basin on the east. In 3 b. occupied in parts by lakes without outlet. Towards the it turns east, and in its lower course (known as the Sabaki) e west a basin of lower elevation is partially occupied by traverses the sterile quartz-land of the outer plateau. Victoria Nyanza, drained north to the Nile, while still actual valley is in parts low and flat, covered with forest farther inland the ground again rises to a second volcanic and scrub, and containing small lakes and backwaters conbelt, culminating in Mount Ruwenzori (18,000 feet), and nected with the river in the rains. At. this season the traversed by a line of depression occupied by Lakes Albert stream is deep and strong, and of a turbid yellow cok^b Edward and Albert, the Western Nile reservoirs. The but navigation is interrupted by the Lugard falls, about 1W western boundary of British East Africa is mainly formed, miles from its mouth. Its total length is about 400 miles, beyond the western rift-valley, by the crest of the water- but, apart from the numerous small feeders of the upper river, almost the only tributary is the Tzavo, from tiie shed between the Nile and Congo basins. 610
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