mountainous parts embrace many deep valleys, most of them seamed with the dry beds of ancient rivers, as the Igharghar and the Mya, both going some hundreds of miles northwards towards the 'shotts' (see below) of Algeria and Tunis. These valleys always yield an abundance of water, if not on the surface in the watercourses, then a short distance below it, and are mostly inhabited, and grazed by the cattle and sheep and camels of the natives. Another characteristic type of Saharan landscape is a low plateau strewn with rough blocks of granite and other rocks, and perfectly barren. These elevated stone-fields, called 'hammada -the best known is the Hammada el-Homra, south-east of Ghadames and on the border of Tripoli-alternate with tracts of bare flat sand, with broad marshes, where water has stood and evaporated, leaving salt behind it, and with extensive tracts of small, polished, smoothly-rounded stones. In very many parts of the Sahara, especially in the valleys of the mountainous parts, in the recesses or bays at the foot of the hills, alongside the watercourses, and in the hollows of the sanddunes, in all which localities water is wont to exist, there are oases-habitable, cultivable spots, islands of verdure in the midst of the ocean of desert. These oases occur in greatest number along the southern face of the Atlas and the Algerian mountains, on the northern side of the Ahaggar plateau, and along certain definite lines, the chief of which extend between Murzuk in Tripoli and Lake Tsad, the Igharghar and Sokoto by way of Air, the Igharghar and the bend of the Niger by way of Timissao, Morocco and Cairo by way of Tafilet, Tuat (Ainsalah), and Ghadames, and Morocco and Timbuctoo by way of Tenduf and Taudeni. These lines of oases mark the great caravan-routes between the central Soudan states and the Mediterranean.

A large portion of the Sahara, though not the whole, was undoubtedly under water at one time, probably in the Cretaceous period and earlier. | Then the surface seems to have been in great part elevated, so that the water remained only in some lakes and in gulfs near the Mediterranean coast. The physical features that at present characterise the Sahara are undoubtedly due in their broad essentials to atmospheric, chemical, and even mechanical causes, and only in a very small degree to the action of water. Water has exercised scarcely any influence on a large scale here since the Tertiary period; and there can be no doubt that a process of desiccation, similar to that which is now going on in the Turkestan deserts, has been in operation throughout the whole of this region from the earliest historic time. The Romans had colonies or military posts a long way southwards, in what are now desert regions; and both Herodotus and Pliny tell us that the elephant, the rhinoceros, and the crocodile, all animals that only live near abundant supplies of water, were common throughout North Africa in their day. None of the Egyptian inscriptions or animal-sculptures represent the camel, nor do the Greek and Roman historians mention it either as being a denizen of North Africa. The camel is now the principal carrier across the Sahara, and must have been introduced since the beginning of the Christian era. The inference from these and other facts is that the process of desiccation has gone on more rapidly during the last 2000 years. The position of the sand-dunes is determined by the unchangeable configuration of the surface; the wind and chemical action do all the rest. The sand itself is simply the Saharan rocks (granite, gneiss, mica-schists, and cretaceous rocks) ground to dust.

The great heat by day causes the rocks to expand; the great fall of the temperature at night, combined with the enormous evaporation that then

75

takes place, makes them split and crack, and break into pieces; and the strong, often violent, winds use these fragments like files, or even sand-blasts, with which to grind to pieces other rocky frag ments. The terrors of the desert sand-storm have been often described (see DESERT). Thick deposits of Saharan quartz sand-dust were discovered by the Challenger on the floor of the Atlantic a long way west of the African coast. The sand in the dunes is so dry that in several places the tread of a camel or a man will make the hill hum, or even thunder, as a vast quantity of it slips down to a lower level. The range of temperature is exceedingly great : often the thermometer falls from considerably more than 100° F. during the day to just below freezingpoint at night. In the west of the Sahara the daily average is 85° in the shade in the month of May. Rain does fall in certain parts of the Sahara with more or less frequency; but in most districts on the average after intervals of two to five years. After a fall of rain it is not unusual to see the riverbeds in the mountainous regions filled with foaming torrents. But the atmosphere is so dry and clear that objects can be seen and sounds heard at a vast distance. The Mirage (q.v.) is no uncommon feature. Owing to this extreme dryness of the air, the Sahara, especially where it is reached by the prevailing west and north-west winds, is very healthy,

The plant-life is very rich in the oases, the datepalm, which has its home in these regions, being the principal ornament as well as the most valuable possession of these fertile spots. But fruit trees, as oranges, lemons, peaches, figs, pomegranates, &c., are also grown, with cereals, rice, durrha, millet, and such-like food crops. In the desert regions the plant-life is confined principally to tamarisks, prickly acacias and similar thorny shrubs and trees, salsolacea, and coarse grasses. The animals most commonly met with include the giraffe, two or three kinds of antelope, wild cattle, the wild ass, desert fox, jackal, hare, lion (only on the borders of the desert), ostrich, desert lark, crow, viper, python, locusts, flies. The people keep as domestic animals the camel, horse, ox, sheep, and goat.

The human inhabitants, who are estimated altogether at between 1,400,000 and 2,500,000, consist of Moors, Tuareg, Tibbu, Negroes, Arabs, and Jews. The Moors and Tuareg are both Berbers (q.v.); the former live between Morocco and Senegal, the latter in the middle, south of Algeria and Tunis. The Tuareg are great traders, and control the principal caravan-routes. The Tibbu, who number about 200,000, and are regarded as being ethnically intermediate between the Berbers and the Negroes, occupy the oases between Fezzan and Lake Tsad. The Arabs of pure stock are very few; they have become mixed with the Berbers and the Negroes. The most valuable products of the Sahara are dates and salt, the latter collected on the salt pans, and made from the rocksalt of Taudeni in the west, and of Kawar (Bilma) in the east; the remaining products are horses, soda, and a little saltpetre. But for many long years there has been a very active trade carried on by caravans, between the central Soudan and Niger countries and the Mediterranean states, the ivory, ostrich-feathers, gums, spices, musk, hides, gold dust, indigo, cotton, palm-oil, shea-butter, kola-nuts, ground-nuts, silver, dates, salt, and alum of the interior lands being exchanged for the manufactured wares (textiles, weapons, gunpowder, &c.) of European countries. The French desire to get this trade into their own hands, and are proposing to construct a trans-Saharan railway, light and of narrow gauge, from the coast to the shores of Lake Tsad and the Niger.

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·

SAHARA

between

They also entertain the grandly ambitious idea of uniting their possessions on the Senegal and on the Niger with Algeria and Tunis. This union has, indeed, been theoretically accomplished already by the agreement of 1890 Great Britain and France, by which the whole of the Sahara, except the west coast (which is claimed by Morocco and Spain and Great Britain) and the extreme east (beyond a line drawn from Murzuk in Fezzan to Lake Tsad), was acknowledged to be within the French sphere of influence.' The proposed trans-Saharan railway would make this union more practical, especially if the railway line were taken from Algeria to near Timbuctoo, a distance of 1750 miles, as one scheme proposes. Alternative routes are to connect the Algerian system with Kuka on Lake Tsad (2250 miles), to build a line from near Cape Nun on the Atlantic to Timbuctoo (1100 miles), and to connect the Senegambian coast by a line over Futa-Jallon with the upper Niger.

Within recent years scientific men have eagerly discussed the possibility of reclaiming the Sahara from the arid desolation to which such a vast proportion of its surface is now abandoned. That no amelioration can be effected in the great bulk of its area is pretty well agreed; and if the desiccation is principally due, as has been maintained, to continental changes of elevation, it is pretty certain that nothing can be done. But the destruction of forests on the northern mountain-slopes is believed to be a co-operating cause. If so-for the fact is doubtful-this could be remedied. Two other schemes have, however, been proposed, and one of them has been carried out with admirable success. Westward from the Gulf of Cabes stretches for 250 miles a chain of salt lakes (shotts) right along the south of Tunis and Algeria, to the meridian of Biskra. Into these Captain Roudaire proposed (1874) to let the waters of the Gulf of Cabes by cutting through a ridge, 13 miles wide and 150 feet high, and so making an inland sea of some 3100 sq. m. in area with an average depth of close upon 80 feet. The scheme is, in point of engineering, practicable; but it is questionable whether it would accomplish the desired effect of modifying the climate and soil of the surrounding regions any more than the Sea of Aral or the Caspian does. At all events the proposal has been allowed to drop. In 1877 Mr Donald Mackenzie propounded the idea of flooding the western Sahara, the district called El Juf, by letting in the waters of the Atlantic; but the German traveller Lenz ascertained that El Juf was not a vast depression, but only a small valley. The other measure is the boring of Artesian Wells (q.v.), and with the water so obtained irrigating the soil in the vicinity. This method of reclaiming the desert, which was apparently known to the ancients, has been prosecuted by the French with great energy since 1856. By 1890 they had made a string of these wells from the cultivated districts of Algeria as far as Tugurt, on the edge of the desert, south of Biskra. Water is generally found at depths varying from 10 to 300 feet, and in great abundance. Wherever these wells have been bored the date-palm groves and the orchards have increased greatly in extent, and the population has become much denser.

In 1890 Cardinal Lavigerie, Archbishop of Carthage (Tunis), founded at Biskra a lay order called the Armed Brothers of the Sahara; their duties are to convert the native inhabitants, to protect and assist escaped slaves, and to tend the sick and wounded.

There is no single work treating of the Sahara as a whole. The best sources are the reports of French explorers, to be found in the Proceedings of the Paris Geographical Society, and Zittel, Die Sahara, ihre

SAIL

physische und geologische Beschaffenheit (Kassel, 1884); Nachtigal, Sahara und Sudan (3 vols. 1879-89); Barth, Travels in North and Central Africa (5 vols. 1857-58); Lenz, Timbuktu (1884); Rohlis, Quer durch Afrika (1874), &c.; Duveyrier, Les Touaregs du Nord (1864); Tchihatchef, The Deserts of Africa and Asia (Brit. Assoc. French books of travel by Soleillet (1876), Choisy (1881), Reports, 1882); Rolland, Géologie du Sahara (1891); Largeau (1882), and Douls (1888). For the railway schemes, see Comptes Rendus of Paris Geog. Soc. (1890); and Donald Mackenzie, Flooding of the Sahara (1877).

west Provinces, is situated 125 miles by rail N. of Saharanpur, a town of British India, NorthDelhi, and is the station for the hill sanatorium of Masuri (Mussoorie). It has an old Rohilla fort, a handsome new mosque, St Thomas' Church (1858), numerous administrative offices, and government botanical gardens (1817). It was formerly notorious for its malaria, but has vastly improved in this respect since a marsh to the east of the town has been drained. Pop. (1872) 43,844; (1881) 59,194; (1891) 63,194.-The district has an area of 2221 sq. m. and a pop. of 979,544.

in India and Persia of a respectable European, Sahib (Arab., 'master,' 'lord'), the usual title equivalent to Mr, Sir, &c. Hence Sahibah is the term for Lady, Madam.

Saida. See SIDON.

Sa'id Pasha. See EGYPT, Vol. IV. p. 242.
Saiga. See ANTELOPES.

Saigon, capital of French Cochin-China, stands on the river Saigon, a branch of the delta of the Mekhong, about 60 miles from the sea by river. The present town has grown up under French influences since 1861, and with its fine streets and squares, and boulevards, is one of the handsomest cities of the East. It has a magnificent governor's palace, a cathedral (1877), two higher colleges, an arsenal, a floating-dock and a dry-dock, administrative offices, and a botanical and zoological garden. Its population, consisting principally of Chinese, Annamese, and French, amounted to (1881) of Cholon, 4 miles to the south-west, had (1885) 13,481, and (1890) 16,213. But the business suburb 27,589, and (1890) 39,925 inhabitants, more than half Chinese. Saigon (properly Gia-dinh) is the most important port between Singapore and Hong-kong. It exports every year rice, chiefly to China, the Philippines, Japan, and the Straits Settlements, to the value of £1,440,000 to £1,720,000. The remaining exports include fish, salt, cotton, wood, beans, and hides. The port is entered by 400 to 500 vessels of 460,000 to 560,000 tons annually, of which nearly one-fourth are British; then come German and French. Previous to the French occupation (1861) Saigon, although only a collection of common Siamese huts, was the capital of the province of Lower Cochin-China.

Sail, a sheet of canvas or other suitable material which is spread to the wind to cause a boat or ship to move through the water. In Britain flax and hemp are the materials of which sail-cloth is usually made; jute, cotton, and linen, and mixtures of these are also used by civilised peoples. Amongst savages matting and tissues of various vegetable fibres are used. Sails are extended by means of masts, yards, booms (at lower edge of fore-and-aft sails), gaff's (at upper edge), ropes, and combinations of these. Sails may be of various shapes, and of any size, according to the carrying power of the vessel. A vessel of shallow draught or of narrow beam can bear comparatively little sail; while a vessel of proportionately deep draught, and heavily ballasted -as a yacht-or a vessel of great breadth of beam, can carry sail of great area. A sail acts with the greatest power when the wind is directly astern, as in fig. 1; but it can be applied, though with

less strength, when on either beam. The action of the wind on an oblique sail is a good example of what is known in mechanics as 'the composition

T

WIND'S

DIRECTION

W

S

P

S

Fig. 1.

D

SHIP S

COURSE

and resolution of forces.' Let TD, fig. 2, be a ship, PAS its sail, WA the direction of the wind, and let the length of WA represent the pressure of the wind on the sail. WA can be resolved into AB perpendicular to the sail, and BW parallel to it, the latter of which has no effect in pressing on the sail; therefore AB is the effective pressure on the sail. Were the vessel round, it would move in the direction BA. Let BA be resolved into CA and BC, the former, CA, acting in the direction of the keel or length of the vessel, or in the direction CAD, and the latter perpendicular to it, or in the direction of the breadth. The former pressure, CA, is the only pressure that moves the vessel forward, the other, BC, makes it move sideways. From the form of the vessel, however, this latter force, BC,

Fig. 2.

MAINSAIL, A.-1, main-tack; 2, main-tack tackle; 3, main-tack tricing-line; 4, neck or throat; 5, peak; 6, clew; 7, head;

8, leach; 9, luff; 10, foot; 11, strengthening pieces; 12, cringles; 13, reef pennants rove; 14, main clew lashing; 15, mast hoops and seizings; 16, peak earing; 17, reef knittles or points.

GAFF-TOPSAIL, B.-18, head; 19, peak; 20, clew; 21, foot; 22, tack; 23, luff; 24, leach; 25, peak earing; 26, head earing. FORESAIL, C.-27, fore-tack; 28, clew; 29, head; 30, foot; 31, luff; 32, leach; 33, reef knittles or points; 34, fore-tack tackle rove through a sheave in stem-head.

JIB, D.-35, tack, hooked on to the traveller; 36, clew; 37, head; 38, foot; 89, luff; 40, leach; 41, inhaul of the traveller. produces comparatively little lateral motion; any that it does occasion is called leeway. It results, therefore, that with the wind exerting an oblique pressure, the actual progress will be to the power of the wind only as CA is to WA.

Sails may practically be divided by their shape into the approximately triangular and approximately square; and according as they are set parallel to the keel of the ship or across the ship, they are fore-and-aft sails or square sails. The sails which are set square across the ship are not exactly, but nearly, square in shape. But many

77

fore-and-aft sails are also nearly square, or at least four-sided; the chief exception to this being staysails, which are purely triangular, and are suspended on the ropes which stay the masts upon the foresides from the jib-boom, bowsprit, and deck in the case of the foremast, and from the deck in the case of the mainmast. Two of these staysails, the fore-staysail and the jib, are common to most types of boats referred to in this article.

The larger sailing-vessels are usually propelled by a combination of fore-and-aft and square sails in varying number; the name and position of these are illustrated at the article SHIPBUILDING. The Schooner (q.v.) has mainly fore-and-aft sails on both masts, though the square-topsail schooner carries square topsails. The two-masted Brig (q.v.) is mainly square-rigged; and the brigantine is a cross between brig and schooner. The Cutter (q.v.) is the typical fore-and-aft one-master. The names of the several sails, and the technical terms for the parts of the sails, will be gathered from the accompanying illustration (fig. 3). A sloop is supposed to have a fixed bowsprit, whereas that of the cutter is a running one. A yawl has a foremast rigged exactly like a cutter, but has a small mizzenmast carrying a spanker or driver. See YACHT.

Some other types of sail not shown in the figures in the articles referred to may be noted here. The lug-sail, a four-sided sail hung from a yard fastened obliquely to the mast, about one-third of its length from the one

Fig. 4.-Lug-sail.

end. Luggers may be one, two, or three masted, and may accordingly vary much in size. The typical shoulder-of-mutton sail is a triangular sail set on a boat's mast; the tip is sometimes made into a separate gaff-topsail. The sprit-sail is

a quadrangular sail stretched from the mast by help, not of a gaff along its top, but by a sprit extending from the foot of the mast

diagonally to the upper aftmost corner of the sail. The London barge has its heavy mainsail partly supported by a

sprit, and there is a spanker on a small mast behind (see Vol. VI. p. 702). The spinnaker is a jib-like racing sail carried by yachts, and extended to catch the wind on the side opposite the mainsail. Many American centre-board boats carry one large quadrangular fore-and-aft sail only, the mast rising out of the bow of the boat.

The lateen sail, much used in the Mediterranean, is a triangular sail stretched from a long yard attached to a short mast, as shown in fig. 6. The felucca is a two-masted lateen-sailed boat; the sails of the Egyptian dahabeeah and of the Arab dhow are of the same type. A xebec carries a combination of lateen and square sails.