Page:Encyclopædia Britannica, Ninth Edition, v. 20.djvu/334

Rh 316 R E D R E D monument to Lord de Dunstanville, is the parish church dedicated to St Uny, with a fine old 15th-century tower and peal of bells. The industries include brewing, tin- smelting, making of safety fuses, and iron-founding. Be- sides the market-house, there are a granite town-hall, a masonic hall, and the public rooms with Druids' Hall. At the west end of the town is the West Cornwall Miners' Hospital (thirty beds), erected by Lord Robartes in 1863 and since added to by the same nobleman. The popula- tion of the urban sanitary district (area 4006 acres) in 1871 was 10,685, and in 1881 it was 9335. See Plate RED SEA. The Red Sea runs north-north-west from V., vol. t ne G u if o f Aden in the Indian Ocean for about 1200 " miles, extending from 12 40' to 30 N. lat. The Strait of Bab-el- Mandeb at the entrance to the Gulf of Aden is 13i miles across, and is divided by Perim Island into two channels, the north-eastern narrow and shallow, the south-western 10 miles wide, and deep. The sea widens rapidly to 140 miles in 16 N. lat., and more gradually to 205 miles off Kunfuda in 19 N. lat. ; from this point it narrows to 115 miles in 24 N. lat., a breadth which is maintained up to 27 45' N. lat., where the sea divides into two gulfs, those of Suez and 'Akaba. The Gulf of Suez continues in the north-north-west direction for 170 miles, with an average width of 30 miles ; that of 'Akaba is narrower, and runs north-north-east for 97 miles. The Sinaitic peninsula between the two gulfs bounds the Red Sea to the north ; on the east the Arabian coast and on the west the coasts of Egypt, Nubia, and Abyssinia form the boundaries. The Arabian coast (see ARABIA) is generally a narrow sandy plain backed by ranges of barren mountains abrupt in outline and of moderate height. Enormous coral reefs run along the coast in broken lines, parallel to the shore but not connected with it. They usually rise out of deep water to within a few feet of the surface ; and a navigable channel of from 2 to 3 miles in width, in which the water is always calm, extends between them and the land. The Farisan Archipelago in 17" N. lat. is the largest and most important of the island groups of the eastern reef. It is entirely of organic formation. The most important har- bours of Arabia on the Red Sea are Mokha in 13 30' N. lat. (now nearly deserted for those of Aden and Hodeida, the port of San'a), Lokeyyah about 200 miles farther north, Jiddah in 21 20' N. lat. (the only w.ell protected harbour), and Yenbo' in 24 N. lat. The western coast is flat and desert in the north, but gives place farther south to high tablelands rising at some distance from the shore, and then to the lofty Abyssinian mountains (see ABYSSINIA, AFRICA, EGYPT). The parallel system of coral reefs is not so extensive as on the east coast, and being nearer the land the inshore channel is narrower. The large and curiously shaped coral -rock island of Dahlak, lying off Annesley Bay, is the most important on the reef. There are seven or eight harbours, of which the best known are Massowah, a little to the north of Annesley Bay (the largest inlet on the sea), and the port of disembarkation of the British troops in the Abyssinian War of 1868, Khor Nowarat, which, though small, is the best bay in the Red Sea, and Sawakin (Suakim) in 19' 30' N. lat., the chief port of the Soudan trade. The only islands of importance not already mentioned are those of the volcanic group in 14 N. lat., one of which, Jebel Zugur, 10 miles long and 7 wide, rises in a series of bare hills to the altitude of 2074 feet, and the islet Jebel Teir in 15 30' N. lat., on which a volcano has only recently become inactive. A dangerous reef named the Daedalus in 24 26' N. lat. lies right in the way of steamships traversing the sea ; it is covered with a few feet of water or uncovered, according to the season, and, like most of the reefs and islands on the usual track of vessels, is furnished with a lighthouse. The Red Sea area is in a state of gradual upheaval, the former seaport of Adulis on Annesley Bay is now 4 miles from the shore, and at Suez the former limits of the sea can be traced for several miles northwards ; whereas the north coast of Egypt is undergoing gradual subsidence. Tides. The tides are imperceptible at many places on the Red Sea, and where observable they are extremely uncertain, varying both as to time and to amount of rise with the direction and force of the wind. At Suez, where they are most regular, the rise varies from 7 feet at spring to 4 feet at neap tides. The surface-currents of the sea are also variable and perplexing ; they are chiefly pro- duced by the wind, and change in velocity and direction accordingly. Traffic. From the decline of the old Indian ftade with Egypt till the formation of the Peninsular and Oriental Steam Navigation Company and the overland route to India in 1840, traffic in the Red Sea was almost entirely confined to small native vessels trading with grain and fruit between Fgypt and Arabia, and carrying pil- grims to Jiddah, the port of Mecca. Since 1840 passenger tiallic, and since the opening of the Suez Canal in 1869 trade of all kinds in European vessels, have greatly increased. A telegraphic cable was laid from Bombay to Suez in 1859. Meteorology. The climate of the Red Sea region is one of the hottest in the world. The altitude of the sun, the almost con- tinually cloudless skies, the arid rainless character of the shores, and the complete absence of rivers combine to make the mean temperature high. That of the air usually ranges from 70 to 94 Fahr., though it has been frequently observed as high as 105 in the shade on board ship, and in the northern part of the sea the clearness of the nights promotes radiation, so that by morning the thermometer may fall to the freezing-point on shore. The atmo- sphere over the land is very dry ; the difference between the read- ings of the wet and dry bulb thermometers is frequently as much as 25, and sometimes, during the prevalence of the desert wind, it rises to 40. The evaporation from the Red Sea is naturally excess- ive ; the humidity of the air over the water is always great in summer, and when the wind blows off the sea the atmosphere is frequently saturated on shore. From the direction of the prevail- ing winds, precipitation takes place chiefly on the mountains of Abyssinia. North-north-west winds prevail on shore all the year round with very slight exception ; but in the middle of the sea they are only universal from June to September, and are confined to the northern half from October to May. During the latter season south- south-east winds prevail in the southern part of the sea, while a belt of calms and light variable breezes occupies a changing position near the centre. The southerly winds are often accompanied with rain squalls, and in September there are frequently calms and hazy weather. Hurricanes and heavy storms seldom occur in the sea, but moderate gales are common and sandstorms not unusual. From the admiralty temperature charts it appears that the mean temper- ature of the surface-water at the four typical seasons of the year, taking all available data into account, is as follows : Gulf of About South Adjacent Suez. 20" N. lat. End. Indian Ocean. February 65 75 78* 84 May 76 80 87" 85 August 79 85 89" 79' November 76 86 82 82" The temperature of the water at the south end of the sea is usually in excess of that of the air, and it is on record that on four consecu- tive days the temperature of the surface-water was 100, 106, 100, and 96, while at the same time that of the air was 80, 82, 83, and 82. The surface-temperature varies from 70 to 90, according to the position and the season. The winter mean of the northern part is about 71, and this temperature continues to the bottom at that season. When the temperature on the surface is higher than 71 it gradually falls as the depth increases, until at about 200 fathoms it becomes uniform in all parts of the sea as 71, a temperature which is maintained from that depth to the bottom all the year round. This is in consonance with all observations made on enclosed seas, the water below the point to which the barrier reaches being of uniform temperature. According to some authori- ties this is the isocheimal or mean winter temperature of the sur- face ; but the researches of the " Challenger " seem to indicate that the temperature of the external ocean at the summit of the barrier is that which extends to the bottom of the enclosed sea, Physical Conditions. The greatest depth, which occurs in 21 N. lat., is about 1200 fathoms, and from this point the sea shoals to each end. The general conformation of the bottom is that of a series of gradually sloping rounded elevations with rounded basins between them. The water is shallow in the Gulf of Suez and also at the Strait of Bab-el-Mandeb, where the depth in the centre < f the large channel is a little under 200 fathoms. The Red Sea basin is cut off from the general oceanic circulation by a barrier rising