Page:The New International Encyclopædia 1st ed. v. 02.djvu/237

ATLANTIC OCEAN. and is merged with tlie general eastern surface drift. This latter spreads and divides, one braneh of it flowing northward along the western ooast of nortliern Europe, there, aliove latitude 70°, to join the colder currents llowing to the west; the other branch of it flowing southward along the western coast of southern Europe and that of northern Africa, there, below latitude 20° N., to join the warm westward current, and forming, between latitudes 10° and 45° X., a clockwise moving circulatory system. Off' the western shores of the Atlantic the cold Arctic current flows southward from the north (called the Greenland Stream on the coast of Green- land and the Labrador Stream farther south), part of it branching oft" toward the east about latitude 50°. and forming a return current, com- pleting another counter-clockwise system of cir- culation between latitudes 45° and 00° N.

In the South 'Atlantic there appears to be but a single great circulatory system, moving in a eoimter-clockwise direction. The sub-equatorial water-current flows westward across the Atlantic in the region of the equator, but on reaching longitude 25° W., it begins to separate, the north- ern branch moving toward the northwest along the Brazilian coast toward the Gulf of Mexico, and the southern branch moving toward the southwest and forming the Brazilian Stream along the eastern coast of Brazil ; but it turns eastward I)eyond latitude 40° S. and flows across the Atlantic with the general eastward drift of those southern latitudes. As the coast of Africa is approached, a part of the stream turns northward and flows along the southern part of the western coast of (iuinea, where it is known as the Benguela Current, to join again the west- ward current across the Atlantic near the equa- tor. These various oceanic currents range in velocity from 20 to 75 miles per day.

The northern Atlantic lies in the path of the great procession of cyclones and anti-cyclones of middle latitudes, and also in the path of the West Indian hurricanes over its lower latitudes; the counterparts of these atmospheric disturb- ances are foiuid in the South Atlantic. The winds of the Atlantic are ilivided into two .systems, these of the North and South Atlantic. In January and February, in the Xortli Atlantic, north of latitude .35°, the winds are chiefly from the west; they are northwest on the Xorth American coast, west toward the middle, and southwest on the Euro|)ean coast ; but between Iceland and Greenland there is an area of aver- age cyclonic circtilation (counter-clockwise). South of about latitude 35° X. the winds are generally from the northeast almost to the equator. In the South Atlantic, north of lati- tude 20° S., in the western part, and north of latitude .35° S., in the eastern part, the winds are from the southeast, becoming more distinctly from the south just at the equator. In latitude 30° S. the winds are from the south on the eastern side, and from the north on the western side; but southward of latitude 40° S. they are in general from the west. Over an area whose centre is about latitude 30° S. and longitude 10° W. there is a system of winds flowing counter- clockwise. In July and .ugust the dividing lines between the wind systems of the North and South .tlantic are pushed farther northward by from 10° to 15°.

The mean annual rainfall over the Atlantic Ocean is in general from (JO to 80 inches between latitude 4° S. and 8° N. ; between 10° and 30° X., 10 inches; from 30° to 40° X. it increases from 10 to 40 inches; in the middle ocean, from 42° to 58° X., 80 inches. South of the equator the rainfall is from 20 to 40 inches in the western part, but from 10 to 20 inches in most of the eastern part ; and increases in the middle ocean from 20 to 40 inches from latitude 10° to 35° S.

The vegetaljle and animal life of the Atlantic is treated under the subject Ocean Life.

The distribution of algiP is dependent on the light and temperature of the water, and so rapid is the decrease of the former that below a depth of from 800 to 1000 feet few algfe are found; those in the surface waters belong mainly to the Fucaceae, and those at greater depths are mainly Ceraminacefe. The chief feature of the flora which can receive mention here is the great Sar- gasso region between latitudes 24° and 30° N. and longitudes 40° and 80° V., where the sea- weed Sargassum hdcciftirum is found in such great abundance as to interfere in some places with the progress of sailing vessels.

The distribution of mammalia, fishes, and floating mollusks is determined largely by the temperature of the surface waters. Of the ceta- cea, some species of whales are distributed over various sections of the Atlantic Ocean, but those found in polar regions do not descend to lower latitudes, and vice versa.

The ocean bottom, near the coasts, is covered with a great variety of deposits of continentiil waste. The great portion, that between depths of 3000 and 12,000 feet, is, however, covered with Foraminiferae (Globigerina, Orbulina, Pulvinu- lina, iiphwroidina). At these latter depths the calcareous bottom is replaced by gray clay, which forms a transition region between the foramini- feran ooze and the red clay of the greater depths below 14,000 feet, which consequently covers a large area. The flora and the fauna of the regions of the Atlantic visited by the Challenger are given in minute detail in the Report of the Challenger Expedition, prepared under the direc- tion of C. Wyville Thomson and John ilurray (London, 1880-05). See Oce-^n; OcEiiNic De- P0S1T,S; PlSTRIIiUTION OF ANIMALS.

ATLANTIC TEL'EGRAPH,. The construction of the trans-Atlantic cable followed as the result of the successful laying and operation of various shorter sulmiarine lines. The first definite suggestion of telegraphic com- mimication between England and America dates from 1845. when the Messrs. Brett, who a few years later were active in the construction of the first telegraph lines across the English Chan- nel, registered a 'General Oceanic Telegraph Company.' Before proceeding with this enter- prise, they successfully laid a cable across the English Channel (185i), which was of such ex- cellent construction that it survived for a num- ber of years. The success of this and other European cables led to the discussion of tele- graphic commimication between America and Europe by way of Newfoundland. The original plan was to carry the line across that island to Saint John's, and there intercept the incoming steamers, and by means of carrier-pigeons and- a direct telegraph line to the United States, transmit messages. The cooperation of Cyrus V. Field was enlisted in 1854, and he became