Until joined by its right-hand affluent the Aldan,which deflects it to the north-west; then, after receiving its most important left-hand tributary, the Vilyui, it makes its way nearly due N.
It then deflects south-east till it touches the Kerulen affluent of the Amur river at a point which is shown in unofficial maps as about 117° 30' E.
This main scheme is complicated in various ways: (r) by the rotation of the earth, which continually deflects currents of water or air to the right in the northern or to the left in the southern hemisphere; (2) by the conformation of the land masses (as in the case of the equatorial stream which is banked up in the Gulf of Mexico and flows out through the Straits of Florida); (3) by the varying depth of the ocean, for currents tend to flow more readily through deep than in shallow waters (as in the case of the main Atlantic drift, which flows most strongly through the deep channel between Shetland and the Faroe Is.); and (4) by the driving force of the winds acting on the surface of the sea (thus the drift of water from the equator is not N.E., as one might expect, but from E.
"If a body moves in any direction on the earth's surface, there is a deflecting force arising from the earth's rotation, which deflects it to the right in the northern hemisphere and to the left in the southern hemisphere."
It is defined by the river Segovia for about one-third of the distance, or from Cape Gracias a Dios to 86° W.; it then deflects across the watershed on the east and south of the Hondurian river Choluteca, crosses the main Nicaraguan cordillera (mountain chain), and follows the river Negro to the Bay of Fonseca.