If the winds be the impelling cause of currents, the _direction_ of the currents will depend upon two circumstances, viz.:—(1) the direction of the prevailing winds of the globe, including, of course, under this term the prevailing winds proper and the trade-winds; and (2) the conformation of land and sea. It follows, therefore, that as a current in any given sea is but a member of a general system of circulation, its direction is determined, not alone by the prevailing winds blowing over the sea in question, but by the general system of prevailing winds. It may consequently sometimes happen that the general system of winds may produce a current directly opposite to the prevailing wind blowing over the current. The accompanying Chart (Plate I.) shows how exactly the system of ocean-currents agrees with the system of the prevailing winds. The fine lines indicate the paths of the prevailing winds, and the fine arrows the direction in which the wind blows along those paths. The large arrows show the direction of the principal ocean-currents. [Illustration: PLATE I. CHART SHOWING THE GENERAL AGREEMENT BETWEEN THE SYSTEM OF OCEAN CURRENTS AND WINDS. W. & A. K. Johnston, Edinb^r. and London.] The directions and paths of the prevailing winds have been taken from Messrs. Johnston’s small physical Atlas, which, I find, agrees exactly with the direction of the prevailing winds as deduced from the four quarterly wind charts lately published by the Hydrographic Department of the Admiralty. The direction of the ocean-currents has been taken from the Current-chart published by the Admiralty.