A current is a progressive motion of the water, causing all floating bodies to move that way towards which the stream is directed. The set of a current is that point of the compass towards which the waters run, and its drift is the rate it runs per hour. The most usual way of discovering the set and drift of an unknown current, is the following, supposing the current at the surface to be much more powerful than at a great distance below the surface:—
Take a boat a short distance from the ship, and, by a rope fastened to the boat's stern, lower down a heavy iron pot or loaded kettle to the depth of 80 or 100 fathoms; then heave the log, and the number of knots run out in half a minute will be the miles the current sets per hour, and the bearing of the log will show the set of it.
There is a very remarkable current, called the Gulf Stream, which sets in a north-east direction along the coast of America, from Cape Florida towards the Isle of Sables, at unequal distances from the land, being about 75 miles from the short of the southern States, but more distant from the shore of the northern States. The width of the stream is about 40 or 50 miles, widening towards the north.