An eddy, vortex, or gulf, where the water is continually turning round. Those in rivers are very common, from various accidents, and are usually very trivial, and of little consequence. In the sea they are more rare, but more dangerous. Sibbald has related the effects of a very remarkable marine whirlpool among the Orcades, "which would prove very dangerous to strangers, though it is of no consequence to the people who are used to it. This is not fixed to any particular place, but appears in various parts of the limits of the sea among these islands. Wherever it appears, it is very furious; the boats, etc, would inevitably be drawn in, and be destroyed by it; but the people who navigate them, are prepared for it, and always carry an empty vessel, a log of wood, or large bundle of straw, or some such thing, in the boat with them. As soon as they perceive the whirlpool, they toss this within its vortex, keeping themselves out; this substance, whatever it be, is immediately received into the centre, and carried under water; and, as soon as this is done, the surface of the place, where the whirlpool was, becomes smooth, and they row over it with safety; and in about an hour, they see the vortex begin again in some other place, usually at about a mile distant from the first."