or Ditch, in fortification, a deep trench dug round the rampart of a fortified place, to prevent surprizes.

The brink of the moat, next the rampart, is called the scarpe; and the opposite one, the counter-scarpe.

A dry moat round a large place, with a strong garison, is preferable to one full of water; because the passage may be disputed inch by inch, and the besiegers, when lodged in it, are continually exposed to the bombs, grenades, and other fire-works, which are thrown incessantly from the rampart into their works. In the middle of dry moats, there is sometimes another small one, called cunette; which is generally dug so deep, till they find water to fill it.

The deepest and broadest moats are accounted the best; but a deep one is preferable to a broad one: the ordinary breadth is about 20 fathoms, and the depth about 16.

To drain a moat that is full of water, they dig a trench deeper than the level of the water, to let it run off; and then throw hurdles upon the mud and slime, covering them with earth or bundles of rushes, to make a sure and firm passage.