Ravelin.
To the faces of the work draw the following parallels:—
1. At the distance of 6 yards, for the parapet.
2. From which 8 yards, for the terreplein.
3. From which 5 yards, for the interior slope.
Covered way.
Draw lines parallel to the counterscarp, at the distance of 11 yards, for the breadth of the covered way.
Salient places of arms.
These are formed by the salients of the branches of the covered way.
Re-entering places of arms.
Set off 40 yards on each side of the re-entering angle of the counterscarp for their demi-gorges, from which points draw their faces at an angle of 100 degrees.
Glacis.