FORELAND

, or Foreness, in Navigation, a point of land jutting out into the sea.

, in Fortification, is a small piece of ground between the wall of a place and the moat; called also Berme and Liziere.

FORE-STAFF, an instrument used at sea, for taking the altitudes of the heavenly bodies; being so called, because the observer, in using it, turns his face forward or towards the object, in contradistinction to the Back-staff, with which he turns his back to the object. It is also called the Cross-staff, because it consists of several pieces set across a staff.

The Fore-staff is formed of a straight square staff AB, of about 3 feet long, having each of its four sides graduated like a line of tangents, and four crosses, or vanes, FF, EE, DD, CC, sliding upon it, of unequal lengths, the halves of which represent the radii to the lines of tangents on the different sides of the staff. The first or shortest of these vanes, FF, is called the Ten Cross, or Ten Vane, and belongs to the 10 scale, or that side of the instrument on which divisions begin at 3 degrees, and end at 10. The next longer cross, EE, is called the 30 Cross, belonging to that side of the staff where the divisions begin at 10 degrees, and end at 30, called the 30 scale. The third vane DD, is called the 60 Cross, and belongs to that side where the divisions begin at 20 degrees, and end at 60. The last or longest vane CC, called the 90 Cross, belongs to the side where the divisions begin at 30 degrees, and end at 90.

The chief use of this instrument, is to take the height of the sun, and stars, or the distance between two stars: and the 10, 30, 60, or 90 Cross is to be used, according as the altitude is more or less; that is, if the altitude be less than 10 degrees, the 10 Cross is to be used; if above 10, but less than 30, the 30 Cross is to be used; and so on.

To observe an Altitude with the Fore-staff. Apply the flat end of the staff to the eye, and slide one of the crosses backwards and forwards upon it, till over the upper end of the Cross be just seen the centre of the sun or star, and over the under end the extreme horizon; then the degrees and minutes cut by the cross on the side of the staff proper to the vane in use, gives the altitude above the horizon.

In like manner, for the Distance between two luminaries; the Staff being set to the eye, bring the cross just to subtend or cover that distance, by having the one luminary just at the one end of it, and the other luminary at the other end of it; and the degrees and minutes, in the distance, will be cut on the proper side of the staff, as before.