FESTOON
, in Architecture &c, a decoration in form of a garland or cluster of flowers.
FICHANT Flank. See Flank.
Fichant Line of Defence. See Fixed Line of Defence.
FIELD-Fort. See Fortine.
Field-Pieces, are small cannon, usually carried along with an army in the field: such as, one pounders, one and a half, two, three, four, six, nine, and 12 pounders; which, being light and small, are easily carried.
Field-Staff, is a staff carried by the gunners, in which they screw lighted matches, when they are on service; which is called arming the Field-staffs. See Linstock.
Field of View, or of Vision, is the whole space or extent within which objects can be seen through an optical machine, or at one view of the eye without turning it.
The precise limits of this space are not easily ascertained, for the natural view of the eye. In looking at a small distance, we have an imperfect glimpse of objects through almost the extent of a hemisphere, or at least for above 60 degrees each way from the optic axis; but towards the extremity of this space, objects are very imperfectly seen; and the diameter of the field of distinct vision does not subtend an angle of more than 5 degrees at most, so that the diameter of a distinct image on the retina is less than 6/100 of an inch; but it is probably much less.
Field-Book, in Surveying, a book used for setting down angles, distances, and other things, remarkable in taking surveys.
The pages of the Field-book may be conveniently divided into three columns. In the middle column are to be entered the angles taken at the several stations by the theodolite, with the distances measured from station to station. And the offsets, taken with the offset-staff, on either side of the station line, are to be entered in the columns on either side of the middle column, according to their position, on the right or left, with respect to that line: also on the right or left of these are to be set down the names and characters of the objects, with proper remarks, &c. See a specimen in my Treatise on Mensuration, pa. 517, ed. 2d.
