/ 
LINE. 
anther ; capsule one-celled. There are three 
species. 
LINE, in geometry, a quantitj' extended 
in length only, without any breadth or 
thickness. It is formed by the flux or mo- 
tion of a point. See Fluxion. 
Lines in perspective, are, 1. Geometri- 
cal line, which is a right line drawn in any 
manner on the geometrical plane. 2. Ter- 
restrial line, or fundamental line, is a right 
line wherein the geometrical plane, and that 
of the picture or draught intersect one ano- 
ther, formed by the intersection of the 
geometrical plane, and the perspective 
plane. 3. Line of the front, is any right 
line parallel to the terrestrial line. 4. Ver- 
tical line, the common section of the verti- 
tical and of the draught. 5. Visual line, 
the line or ray imagined to pass from the 
object to the eye. 6. Line of station, ac- 
cording to some writers, is the common 
section of the vertical and geometrical 
planes. 7. Objective line, the line of an 
object from whence the appearance is 
sought for in the draught or picture. 
Lines, in dialling, are, 1. Horizontal line, 
the common section of the horizon and the 
dial plane. See Dialling. 2. Horary 
lines, or hour-lines, the common intersec- 
tions of the hour-circles of the sphere, with 
the plane of the dial. See Horary. 3, 
Substylar line, that line on which the style 
or cock of a dial is duly erected, and the 
representation of such an hour circle as 
is perpendicular to the plane of that dial. 
4. Equinoctial line, the common intersec- 
tion of the equinoctial and plane of the 
dial. 
Line of measures, is used by Oughtred, 
to denote the diameter of the primitive cir- 
cle in the projection of the sphere in piano, 
or that line in which the diameter of any 
circle to be projected falls. In the stereo- 
graphic projection of the sphere in piano 
the line of measures is that line in which 
the plane of a great circle perpendicular 
to the plane of the projection, and that 
oblique circle which is to be projected, 
intersects tlie plane of the projection ; or it 
is the common section of a plane passing 
through the eye point and the centre of the 
primitive at right angles to any oblique 
circle .which is to be projected, and in 
which the centre and pole of such circle 
will be found. 
Line of direction on the earth’s axis, iii 
the Pythagorean system of astronomy, the 
line connecting the two poles of the eclip. 
VOL. IV. 
tic and of the equator when they are pro 
jected on the plane of the former. 
Line of direction, in mechanics, that 
wherein a body actually moves, or would 
move, if it were not hindered. It also de- 
notes the line that passes through the cen- 
tre of gravity of the heavy body to the 
centre of the earth, which must also pass 
through the fulcrum, or support of the 
heavy body, without which it would fall. 
Line of gravitation, of any heavy body, 
a line drawn through its centre of gravity, 
and according to which it tends downwards. 
Line of the su^test descent, of a heavy 
body is the cycloid. See Cycloid. 
Lines on the plain scale, are the line of 
chords, line of sines, line of tangents, line 
of secants, line of semitangents, line of 
leagues ; the construction and application of 
which see under Mathematical Instru- 
ments, Sailing, &c. 
Lines on Gunter's scale, are the line of 
numbers, line of artificial sines, line of arti- 
ficial tangents, line of artificial versed sines, 
line of artificial sines of rhumbs, line of arti- 
ficial tangents of the meridian line, and line 
of equal parts ; for the construction and 
application whereof. See Gunter’s scale. 
Lines of the sectoi', are the line of equal 
parts, or line of lines, line of chords, line of 
sines, line of tangents, line of secants, 
line of polygons, line of numbers, line of 
hours, line of latitudes, line of meridians, 
line of metals, line of solids, line of planes ; 
for the construction and use whereof, see 
Sector. 
Lines, in fortification, are those of ap- 
proach, capital, defence, circumvallation, 
contravallation, of the base, &c. See Ap- 
proach, &c. 
To Line a work, signifies to strengthen a 
rampart with a firm wall ; or to encompass 
a parapet or moat with good turf, &c. 
Line, in the art of war, is understood of 
the disposition of an army, ranged in order 
of battle, with the front extended as far as 
may be, that it may not be flanked. See 
Army. 
Line of battle, is also understood of the 
disposition of a fleet on the day of engage- 
ment, on which occasion the vessels are 
usually drawn up as much as possible in a 
straight line, as well to gain and keep the 
advantage of the wind, as to run the same 
board. , 
Line, ship of the, a vessel large enough 
to be drawn up in the line, and to have a 
place in a sea-fight. See Ship. 
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