10147on PERSPECTIVE.
take the Part 2 s, equal to the Height of the Eye
above the Point 2, which is in the Baſe of the
Column; likewiſe aſſume s a in the ſaid Line
equal to S A of the precedent Figure, and from the
Point a draw to a s the indefinite Perpendicular
a Y. Theſe General Preparations being made,
take at Pleaſure the ſmall equal Parts 6 i and 69
in the Line s a; draw the Lines i h and 9 m Pa-
rallel to 63 z, and from the Point h draw the Line
h 3 4, thro’ the Center 3 of the Semicircle h m;
aſſume a 5 in a Y equal to i 4, and draw the Line
5 s cutting i b in g, and 9 m in q. And, (in Figure
32.) about the Point A, as a Center, with the
Radius i h or 9 m, which are equal, deſcribe the
Circle F L M H, cutting the Arc B A C in the
Points D and E; then draw the Line D E cut-
ting the Line A S in I; aſſume I G equal to i g,
and I Q equal to 9 q; and thro’ the Points Q and
G, draw F H and L M, parallel to the Line E D,
cutting the Circle D M E F in the Points L,
M, F, and H. Now if the Repreſentations of Four
Points, whereof L M F and H, are the Seats, and
the two firſt of which is equal to 29, and of the
two others 2 i, be found*; the Repreſentation
of the ſaid four Points will be ſo many Points of
Appearance ſought. And by drawing two other
Lines, as i h and 9 m, and proceeding as be-
fore, the Repreſentation of ſo many more Points
will be had.
above the Point 2, which is in the Baſe of the
Column; likewiſe aſſume s a in the ſaid Line
equal to S A of the precedent Figure, and from the
Point a draw to a s the indefinite Perpendicular
a Y. Theſe General Preparations being made,
take at Pleaſure the ſmall equal Parts 6 i and 69
in the Line s a; draw the Lines i h and 9 m Pa-
rallel to 63 z, and from the Point h draw the Line
h 3 4, thro’ the Center 3 of the Semicircle h m;
aſſume a 5 in a Y equal to i 4, and draw the Line
5 s cutting i b in g, and 9 m in q. And, (in Figure
32.) about the Point A, as a Center, with the
Radius i h or 9 m, which are equal, deſcribe the
Circle F L M H, cutting the Arc B A C in the
Points D and E; then draw the Line D E cut-
ting the Line A S in I; aſſume I G equal to i g,
and I Q equal to 9 q; and thro’ the Points Q and
G, draw F H and L M, parallel to the Line E D,
cutting the Circle D M E F in the Points L,
M, F, and H. Now if the Repreſentations of Four
Points, whereof L M F and H, are the Seats, and
the two firſt of which is equal to 29, and of the
two others 2 i, be found*; the Repreſentation
of the ſaid four Points will be ſo many Points of
Appearance ſought. And by drawing two other
Lines, as i h and 9 m, and proceeding as be-
fore, the Repreſentation of ſo many more Points
will be had.
Note, Becauſe a part of the Torus is hid by
11Fig. 32. the Column, therefore to avoid uſeleſs Operations,
a Circle muſt be deſcribed about the Center A,
with the Radius 36, cutting the Arc B C A in
the Points T and O, and the Lines STY and SOZ
muſt be drawn; then all the Points as F and H,
falling between the Lines TY and O Z are uſeleſs,
and L and M not coming under this Obſervation
muſt only be uſed; Note alſo, that there is no
neceſſity to determine Geometrically
11Fig. 32. the Column, therefore to avoid uſeleſs Operations,
a Circle muſt be deſcribed about the Center A,
with the Radius 36, cutting the Arc B C A in
the Points T and O, and the Lines STY and SOZ
muſt be drawn; then all the Points as F and H,
falling between the Lines TY and O Z are uſeleſs,
and L and M not coming under this Obſervation
muſt only be uſed; Note alſo, that there is no
neceſſity to determine Geometrically