DOI Seite / Zitierlink:
https://doi.org/10.11588/diglit.18826#0099
LECT. II.]
ON PERSPECTIVE.
71
PLATE XXII.
No. L A cube in perfpective, ftanding oblique
to the picture : find its perfpective plan, as before :
erect perpendiculars from its extremes • for the
height, draw 5 H, which gives by its interferons
part of the top; from L draw lines through thefe
interferons, which by cutting the remaining per-
pendiculars complete the figure. Obferve, that
when the fquare irood parallel to the picture, as in
No. I. Plate XXI. the height was ruled to C, the
center; but when it ftands oblique, the height is
ruled to the vanifhing points of the fides.
A cube, like a cylinder, is compofed of fimilar
faces united by right lines, and therefore may be
confidered as being two perfpective plans of the
fame figure, at different heights, connected together;
and the fame idea may be attached to various poly-
gonal figures.
No. II. Is a double crofs in perfpective: A BCD
is the ground line, on which the thlcknefs of the up-
right is to be marked, as BC; and the extent of the
crofs bar, as A D : thefe meafures are ruled to L
(the center in this example), and by the diagonal D
ruled to H, form a fquare, which is the plan of the
figure. On C erect a perpendicular to receive the
meafures for the heights, as G F, and E; from the
interferons of the plan, raife perpendiculars for
the upright, as from b cf; where thefe are cut by
the meafures GL, FL, and EL, rule horizontal lines
for the fituations of the bars, whofe lengths are deter-
mined by perpendiculars from the plan below: thus
1 2 are governed by a h; and 3 4, by de: the figure
diftincrly defcribes the whole,
No. III. Another crofs which ftands oblique to
the picture : it follows the fame rules as the former,
except as to the obliquity of its vanifhing points, as
appears by the figure.
PLATE
ON PERSPECTIVE.
71
PLATE XXII.
No. L A cube in perfpective, ftanding oblique
to the picture : find its perfpective plan, as before :
erect perpendiculars from its extremes • for the
height, draw 5 H, which gives by its interferons
part of the top; from L draw lines through thefe
interferons, which by cutting the remaining per-
pendiculars complete the figure. Obferve, that
when the fquare irood parallel to the picture, as in
No. I. Plate XXI. the height was ruled to C, the
center; but when it ftands oblique, the height is
ruled to the vanifhing points of the fides.
A cube, like a cylinder, is compofed of fimilar
faces united by right lines, and therefore may be
confidered as being two perfpective plans of the
fame figure, at different heights, connected together;
and the fame idea may be attached to various poly-
gonal figures.
No. II. Is a double crofs in perfpective: A BCD
is the ground line, on which the thlcknefs of the up-
right is to be marked, as BC; and the extent of the
crofs bar, as A D : thefe meafures are ruled to L
(the center in this example), and by the diagonal D
ruled to H, form a fquare, which is the plan of the
figure. On C erect a perpendicular to receive the
meafures for the heights, as G F, and E; from the
interferons of the plan, raife perpendiculars for
the upright, as from b cf; where thefe are cut by
the meafures GL, FL, and EL, rule horizontal lines
for the fituations of the bars, whofe lengths are deter-
mined by perpendiculars from the plan below: thus
1 2 are governed by a h; and 3 4, by de: the figure
diftincrly defcribes the whole,
No. III. Another crofs which ftands oblique to
the picture : it follows the fame rules as the former,
except as to the obliquity of its vanifhing points, as
appears by the figure.
PLATE