Gravesande, Willem Jacob 's - An essay on perspective

Scan	Original
51	24
52
53
54
55	25
56	26
57
58
59
60	27
61	28
62	29
63	30
64
65
66
67
68
69
70	31
71	32
72	33
73	34
74	35
75	36
76
77
78
79
80

6027on PERSPECTIVE. actly determined, this Method ought not then to
be uſed.

Problem III.

44. To find the Appearance of the Diviſions of a
Line in the Geometrical Plane.

Let A B be a Line, whoſe Appearance is ab.
11Fig. 14. Now to find the Repreſentation of the Diviſions
of this Line, there muſt be Lines drawn from
the Diviſions of the Line to the Eye, whoſe
Interſections with a b will give the Points
ſought.

Note, When theſe Lines very obliquely cut
a b, the following Way ought to uſed.

Method. II.

45. To find the Repreſentations of the Di-
viſions of the Line G C, make choice of the
22Fig. 14. Point D at Pleaſure without this Line, and find
the Repreſentation d thereof; then draw 3321. through the propoſed Diviſions to the Point D;
and from the Points wherein theſe Lines con-
tinued out cut the Baſe Line, draw other Lines
through the Repreſentation d, which will cut c g
the Repreſentation of C G in the Points ſought.

Problem IV.

46. To throw a Polygon, or any other regular
Figure on the Geometrical Plane into Perſpective.

The Repreſentation of any Kinds of Figures
may be found by any one of the Methods 4421. Problem I. the fourth in general is the eaſieſt;
and may be firſt uſed in finding the 5522. ſentations of Points, or ſometimes of one
only; and then the fifth Method ſerves 6631.

Page concordance

Text layer

Text normalization

Search

Scan	Original
51	24
52
53
54
55	25
56	26
57
58
59
60	27
61	28
62	29
63	30
64
65
66
67
68
69
70	31
71	32
72	33
73	34
74	35
75	36
76
77
78
79
80

Scan	Original
51	24
52
53
54
55	25
56	26
57
58
59
60	27
61	28
62	29
63	30
64
65
66
67
68
69
70	31
71	32
72	33
73	34
74	35
75	36
76
77
78
79
80

Scan	Original
51	24
52
53
54
55	25
56	26
57
58
59
60	27
61	28
62	29
63	30
64
65
66
67
68
69
70	31
71	32
72	33
73	34
74	35
75	36
76
77
78
79
80