DOI Page / Citation link:
https://doi.org/10.11588/diglit.62828#0287
( 2>5<- )
Of the various Pofitions of Lines and Planes to the Picture, and
to the Ground Plane—alfo of their RepreJent at ion on the Pic-
ture agreeing therewith, and of their various Modes of Pa-
nifhing..
The original line ZX, in Fig. 2, is oblique to the picture,
and is therefore treated in a diverfe manner from the lines in
the cheft of drawers, which are all either parallel and perpen-
dicular to the picture, or parallel to the ground plane and per-
pendicular to it..
Cafe 1.—When any line 1, 3, Fig. 2, is parallel to the pic-
ture and to the ground line G R, its reprefentation is parallel!
alfo. This is felf-evident by infpediing the figure.
Cafe 2.—Lines in the aforefaid pofitions can have no va-
nifhing line or point in the picture, becaufe if infinitely pro-
duced would never cut it; that is, the lines 1, 3, and GR, Fig. 2,
would never meet in a point, however far produced, for lines
truly parallel can never cut each other.
Cafe 3.—The reprelentations of lines originally parallel to >
each other and to the picture, are parallel to one another'
om
Of the various Pofitions of Lines and Planes to the Picture, and
to the Ground Plane—alfo of their RepreJent at ion on the Pic-
ture agreeing therewith, and of their various Modes of Pa-
nifhing..
The original line ZX, in Fig. 2, is oblique to the picture,
and is therefore treated in a diverfe manner from the lines in
the cheft of drawers, which are all either parallel and perpen-
dicular to the picture, or parallel to the ground plane and per-
pendicular to it..
Cafe 1.—When any line 1, 3, Fig. 2, is parallel to the pic-
ture and to the ground line G R, its reprefentation is parallel!
alfo. This is felf-evident by infpediing the figure.
Cafe 2.—Lines in the aforefaid pofitions can have no va-
nifhing line or point in the picture, becaufe if infinitely pro-
duced would never cut it; that is, the lines 1, 3, and GR, Fig. 2,
would never meet in a point, however far produced, for lines
truly parallel can never cut each other.
Cafe 3.—The reprelentations of lines originally parallel to >
each other and to the picture, are parallel to one another'
om