The artists repository and drawing magazine: exhibiting the principles of the polite arts in their various branches (3.1789)

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l&mmodating kind of science, and very adhe^
sive to principles it has once assumed s there*
fore I wish to leave the matter rather to judg~
ment, than to geometry.
Having fixed the height of the eye, and
thosen a difiance from whence the objects re-
presented in the picture may be mofi conve-
niently seen, we proceed to prepare the picture
for pra<5tice: by which I mean nothing more
than inscribing upon it those imaginary lines,
to whose properties we have already paid somc
attention. First rule the horizontal line, then,
having determined its center, ere£t there the
vertical line, and thus we have two lines,
whereon all relative planes (z. e. horizontal or
vertical) will vanish. Moreover, as all hori-
zontal planes will vanish on the horizontal line, j
we have the proper vanishing point for them
in the center ; because the vanishing point to
any plane (in whatever dire&ion) is that point
at which a line drawn from the eye, parallel to
that particular plane, firikes the pi&ure.
Observe further that these two planes are of
necessity perpendicular to each other j I say the
horizontal plane is perpendicular to the verti«
cal, and the vertical to that: for as to its
situation with resped to the natural horizon, Jet
it now be forgotten.
We have already observed, that planes are
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