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

L 86 ]
light on the further side of the room, rule from the seat
of light on the ssoor, to C (the center of the pi&ure) ;
where this line touches the bottom of the wall, ere£t a
perpendicular, on which the required point is determin-
ed, by a line from the luminary to C, as at E : the same
may be obtained by a similar process from D on the
ceiling.
The shadows of all objects perpendicular to a plane
tend toward the seat of light on that plane. Thus the
shadows of i and 2 on the ceiling, are found by the in-
terse&ion Of lines drawn from the seat of light D through
their bottoms, and others from the luminary itself,
through their tops.
The same is precisely the' of 3, whose shadow
tends to B. *
The objeft 4 follows the same rules; and the shadows
of its sides, as c, tend to the seat os light on the floor.
The shadow of 5 falls at 6, and, not being perpendicular
but parallel to the plane B, the shadow of this side of
the objedl 4 vanishes in C ; as do the shadows on the
ground of the sides a and b of the table.
One instance of the utility of shadows appears in 5 ;
which may, or may not, be united to 4, by its sstuation
in the finure ; but which is determined by the shadow
O’ J
at 6 to be affixed to it.
As this process is so very easy, these examples may
sussice.
To represent shadows caused by the Sijn, we muss
fix a point in the picture sor the luminary, and
likewise, as its seat, a point on the plane on which the
shadow is to be cass : this is found, by letting fall a per-
pendicular