»24 ThE art of projecting.
For holding pictures, and other objects, for projec¬
tion, the retort-holder will answer, in many cases, just
as well as a more costly fixture. Not only may the
larger pieces, such as photographic transparencies,
leaves of trees, and the like, be held well in it, but
microscopic specimens in glass slides, also small un¬
mounted objects, such as parts of flowers, insects, etc.,
_____ ^ may be held in
— small forceps
Fig, 16, (Fig. 16), which
in turn may be held in the retort-holder. It will be
found convenient to have as many as three of the
latter.
PROJECTIONS.
TO PROJECT WITH THE PORTE
SINGLE LENS.
LUMIERE AND A
Fasten the porte lumière in its place, and so adjust it
that the beam of light / (Fig. 17) is reflected horizon¬
tally, and falls upon the screen s. It will appear as
a bright spot,
H five or six inch¬
es in diameter.
Darken the
room, by draw¬
ing the curtains
or closing the
shutters, and
the beam of
light can then
Fig. 17,