40 THE ART OF PROJECTING.
inches in diameter, with a focus of from eighteen to
twenty-four inches, will be found best for the purpose.
This may be held in the re¬
tort-holder before mentioned*
and set at such a distance in
front of the hole that an ob¬
ject cy when strongly lighted*
will be plainly projected upon
the screen s. The whole of
the back on the in side should
be covered with white paper.
Let a black cloth flap hang
over the hole at r, so that no
light will enter the room, save
what is reflected from the il¬
luminated object.
With these conditions a
dark photograph of an in¬
dividual, upon a white background, will show quite
well. Objects held in the hand, such as a watch with
its movements, cameo pins, small flowers, surface of
half an apple or orange. The latter, if squeezed when
being shown, presents a very amusing appearance.
Minerals, crystals, shells, bright-colored beetles, bugs,,
butterflies, etc., may all be exhibited, and appear, with
the shades and shadows, like real objects. This con¬
stitutes the megascope.
The accompanying cut ( Fig. 24 ) represents the
scenic effect of the human hand, as projected by the
megascope. t
THE VERTICAL ATTACHMENT.
It is often very desirable to project such phenomena
as the ripples upon the surface of water, the move-
Fia. 23.