144 Mr Tait on a Portable Diorama. 
through it, ought to be made as black as possible ; for which 
purpose black velvet is very effectual. The rest of the in- 
side, including the inner surface of the shades, ought to be 
white, in order to reflect light. The front of the box ought 
to be black outside, and surrounded by a black curtain. 
It is necessary to have a small opening and tube through 
which an exhibitor may view the pictures, when the spectator 
is unacquainted with the management of the apparatus. It 
should be on the same level as the spectator’s tube. If the 
box be large, so as to admit of a distance of 8 or 9 inches 
from the spectator’s tube, it may be on the front ; if not, it 
will be necessary to have it on the side close by the front, and 
the pictures may be reflected to it by a very small mirror 
within the box. There should be placed over and behind it, 
to screen the eye of the exhibitor from the light without, a 
black moveable shade, which may be conveniently made of 
two parts, the upright part to support the horizontal part 
when in use, and both when not in use to fold upon the box. 
The part of the box within this shade is to be painted black. 
The front and back shades should be fitted up in such a 
manner as to be opened conveniently, either by a spectator or 
by an exhibitor. 
The box may be made of any size or proportions—the 
larger, the more striking the effect. And it may be supported 
upon a stand, or in any other manner convenient. 
The annexed figures show a perspective view, side elevation, 
and plan of the box. The letters of reference are the same 
in all the figures. 
A, Eye-hole for the spectator. 
B, Ditto for the exhibitor, with a shade over it. 
C, Small mirror reflecting the picture to the exhibitor. 
DEF, Form of front light. 
HI, Triangle to prevent a too sudden increase of light on raising the shade 
RS. 
KL, Picture in its groove. 
MQN, Back-light. The slope NQ is close. The slope MQ is open. It 
and the front-light DEF, are covered with tissue paper or other ap- 
propriate material. The back-shade PO extends beyond the opening. 
The intention of this construction is to admit the light in a proper 
position, and very gradually. 
TT, Curtain hung in front, to shade completely the light from the spectator. 
XXX, Levers for raising the shades easily, with cords attached. 
