146 Mr Tait on a Portable Diorama. 
2. The Pictures—The pictures may be either in water- 
colours upon paper, stretched in the usual manner on the 
frames, or in oil upon linen. 
In painting the front, whether in water-colours or in oil, 
the lights are left out, as in ordinary water-colour painting, 
so as to admit the light from behind to pass through, and body 
colours are to be avoided. The back of the pictures is cover- 
ed with a strong semi-transparent tint in those parts where it 
is wished that light shall not pass freely, or it may be ren- 
dered opaque if required. When painting the back, no light 
is to be used except that transmitted through the front. 
Objects painted behind are, of course, not seen by the front 
light ; and objects painted in front appear so faint when seen 
by transmitted light, that it is easy to paint the back in such 
a manner as to make them disappear when the back light 
only is admitted, by which means‘"great changes may be pro- 
duced. 
Yor farther information with regard to the execution of the 
pictures, see Daguerre’s description of his method of diora- 
mic painting. There is an English translation of it by Dr 
Memes. 
The appearance of fog, which is not mentioned in Daguerre’s 
description, is produced by painting the objects intended to 
be affected by it on a second surface, immediately behind the 
front surface. Light is admitted behind. When the second 
surface is removed more or less from the other, the objects on 
it appear more or less involved in fog. And, as it is brought 
into contact with the other, the fog appears to clear away., 
A great variety of effects of day-light and moon-light may 
be produced by judicious management of the pictures, and by 
the adoption of contrivances sufficiently known or obvious to 
those who have paid any attention to art generally. 
3. The Light.—In day-light the back of the box is placed 
close to a window, and no more light ought to be admitted 
into the apartment than is necessary fully to light the box. 
At night the openings may be lighted with oil or gas, or even 
with a few candles, if the box be small. The very strong 
orange tinge of ordinary artificial light is unfavourable to the 
