W. M. GRAHAM—THE PHOTOGRAPHY OF DIPTERA. Log 
a background and to render the outlines of the insect distinct. If the light 
reflected by it be too strong the surface markings of the insect are rendered 
indistinct. The lighting from behind must therefore be completely subordinated 
to that from the front, supplied by the window and by the two mirrors. The 
object of the square mirror on the base-board is to light the head of the insect 
which, as already emphasised, should always be arranged upon the easel head 
downwards. he object of the side mirror is to light the side of the insect 
which would otherwise be in shadow. 
Fig. 2.—Arrangement of mirrors and reflector for illuminating the object 
to be photographed. 
The more oblique the lighting the greater relief of the picture, but care is 
necessary to avoid reflections from shiny surfaces, especially in black insects. 
For the production of a successful negative the lighting must be so arranged that 
the outlines are sharp, and that as much relief is obtained as is possible without 
causing any reflections. If the lighting is correct the picture on the ground- 
glass will have these three qualities. If the details of the picture on the ground- 
glass be indistinct the lighting is wrong and requires alteration. 
MAGNIFICATION. 
The insect is now ready to be photographed, and the amount of the magnifica- 
tion desired should be decided. This will depend upon the size of the picture, 
which will again be conditioned by the size of the plate employed. I have found 
eaeerivie a suitable size. 
The amount of the magnification being decided upon, it only is necessary to 
place the front and back of the camera in correct relative positions. To do this 
it must be remembered that the distance from the lens to the insect must bear a 
