have not been able by any arrangement of reflected light to get power
enough to print negatives of the ordinary density, and have only succeeded
by causing the light to be equally dispersed over the negative by a lens as
used in the optical lantern, but the arrangements required are somewhat
different to that of the enlarging lantern.

The following is the plan by which I have succeeded best in the production
of transparencies:

[Illustration]

B is a lamp with a circular wick, which burns petroleum and gives a good
body of light.

C is a frame for holding the negative, on the opposite side of which is a
double convex lens facing the light.

D is the camera and lens.

All these must be placed in a line, so that the best part of the light, the
center of the condenser, and the lens are of equal height.

The method of working is as follows: The lamp, B, is placed at such a
distance from the condenser that the rays come to a focus and enter the
lens; the negative is then placed in the frame, the focus obtained, and the
size of reduction adjusted by moving the camera nearer to or further from
the condenser and negative. In doing this no attention need be paid to the
light properly covering the field, as that cannot be adjusted while the
negative is in its place. When the size and focus are obtained, remove the
negative, and carefully move the lamp till it illuminates the ground glass