must be
fastened perfectly upright upon the base-board B. The stand C should be
made so that it slides without any side play between the guides D, and
should be of such a height that the lens of the camera comes exactly
opposite the {119} [Illustration] [Illustration] centre of the board A. The
camera, if of the box type, can be secured to the stand by means of a screw
and wingnut, the screw being passed from the inside as shown. The beginner
is advised to photograph only very bold and simple subjects, such as black
and white drawings or enlargements. It is not safe to trust to the
view-finders as to whether the whole of the picture is included on the
plate, a piece of ground glass the same size as the plate sheaths, and used
as a focussing screen, being much more reliable. It is a good plan to focus
the camera for a number of different-sized pictures, marking the board A,
and the {120} guides D, so that adjustment is afterwards a very simple
matter.

The make of plate used is also a great factor in getting a good negative,
and Wratten Process Plates will be found excellent. As already mentioned,
such subjects as the exposure and the development of the plate cannot be
dealt with here, these subjects having been exhaustively treated in several
text-books on photography. With an arc lamp the exposure is about twice as
long as in daylight, but the exposure varies with the amount of light
admitted to the plate, character of the source of light, and the
sensitiveness of the plate used, etc. The writer has used acetylene gas
lamps for this purpose with great success. The beginner is advised to use
artificial light, as this can be kept perfectly even. With daylight,
however, the light is constantly fluctuating, and this renders the use of
an actinometer a necessity for correct exposure. After development, if the
plate is required for immediate use, it can be quickly dried by soaking for
a few minutes in methylated spirit.

Having obtained a good negative, the next operation is to prepare what is
known as a metal print. For this we shall require some stout tin-foil or
lead-foil, about 12 or 15 square feet to the pound, and this should be cut
into pieces of such a size that it allows a lap of 3/16 inch when wrapped
round the drum of the transmitting machine. Obtain some good fish-glue and
add a saturated solution of bichromate of potash in the proportion of 4
parts of potash to 40 or 50 parts of glue. Pour a little of this glue