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Full text of "Modern Mechanical Engineering Vol-I"

THE   PHOTOGRAPHIC  ROOM

39

quick speed, and on either side of it is the flat plate-glass of the width of
the machine. A print can be taken on either side, and each side can be
geared to different speeds of feed, so that they may be kept geared one for
blue prints and one for black-and-white prints. The lamp travels back-
wards and forwards like a shuttle, and is operated by an electric switch.
The frame is never removed, so there is no danger to the lamp, and if a

Fig. 12.—Haldcn's Duplex Radial Electric Photo Copying Frame.   Prints being inserted.
sheet of glass does get broken, there are generally a number of spares kept
so that it can be replaced very quickly and readily.
Prints of both circular and flat glass types of machines are shown (figs. 12 to
14). The former is technically known as Messrs. Halden's Duplex Radial
Electric Photo Copying Frame, and the latter is the same firm's Double Pattern
Single-lamp Type Continuous Electric Photo Copying Machine, and both
are shown by the courtesy of Messrs. Halden, who very kindly supplied
the blocks for these illustrations. In the case of this latter type, the single-
lamp type has now almost entirely superseded the original machine, which