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12 MODERN MAGIC LANTERNS.
lanterns, whether provided with petroleum lamps or not,
have a couple of grooves running down their base inside,
about 4in. apart, in which slides the lamp when petroleum is
employed, or the tray when limelight is being used. This tray
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Fig. 7. OXY-CALCIUM JET.
Fig, S. BLOW-THROUGH JET.
is shown in Fig. 8, in which A A are the edges which enter
the grooves ; B, a narrow, turned-up rim to stiffen the tray
and to retain any fragments of lime which may drop from
the jet ; and c, the pin which carries the jet itself. The tray
should slide easily in the grooves provided for it, but should
THE LIMELIGHT. 13
be incapable of being moved or " wobbled " from side to
side when in position, and the pin to carry the jet should be
rigid and smooth, that the jet may be easily adjusted on it.
Fig. 9. MIXED JET.
During the last year or two a much more elaborate form
of tray has been introduced by several makers, one of which
is shown, carrying a jet, in Fig. 10. This, it will be seen,
Fig. 10. ADJUSTING-TRAY WITH JET.
has racks and pinions for raising and lowering the jet, and
for shifting it from side to side ; these are very convenient,
but, of course, have to be paid for.