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The Optical Magic Lantern Journal and Photographic Enlarger.
149
A Lantern Screen for the
Lecture Room. By E. D. B.
3 >
fea HE readers of the Lantern JouRNAL may be interested in a_ brief description of a lantern screen which I saw in use in a London institution. The screen is particularly constructed with a view to showing experiments from the lecture table, such as experiments on light, and at the same time it is readily and accurately shifted so that a lantern placed at the opposite
end of the room facing the lecture table will .
throw a image upon the screen. The screen is
easily removed and can be replaced in a few
seconds.
Fig. I. shows a general view of the movable screen avd fixed parts on to which the screen is hung. The screen was a simple one of linen
or it may have been four sheets of white |
drawing paper neatly joined to two central cross bars which formed part of the framework of the screen.
Attached to the two top corners |
of the screen were two wheels arranged to |
freely revolve upon horizontal steel arbors and vertical pins as seen clearly in the enlarged view Fig. II., in which BB are the wheels turning upon the arbor c. The wheels run upon a rail D, which is screwed to a piece of mouldin permanently secured to the wall. The bent
a
(
| brass L pieces carrying the wheels B B are
allowed to freely turn upon a pivot 5, rivetted to an angle piece of brass attached to the framework of the screen. By meansof the said pivot E, the frame when being drawn along the rails will readily adapt itself to any angle which it is desired to place it in. The most convenient position in which to place the rails p, depend entirely upon the room in which the screen is going to be placed.
Two points must be borne: in mind, namely, the centre line of the wheel B must pass
through the centre of the rail and also the vertical pivot E. The centre line above mentioned must be brought as near the ends of the screen as possible to allow the screen to turn freely without damaging or scraping the wall.
By means of the above description aud the two sketches, any readers of this Journal will have little difficulty in constructing the screen and parts, should he intend making one for himself.