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The Optical Magic Lantern J ournal and Photographic Enlarger.
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the Crystal Palace on April 27th. In addition to the usual displays of pictures, etc., the leading firms, manufacturers and dealers will be largely represented. There will also be extensive loan collections, illustrating not only the history of photography, but its enormous scientific and commercial applications, photomechanical processes, photographs in colours, photographs by means of the X-rays, and kindred exhibits. The exhibition, the arrangements for which are in the hands of a joint committee of members of the society and exhibitors, bids fair to be the largest and most interesting coliection dealing with photography which has ever been got together.
a enod ee
Blackboard in the Pulpit.—Evidently the | Rev. Dr. W. E. Needham, of Brooklyn, U.S.A., has ‘‘gone one better” than the lantern in church, for he emphasises his sermons by sundry
lightning sketches on a blackboard. ~ ~
~* Gwyer Jets.—A new form of this jet is on |
the market, and we hope to give particulars in our next issue.
wiih met Diet, |
Viewing Film Transparencies in the Cinematograph Without Projection.—No. II.
ITH reference to the methods of #) inverting the image, which we
described in our last issue, the |
following, though perhaps not s0 |
gives fairly good results. A thin glass mirror is all that is required ; this | is simply held in front of the objective, : as shown in the illustration, when, if a person
Fie ly
standing in front of the lantern looks down in the mirror, the pictures will appear the right way up. Glass or metal, silvered on the surface prevents all chance of double reflection, hence
satisfactory as the use of a prism, |
are superior to ordinary looking glass.
Water Pressure.
CORRESPONDENT writes :— I have several times seen it stated in the Macic Lantern Journa that y gas was used at so many inches
i) ‘\) pressure. I am totally unacquainted Uz with the meaning. It is possible that many other readers may also like to be enlightened, so perhaps you would inform us in your Notes and Queries Column.” This subject being one which cannot well be explained without a diagram, we will describe it in the form of a short illustrated article instead of replying to the question in the usual column.
Fig |
When gas is spoken of at so many inches pressure the term water pressure is understood, aud this is calculated according to the distance that the pressure of gas will force a column of water in a tube bent in U shape. The following sketches will better illustrate our meaning. Fig. I. represents the bent glass tube A, into one end of which is inserted a cork carrying a smaller tube, so that the gas can be connected therewith. Water (which is represented at the black portion) is poured into the tube at the open end. A scale, as shown, which we will suppose to be divided into inches, is placed so that the zero, is at the junction of