The Optical Magic Lantern Journal (October 1899)

120 which after being covered with black varnish has a number of slanting lines etched upon it to represent the falling rain drops. In front of this is a circular piece of perforated zinc working upon a pivot in its centre and capable of being revolved at any given rate by means of a pulley and band, the latter passing round a multiplying wheel to which is fixed the actuating handle. As the minute openings in the zinc pass across and along the lines etched on the glass, a very fair representation of falling rain is presented when thrown on to the screen. Fig. NNNIV. The Optical Magic Lantern Journal and Photographic Enlarger. requisite in getting the lines at the exact angle, and both alike to a hair’s breadth, that the aspiring amateur had best pass these by as something which it would be unwise for him to attempt, as the slightest deviation from absolutely mathematical precision will result in a slide which may perhaps cause the rain to descend when the glass is moved one way, but which will quite as certainly cause it to ascend when moved the other way. When these two effects, the lightning flash and the rain, are worked on the screen at the same time upon a suitable view as a_background most effective and realistic pictures result, especially if the foundation view is for instance a storin at sea, launching a lifeboat, the rocket life saving apparatus, or any subject of a kindred nature. So far we have only mentioned the appearance of the lightning flash without going into details concerning its results, but a flash of forked lightning which brings about no change in the picture is in the nature of an anti-climax. We are not content with witnessing the cause, we also wish to see the effect, and this it will be ' my endeavour to describe in the next paper. Another rain slide which is very popular is © shown at Fig. N\NXIV.; this also has a blacked out glass with the lines drawn upon it, but the , motion of the falling rain is obtained in another manner. Across the top and bottom ends of the slide are rods of metal terminating in handles which come out on the operating side of ~ the lantern. Round one of these is wound a long strip of some woven material very much resembling coarse muslin but with particular character especially prepared for this purpose, the other end of the fastened to the other rod just as the strip of black material is arranged in the ordinary snow slide. The effect of this is that when the one | handle is revolyed and the woven material caused to pass along the markings on the fixed glass, a gentle shower appears to descend, and continues to do so as long as there remains anything to draw down. Yet another rain slide is to be obtained and of an entirely different character to those we have just described, as in this case it consists of two plates of glass, one fixed and the other movable. The markings on these plates are identically the same on both, but so much care and skill is | strip being | an open web of a | gio 2 OD aah OT Lantern Slides from Line Subjects.—No. I. By G. E. BROWN. FTER fixation the negative is examined carefully, glass side down, against a piece of white paper. The Imes should be absolutely bare Y glass. If they are not, reduce them 4 till they are. Let the ground weaken ay as it may; itcan be brought up to es good density afterwards. Farmer’s reducer is very suitable, or a mixture of Mercuric chloride 10 grains 2°5 gms. Potass. iodide 10 ‘3 25) 46 Potass. cyanide 20 =~, 50 ,, Water 10 ounces .. 1,000 ccs. which acts very evenly, with a tendency to eat out the lines rather than the ground. It is used after rinsing well under the tap from hypo. Should the plate now require intensification several processes can be used. Two good formule are given here :— Acip SinveR.—Make two Solutions. Pyro .. 60 grains .. 84 gms. Nitric acid 1 fluiddram 8 ces. Glacial acetic acid .. 2 fluiddrams 16 ,, Distilled water 1G ounces ..1,000 ,,