The Optical Magic Lantern Journal (October 1901)

64 The Optical Magic Lantern Journal and Photographic Bnlarger. by means of templates, and whether for a biunial or a triple two will be required. These templates consist of two framed slides, contain ing lines which in each bear precisely the same | relation to the base and end of the wooden | frame. Such slides may of course be purchased ready made, but as their making is no difficult matter this need give the lanternist little trouble. A simple method of preparing templates is as follows:—Take a couple of sensitive lantern plates, and without exposing them to the light, place them in a solution of hypo for some minutes, then wash well, after which immerse | in a solution of aniline dye and allow to dry. These glasses must then be firmly secured in ordinary wooden slide frames and lines scratched on the gelatine film with a carpenter’s gauge. Care must be taken that the tool is operated from the bottom (A) and one end of each frame (x), they form the base line and end which is inserted =n in lantern. After the gauge is set for any particular line this must be ruled on both template slides before any alteration is made. The templates will now consist of two framed slides, each containing cross lines, and in order to prevent any mistake it will be well to saw off the corner of the frame furthest from where the measurements were taken, as shown at c in sketch. In the case of a triple, light up and place one of the template slides in the middle stage and adjust the runner until the cross lines are in a suitable position on the screen, and make sure that the butting or end screw of the runner is tight against the frame of the template. Next, the bcttom lantern is adjusted to the middle by inserting the other template slide and adjusting the front of the lantern and screws of the runner until the lines on this slide coincide with those of the other, as shown on the screen. This having been done, withdraw the template from the bottom lantern and use it for adjusting the top lantern in the same manner. If care has been taken in making the templates they can be interchanged in the relative lanterns, and the projected lines in all instances should coincide, We now have our triple registered, and our stock of framed effect slides must be gone through and made to fall in their correct position on the screen ; this is slow and tedious work and there is only one way of doingit. Insert the first slide and see how it looks upon the screen, and if right, welland good. Leave this slide in, and in another stage place the next slide and see how it falls in relation to the previous one. It may probably require a little piece planed off the top which of course lies on the runner, or it may require a little off the end which abuts on the screw at the far end of runner. Should by chance too much be taken off, then a thin strip of wood must be glued on. Each slide must be gone through in this manner. True it is slow work, but it is the only way by which slides can be properly registered; then when all this has been done what a pleasure it is to operate and find that everything comes up in its exact position merely by inserting the slide and push ing it home. a >< What is Rubber? ‘8eY ANTERNISTS who have fitted up / lantern apparatus with what they at first thought was indiarubber tubing and soon afterwards found as it fell to pieces that it was just so much rubbish will be interested in the following remarks by 5 “ Kuhlow” :— “To answer the question which heads our article is almost as difficult as to reply to the memorable query respecting Truth. It is one that compels those best able to deal with the subject to hesitate before committing themselves to an absolute and definite statement. To start with, the term, ‘rubber,’ is somewhat vague, and is one that has become attached to certain materials through long usage. As most of our readers are aware, the name was given to it from the first use it was put to in this country, viz., rubbing out lead-pencil marks, but as it was introduced from Brazil (where the natives were termed Indians), the name india-rubber at last became the familiar one, which term is as far-fetched as it is ambiguous. We need not pause here to deal with the mistakes often made by people who confound india-rubber and gutta-percha, and use the terms generally when speaking of either, but we pass on to endeavour to place before our readers some of the. chief points that have to be considered in arriving at