The magic lantern and its management

Before the advent of the art of photography, pictures or slides for the lantern were traced on glass and painted by hand; and this art was carried to very great perfection. But no handiwork can equal the productions of the photographic camera; so that when it was found possible to produce transparent positives on glass, that could be magnified on the sheet to any extent without deterioration, the occupation of the artist on glass was almost gone. Photographs are now almost exclusively used, and form, when properly executed, the finest pictures for lantern use. The manner of their production is fully described in my little book ‘How to Photograph;’ but as there may be many would-be lanternists who do not care to dabble in photography, I will here give a few plain directions by which lantern slides can be extemporised.

The standard size for lantern pictures is 3¼ × 3¼ inches. The glass chosen should be as thin as possible, and quite free from scratches, bubbles, or flaws of any kind whatever. Remember that a piece of the finest hair which may well be overlooked upon the slide itself, will appear on the screen as a huge snake. In like manner a tiny bubble in the glass is magnified into a blemish the size of a soup-plate. Glass presents a very difficult surface to draw or paint upon, particularly if water-colours are employed, but by coating it with a transparent medium in the first instance the difficulty is much reduced. A film of plain collodion will, when dry, give a surface that can be easily sketched upon with a fine pen and Indian ink. The sketch so made can afterwards be filled in with water-colour, tempered with prepared ox-gall, and taking care that the colours used are those which are naturally transparent. Prussian blue, indigo, lake, the madders, gamboge, burnt and raw Sienna, Vandyke brown, are all transparent pigments, and will answer every purpose. Mixed with one another in the manner detailed in any manual of water-colour painting, greens, purples, and all secondary and tertiary tints are readily obtainable.

Another method, and an easier one, for producing lantern slides was introduced some years ago by the Rev. W. H. Dallinger; and although the author of the method intended it for drawings of microscopic subjects only, and with that idea brought it before the notice of the Royal Microscopical Society, it will be readily seen that it is adapted to all manner of lantern pictures. This method is best described in its inventor’s own words: ‘On finely ground glass drawing with a black-lead pencil is as easy as drawing upon cardboard. I get squares of glass to suit the size of my lantern carefully ground on one side like the focusing-glass of a camera.’ The author goes on to describe how, by sketching upon the finely ground surface with a well-pointed hard pencil—HH or HHH—and shading with a softer one, such as HB, capital effects can be obtained. ‘If it be necessary to put in colour it may be done, cleanly and carefully over the shading; thus one layer of colour suffices. Now, of course, although we have a perfect drawing of the object, with all the detail accurately given, it is not a transparency. But we can easily make it one. Thin some good pale Canada balsam with benzine to about the consistency of cream, and simply float it over the ground surface of your glass; pour off until the drop comes very sluggishly. Then reverse the glass so that the corner from which the balsam was flowing off be placed upwards. Let the return flow reach about the middle; then reverse it again, and move it in several directions to get the balsam level. This may be done with a very little practice, so that the surface shall be undistinguishable from glass. We have now a perfect transparency. All that is required is twenty-four hours for hardening (keeping the glass level), and then another square of glass fastened on to it by strips of paper at the edges, with small pieces of card at the corners to prevent contact, and it makes an admirable lantern transparency.’

A hint about giving a fine grain to glass will not be out of place. Upon a perfectly flat and firm table lay a piece of glass say six and a half inches square, for this size can afterwards be cut across into four lantern pictures. A sheet of wet blotting-paper under the glass will keep it steady. Now pour upon its surface a mixture of flour-emery and water. Place another piece of glass above, and work it round with a circular motion, constantly spooning up the mud formed by the emery and water, and which oozes out between the glasses, and replacing it between them. In a short time both glasses will be beautifully ground on the surfaces which have been rubbed together. A moment’s consideration will show that the ground effect is produced by the surface being broken up into innumerable tiny pits, each one of which scatters the light. By Mr. Dallinger’s method of filling up these pits with a glassy medium like Canada balsam, the glass is once more presented with a flat surface, and therefore becomes once more transparent.

By whatever means the picture is produced the operator should have a glass transparent easel to work upon placed at an angle of forty-five degrees, with a sheet of paper underneath it to throw the light up through the glass he is drawing upon. A good easel can be made of a small frame—that belonging to a twopenny slate will do—attached to a base-board, and supported on each side by struts. A ledge of wood screwed across the frame makes a convenient support for the picture. The annexed cut will sufficiently explain the arrangements described.

And now a word or two about mounting the picture. As Mr. Dallinger points out, a cover-glass should be provided, but it should be prevented from actually touching the painted surface. This is best brought about by using the masks cut out of black paper, and sold for the purpose. A mask is inserted between the glasses, after which the whole is fastened together by pasting a slip of paper round the edges of the double glass, and turning it over on either side. Gum arabic with twenty-five per cent. loaf-sugar added, is a good medium by which to attach paper to glass.