You may need to encourage it to flow by slightly tilting the slide, and sometimes it may even be needful to take a clean quill toothpick and direct it into some corners that otherwise would be missed. Then pour back all the superfluous varnish into the bottle from one corner of the slide; the varnish remaining will rapidly harden, as the benzole evaporates quickly, and the hardening may be hastened by applying a little heat, but while hardening the slides should be protected from dust. [Illustration: FIG. 2.] I make mine perfectly hard by baking them on a thin iron plate fixed a few inches above a small spirit lamp, but you need to take care not to make the slides too hot, or they may crack. I can easily varnish and harden a dozen slides in less than an hour. A thin plate of iron, such as is used for an oven plate, can be arranged on blocks of wood, a sufficient height over the spirit lamp. One coat of this varnish is usually sufficient to render the slides perfectly transparent, but a second coat can be applied as soon as the first is hard if necessary. The slides are now finished, but the varnished surface will easily scratch, and must be protected by a piece of clean glass. Between the glasses a thin paper mount should be laid, which may be a circle, an oval, or a square, according to which is most suitable to the pictures, and then the two glasses must be fastened together by narrow slips of paper gummed round the edge. These mounts, and slips of paper ready gummed, can be procured from any optician, and will save labor, especially in fixing up the edges. Before you join the glasses together insert at the right hand top corner a number, so that by looking at this number you can readily arrange the pictures in their proper sequence, and also tell which is the right side up when putting them into the lantern carrier. Sometimes you may wish to copy some other slides, but owing to their having the covering glasses on you cannot trace them readily direct on to your ground glasses. This difficulty is overcome by using tracing paper, making the lines with a fine crow-quill and ink. Then you can easily trace from these copies through the ground glass. We also made some very good sets of shadow pictures by cutting out suitable sketches in paper from the comic and other illustrated journals, and mounting them between two sheets of glass. These answered admirably, and when carefully cut out, no one would believe, when thrown on the sheet, that they had not been painted. We also made some sets of tracings on plain glass, of sketches in black and white. Of course ink would not do, as a fine line could not be drawn with it, and it was too transparent, but we found that, by using black water color, in which a drop or two of thin gum had been mixed, it was quite easy to draw upon plain glass with a fine pen, and then the solid parts could be filled in with a sable brush.