Bought hand-painted slides are usually first photographed on to the glass from a large outline drawing, and then colored; but so few boys have the means of making their slides in this manner that it will be best to pass this system by, especially as I shall describe a method of making the sketch which answers as well, and is much easier.
At the very outset, we were met with a difficulty that we feared would be insurmountable, and that was that it was almost impossible to make a neat, fine-lined sketch with a brush and paint on plain, smooth glass; and, even when this last had been managed, the coloring process often washed out the outlines and made unsightly smudges, and, as every little line, spot or smear shows with painful distinctness when magnified on the sheet, we soon saw that amateur work on these lines would never do. Fortunately I remembered a process, which I once saw used by a microscopist, to make diagrams for the lantern to illustrate his lectures, which answered admirably.
This was simply to draw, with a very hard lead pencil, on ground glass, then to cover the ground surface with varnish, which rendered the glass perfectly transparent.
I tried this plan, and got such good results from it that I can strongly recommend it. By following out the instructions and hints I shall give, any boy can readily and rapidly make a large series of excellent pictures for his lantern, which will answer his purpose quite as well as the most expensive bought slides.
This system has four great advantages: 1. Pictures can easily be traced on the ground glass, and to those who, like myself, would find it difficult to invent their own pictures, or to copy them, this counts for a great deal. 2. The outline can be made very fine, but still very distinct. 3. The paint will not take on the lead-marks; this renders it much easier to prevent the color going over the edge of an outline. 4. It is also very much easier to paint on the slightly rough surface of the ground glass.
There should be no difficulty in procuring this glass at any glazier's. It need not be plate glass; ordinary ground glass will do, care being taken to select that with a sufficiently fine and smooth surface, and not too thick.