If you want to reproduce these, to fix their outlines, you have only to interpose a transparent paper, to draw along the glass pane a line in pencil and to trace over the part of the picture which terminates at the foot of the pane. Fold the transparent paper along this pencil line, and to get the whole reproduced you have only to copy over the designs just traced. The glass, which does the duty of a mirror, doubles the forms in a symmetrical way, and as it is moved new forms come to view. Elementary Gas-Burner. Fill an old round tin box, at least two inches high, with sawdust and pieces of blotting paper. Close it as well as possible, and introduce a small metal, or glass, tube in the lid to a depth of about one-third of the box. Make the joint tight with putty. Put this box on any two supports and place the flame of a lamp or candle underneath it. [Illustration] Soon the overheated sawdust and blotting paper will evolve vapors of alcohol and combustible gases. Approach a lighted match to the upper end of the tube and you will see the gas ignite and continue to burn. Rapid Vegetation. A cheap sponge can be converted into a hanging bunch of greenery for room decoration. Plunge it into hot water, press it dry, then put in its holes or pores seeds of millet, red clover, barley, linseed, grasses, etc., in fact any species of plants which germinate easily and produce, as far as possible, leaves or blades of different shades. Place the sponge thus prepared on a vase or in a saucer, or better still, suspend it in the recess of a window, where it may get as much sunshine as possible. Every morning, for a week, sprinkle its surface lightly with water. Soon the seeds will germinate and grow. In a short time they will form a ball of greenery, making a charming decoration for a room. [Illustration] Miniature Volcanoes. In a rather large porcelain or glazed earthenware basin place a small quantity of nitrate of lead. This may be obtained for a few cents from any painters’ supplies store. Then upon it throw some flakes of sal ammoniac. Immediately a number of conical elevations will be formed, which give off vapors and burst with a popping noise. [Illustration] Altogether the experiment represents very exactly, volcanoes in a state of eruption. When the eruption ceases, the rough, broken state of the remaining mats, represents as nearly as a thing on this earth of ours can, the appearance of the moon through a powerful telescope. Indeed the moon at one time of its history was undoubtedly in the soft lava-like state that you will observe in the basin, during the first stage of this elegant and instructive experiment. [Illustration: THE END.] * * * * * USEFUL AND INSTRUCTIVE BOOKS.