Observe the various colours which are reflected from the glass drops usually suspended from a lustre or chandelier, and you will witness a mimic rainbow. A rainbow may also be made by a garden engine, if the water be thrown high in the air, and the spectator stand between it and the sun. FRINGE ABOUT A CANDLE. Provide two small pieces of plate glass, moisten two of their sides with water, and put them together; then look through them at a candle, and you will perceive the flame surrounded with beautifully coloured fringes: these are the effect of moisture, intermixed with portions of air, and exhibiting an appearance similar to dew. THE DOUBLE-COLOURED REFLECTION. Provide a circular piece of coloured glass, and pierce its centre by means of a common awl, well moistened with oil of turpentine: encircle the glass with the fingers and thumb, hold it in the sunshine or the strong light of a lamp, and the following beautiful effects will be produced. If the glass be red, the luminous spot in the centre will be reflected green; if the glass be green, the spot will be red; if blue, orange; and if yellow, indigo. LUMINOUS CROSS. Place a lighted candle before a looking-glass, and there will appear a luminous cross radiating from the flame of the candle. This is produced by the direction of the friction by which the glass is polished; the scratches placed in a horizontal direction, exhibiting the perpendicular part of the cross, and the vertical scratches the horizontal part. RINGS OF COLOURS ROUND A CANDLE. Look at a candle through a plate of glass, upon which you have gently breathed, or over which are scattered particles of dust, or any fine powder, and you will perceive the flame surrounded with beautiful rings of colours. By using the seed of the lycopodium, or by placing a drop of blood diluted with water between two pieces of glass, the rings of colour will be still more finely exhibited. Round the luminous body there will be seen a light area, terminating in a reddish dark margin; this will be succeeded by a ring of bluish-green, and then by a red ring; these two last colours succeeding each other several times when the particles are of uniform diameter, as are the seeds of the lycopodium, each of which is but the 850th part of an inch in diameter. SIMPLE AND CHEAP OPERA-GLASS. In this new instrument, no tubes are necessary, as in the ordinary opera-glass; their place being supplied by a slender elastic conical spring of wire, into the upper extremity of which is inserted the eye-glass; the object-glass being fixed to the other extremity, as shown in the engraving. The two glasses must, of course, be kept parallel to each other when in use; which is very easily effected. [Illustration]