the same succession of symmetrical pictures; but in this case every alternate sector is stationary, and the same number in motion, the moving figures always changing their form, and assuming that of the figures in the stationary sectors, which of course change, while the ends of the mirror pass over the fixed objects.

When the simple Kaleidoscope is applied to opaque objects, such as a seal, a watch-chain, the seconds hands of a watch, coins, pictures, gems, shells, flowers, leaves, and petals of plants, impressions from seals, etc., the object, instead of being held between the eye and the light, must be viewed in the same manner as we view objects through a microscope, being always placed as near the instrument as possible, and so as to allow the light to fall freely upon the object. The object-plates, and all transparent objects, may be viewed in this manner; but the most splendid exhibition of this kind is to view minute fragments of coloured glass, and objects with opaque colours, etc., placed in a flat box, the bottom of which is made of mirror-glass. The light reflected from the mirror-glass, and transmitted through the transparent fragments, is combined with the light reflected both from the transparent and opaque fragments, and forms an effect of the finest kind.

As dust is apt to collect in the angle formed by the reflectors, it may be removed when the reflectors are fixed, either by the end of a strong feather, or blown away with a pair of bellows. When the dust is lodged upon the face of the reflectors, it should be removed by a piece of soft leather.

CHAPTER VIII.

ON THE SELECTION OF OBJECTS FOR THE KALEIDOSCOPE, AND ON THE MODE OF CONSTRUCTING THE OBJECT-BOX.

ALTHOUGH the Kaleidoscope is capable of creating beautiful forms from the most ugly and shapeless objects, yet the combinations which it presents, when obtained from certain shapes and colours, are so superior to those which it produces from others, that no idea can be formed of the power and effects of the instrument, unless the objects are judiciously selected.

When the inclination of the reflectors is great, the objects, or the fragments of coloured glass, should be larger than when the inclination is small; for when small fragments are presented before a large aperture, the pattern which is created has a spotted appearance, and derives no beauty from the inversion of the images, in consequence of the outline of each separate fragment not joining with the inverted image of it.

The objects which give the finest outlines by inversion, are those which have a curvilineal form, such as circles, ellipses, looped curves like the figure 8, curves like the figure 3 and the letter S; spirals, and other forms, such as squares, rectangles, and triangles, may be applied with advantage. Glass, both spun and twisted, and of all colours, and shades

of colours, should be formed into the preceding shapes; and when these are mixed with pieces of flat coloured glass, blue vitriol, native sulphur, yellow orpiment, differently coloured fluids, enclosed and moving in small vessels of glass, etc., they will make the finest transparent objects for the Kaleidoscope. When the objects are to be laid upon a mirror plate, fragments of opaquely-coloured glass should be added to the transparent fragments, along with pieces of brass wire, of coloured foils, and grains of spelter. In selecting transparent objects, the greatest care must be taken to reject fragments of opaque glass, and dark colours that do not transmit much light; and all the pieces of spun glass, or coloured plates, should be as thin as possible.

When the objects are thus prepared, the next step is to place them in the object-box. The distance between the interior surfaces of the two plane glasses, of which the object-plates are generally composed, should be as small as possible, not exceeding 1-8th of an inch. The outermost of these glasses has its external surface rough ground, or is what is called a grey glass, the principal use of which is to prevent the lines of external objects, such as the bars of the window, or the outlines of the illuminating flame from being introduced into the picture. When a strong light is used, a circular disk of fine thin paper placed outside of the object-box may be advantageously employed in place of the ground glass. The thickness of the transparent glass plate next the reflectors should be just sufficient to keep the glass from breaking; and the interior diameter of the brass rings into which the transparent and the grey or ground plates of glass are burnished, should be so great that no part of the brass rim may be opposite the angular part of the reflec

If this precau

tors during the rotatory motion of the cell. tion is not attended to, the central part of the pattern, where the development of new forms is generally the most beautiful, will be entirely obliterated by the interposition of the brass rim. Instead of using transparent or grey glasses on the sides of every object-box, some of the boxes should be made with disks of flint glass, the interior surface of which have been stamped while in a state of fusion with a sort of pattern, or with curved lines of a pleasing form. In others, the outer surface alone of the plate next the reflectors might be thus formed. An object-box might also be formed of disks of glass, one side of which is colourless, and the other coloured, some of the coloured portions being ground away irregularly, as in certain Bohemian articles of glass; and the colour in one disk may be complementary to that in the other. In object-boxes of this kind, pieces of coloured glass may also be placed. When the two parts of the object-boxes thus constructed are screwed or fixed together, the box should be nearly two-thirds filled with the mixture of regular and irregular objects, already mentioned. If they fall with difficulty during the rotation of the cell, two or three turns of the screw backward, when there is a screw, will relieve them; and if they fall too easily, and accumulate, by slipping behind one another, the space between the glasses may be diminished by placing within the box another glass in contact with the grey glass.

When the object-box, now described, is placed in the cell, and examined by the Kaleidoscope, the pictures which it forms are in a state of perpetual change, and can never be fixed, and shown to another person. To obviate this disadvantage, an object-box with fixed objects generally

accompanies the instrument; the pieces of spun and coloured glass are fixed by a transparent cement to the inner side of the glass of the object-plate, next the eye, so that the patterns are all permanent, and may be exhibited to others. After the cell has performed a complete rotation, the same patterns again recur, and may therefore be at any time recalled at the pleasure of the observer. The same patterns, it is true, will have a different appearance, if the light falls in a different manner upon the objects, but its general character and outline will, in most cases, remain the same.

The object-boxes which have now been described, are made to fit the cell, but at the same time to slip easily into it, so that they themselves have no motion separate from that of the cell. An object-plate, however, of a less diameter, called the vibrating object-plate, and containing loose objects, is an interesting addition to the instrument. When the Kaleidoscope is held horizontally, this small object-plate vibrates on its lower edge, either by a gentle motion of the tube, or by striking it slightly with the finger; and the effect of this vibration is singularly fine, particularly when it is combined with the motion of the coloured fragments.

Another of the object-boxes, in several of the instruments, contains either fragments of colourless glass, or an irregular surface of transparent varnish or indurated Canada balsam. This object-box gives very fine colourless figures when used alone; but its principal use is to be placed in the cell between an object-box with bright colours and the end of the instrument. When this is done, the outline of the pieces of coloured glass are softened down by the refraction of the transparent fragments, and the pattern displays