that a triangular field may be obtained, either by inclining the mirrors 60°, and setting the bounding line at right angles to one of the reflectors, or by making the inclination 120°, and placing the bounding line at an angle of 60° and 30° to the reflectors. An elliptical field may be obtained, by giving the bounding line the shape of one quarter of an ellipse, and placing it in such a manner that the vertex of the conjugate axis falls upon one of the reflectors, and the vertex of the transverse axis upon the other.

The form of the pattern being determined, the next step is to select an outline, and the colours which are to enter into its formation. In order to do this to the greatest advantage, the differently coloured worsteds which the manufacturer proposes to employ should be placed upon a plane surface, either in the state of thread, or, what is much better, when they are wrought into cloth. These differently coloured pieces of carpet, which we may suppose to be blue, green, and yellow, must then be placed at the distance of a few feet from the Kaleidoscope, so that their image may, by means of the lens, be formed at the end of the reflectors. In this state a very perfect pattern will be created by the instrument, and the blue, green, and yellow colour will predominate according as a greater or a lesser portion of these colours happens to be opposite to the angular aperture. By shifting the position of the Kaleidoscope, any one of the colours may be made to predominate at pleasure; and the artist has it thus in his power, not only to produce any kind of outline that he chooses, but regulate the masses of colour by which it is to be filled up; and to try the effects which will be produced by the juxtaposition of two colours, by the separation of others, or by the trans

ference of the separate or combined masses to different parts of the design. It would be foreign to our object to describe the apparatus by which these changes in the quantities of colour, and in their relative position, may be most easily and conveniently effected; the artist can have no difficulty in constructing such an apparatus for himself, and by means of it he will be enabled to obtain results from the Kaleidoscope which he would have sought for in vain from any other method.

As the methods we have described of using the Kaleidoscope in ornamental architecture, or ornamental painting, and in the manufacture of carpets, will apply to the various other professions in which the formation of symmetrical designs is a necessary part, I shall merely state, that it will be found of the greatest advantage to the jeweller in the arrangement of precious stones; to the bookbinder, the wire-worker, the paper-stainer, and the artist who forms windows of painted glass. In this last profession, in particular, the application of the Kaleidoscope cannot fail to indicate combinations far superior to anything that has yet been seen in this branch of art. From the uniformity of tint in the separate pieces of glass which are to be combined, the effect produced by the instrument from portions of the very same glass that is to be used for the windows, may be considered as a perfect fac-simile of the window when well executed on a large scale.

CHAPTER XXI.

ON THE PHOTOGRAPHIC DELINEATION OF THE PICTURES CREATED BY THE KALEIDOSCOPE.

IN a preceding chapter we have referred to the delineation of the pictures created by the Kaleidoscope, when they are received on the ground glass of a camera obscura, or when a camera lucida is placed at the eye-end of the instrument. Both of these methods are very imperfect, and when the pictures have been copied for useful purposes, we believe that they have generally been executed by a skilful draughtsman, who delineated carefully one of the sectors of which the figure is composed, and then repeated it so as to complete the picture.

Since the invention of the Kaleidoscope, the discovery of the photographic art-of the Daguerreotype and Talbotype processes, has given a new value to the instrument. By means of a Kaleidoscope Camera, the most complex figures can be almost instantaneously transferred to paper, or to plated copper, and hundreds of designs offered to the choice of the artist who is to employ them. The very same figure which is obtained by one mode of illumination, may be altered indefinitely, by merely changing the direction or the intensity of the light, all the objects which give the figure

M

remaining fixed in the object-box. The optical arrangement by which these figures may be copied, photographically, is substantially the same as that which is shown in Fig. 52, where C G D F is the Kaleidoscope, AO the object-box, and LL a small achromatic lens, of rock crystal or glass, a quarter of an inch in diameter, placed in contact with the extremities of the glass or metallic reflectors, and having its centre immediately behind the small opening at E. When

the rays of the sun, or any other strong light, containing the actinic rays, are thrown obliquely upon the object-box A O, an image of the Kaleidoscopic figure, produced by the

FIG. 52.

G

A.

0 D

H

objects in the object-box, will be formed at PP, in the focus of the lens LL. If the focal length of the lens L L is equal to one-half c G, the length of the Kaleidoscope, the image will be formed behind L L, at a distance equal to c G, and of the same size as the object-box; but if the focal length of LL is greater than the half of CG, the image will be formed at a greater distance than c G, behind the lens, and the size of it will be greater than that of the object-box, the distance and the size of the picture increasing as the focal length of the lens increases; and when it becomes equal to c G, the size and the distance of the picture will be infinitely great. When the focal length of the lens is less than half CG, the figure will be smaller than the objectbox, and nearer the lens.

P

Р

The Kaleidoscope Camera.

Every camera employed for the purposes of photography may be readily adapted for taking the pictures formed by the Kaleidoscope. We have only to take out the lens or lenses which belong to it, and place the Kaleidoscope furnished with its lens LL, Fig. 52, in the inner tube, which is movable by means of the rack and pinion. If the picture can be made distinct on the grey glass by the rack and pinion, a negative or positive copy of it may be taken on collodion or paper, in the same manner as other photographs. In some cameras the end of the box which contains the grey glass is movable, backwards and forwards, so that the adjustment for rendering the picture distinct may be effected, though the Kaleidoscope is fixed in the front portion of the box.

When the camera is made for the express purpose of taking Kaleidoscope pictures, it becomes a very simple instrument and may be constructed easily and cheaply. It requires no lens excepting the small one L L of rock crystal or of glass, a quarter of an inch in diameter. The aperture required for this lens is so small that the spherical and chromatic aberration cannot injure, in any sensible manner, the distinctness of the picture. The difference between the chemical and luminous focus, which cannot be made to coincide with a single lens, may be easily determined by experiment, or in order to avoid this, the small lens may be made achromatic.1

The form of the camera as fitted up with one of Mr.

1 A thin lens of rock crystal will transmit more of the actinic rays than one rendered achromatic.