Upon these principles I constructed an instrument, in which I fixed _permanently_, across the ends of the reflectors, pieces of coloured glass, and other irregular objects; and I showed the instrument in this state to some members of the Royal Society of Edinburgh, who were much struck with the beauty of its effects. In this case, however, the forms were nearly permanent; and slight, though beautiful, variations were produced by varying the position of the instrument with respect to the source of light. The great step, however, towards the completion of the instrument remained yet to be made; and it was not till some time afterwards that the idea occurred to me _of giving motion to objects, such as pieces of coloured glass, &c., which were either fixed or placed loosely in a cell at the end of the instrument_. When this idea was carried into execution, and the reflectors placed in a tube, and fitted up on the preceding principles, the Kaleidoscope, in its _simple form_, was completed. In this form, however, the Kaleidoscope could not be considered as a general philosophical instrument of universal application. The least deviation of the object from the position of symmetry at the end of the reflectors, produced a deviation from beauty and symmetry in the figure, and this deviation increased with the distance of the object. The use of the instrument was therefore limited to objects in contact with the ends of the reflectors, or held close to them, and consequently to objects, or groups of objects, whose magnitudes were less than its triangular aperture. The next, and by far the most important step of the invention, was to remove this limitation, and to extend indefinitely the use and application of the instrument. This effect was obtained by employing a draw tube, containing a convex lens, or, what is better, an achromatic object-glass of such a focal length, that the images of objects, of all magnitudes and at all distances, might be distinctly formed at the end of the reflectors, and introduced into the pictures created by the instrument in the same manner as if they had been reduced in size, and placed in the true position in which alone perfect symmetry could be obtained.