As the power of the Kaleidoscope, therefore, in its simple form, is limited to transparent objects, or to the outline of opaque objects held close to the aperture of the reflectors, it becomes a matter of consequence to extend its power by enabling it to produce perfectly symmetrical patterns from opaque objects, from movable or immovable objects at a distance, or from objects of such a magnitude that they cannot be introduced before the opening of the reflectors. Without such an extension of its power, the Kaleidoscope might only be regarded as an instrument of amusement; but when it is made to embrace objects of all magnitudes, and at all distances, it takes its place as a general philosophical instrument, and becomes of the greatest use in the fine, as well as the useful arts. [Illustration: FIG. 27.] In considering how this change might be effected, it occurred to me, that if =M N=, Fig. 27, were a distant object, either opaque or transparent, it might be introduced into the picture by placing a lens =L L=, single or achromatic, at such a distance before the aperture =A O B=, that the image of the object may be distinctly formed in the air, or upon a plate of glass, the inner side of which was finely ground, and in contact with the ends =A O=, =B O= of the reflectors, the plane passing through =A O B=. By submitting this idea to experiment, I found it to answer my most sanguine expectations. The image formed by the lens at =A O B= became a new object, as it were, and was multiplied and arranged by successive reflexions in the very same manner as if the object =M N= had been reduced in the ratio of =M L= to =L A=, and placed close to the aperture. [Illustration: FIG. 28.] The Compound or Telescopic Kaleidoscope is therefore fitted up as shown in Fig. 28, with two tubes, =A B=, =C D=. The inner tube, =A B=, contains the reflectors as in Fig. 27, and at the extremity =C=, of the outer tube =C D=, is placed a lens which, along with the tube, may be taken off or put on at pleasure. The focal length of this lens should always be much less than the length of the outer tube =C D=, and should in general be such that it is capable of forming an image at the end of the reflectors, when =A B= is pulled out as much as possible, and when the object is within three or four inches of the lens. When it is required to introduce into the picture very large objects placed near the lens, another lens of a less focal length should be used; and when the objects are distant, and not very large, a lens, whose principal focal length is nearly equal to the greatest distance of the lens from the reflectors, should be employed. When this compound Kaleidoscope is used as a simple instrument for viewing objects held close to the aperture, the tube =A B= is _pushed in as far as it will go_, the cell with the object-plate is slipped upon the end =C= of the outer tube, and the instrument is used in the same way as the simple Kaleidoscope.