The simplest method of thus illuminating the objects, is to fix on the end of the Kaleidoscope the portion of a metallic or silvered-glass cone. The light of a bright flame, placed in front of the cone, will be reflected from its interior surface, and fall obliquely on the fragments of coloured glass. In many cases the effect will be increased by placing in the base or mouth of the cone a circular stop, or opaque disk, in order to prevent any light from falling directly upon the objects, their oblique illumination being produced solely by the rays reflected from the interior surface of the cone. This will be understood from the annexed figure, where =M A N C= is a portion of the cone, fixed to the end =E F= of the Kaleidoscope, and _m n o p_ the object-box. If the angle formed by the sides of the cone is such that a ray of the sun’s light falling upon =M=, the upper margin of the reflecting surface of the cone, is reflected to _o_, the lower side of the object-box, then all the rays of a beam of the sun’s light incident upon the upper half of the conical surface, will be reflected upon the object-box; and, for the same reason, if a ray falling on =N= is reflected to _m_, all the other rays falling on the lower half of the conical surface will be reflected upon the object-box, and illuminate obliquely the objects which it contains. In the Kaleidoscopes of more recent construction, the object-box is made transparent throughout,—the plates of glass _m n_, _o p_ being fixed in a cylindrical case of glass _m n o p_, so that rays =R R=, either parallel or diverging, may be reflected from the cone =A B C D=, and after passing through the transparent cylindrical rim _m n o p_, illuminate the objects. Another cone =A M N C=, with its angle less than a right angle, may be joined to =A B D C=, so as to throw the rays obliquely, into _m n_ and _o p_, and also, if desired, upon the front glass _m o_ of the object-box, the direct rays being excluded by an opaque disk =S S=. In this construction, the outer face of the glass _m o_ should not be ground, as it would prevent the admission of the light to the objects, the exclusion of external objects, the purpose for which the grey glass is required, being effected by the stop =S S=. The illuminating cone may be of tin, or, what is much better, of plated copper, which reflects more light than any other metal, and it must be so attached to the tube containing the reflectors, as to have a rotatory motion.