146 SCIOPTICON MANUAL. Large Slides—A New Departure.—To improve the size and brilliancy of a Seiopticon exhibition, the expe¬ dient, next to perfecting the instrument itself, is to bring into use larger and clearer views. A magic lantern picture of the standard size is 3 in¬ ches in diameter, mounted in a frame 7 inches long by 4 inches wide. The new picture is 3 J inches in the clear,, in a frame 7 inches by 4£ inches. The new picture having a third more surface, the illuminated disk shows larger in proportion and to very much better advantage. No one seeing an exhibition of the new slides, would willingly select from the old. No inconvenience arises from using both kinds in the same exhibition. The larger frame, reaching a little higher than where the spring meets the condenser, slides more smoothly into place. Great pains has been taken to get the best subjects with which to inaugurate this new departure, and to have them worked up in the most artistic style. Marcy’s Eidotrope.—Two disks of perforated tin are mounted so that one extends beyond the frame to the right, and the other to the left ; and so, not having a common centre, an eccentric revolution is given to each, little by little, when moved by the fingers at either side of the lantern, producing upon the screen a great variety of strikingly beautiful patterns, which maybe pleasingly modified by a varying use of the tinters. Its simplicity, however, may be against it, for effects are quite apt to be valued in proportion to their cost and trouble. "Wheel op Life.—In the English Wheel of Life, in its best form, the opaque disk with the open section, as seen in Fig. 33, is revolved rapidly, while the transpar-