“Now,” said Mr. Seymour, “attend to my explanation. Each figure is seen through the aperture, and as it passes and is succeeded in rapid succession by another and another, differing from the former only in attitude, the eye is cheated into the belief of its being the same object successively changing the position of its body. Consider what takes place in an image on the retina when we actually witness a man in motion; for instance, a man jumping over a gate, in the first moment he appears on the ground, in the next his legs are a few inches above it, in the third they are nearly on a level with the rail, in the fourth he is above it, and then in the successive moments he is seen descending as he had previously risen. A precisely similar effect is produced on the retina, by the successive substitution of figures in corresponding attitudes, as seen through the orifices of the revolving disc; each figure remaining on the retina long enough to allow its successor to take its place without an interval that would destroy the illusion.” “Nothing can be more satisfactory than your explanation of this very extraordinary toy,” observed the vicar. “I am now about to exhibit what I consider a great improvement in its construction, inasmuch as we thus get rid of the mirror, and enable two persons to witness the deception at the same time,” said Mr. Seymour. “For this purpose I have a spindle, at each end of which a disc is placed, and which I hold in my hand.” We deem it expedient to illustrate this arrangement by a wood-cut. [Illustration: Two-sided phantasmascope.] “By revolving the spindle, you perceive that both cards are made to turn round with equal velocity. Tom,” said his father, “look through the orifices of the disc, on my right hand, and Louisa, do the same on my left.” The children obeyed, and simultaneously expressed their wonder at what they witnessed. “The figures are all dancing!” cried Tom; “The horses are all prancing!” exclaimed Louisa. “You have not yet told us the name of this toy,” observed the vicar. “It has received several names,” answered Mr. Seymour, “as _Phantasmascope_, _Phenakistiscope_, &c. derived, as you no doubt perceive, from the Greek.” It is scarcely necessary to observe, that the appearances thus produced may be infinitely varied--heads opening their mouths, and distorting their countenances; creeping serpents, and machinery in active operation, are amongst the subjects that have excited the greatest admiration. The party now dispersed, not less gratified than they had been instructed by the lesson of the morning. * * * * *