intensities, seen under different angles, and presenting different sides to the eye. This mode of grouping images, dissimilar in their degree of light, dissimilar in their magnitude, and dissimilar in their very outlines, produced such a poor effect, that the reflecting show-boxes have for a long series of years disappeared from among the number of philosophical toys. From these causes, the candidates for the merit of inventing the Kaleidoscope have been so numerous, that they have started up in every part of the world; and many individuals, who are scarcely acquainted with the equality of the angles of incidence and reflexion, have not scrupled to favour the world with an account of the improvements which they fancy they have made upon the instrument.[19] [19] It would be an easy matter to amuse the reader with an account of these improvements. One of the most notable of them consists in covering the back of the reflectors with white paint, for the purpose of increasing the light of the circular field. This scheme is identically the same as if the author had proposed to improve the magnificent telescopes of Herschel, when rendered dark with a high magnifying power, by _white-washing_ the interior of the tube. The earliest writer who appears to have described the use of two plane mirrors, was Baptista Porta, who has given an account of several experiments which he performed with them, in the second chapter of the seventh book of his _Magia Naturalis_. As the combination of plane mirrors which he there describes has been represented as the same as the Kaleidoscope, we shall give the passage at full length:— _Speculum è planis multividum construere._ “Speculum construitur, quod _polyphaton_ id est multorum visibilium dicitur, illud enim aperiendo et claudendo solius digiti viginti et plura demonstrat simulacra. Sic igitur id parabis. Ærea duo specula vel crystallina rectangula super basim eandem erigantur, sintque in hemiolia proportione, vel alia, et secundum longitudinis latus unum simul colligentur, ut libri instar apte claudi et aperiri possint, et anguli diversentur, qualia Venetiis factitari solent: faciem enim unam objiciens, in utroque plura cernes ora, et hoc quanto arctius clauseris, minorique fuerint angulo: aperiendo autem minuentur; et obtusiori cernes angulo, pauciora numero conspicientur. Sic digitum ostendens, non nisi digitos cernes, dextra insuper dextra, et sinistra sinistra convisuntur; quod speculis contrarium est: mutuaque id evenit reflexione, et pulsatione, unde imaginum vicissitudo.” —_Edit. Amstelod_, 1664. The following is an exact and literal translation of this passage:— _How to construct a multiplying speculum out of plane ones._