In the seventh edition of a work on gardening and planting, published in 1739, by Richard Bradley, F.R.S., late Professor of Botany in the University of Cambridge, we find the following details of an invention, “by which the best designers and draughtsmen may improve and help their fancies. They must choose two pieces of looking-glass of equal bigness, of the figure of a long square. These must be covered on the back with paper or silk, to prevent rubbing off the silver. This covering must be so put on that nothing of it appears about the edges of the bright side. The glasses being thus prepared, must be laid face to face, and hinged together so that they may be made to open and shut at pleasure like the leaves of a book.” After showing how various figures are to be looked at in these glasses under the same opening, and how the same figure may be varied under the different openings, the ingenious artist thus concludes: “If it should happen that the reader has any number of plans for parterres or wildernesses by him, he may by this method alter them at his pleasure, and produce such innumerable varieties as it is not possible the most able designer could ever have contrived.” MAGIC OF PHOTOGRAPHY. Professor Moser of Königsberg has discovered that all bodies, even in the dark, throw out invisible rays; and that these bodies, when placed at a small distance from polished surfaces of all kinds, depict themselves upon such surfaces in forms which remain invisible till they are developed by the human breath or by the vapours of mercury or iodine. Even if the sun’s image is made to pass over a plate of glass, the light tread of its rays will leave behind it an invisible track, which the human breath will instantly reveal. Among the early attempts to take pictures by the rays of the sun was a very interesting and successful experiment made by Dr. Thomas Young. In 1802, when Mr. Wedgewood was “making profiles by the agency of light,” and Sir Humphry Davy was “copying on prepared paper the images of small objects produced by means of the solar microscope,” Dr. Young was taking photographs upon paper dipped in a solution of nitrate of silver, of the coloured rings observed by Newton; and his experiments clearly proved that the agent was not the luminous rays in the sun’s light, but the invisible or chemical rays beyond the violet. This experiment is described in the Bakerian Lecture, 1803.