Twin-lens cameras are manufactured by several well-known firms, but the trade size is of too short focus to be desirable. In this type of camera two lenses of equal foci are employed. They are set one above the other in bellows, which move as one. The lower lens makes the picture, the upper projects a duplicate of the image cast by the lower lens to a mirror set at an angle of forty-five degrees to the plane of the plate, whence it is reflected upward to a ground glass, which is protected by a hood, on top of the camera. To focus perfectly the lenses should be “matched” or “paired”—in short, interchangeable—thereby greatly increasing the cost of the camera, which is also rendered objectionable by its large size. The reflecting camera possesses all the advantages of the twin-lens, but requires only one lens, and when in use is not materially larger than the ordinary 4 × 5 long-focus box. The reflecting camera now in my possession was designed and made by John Rowley, of the American Museum of Natural History, and was fully described and illustrated by him in Bird-Lore for April, 1900. It resembles the upper half of the twin-lens camera in that a mirror, set at an angle of forty-five degrees to the plate, is interposed between the latter and the lens, and reflects its image to a ground glass on top of the camera. This mirror, however, is movable, and the desired object appearing in focus on the ground glass, a lever is pressed downward which raises the mirror to the top of the box, where it automatically releases a focal-plane shutter (see beyond, under The Shutter) directly in front of the plate, when the image-bearing rays, before intercepted and reflected by the mirror, are registered on the plate, from which the slide had previously been drawn. When the focal-plane or curtain shutter has been set and the slide drawn from the plate holder, this camera is like a cocked gun, which may be fired the moment it is sighted; or, in other words, the exposure may be made the instant focus is secured. With this camera one may take advantage of any offering opportunity to secure a picture of a bird or beast when afield, and this fact, by increasing the possibilities of an outing, adds greatly to its pleasure. Mr. Rowley has so designed this camera that it may be used from a tripod as well as in the hands; but when the tripod camera is to be left, perhaps for hours, hidden near some bird’s nest, I prefer to employ the long-focus for this purpose, and retain the reflecting camera for possible use on the birds that so often approach closely when one is in hiding. The advantages possessed by this camera are so apparent that it doubtless will soon be placed on the market.