In the case illustrated, these mirrors are inclined at an angle of seventy-two degrees; four images are produced. The exposure is made, and on the negative appears not only the back view of the subject, but also the four reflected images in profile and different three-quarter positions.
The courses taken by the rays of light are determined by the law that the angle of incidence is equal to the angle of reflection. In the diagram the rays of light are traced in their course from the subject to the mirror, and back and forth, giving a good idea of the relation of the images to the subject and of the five images to the focal plane, the virtual position of the images being further from the instrument than the subject proper. We also give an [engraving] showing images of a full-length figure.
IMAGES OF A FULL-LENGTH PORTRAIT.
PINHOLE CAMERA.
We illustrate in the [cut] a camera for photography in which the ne plus ultra of simplicity may fairly be said to be attained. It is a little tin box two inches in diameter and three-quarters deep from cover to bottom. A hole was punched in the center of the cover, and over this a piece of foil was secured by varnish. The foil was taken from a button card. Small mother-of-pearl buttons are generally mounted on pieces of pasteboard with this foil under them. Through the foil, where it extended across the hole in the box cover, a hole was made with a No. 10 needle. The needle was pressed through until its point could be just felt by the finger held against the opposite side of the foil. This made an aperture one-sixtieth inch in diameter. The interior of the box was blackened. A piece of Eastman’s “A” bromide paper, cut circular so as to fit in the box, was placed in it against the bottom, and the cover put on. This, of course, was done in the absence of actinic light. Then, with an exposure of four minutes, at a distance of about ten feet from the object, the negative shown in the sketch was taken. It was developed with oxalate developer. Castor oil or vaseline was used to make it transparent, so as to adapt it for printing from. The subject of the negative was the old armory at Summit Hill, Mt. Jefferson, Pa.