Page:Popular Science Monthly Volume 33.djvu/669

Rh other toothed. As each pin can be disposed in the holes in sixteen different ways, it is easy to see that the system has considerable capacity. But the blind find it difficult to adjust the pins. A case has been made for working in vulgar fractions, in which metallic figures are set in square holes; but the apparatus can hardly be called a practical one. M. Oury has devised a modification of Taylor's tablets which has advantages over both of these instruments (Fig. 5, No. 2, 2'). M. Mauler's writing-machine consists essentially of a horizontal plate, having on its circular border a series of keys, each of which bears one of the



signs of the Braille alphabet and the corresponding letter of the ordinary alphabet, the two systems being arranged upon two concentric circlets. The plate, turning around a vertical axis, may be fixed at any position for the moment by means of a spring working into a notch. A frame, which turns upon a horizontal axis, supports two rollers upon which the paper is wound, and is moved by a lever which the writer holds in his left hand. Upon this lever slides a little tampon tipped with India-rubber, which may be fixed at will immediately over the line of either of the alphabets of the plate. When the writer has brought the letter he wants in front of him, and has fastened it for the moment in