Patent GB-190022539-A (GB)
Title: Improvements in or relating to Cipher Typewriting Machines.
Inventor: BOULT ALFRED JULIUS
Filed: 1900-12-11
Granted: 1901-02-09
Abstract: 22,539. Boult, A. J., [Sedgwick, F.]. Dec.11. Type-writers.-Relates to machines adapted for writing in cipher and for translating therefrom. The invention is described as applied to the Hammond type-writer, but it is also applicable to other forms of machine. Fig. 4 shows the machine in section. The key levers 3, carriage 4, and type hammer 5 are of the usual construction. The type-wheel 15, Figs. 3, 4, and 7, is loosely mounted on a fixed stud 13, and bears on its base a crown ratchet-wheel 16 engaging with a similar wheel on the pinion 11, which is also carried by the stud 13. This device enables the type-wheel to be adjusted so as to bring any desired character to the initial or zero position. The pinion 11 engages with a toothed wheel 10 mounted on the shaft 6, which is driven from a coiled spring 9 through a train of gears 8, 7. An arm 21, Fig. 5, rotates with the shaft 6, and carries a stop 22 adapted to engage with a detent 23 carried by a spring plate 24 operated from a universal bar through the medium of a rod 26. The depression of any key lever thus releases the arm 21, and enables the shaft 6 to make one revolution, the completion of which is, however, interrupted by the temporary arrest of the selected character at the impression-point. The arm 21 carries with it a Geneva stop-wheel 33 mounted loosely on the shaft 6. The stop-wheel 33 carries a pin 34, into the path of which one of a number of radial arms 30 is raised against the tension of a spring 29 whenever a key is depressed. A weak spring 35 passes over the arm 30, or prevents recoil when the arrest of the wheel 33 takes place. The type - hammer 5 makes the impression, and on the release of the key the shaft 6 completes its revolution, and the stop 22 again engages the detent 23. The characters are arranged indiscriminately on the type-wheel, so that the printed matter is in cipher, the key to which is given by the zero character. The message can be automatically translated by re-writing it on a similar machine, in which the type-wheel has been adjusted in accordance with the known keyletter of the cipher. In order to complicate the cipher and prevent its solution by studying the sequence of characters &c., a device is employed for periodically varying the relative position of the stop pin 34 and type - wheel 15. On a lateral extension of the arm 21 is pivoted a wheel 37, Fig. 5, which normally engages with one of the concave faces of the stop-wheel 33, and locks the arm 21 or wheel 33 together. Rigidly connected with the wheel 37 is a star-wheel 41, having three radial arms 48 adapted to engage with a pin 46 carried by a lever 43. At each third revolution of the arm 21 the tooth 39 turns the stop-wheel 33 through one stop relatively to the type-wheel,'the printed character corresponding to each key being thus varied intermittently. In translating the message, it is necessary that the relative movement of the stop-wheel and type-wheel be reversed, and for this reason the lever 43 is pivoted so that the pins 47 can be brought into the path of the arms 48 instead of the pin 46. The star-wheel may be turned by hand at predetermined intervals to complicate still further the cipher. For the Geneva stop gear may be substituted an escapement-wheel which moves through one stop relatively to the type-wheel at each revolution of the latter. As such an escapement is not adapted to be reversed. the characters on the translating type-wheel must be arranged in inverse order to those in the other machine.