Page:Popular Science Monthly Volume 92.djvu/970

 954

��Popular Science Monthly

��Interesting Method of Learning the Telegraph Code

IN learning either of the telegraph codes one finds it easy enough to learn to transmit correctly without the aid of

��Fig. I

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���A metal ball rolling in V-shaped notches having alternate contacts and insulation

any other person, but, when it is desired to learn to receive, it becomes abso- lutely necessary either to have a teacher or some kind of apparatus to take his place. There are very few students who can afford the services of a teacher and consequently the majority must secure some sort of mechanical device to make the signals. There are several of these devices on the market but as a rule the price is a good deal beyond reach. Fur- thermore, in these mechanical transmit- ters there is not enough of the element of chance; that is, when one has used one of these instruments for a short time he gets used to the combinations employed to such an extent that the instrument loses its usefulness.

In learning the code quickly it is absolutely necessary that one never know what letter is coming next and it was to provide an arrangement in which the element of chance enters that the ap- paratus herewith described was developed.

Reference to Fig. 1 will serve to give an idea of the method used. The princi- ple in use is to provide a V-shaped trough, for a metal ball to roll in, and to cover the sides of the trough with metal pads »o arranged as to correspond to the telegraph signals. When the ball is caused to roll over the signals it makes corresponding contacts and a buzzer or sounder repeats them.

Thus in Fig. 1, A is a baseboard and BB are metal angles fastened to the board so as to form troughs, CC, be-

��tween them. In each trough is glued pieces of paper or other insulation bent at right angles, as at EE, so arranged along the length of the trough as to form the signals. The arrangement of the parts is clearly shown in the view. Fig. 2, which is a corner of the apparatus with the cover and the front removed. It will be seen that there is provided one trough for each letter and numeral of the telegraph alphabet and the insulating pieces are pasted in to correspond to the characters forming each letter. The author uses forty characters; 26 for the letters, 9 for the numerals and 5 for punctuation marks, etc.

A cover for the box is to be made of wood or cardboard so that the ball will be prevented (when the cover is on) from jumping from one groove to another.

The simplest method of using the ap- paratus is to take it up with the two hands with the cover on and by tilting the box to cause the ball to roll back and forth through first one groove and then another, thus producing signals at ran- dom. It will be evident after a little thought that signals will be produced with this form of the apparatus only when the ball rolls in one direction for all letters except those which are symmetri- cally arranged, as for instance, D, E,

���The ball may roll into any one of the notches without the operators' knowledge

etc. It will be evident to anyone with the ability to build the apparatus that a passage could be provided for the return of the ball so that meaningless signals would be prevented and also that a pivoted frame might be constructed so

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