Page:Popular Science Monthly Volume 91.djvu/624

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��Popular Science Monthly

��have learned all the letters, and are able to call them to mind easily, try to get some trained wireless operator to call on you and send over your buzzer line. If you will send the alphabet through from A to Z several times, and follow it with the

���A rotating disk with notches in its circum- ference to make the -dots, dashes and spaces

classical sentence, "The quick brown fox jumps over the lazy dog" (which contains every letter of the alphabet) , he will soon be able to judge wherein your sending is in need of improvement, and to correct you. Be sure to pay strict attention to his sugges- tions, for they will probably be valuable to you.

After your sending has been passed on by a seasoned operator, try to have him send for you a little while. Ask him to send so slowly that you can get every letter, and pay close attention to the smoothness with which he forms the dot and dash combina- tions. If you can, have him take the key at the station at one end of your line, and go to the other end yourself. By exchanging a few messages with him, and listening sharply to his style of Morse sending, as well as by having him note the imperfec- tions in your sending, you can do a great deal toward perfecting yourself in the art of telegraphing.

Three- Station Lines

Occasionally it is possible to run the buzzer telegraph . line by the home of a wireless operator, and to install a third station in his house. If he is willing to help you out, he will send from a newspaper for half an hour or so each evening, and then let you send to him for ten or fifteen minutes. This sort of practice will be exceedingly valuable, if it can be arranged. Sometimes half a dozen students wish to get on the same buzzer-telegraph wire and to practice together. Fig. 8 shows how

��three stations may be connected with the same line. wire, and identical station-units may be added almost without limit. Pressing the key K at any one of them will operate its buzzer Z, by reason of closing the circuit from the battery B through the buzzer magnet windings, and the signal- tone of the buzzer will be reproduced in the telephones T at all of the stations. It is only necessary to keep the insulation of the line wire L L L fairly good, so as to prevent leakage, and to make a good connection to earth through a scraped water, gas or steam pipe at each of the points marked £ in the diagram Fig. 8. The higher the resistance of the telephones, up to several thousand ohms, and the more powerful the buzzers and batteries, the better the line will work when a comparatively large num- ber of stations are added to it. If the signals in any of the telephones are found to be too loud, their terminals may be shunted by a resistance of fifty or a hundred ohms or thereabouts (the best amount being found by trial), as shown in Fig. 5 (last month's article).

It is not always easy or even possible to get a wireless operator to visit your home and try out your buzzer line; if you find this difficult, it is a good plan to call at some local telegraph office and to try to pick up a few pointers from the operators there. Although the line telegraphers in the United States use the American Morse code, which differs as to some of its charac- ters from the International Morse used in wireless, the two systems have much in common and a few words of criticism from a skilled line operator will often be of inestimable value to the student.

Copying Perfect Signals Such a plan, however, does not give the

���Another type of automatic sender in which a tape is used having holes in it for the letters

student any opportunity to listen to and copy perfectly formed Morse characters at gradually increasing speeds. The two-

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