. An elementary manual of radiotelegraphy and radiotelephony for students and operators . confirmed by the author, for 10 \ \ k 0-5 5 >s^ Xj V^^)C 1 2 3 4 SPARK LENGTH IN MM. Fig. 17. an oscillatory circuit comprising a capacity of 0-002G1 mfd., aninductance of 000636 millihenry and a spark gap varying from1 to 6 millimetres, as shown by the curve given in Fig. 17. The larger the capacity used, the^ lower is found to be the re- sistance of a spark for givenlength. The resistance ofthe spark is therefore notmerely a function of itslength but is dependent uponthe circumstances underwhich it i
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . confirmed by the author, for 10 \ \ k 0-5 5 >s^ Xj V^^)C 1 2 3 4 SPARK LENGTH IN MM. Fig. 17. an oscillatory circuit comprising a capacity of 0-002G1 mfd., aninductance of 000636 millihenry and a spark gap varying from1 to 6 millimetres, as shown by the curve given in Fig. 17. The larger the capacity used, the^ lower is found to be the re- sistance of a spark for givenlength. The resistance ofthe spark is therefore notmerely a function of itslength but is dependent uponthe circumstances underwhich it is formed, and isless the larger the quantityof electricity which is carriedby it. We have already referredto the necessity for preventing an arc discharge accompanying thetrue spark discharge of the condenser in those cases in which arapid series of oscillatory sparks is required, and especially whenusing transformers and large condensers. This can be achieved tosome extent by blowing air upon the spark gap, but even betterby employing as the discharger surfaces in very rapid relative. Fig. 18. DAMPED ELECTRIC OSCILLATIOSS 65 motion. This causes them to keep cool and completely preventsthe arc discharge, whilst still permitting the condenser oscillatorydischarge. Tlie arrangement in Fig. 18, due to li. Crisson, shows onemode of causing the oscillatory discharge of a chargedby a dynamo ur battery to take place without arcing. In thisarrangement the discharge is caused to take place between theballs SS by the periodic passage between them of four other ballscarried on the arms of a rapidly rotating cross. Mr. Marconi hasalso devised several forms of non-arcing discharger to which weshall refer in connection with descriptions of radiotelegraphicapparatus and stations. 6. Condensers for Electric Oscillations.—The next element inthe apparatus for the production of electric oscillations to beconsidered if, the condenser. It consists of a sheet of a dielectricor insulator
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
