. An elementary manual of radiotelegraphy and radiotelephony for students and operators . having a frequencyof up to 400,000 by employing a carbon arc operated with a smallcurrent and large voltage. In all probability this was due to theuse of smaller arc currents, enabling a smaller capacity to beemployed, and yet charged with appreciable energy by working ata steeper part of the characteristic curve. Meanwhile it may be UXDAMPEP ELECTRIC OSCILLATIOXS 97 said that the method ^nnerally was not re<,arded, prior to 1903, asanbrdinj^ a very i»; iiuans of obtaining powerful uiuhiinped
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . having a frequencyof up to 400,000 by employing a carbon arc operated with a smallcurrent and large voltage. In all probability this was due to theuse of smaller arc currents, enabling a smaller capacity to beemployed, and yet charged with appreciable energy by working ata steeper part of the characteristic curve. Meanwhile it may be UXDAMPEP ELECTRIC OSCILLATIOXS 97 said that the method ^nnerally was not re<,arded, prior to 1903, asanbrdinj^ a very i»; iiuans of obtaining powerful uiuhiinpedosciUations of the hii;h frei|uenoy and energy recjuired in radio-telegraphy. Nevertheless, Duddell had foreseen its application forthis purpose, and specially mentioned it in a Ikitish TatentSpecification, Xo. 21629, of 1900. This suggestion, however, lay dormant, but was revived againby E. A. Fessenden, who patented in 1902 and 1903 in the UnitedStates plans for effecting radiotelegraphy by setting up oscillationsin a circuit consisting of a condenser and inductance connected in 30. 4. 5 6 7 8 9 10 M CURRENT THROUGH ARC IN AMPERES. Fig. 12.—The numbers on the curves denote the arc length in millimetres. series with a spark gap; the said spark gap being also connectedthrough a high resistance wdth the terminals of a continuouscurrent dynamo. The specification taken alone furnishes no proofthat persistent oscillations were produced and not a series of inter-mittent condenser discharges caused by the drop in voltageresulting from the rush of current through a high , in the absence of definite proof that undamped and un-interrupted oscillations were obtained by this method, we havea right to suspend judgment upon the result. 4. Poulsens Method of Producing Undamped High Frequency 98 JiA DIO TELEGRA PHY Oscillations.—In 1903 -Yalilemar Poiilsen, of Copenhagen, describedimportant improvcmenls in the arc method of creating electricoscillations which give fresh i
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
