. Ein elementares Handbuch der Radioteleographie und Radiotelephonie für Studenten und Bediener. Legraphische Messungen (Kapitel VIII.) westhall beschreiben die Methoden in u.se zur Messung der Dämpfung und logarithmischen Dekrements von elektrischen Schwingungen. Die logarithmische Dekrementierung der Schwingungen, die durch den Poulsen-Bogen von IJausch von Traubenberg aufgestellt wurden, wurde abgemaskiert, und er fand heraus, dass der log. dec. Praktisch Null ist. Dies bedeutet, dass die Amplitude jeder Oszillation die gleiche ist wie die des Präzedenzfalls nach einer, mit anderen Worten, dass die Oszillationen persistent sind.Neverthel
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. An elementary manual of radiotelegraphy and radiotelephony for students and operators . legraphic measurements (Chapter VIII.) weshall describe the methods in u.se for measuring the damping andlogarithmic decrements of electric oscillations. Measurementshave been made of the logarithmic decrement of the oscillationsset up by the Poulsen arc by IJausch von Traubenberg, and he hasfound that the log. dec. is practically zero. This implies that theamplitude of each oscillation is the same as that of the precedin<Tor following one, in other words, that the oscillations are persistent.Nevertheless, we must conclude from the authors experimentsthat under some circumstances short interruptions in the uniformflow of the oscillationsmay take place. ThePoulsen method may, however, be properlydescribed as a methodfor the production ofundamped oscillations.The claims that havebeen made for other arcor spark methods, suchas that of Elihu Thom-son, or the modificationof it suggested by fes-senden or S. G. Brown, have not yet been justi-fied to the same extent, decrement, or established. ^DTO5»-^ [Reproduced by pertnitsion from FlQ, 18. The Electrician. by measurement of the logarithmicthemselves by definite evidence asproved methods for the production of persistent oscillations. S. G. Brown, in 1906, devii^ed a modification of Elihu Thomsonsmethod, as follows : A disc of metal W, preferably of aluminium, isfixed to a shaft and kept in slow rotation (see Fig. 18). A<^ainstthe edge of this disc a copper block C rests, pressing lightly, anda direct current under a pressure of about 200 volts is passedthrough a resistance Ei and large inductance Li and across the loosecontact between the block and the disc. A condenser K and smallinductance Lo in series are also joined as a shunt between the block io6 RADIOTELEGRAPHY and the disc. When the direct current passes, oscillations of highfrequency are set up in this condenser circuit, and these can betransformed up or down by an oscil
