128 Intelligence and, Miscellaneous Articles. 



there is no deflexion, it shows that the space in which the observa- 

 tions are made is free from the products of combustion of the lamp. 

 When the mica disk has been again pushed forward the zinc plate 

 is blown on from a hand-bellows, when there is no deflexion of the 

 gold leaf. If then the mica disk is withdrawn, a few separate puffs 

 with the bellows are sufficient to produce considerable deflexions, 

 so as to drive the leaf off the scale. That the direction of the 

 deflexion corresponds to a positive electrification follows from the 

 sign of the potential when the electrometer is charged for deter- 

 mining its sensitiveness, and from the deflexions thereby produced. 

 Wiedemann's Annalen, xl. p. 343 (1890). 



INVESTIGATION OF ELECTRICAL RESONANCE. 

 BY DR. ERNEST LECHNER. 



The author describes first of all a method of observing electrical 

 vibrations in wires. Opposite each of the two terminal plates of a 

 Hertz's arrangement for vibrations an equally large insulated plate 

 is arranged, and from each plate is led a wire several metres in 

 length, the two wires being parallel. Over the end of the wire a 

 rarefied tube, without an electrode, is placed, which becomes lumi- 

 nous in consequence of the electrical oscillations in the wires. If 

 the parallel wires are connected by a cross wire the luminosity in 

 general ceases. If this bridge is moved backwards and forwards 

 along the parallel wires, a few very sharply defined places are 

 found where the tube suddenly becomes luminous ; these are the 

 ventral segments of the electrical motion. 



After the author had studied the conditions of the experiment, 

 and had shown that the whole is an electrical phenomenon of 

 resonance, the shape and position of the electrical wave was precisely 

 determined by seeking the common ventral segment. The influence 

 of the introduction of capacities at the end of the wires was also 

 examined. 



The author invariably found that Hertz's observations were 

 always confirmed ; in one important point, however, he obtained a 

 different result. While Hertz found for the velocity of electricity in 

 wires 200,000 kilometres per second, the author obtained within 

 2 per cent, of the exact velocity required by Maxwell's and all 

 other theories ; he cannot, however, explain why his results differ 

 from that of Hertz. A possible source of error in the experiments 

 of Hertz was found on closer inquiry to be too small. As the 

 method used by the author is very simple and comprehensive, and 

 can be very easily made, in the form even of a lecture-experiment, 

 he considers his value not only theoretically but also practically the 

 most probable. — Wiener Berichte, May 8, 1890. 



