570 REPORT— 1897. 



TUESDAY, AUGUST 2^. 

 The Section was divided into two Departments. 

 The following Papers and Report were read : — 



Department I. — Electricity. 



1. Demonstrations on the Form of Alternating Currents. 

 By Professor Dr. F. Braun, Strasshurg. 



Ein Katbodenstrahl wird in einein Magnetfeld, welches durch einen Wechsel- 

 strom erzeugt ist, abgelenkt. Der vom Kathodenstrahl auf einer fluorescirenden 

 Flache erzeugte Fleck macht daher Schwingungen, welche in einem rotirenden 

 Spiegel analysirt werden konnen. Wirken auf den Kathodenstrahl zwei unter 

 einem rechten Winkel gekreuzte Felder, so entstehen Lissajous'sche Curven, 

 welche gestatten Phasenverschiebungen der Felder in Folge von Selbstinduction, 

 Capaeitat, Polarisation, u.s.w., nachzuweisen und zu messen. Eine Tragheit des 

 Kathodenstrahles konnte nicht gefunden werden ; den Schwingungen von Ley- 

 dener Flaschenentladungen folgt er noch. Eine magnetische Wirkung von Licht- 

 strahlen wurde aber vergebens gesucht. Ein dem Kathodenstrahl mit seiner 

 Axe parallel gestellter Magnet breitet denselben zu einem Gebilde aus, wie es 

 entstehen musste, wenn der Kathodenstrahl ein beweglicher Stromleiter ware; 

 ob aber dieses Gebilde entsteht durch eine ausserordentlich rasche Rotation oder 

 ■ob es ruht, ist unentschieden. Von Interesse ist es, dass das Magnetfeld der Erde 

 echon hinreichend stark das Ende des Kathodenstrahles ablenkt, so dassjeden- 

 falls angenaherte Bestimmungen der Inclination damit moglich sind. 



2. Note on an Electrical Oscillator. By Nicola Tesla. 



The instrument exhibited belongs to a novel class of electrical transformers, the 

 primary of whicli is operated by the oscillatory discharge of a condenser. The 

 above name seems, therefore, particularly appropriate. 



The condenser is charged from any suitable, direct or alternating, current 

 source. 



By observing the well-known conditions governing the oscillatory discharge of 

 the condenser, which have been established by Lord Kelvin, and selecting properly 

 the physical constants of the primary or " discharge circuit," extremely rapid oscilla- 

 tions in ^is circuit are obtained, which set up, by inductive action, corresponding 

 high-frequency current impulses in the secondary circuit. 



The fundamental disturbances in the primary circuit are produced either by 

 simply adjusting the quantities concerned, so that the average rate of supply of 

 energy to the condenser shall be inferior to the average rate of discharge, or else 

 positively-acting mechanical means, irrespective of such adjustment, are employed 

 to periodically open and close the circuit. 



The circuit connections in the instrument exhibited are indicated in a diagram, 

 while a photograph showed the actual arrangement of the parts in the instrument. 



Referring to these illustrations, the condenser is contained in a box, upon 

 which is mounted in front the circuit controller, consisting of spring contacts, and 

 a self-induction coil. The latter, designated as a '• charging coil," serves at the 

 same time to raise the pressure of the source to any value desired for charging 

 the condenser. This is an important practical advantage, as it enables the 

 capacity of the latter to be reduced, so that it need not be more than a few 

 per cent, of that otherwise required for an equivalent conversion of energy. 

 Besides, the smaller the capacity, the quicker is the oscillation, and the shorter need 

 be the high-tension secondary wire. 



The primary or discharge circuit surrounding the secondary coil or coils is 

 formed of a few turns of copper ribbon mounted on the top of the box behind the 



