Manchester Memoirs, Vol. lx. (1916), No. 11. 



capable of recording vibrations as rapid as 6,000 per 

 second. A pencil of light was focussed on the mirror and 

 from thence on to a moving photographic film. 



A diagram of Le Blanc's arrangement is given below. 



rroV 



'I'l'I'M'l' 



L ^n rAAAA — ' 



Or'-- 



A = GleichslronvAmperemeter 

 K = Kommutaior 

 M = MeCschleife 

 It', \V t W % = Widerstande 

 Z = Vcrsuchszellc 



Text-fig. 2. 



By means of the rotating commutator K, a current 

 was sent through the experimental cell Z from the battery 

 V for a certain interval, cut off for the same period, 

 reversed and again cut off, etc. 



The maximum current allowed to pass through the 

 galvanometer was 001 amp., the fraction of the total 

 current passing through the galvanometer being adjusted 

 by means of the resistance W r 



W x was an induction free resistance made equal to 

 that of the experimental cell. The commutator was 

 generally rotated at such a speed that there were 50 — 60 

 alternations per second. 



When a metallic conductor was put in place of the 

 electrolytic cell, the graph obtained on the photographic 

 film was of the type shown in Text-fig. 3, which is taken 

 from Le Blanc's book " Die Electromotorischen Krafte 

 der Polarisation." 



