THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



MA Y 1852. 



XLVI. Reports on the Progress of the Physical Sciences. 



By John Tyndall, Ph.D. 



[With a Plate.] 



On the Electroscopic Properties of the Voltaic Circuit • being an experi- 

 mental verification of the Theory of Ohm. By Dr. Kohlrausch, Pog- 

 gendorff's Annulen, vol. lxxv.p.^':20; vol. lxxviii. p.l; and vol. lxxxii.p. 1. 



THE following quotation bears so pertinently upon the sub- 

 ject of the present report, that an apology for its intro- 

 duction here is scarcely necessary. It is extracted from a dis- 

 course by Professor Dove, before the Berlin Society for Scientific 

 Lectures. 



" As the (then considered) essential portions of a galvanic 

 circuit were two metals and a fluid, innumerable combinations 

 were possible, from which the most suitable must be chosen. 

 This gigantic task was undertaken by Ritter, an inhabitant of a 

 village near Liegnitz, who almost sacrificed his senses to the in- 

 vestigation. He discovered the peculiar pile which bears his 

 name, and opened that wonderful circle of actions and reactions 

 which, through the subsequent discoveries of (Ersted, Faraday, 

 Seebeck and Peltier, drew with ever-narrowing band the isolated 

 forces of nature into an organic whole. But he died early, as 

 Gunther did before him, exhausted by restless labour, sorrow, 

 and disordered living. It was soon found that many experiments 

 succeeded better with a single pair of large plates than with 

 several small ones ; and, in short, that every apparatus exhibited 

 certain actions better than all others. Here men of science long 

 groped in darkness, when in the year 1827, the theory of galva- 

 nism by Ohm, then of Berlin, now of Xurnborg, rose like a pole- 

 star to illumine the obscurity. He showed that, as the apparatus 

 itself was composed solely of conductors, the electric current 



Phil. Mag. S. 1. Vol. 3. No. 10. May 1852. Y 



