270 Mr Kenwood on the Electric Currents 



The Haliacmon or Nazlitza and Karasu basin in Southern 

 Macedonia, is probably similar to the Vardar basin. On the 

 other side of the Olympus is the Thessalian tertiary basin. 

 Lastly, the great tertiary basin ofAdrianople seems to be con- 

 nected with that vast extent of high land which forms the cen- 

 tral part of Asia Minor between the Taurus to the S., and the 

 group of hills between Amastrah and Bafra, to the N. Major 

 Hauslab is right in the idea which he has formed of the course 

 of the rivers, and the position of the salt lakes. Trachytic and 

 other igneous eruptions occur in this basin, particularly on the 

 Bosphorus and in Asia Minor. 



(To be concluded in next Number.) 



On the Electric Currents observed in some Metalliferous Veins. 

 By W. J. KENWOOD, Esq. F. G. S. London and Paris 

 Hon. M. Y. P, S., Assay Master of Tin in H. M. Duchy 

 of Cornwall *. 



IT is my object, in the following pages, to describe briefly the 

 geological features of the district (Cornwall) in which most of 

 the experiments on this subject have been made, the method of 

 observing which has been pursued, the results obtained, to en- 

 quire into the probable causes of the currents observed, and to 

 examine whether the theories which have been erected on them 

 be well founded. 



The discovery of electric currents in some of the metallifer- 

 ous veins of Cornwall, is well known to have been made by Mr 

 Fox (Phil Trans. 1830, p. 399) ; it was soon followed by a 

 beautiful experiment of Mr Barlow's, in which the phenomena 

 of the dip of the magnetic needle were well approximated, by 

 suspending a magnetized bar over various parts of a hollow 

 globe, around which voltaic electricity circulated through wires 

 of copper placed in the parallels of latitude (Phil. Trans. 1831, 

 p. 99). These discoveries must have been regarded as very 



* This paper is altered and amended by the author from the edition 

 which has just appeared in Mr Sturgeon's interesting Annals of Electri- 

 city. 



