40 THE SCIENTIFIC PAPERS OF 



that the influence of an electric current on a magnetic needle, and 

 its effect in magnetising an iron bar, had been noticed and 

 published long prior to the date of Oersted's discovery. Mr. 

 Siemens had erroneously attributed to Professor Faraday, the 

 discovery of the possibility of the co-existence of several waves of 

 electricity in one submerged wire. The phenomenon of the slow 

 transmission of currents through submerged wires, was first 

 noticed by him (Mr. Clark), in April, 1852, in the course of a 

 series of experiments undertaken at the works of the Gutta-percha 

 Company to ascertain how far it would be practicable to work 

 through gutta-percha wires laid underground between London 

 and Liverpool ; and, in 1853, a patent was taken out to obviate 

 that effect by surrounding the gutta-percha wire with a coating of 

 asphalt, or some cheap dielectric substance. The Elective Tele 

 graph Company having completed eight underground wires from 

 London to Liverpool, and meeting with much annoyance from the 

 induction, Professor Faraday and Professor Airy were requested to 

 attend at Lothbury, and early in 1854, he (Mr. Clark) exhibited 

 the phenomena of induction, and produced diagrams with three 

 needles on chemically prepared paper, showing, in a very perfect 

 manner, the passage and retardation of the current. These 

 diagrams were afterwards exhibited by Professor Faraday at the 

 Royal Institution, and formed the subject of a lecture there. 

 He (Mr. Clark) had not met with much practical inconvenience 

 from the breakage of the internal copper wire in submerged wires 

 and single submarine cables, and cases of fracture were very 

 unfrequent. In deep submarine cables, where every precaution 

 was requisite, the difficulty bad been successfully surmounted by 

 the use of the twisted strand of wires, but as this necessarily 

 occasioned some additional resistance, he did not consider its 



mettre a 1'experience ; et a la place des boutons b, b, qui sont viss^s sur leur tige 

 respective, adaptez aux tiges, ou une petite pince, ou bien un petit ajutage 

 applati. 



"Usage. Apres avoir place 1'aiguille, de maniere que ses deux extremites 

 soient prises dans les deux petites pinces, etablissez une communication de d avec 

 une des extremites d'un electromoteur, et de a avec 1'extremite opposee. 



' ' Effets. D'apres les observations de Romagnosi, physicien de Trente, 

 1'aiguille deja aunantee, et que Ton soumet ainsi au courant galvanique, 6prouve 

 une d6clinaison ; et d'apres celles de J. Mojon, savant chimiste de Genes, les 

 aiguilles non-aimantees acquierent, par ce moyen, une sorte de polarite mag- 

 netique." 



