396 Prof. Faraday on Subterraneous Electro-telegraph Wires. 



3rd. That the quantity of motiou communicated to the carbine 

 bullet is equal to that possessed by the belted ritle bullet, although 

 the carbine is shorter and its bullet lighter ; this result being 

 due to the greater friction of the bullet in the rifle barrel. 



4th. That in traversing 80 feet of still air, the quantity of 

 motion of the Minie bullet is diminished by y'gth ; of the sugar- 

 loaf bullet, by j\ih; and of the belted bullet, by Yr&^^; the 

 remarkable inferiority of the belted bullet being principally due 

 to its shape, which appears to have been contrived so as to cause 

 the maximum amount of resistance to its passage through the air. 



5th. That the large stock of Brunswick two-groove rifles con- 

 structed for the use of the British rifle service, might be made as 

 useful as the regulation Minie rifles, by adapting to them a bul- 

 let of the proper weight, shaped like the Minie bullet, provided 

 with two projections at the side to fit the grooves of the rifle, 

 and used with or without the iron ' culot ' of the French bullets. 



The length of barrel of the Brunswick rifle is 30 inches, and 

 the size of bore is 0'704 inch. Calculating from these data the 

 weight of the ball which should be used with this rifle in order 

 to produce the same quantity of motion as in the Minie regulation 

 rifle, I find it to be 967 grs., or 7\ balls to the pound. If Minie 

 balls of this weight were constructed to suit the bore of the 

 Brunswick rifle, and provided with projections or wings to fit the 

 grooves, they would be as efl&cient as the regulation rifles of 39 

 inches in length. 



Trinity College, Dublin, 

 May 12, 1854. 



LXII. On Subterraneous Electro-telegraph Wires. 

 By Professor Faraday, F.R.S. 6^c. 



To the Editors of the Philosophical Magazine and Journal. 



Royal Institution, 

 Gentlemen, April 28, 1854. 



A COMMUNICATION has been just brought to my notice 

 on some remarkable phsenomena presented by subter- 

 raneous electro- telegraph wii'es observed and described by M. 

 Werner Siemens of Berlin, in a communication bearing date 

 April 15, 1850. They are the same phajnomena as those shown 

 to me by Mr. Latimer Clarke, and used in my communication 

 (inserted in your Magazine for March 1854, p. 197) as illustra- 

 tions of the truth of my ancient views of the nature of insulation, 

 induction and conduction. It is only justice that I should refer 

 to them ; and I think they are so interesting, that you will be 

 willing to reprint the account, very slightly abbreviated, which I 



