Curiosities of Science. 



mersion in the sea, new forces come into play. The electric ex- 

 citement of the wire acts by induction, through the envelope, 

 upon the particles of water in contact with that envelope, and 

 calls up an electric force of an opposite kind. There are two 

 forces, in fact, pulling against each other through the gutta- 

 percha as a neutral medium, that is, the electricity in the 

 wire, and the opposite electricity in the film of water imme- 

 diately surrounding the cable ; and to that extent the power of 

 the current in the enclosed wire is weakened. A submarine 

 cable, when in the water, is virtually a lengthened-out Leyden 

 jar ; it transmits signals while being charged and discharged, 

 instead of merely allowing a stream to flow evenly along it : it 

 is a bottle for holding electricity rather than a pipe for carrying 

 it ; and this has to be filled for every time of using. The wire 

 being carried underground, or through the water, the speed be- 

 comes quite measurable, say a thousand miles in a second, in- 

 stead of two hundred thousand, owing to the retardation by in- 

 duced or retrograde currents. The energy of the currents and 

 the quality of the wire also affect the speed. Until lately it 

 was supposed that the wire acts only as a conductor of electri- 

 city, and that a long wire must produce a weaker effect than a 

 short one, on account of the consequent attenuation of the elec- 

 trical influence ; but it is now known that, the cable being a re- 

 servoir as well as a conductor, its electrical supply is increased 

 in proportion to its length. 



The electro-magnetic current is employed, since it possesses 

 a treble velocity of transmission, and realises consequently a 

 threefold working speed as compared with simple voltaic electri- 

 city. Mr. Wildraaii Whitehouse has determined by his inge- 

 nious apparatus that the speed of the voltaic current might be 

 raised under special circumstances to 1800 miles per second ; 

 but that of the induced current, or the electro-magnetic, might 

 be augmented to 6000 miles per second. 



Next as to a Quantity Battery employed in these investiga- 

 tions. To effect a charge, and transmit a current through some 

 thousand miles of the Atlantic Cable, Mr. Whitehouse had a 

 piece of apparatus prepared consisting of twenty -five pairs of 

 zinc and silver plates about the 20th part of a square inch 

 large, and the pairs so arranged that they would hold a drop of 

 acidulated water or brine between them. On charging this Lil- 

 liputian battery by dipping the plates in salt and water, mes- 

 sages were sent from it through a thousand miles of cable with 

 the utmost ease ; and not only so, pair after pair was dropped 

 out from the series, the messages being still sent on with equal 

 facility, until at last only a single pair, charged by one single 

 drop of liquid, was used. Strange to say, with this single pair 

 and single drop distinct signals were effected through the thou- 



