NATURAL PHILOSOPHY. 121 



to give, after a few minutes' action, a spark of extraordinary intensity when 

 the current is closed. The apparatus plays, in fact, just the part of a con- 

 denser; for by its means the work performed by a battery, after the lapse of 

 a certain time, may be collected in an instant. An idea of the intensity of 

 the charge will be obtained by remembering that to produce a similar effect 

 it would be necessary to arrange three hundred Bunsen's elements of the 

 ordinary size (thirteen centinietres in height), so as to form four or five 

 elements of three and a half square metres of surface, or three elements 

 of still greater surface. If the secondary battery be arranged for intensity, 

 the principal battery should be formed of a number of elements sufficient 

 to overcome the inverse electro-motive force developed. For nine secondary 

 elements, about fifteen Bunsen's cells should be taken, which might, how- 

 ever, be very small. 



From the malleability of the metal of which it is formed, this battery is 

 readily constructed ; by taking the plates of lead sufficiently thin, a large 

 surface may be placed in a small space. The nine elements used by Plante 

 are placed in a box thirty-six centimetres square, filled with liquid once for 

 all, and placed in closed jars ; they may also be kept charged in a physical 

 cabinet, and ready to be used whenever it is desired to procure, by means 

 of a weak battery, powerful discharges of dynamic electricity. Comptes 

 Rcndus, March 26th, 1860. 



EFFECT OF PRESSURE ON ELECTRO-CONDUCTING POWER. 



M. Elie Wartmann has found experimentally that the electric conductibility 

 of copper wire is sensibly diminished by a pressure of fifty atmospheres, 

 that this diminution increases with the pressure, and disappears when the 

 pressure is relieved. The experiments were carried up to four hundred 

 atmospheres. These results establish a new analogy between heat, light, 

 and electricity. L'1/tstitut. 



ON THE TRANSMISSION OF ELECTRIC EFFECTS ACROSS WATER 

 WITHOUT THE AID OF TRANSVERSE WIRES. 



At the Aberdeen meeting of the British Association, 18-39, Mr. Lindsay, of 

 Dundee, stated that he commenced experimenting in 1814 in telegraphing 

 across water, without wires first, and then by means of two uninsulated wires ; 

 and finding the latter method much more powerful, he preferred it, and tele- 

 graphed in that way through several ponds in Dundee. In 1852 he resumed 

 experiments without transverse wires. In 18-33 he made experiments on a 

 larger scale at Portsmouth, and succeeded in crossing more than a quarter 

 of a mile. More recently he had made additional experiments, and succeeded 

 in crossing the Tay where it was three-quarters of a mile broad. His method 

 ' had always been to immerse two plates or sheets of metal on the one side, 

 and connect them by a wire passing through a coil to move a needle, and to 

 have on the other side two sheets similarly connected, and nearly opposite 

 the two former. Experiments had shown that only a fractional part of the 

 electricity generated goes across, and that the quantity that thus goes across 

 can be increassed in four ways: first, by an increase of battery power; 

 second, by increasing the surface of the immersed sheet; third, by increas- 

 ing the coil that moves the receiving needle; and fourth, by increasing the 

 lateral distance. In cases where lateral distance could be got, he recom- 



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