ELECTRICAL SCIENCE. 161 



battery depends on the manner in which the secondary couples 

 are arranged. If they are arranged so as to give three elements of 

 triple surface, five small Bunsen's cells, the zincs of which are im- 

 mersed to a depth of seven centimetres, are sufficient 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 

 condenser ; for by its means the work performed by the 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 300 

 Bunsen's elements of the ordinary size (13 centimetres in height), 

 so as to form, four or five elements of 3i 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, however, 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 suffi- 

 ciently thin, a large surface may be placed in a small space. The 

 nine elements used by Plaute" are placed in a box 36 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 llendus ; Philos. 

 Mag., No. 129. 



APPLICATION OF ELECTRICAL DISCHARGES FROM THE INDUCTION COIL 

 TO ILLUMINATION. 



Mr. Gassiot proposes to take a carbonic-acid vacuum tube of 

 about ^th of an inch internal diameter, wound in the form of a 

 flattened spiral. The wider ends of the tube, in which the platinum 

 wires are sealed, are two inches in length and about half an inch in 

 diameter ; they are enclosed in a wooden case, so as to permit only the 

 spiral to be exposed. 



When the discharge from a Ruhmkorff's induction apparatus is 

 passed through the vacuum-tube, the spiral becomes intensely 

 luminous, exhibiting a brilliant white light. Mr. Gassiot, who 

 has exhibited the experiment to the Royal Society, caused the dis- 

 charge from the induction coil to pass through two miles of copper 

 wire ; with the same coil excited so as to give a spark through air of 

 one inch in length, he ascertained that the luminosity in the spiral 

 was not reduced when the discharge passed through fourteen miles 

 of No. 32 copper wire. 



NEW KIND OF ELECTRIC CURRENT. 



The fifth number of Poggendorffs Annalen for 1859 contains an 

 article of considerable length, the leading points in which are in- 

 cluded in the following abstract : — 



L 



