NATURAL PHILOSOPHY. 157 



rod of platinum is secured in the same manner to a spring which presses 

 them together ; another spring loaded acts like a hammer upon the end 

 of the first spring, to separate the platinum rods. A ratchet wheel presses 

 down this spring hammer, and allows it to recoil and strike the other spring. 

 By this the interruption is more instantaneously made, and the distance to 

 which the platinum rods are separated easily regulated. This point appears 

 to be of importance. The spark is lessened if the platinum rods are sepa- 

 rated farther than actually to break their contact. The usual primary helix 

 of large wire and the interior bundle of iron wires are placed within the glass 

 tube. 



In my last instrument, I used a tube closed at the top, more effectually 

 to cut off the passage of the current from one end to the other, through the 

 primary helix or iron wires. I have used a Bunsen's battery of four to six 

 cells ; four give the spark of as great length, but a few more cells increase 

 the volume. I have applied a battery of eighteen cells and also a plate bat- 

 tery of fifty-six pairs without endangering the coil. The instrument is un-* 

 doubtcdly capable of being greatly increased in size and power. 



Since writing the above, Mr. Ritchie further states : I have constructed 

 a helix in which the plane of the strata of wires is perpendicular to the tube, 

 insulated as before. With one of the same length of wire as the largest one 

 before mentioned, throwing a spark, with six cells, six inches, I have 

 used a battery of eighteen cells, (Bunsen's) ; but by using a battery of three 

 series of six cells (that is, an intensity of six, and quantity of three), a very 

 voluminous spark was obtained ; as the action soon became feeble, I took 

 the secondary coil from the glass cylinder and found that the current had 

 passed through the glass near each end of the coil, forming a circuit through 

 the primary wire ; two minute holes, of a hair's breadth, from one-tenth to 

 onc-3ighth inch diameter, were drilled through, but the glass was not frac- 

 tured ; it also passed through several thicknesses of vulcanized rubber. The 

 helix was uninjured, proving the insulation obtained by the mode of wind- 

 ing it. A more perfect insulation between the helices is readily made ; and 

 I now use a tube of gutta pcrcha over the glass. With powerful batteries 

 the condenser of varnished paper is not sufficient, as the current passes en- 

 tirely through, and with such I use oiled silk. I have put several condens- 

 ers in the same instrument, connecting each by turning a screw, so that 

 either or all can be used. Varied and beautiful effects are produced, par- 

 ticularly in vacuo, by using different amounts of surface of condenser. 



At an exhibition of this apparatus before the American Association at its 

 last meeting, the various phenomena of electrical light, were developed with 

 a splendor rarely if ever equalled. In a subsequent discussion, Professor 

 Henry observed that the phenomena developed by this machine indicated 

 that electricity is only a polarization of matter, all of which is capable of one 

 of the two forms of polarization one by friction and one by magnetism ; 

 and the polarization of ponderable matter draws a line between electricity 

 and magnetism. 



14 



Y 





