POLYTECHXIC ASSOCIATION PROCEEDINGS. 1001 



with a view of increasing its electrostatic powers. Du Moncel, the 

 author of a special treatise on the Ruhmkorff coil, says that 

 " Ruhmkorff, profiting by the experiments and observations of, 

 Masson & Breguet, sought to provide for a better insulation of 

 the wire of the secondary circuit, and to prevent the loss of static 

 electricity;" and, to accomplish this, he "drowned" the wire in 

 shellac. The fine wire coils were very long — in some cases even 

 ten miles. He also increased the dimensions of the coil length- 

 wise, or in the direction of its axis, and diminished its tranverse 

 diameter, in comparison with coils that had generally been made 

 in Europe. In fact, they were made more according to the form 

 of Prof. Page's coils. The terminals of the secondary wire were 

 attached to glass pillars, and the circuit was broken by the Mc- 

 Gauley circuit-breaker, heretofore described. With this apparatus, 

 Euhmkorff obtained sparks in air about one-eighth of an inch long, 

 and very beautiful luminous eflects in vacuuo. Sparks could be 

 taken from either extremity of the secondary wire alone, and the 

 shocks were dangerous to encounter. Subsequently, Fizeau dis 

 covered that' the connection of a condenser with the primary coil 

 had the efiect of suddenly arresting the secondary current of this 

 coil, and to greatly increase the intensity of the current of the 

 secondary wire. At his suggestion it was applied to the Ruhmkorff 

 coil, and at once gave it a celebrity which, perhaps, otherwise it 

 might not have attained. This coil was announced in this country, in 

 SiUiman's Journal, by Prof. J. Nickles, in 1853 (vol. 15, page 114), 

 and excited but little interest at the time. The editors of the Jour- 

 nal added, in a foot note to this communication, that "there were 

 many points of resemblance between the apparatus of M. Ruhm- 

 korff and the compound-magnet and electrotome of Dr. Page, whose 

 apparatus appeared to be but little known in Europe." And, in 

 reference to the circuit-breaker described by Nickles, the editors 

 said, that " this apparatus is very nearly indentical with the vibrating 

 armature breakpiece of Dr. Page and Daniel Davis, for more than 

 ten years in use in all the forms of electro-medical apparatus. The 

 American contrivance has the additional convenience of an easy 

 adjustment for the rapidity of its vibrations." 



In the latter part of 1854 and beginning of 1855, Poggendorff 

 published the results of his experiments with Ruhmkorff's coil, 

 and suggested several modifications, none of which, however, 

 seem to have been of much practical importance, except that 

 of making the secondary coil, in several sections, to avoid the 



