M. E. Stohrer on an Improved Induction Apparatus. 61 



mities with platinum points. They may be caused to approach 

 each other up to contact, and they can be diverted so that a pomt 

 shall stand opposite a disc, or both discs opposite to each other. 

 In addition to the conducting wires which proceed from the 

 induction coils, several wires for the passage of the current for 

 other purposes may be attached to the discharger. 



5. The condenser is known to be a very important part of 

 the apparatus. Prof. Poggendorff and M. Sinsteden have already 

 proved that it may be constructed in different ways. It is 

 important to arrange it so that it may be used to increase or 

 diminish the extent of charged surface. One attempt to con- 

 struct the condenser in this manner I pass over, because no 

 <rood result was obtained, at least it did not produce the effect 

 of an ordinary wax-cloth condenser of the same surface. Never- 

 theless I have not found the fear expressed by M. Sinsteden, 

 that the wax-cloth condenser would be easily broken through 

 by the sparks when the excitement is intense, fulfilled. In the 

 drawer iNl is an ordinary wax-cloth condenser 8 Par. feet long, 

 built into layers separated from each other by varnished par- 

 titions, and connected with the binding screws which stand at 

 the front of the drawer. The attempts to construct a condenser 

 out of single pairs of plates I have not yet given up, as it pos- 

 sesses great advantages. The condenser of M. Smsteden, formed 

 of plates of glass, fulfilled indeed its object ; I believe, however, 

 that on account of the thickness of the glass, it must have a 

 greater surface than the wax-cloth condenser; and besides this, 

 such a condenser is very fragile, as the thinnest glass must be 

 made use of, and the plates, though in a drawer, must be per- 

 mitted to stand free. 



6 Experiments with the apparatus gave a development ot 

 induced currents which, to my knowledge, has never been 

 attained hitherto. The change of the sparks passing between 

 the platinum points of the discharger, when the condenser is 

 introduced, is very striking. While without the condenser the 

 sparks are very slender, are but feebly luminous, produce a fine 

 crackling noise, and reach a length of only 5 or G hnes,they imme- 

 diately assume awhollydifferent characterwhen the condenser, one 

 side of which is in connexion with the lever C, and the other with 

 the copper spring J, is introduced. The sparks become more mas- 

 sive • they are at least four times as wide, and surrounded by 

 coloured fringes; the report is loud, particularly when those oi 

 creater length and rarer occurrence spring over When the room 

 is rendered dark, a brush of electricity, like that of the electric 

 machine, is seen streaming from the points of the discharger, 

 the positive being easily distinguished from the negative, ijy 

 the application of one or two of Bunsen's cells, sparks are oh- 



