428 M. W. Holtz on a new Electrical Machine. 



repelled, while + E collects on the disk, and the latter must 

 again be partially bound, during half a turn, until it comes to a 

 notch and the points of the first coating. Thus it is seen that 

 the one coating charges the other, and it is a question whether 

 these charges will gradually decrease or increase. 



Under the influence of the charge which the rotating disk 

 acquires, the quantity of the electricity on the coatings is resolved 

 into that which is bound and that which is free. If the indu- 

 cing action is very slight, the charge can be so small that its 

 intensity is at first less than the intensity of the latter. If the 

 inducing action is greater, the losses which occur during rota- 

 tion may become so considerable that after half a turn this is 

 still the case. If the glass disk has become more feebly elec- 

 trical than the points of the coatings, the former are not electri- 

 fied by the latter, but the latter by the former. With the dis- 

 appearance of the free E the inducing action is smaller, the 

 charge which the rotating disk assumes, and its inducing action, 

 become less and less ; the induced electricity becomes more and 

 more free, and that which has become free will again disappear : 

 the charges of the coatings must therefore be continually less- 

 ened. But if the glass surface at the notches is more strongly 

 electrical, it must inversely gradually acquire higher and higher 

 charges as long as the insulation permits an increase. The latter 

 is limited by the position of the conductors, and by the attrac- 

 tion which is simultaneously exerted by them on the electrical 

 surface. This attraction is strongest if the circuit is not open, for 

 then it is to be regarded as a body in connexion with the ground. 

 The more completely the circuit is opened, the more will the 

 attraction diminish, since there is on the conductors a continu- 

 ally higher tension which is of the same kind as that of the 

 glass. The tension on the coatings will increase as long as their 

 mutual distance, or the distance from the notches opposite them, 

 permits. From a certain point a discharge takes place through 

 the air. But this point need not be reached within the limits of 

 the striking-distance. 



If we consider more closely the current in the circuit, we shall 

 see that it consists of two currents which are different but in the 

 same direction. One is formed by induction, by the glass disk 

 being continually charged afresh ; the other is formed by the li- 

 beration of this charge, of which only a small part is necessary 

 to retain the tension on the coatings. If we suppose these cur- 

 rents, of which I will call the former the primary, and the latter 

 the secondary, to be separated, they must be different, both 

 quantitatively and in their maximum striking-distance. In the 

 first respect the primary will exceed the secondary, because the 

 charge of the disk is materially weakened during half a turn ; 



