248 



Sir David Salomons on the Electric 



spark from the secondary, because no large amount of current 

 can traverse the primary coil. 



Ffe. 1. 



But there is a point in favour of using an induction-coil such 

 as described which does not appear to have been taken ad- 

 vantage of. The spark at the vibrator is far more pronounced 

 than if a lower electromotive force were employed for the 

 primary current. Indeed, so much energy can be developed 

 at the vibrator on the " break " that it is possible to obtain 

 the equivalent to a direct intermittent current in the tube, or 

 at any rate, so far as the eye is concerned this only exists, the 

 effects due to the current in the opposite direction not being- 

 visible. Consequently two types of current can be produced 

 by means of the induction-coil. 



