264 Mr. J. Wimshuret 



on a 



But there is another ground on which this course is seen to 

 be for him entirely illogical. For though his having taken it is 

 an admission that he regards the proposition in question as 

 incapable of deduction, he has been hasty in reaching this 

 conclusion. We have seen that, in order to maintain complete 

 transformation during tranference, he has confessedly to 

 assume that bodies consist of massive particles without elas- 

 ticity, and that the medium is elastic but without inertia. 

 Now, as pointed out in my paper (p. 141) : — "That energy 

 cannot be transformed without being transferred must of 

 course be true if bodies consist of particles with inertia but 

 without elasticity, and if the medium connecting them possess 

 elasticity but not inertia.''' This is surely quite obvious. 

 Hence with the assumptions already made by Prof. Lodge 

 the proposition under consideration is capable of deduction. 

 For him therefore it cannot be an axiom. 



For those of us who do not hold to his theory of the con- 

 stitution of bodies and media, the proposition is of course not 

 capable of deduction. Whether or not we are to regard it as 

 axiomatic must depend on whether or not it may be shown 

 to be capable of coordinating dynamical phenomena generally. 

 Edinburgh, July 21st, 1893. 



XXIY. A New Form of Influence-Machine. 

 By James Wimshurst*. 



IN April 1891 I had the honour to submit to this Meeting 

 a very useful form of experimental Influence-machine, 

 by means of which I was able to show that almost every 

 combination of glass and metal, and also that plain glass 

 disks, when moved and suitably touched, were capable of 

 producing a flow of electricity. 



It is one of those combinations, somewhat modified and 

 extended, which I have now the further pleasure of bringing 

 to your notice. 



The machine consists of two disks of plate-glass, each of 

 3 ft. 5 in. diameter and J inch thickness, mounted about f inch 

 apart on one boss and spindle. This spindle is driven by 

 means of a handle, and the disks rotate in one direction. 



In the space between the disks are fitted four vertical slips 

 of glass, two being situated on the right-hand side of the 

 machine and two on the left-hand. 



The vertical edges of the slips which come nearest the 

 spindle are cut to an angle, leaving a rather wider opening 



* Communicated by the Phvsical Society : read June 23, 1893. 



