1888.] on Electrical Influence Machines. 305 



several friends were present to witness the fitting of the brushes and 

 the first start. When all was ready the terminals were connected to 

 an electroscope, and the handle was moved so slowly that it occupied 

 thirty seconds in moving one-haK revolution, and at that point violent 

 excitement appeared. 



The machine has now been standing with its handle secured for 

 about eight hours ; no excitement is apparent, but still it may not be 

 absolutely inert ; of this each one present must judge, but I will con- 

 ne<?t it with this electroscope, and then move the handle slowly, so 

 that you may see when the excitement commences and judge of its 

 absolutely reliable behaviour as an instrument for public demonstra- 

 tion. I may say that I have never under any condition found this 

 type of machine to fail in its performance. 



I now propose to show you the beautiful appearances of the dis- 

 charge, then the length of sparks, which appear to be almost con- 

 tinuous, and then in order that you may judge of the relative capa- 

 bilities of each of these three machines, we will work them all at 

 the same time. 



The large frictional machine which is in use for this comparison 

 belongs to this Institution. It was made for Xapoleon in 1S22, and 

 its great power is so well known to you that a better standard could 

 not be desired. 



These five Leyden jars are of equal size ; I will connect one of 

 them only to the large frictional machine, while I connect two jars 

 to each of the two large machines of the influence type. The 

 difference in power of the machines is then seen to be very marked. 

 The exhibition may be considered as a miniature thunderstorm with 

 almost no intermission between the lightning flashes. 



In conclusion I may be permitted to say that it is fortunate I had 

 not read the opinions of Sir William Thomson and Professor Holtz, 

 as quoted in the earlier part of my lecture, previous to my own prac- 

 tical experiments. For had I read such opinions from such authorities 

 I should probably have accepted them without putting them to prac- 

 tical test. As the matter stands I have done those things which they 

 said I ought not to have done, and I have left undone those things 

 which they said I ought to have done, and by so doing I think you 

 must freely admit, that I have produced an electric generating 

 machine of great power, and have placed in the hands of the physicist, 

 for the purposes of public demonstration, or original research, an 

 instrument more reliable than anything hitherto produced. 



[J. W.] 



