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LXI. An Influence-Machine. By W. R. Pidgeon, M.A* 



ON June 23rd, 1893, I showed an influence -machine at a 

 Meeting of this Society, which was described in the 

 Phil. Mag. for September 1893, but which had the disadvan- 

 tage of being an expensive machine to make. I now show a 

 form of machine which not only gives better results, but is 

 both cheap to manufacture, and has qualities which may, I 

 think, interest the Members of this Society, especially in 

 regard to its suitability for exciting Rontgen-ray tubes. 



The machine consists of one or more pairs of glass disks 

 mounted on a spindle and running in opposite directions, 

 with earthing-brushes arranged similarly to a Wimshurst 

 machine. The disks are of ordinary glass, and are covered 

 with sectors about an inch or an inch and a half wide at the 

 circumference, and placed about one-eighth of an inch apart. 

 These sectors stand radially, and each carries a small brass 



contact-knob K. The disks are covered with w r ax composed 

 of half paraffin and half rosin by weight. The wax covers up 

 and insulates the whole of each sector except the small brass 



* Communicated by the Physical Society : read Oct. 28, 1898. 



