THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



DECEMBER 1880. 



XL VI. The Disruptive Discharge of Electricity . 

 By A. Macfaelanb, M.A., D.Sc, F.R.S.E* 



[Plate XI.] 



AT intervals during the last five years I have carried on a 

 research on the disruptive discharge of electricity ; and 

 the results obtained have been printed in the Transactions of 

 the Royal Society of Edinburgh*. I propose in this paper to 

 give a summary of the results. The experiments were made 

 principally in the Physical Laboratory of the University of 

 Edinburgh, where I had the ever-ready advice of Professor 

 Tait ; and in making the observations I had the assistance of 

 several gentlemen, particularly of Mr. R. J. Simpson, M.A., and 

 Mr. P. M. Playfair, M.A. 



The method adopted can be readily explained with the help 

 of the woodcut (fig. 1), which represents the apparatus in situ. 

 The electricity was furnished by means of the Holtz machine, 

 which had one conductor (generally the negative) always earthed 

 by means of a wire, and the other conductor connected with the 

 rod passing through the neck of the air-pump receiver. The 

 diameter of the receiver is 19 centimetres. The electrodes 

 were in general circular disks ; and the one was screwed on to 

 the rod mentioned, the other to a short rod normal to the plate 

 of the air-pump, and in conducting connexion with its metal 



* Communicated by the Author. 



t Vol. xxviii. p. 633, and vol. xxix. p. 501 ; Proceedings, x. p. 555. 



Phil Mag. S. 5. Vol. 10. No. 64. Dec. 1880. 2 F 



