1893.] Presents. 461 



rotational sether has been essayed by Mr. Heaviside, who found it to 

 be unworkable as regards conduction- current, and not sufficiently 

 comprehensive ('Phil. Trans.,' 1892, 16; 'Electrical Papers/ vol.2, 

 p. 543). A method of representing the phenomena of the electric field 

 by the motion of tubes of electric displacement has been developed 

 by Professor J. J. Thomson, who draws attention to their strong 

 analogies to tubes of vortex motion (" Recent Researches . . .," 1893, 

 p. 52). 



Professor Oliver Lodge has kindly looked for an effect of a 

 magnetic field on the velocity of light, but has not been able to detect 

 any, though the means he employed were extremely searching ; the 

 inference would follow, on this theory, that the motion in a magnetic 

 field is very slow, and the density of the medium correspondingly 

 great. December 18, 1893.] 



IV. " On Copper Electrolysis in Vacuo" By WILLIAM GANNON, 

 M.A. Communicated by Professor SCHUSTER, F.R.S. Re- 

 ceived November 14, 1893. 



[Publication deferred.] 



V. " Note on the Action of Copper Sulphate and Sulphuric 



Acid on Metallic Copper." By ARTHUR SCHUSTER, F.R.S. 

 Received November 14, 1893. 



[Publication deferred.] 



VI. " On a Chart of the Symmetrical Curves of the Three-Bar 

 Motion." By W. BRENNAND. Communicated by C. B. 

 CLARKE, F.R.S. Received November 17, 1893. 



Presents, December 7, 1893. 

 Transactions. 



Baltimore: Medical and Chirurgical Faculty of the State of 

 Maryland. Transactions. 94th Annual Session. 8vo. Balti- 

 more 1892. The Faculty. 

 Batavia : Koninkl. Natuurkundige Vereeniging. Natuurkundig 

 Tijdschrift. Deel LII. 8vo. Batavia 1893. 



The Society. 



Berlin : Gesellschaft fur Erdkunde. Zeitschriffc. Bd. XXVIII. 

 No. 3. 8vo. Berlin 1893. The Society. 



