New Evidence, etc. 387 



individually less effective, but they are far more numer- 

 ous. 



In order to eliminate these disturbing effects the work 

 should be done in a room below the surface of the earth, 

 the walls, ceiling and floor being of metal. Insulated 

 copper wires within copper tubes should be connected 

 with the masses. Those connected with the suspended 

 masses should terminate in a cup of mercury. A flexible 

 chain of metal attached to the middle of the bar carrying 

 the suspended masses, should be provided at its lower 

 end with a fine platinum wire, making contact with the 

 mercury surface. These protected copper wires should 

 be grounded in a well of water. The water in this well 

 must be protected from any inductive action of the atmos- 

 phere. 



The continuation of this work has been made possible 

 by the financial assistance, formerly acknowledged, of the 

 Carnegie Institution of Washington, and by the granting 

 of every needed facility by Washington University. 



Issued March 2 1920. 



