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 
mereury 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. 
