112 
MESSRS. W. DE LA RUE AND H. W. MULLER ON THE 
two deflections are very different, it is advantageous to balance tbe swing with the tube approximately 
by a less number of cells, and to calculate the tube-potential with the fresh data. 
In order to prevent worrying oscillations of the needle a slight but important change is made in the 
attachment of the damper to the needle. Sold_ered rigidly to the needle is a _L-shaped wire, to the hori¬ 
zontal ends of which is hung a Y-shaped wire to form a hinge; to the vertical projection of the Y are 
attached three cross-wires which dip into the acid, forming in this way a damper as well as a conductor. 
As the damper is rigidly connected to the needle in the plane of the swing it moves steadily, and its 
extreme swing may be taken for the reading. 
The inducing and induced plate are both 4 inches in diameter, and may be made to touch or be separated 
a distance of 7 inches, 
Fig. 89. 
The following readings were obtained with tbe plates 4 inches apart; the quadrants charged to a 
potential of 20 cells :— 
