188 Trans. Acad. Sci. of St. Louis. 
At 10:25 a. m., June 2, readings were taken until 10:43 
a.m. The suspended masses were at rest. 
The positive terminal was then applied. The result is 
shown in Plate : 
The arrangement of the apparatus was that shown in 
Fig. 3. A sudden decrease in the attraction occurred. It 
was so sudden that forced vibrations were impressed 
upon the suspended masses. The vibrations were small, 
and only occasional readings of consecutive extremes 
were recorded. At 2:20 p. m. the terminals were re- 
versed and at 2:32 p. m. direct contact of the pin-point 
conductors and the large masses and shield was made. 
The attraction at once increased very rapidly. The ab- 
solute zero of potential was reached and passed in a less 
time than that of a semi-vibration. Forced vibrations 
were impressed upon the suspended masses as the at- 
traction began to decrease. These vibrations were ob- 
served, and the extremes were read until 3:30 p.m. The 
masses were then being repelled by a force nearly twice 
as great as the initial gravitational attraction. Direct 
contact between the discharge points was removed, but 
the masses were not grounded. On Monday, June 4, at 
9:20 a. m., the masses were vibrating over a very small 
are (about one scale division). Readings were taken at 
some of the extremes of vibration, which were sufticient 
im number to show that the mean reading was constant 
until 11 a.m. These readings are represented in Plate 
XLVI. The masses were still repelling each other, with 
a force about 50 per cent. greater than the initial attrac- 
tion on the morning of June 2. This conclusion seemed 
beyond belief at the time but subsequent results on that 
day seemed to make it a necessary conclusion. At 11:03 
a.m. the positive terminal was applied and direct con- 
tact between the large masses and the pin-point con- 
ductors of Fig. 3 was made. The time is represented by 
the arrow marked + D.C. on Plate XLVIL 
At once the attraction began to increase. The masses 
were swaying in the opposite direction at the time when 
