417 
horse power. In order to obtain constant potential differences the 
W the Wimshurst, EE the electrodes, 
N the needle-systems, H the wooden 
stick, F,; and F, Leyden jars, Br, 
and Br, electrometers of BRAUN, 
R‚. R, and Rs clamps of a key, G 
the condensator vessel. 
two electrodes were connected with 
two needle systems in front of each 
other, while further a large resi- 
stance, a small wooden stick, was 
inserted between one electrode of 
the electrical machine and one of 
the plates of the condensator vessel. 
The other electrode and the other 
plate were earthed. Moreover a 
Leyden jar of great capacity had 
been conneeted in parallel with the 
condensator vessel. In this way 
satisfying results were reached. 
When during the research it proved 
to be necessary, that two different 
potential differences could be worked 
with soon after each other, the 
arrangement was altered a little bit. 
It now became as is shown by fig. 2. 
For experiments with an alter- 
nating field I could dispose of two 
transformators. One of these trans- 
formators (Tr,) could transform the 
tension of the municipal net of 
110 volt to 10.000 volt, the other 
(Tr,) to 50.000. 
If in the case of an alternating 
ER | Ree at 
Wz 
= Wi 
ANW 
Fig. 3. 
K clamps of the trarisformatorboard, S, and S, switches, W, large 
resistance, W‚ small (lamp-) resistance, Tr transformator. 
field observations at different potential differences had to be made 
soon after each other, the arrangement of fig. 3 was used. Here the 
primary circuit only has been indicated; the condensator vessel 
27 
Proceedings Royal Acad. Amsterdam - Vol. XIX 
