J. J. Minot—Spark Adjuster for the Holtz Machine. 495 
be varied at pleasure. With this arrangement the following 
results were noted. At first the conductors were placed in con- 
which was used was 20 cm. ‘The sparks so obtained were - 
ar result was obtained. When the Se cae were but a few 
be readily studied. In experimenting upon the passage of the 
se thiongh different ee we can, by this method, diminish 
from the spark disch to that of the brush. The change in 
tone of the sound of the discharge when the distance between 
the pointers is varied is quite mark 
