82 Mr. Christie on the mutual action of 
nearly measure the quantity developed on each side of the 
axes of the magnets. The measure, therefore, of the mag¬ 
netism developed when the magnets revolved with their axes 
under the edge of the disc, if continuity produced no accumu¬ 
lating effect, ought certainly not to be less than 2091 ; but as 
it is actually only 680*5, it vvould appear that the continuity 
of mass on each side of the axes of the magnets has the effect 
of increasing the quantity of magnetism developed at least in 
the ratio of 3 to 1. 
The results which I obtained by making a circular cut in 
the disc, lead to a similar conclusion. In this case, the mag¬ 
nets were again adjusted to the distance 3*7 inches from the 
axis of rotation, and the times in which the disc completed 
successive revolutions was noted as before. A circular cut 
through the disc was now made at the distance of an inch 
from its edge, excepting for an inch at the extremities of two 
diameters at right angles to each other, as in fig. 1 ; after 
which the time at the completion of the revolutions was noted. 
The same was done when the disc was cut, as in fig. 2 ; and, 
finally, as in fig. 3 ; in which case tissue paper was placed 
between the ring cut off and the interior disc. 
Fig.l. i^.2. n^.3. 
The results are arranged in the following Table : 
