Nipher—Magnetic Disturbances. 161 
negative electrons moving in the same direction as the ex- 
plosion. In other cases the explosion was not complete. 
In many cases not more than six or eight inches of the 
column would explode, and the results were conflicting. 
In the two cases above referred to the deflection was in 
one case 51 minutes of are and in the other 54. 
It was found that vibrations of the trough, or breaking 
of the bars into long and large fragments which were 
not detached from it resulted in disrupting the column 
of dynamite. It was found that large rocks hung from 
the trough had a tendency to keep it in stable position 
and prevented the vibrations. 
It has since been found that when the dynamite is 
slowly poured into a long rubber tube, which is gently 
tapped in order to make the column continuous, the ex- 
plosion can be made complete. The tube must be hung 
in a vertical position while being filled. This work on 
the convection current is in an unfinished condition. 
