EXPERIMEN ES TN TC MOTION. 925 
Oimthe wax the sevidence On two cunents so clear im Figs 2's 
obscured, as shown in Fig. 6. A close examination, however, 
reveals their continued presence. 
In the case of an escarpment or obstruction with a subsequent 
declivity the basal layer is continued out into the wax from the 
top of the escarpment or obstruction as a narrow line. Fig 48. 
Fic. 10. 
The part continued in the line is, possibly, the part noticed in 
Fig. 2, adhering to the face and top of the obstruction while its 
main current can be seen rising in an arch behind. The same 
feature is less prominently shown in the experiments where lines 
were used instead of the basal layer of darkened wax. Another 
point to be emphasized is the arch-like course taken by the 
upper and principal current. Rising abruptly a little way back 
from its front the currents extend to a considerable distance in its 
rear, where they descend in a much more gentle curve towards 
a point much farther from the escarpment than it originated. 
At all points it is free from contact with the escarpment. This 
