Corrcspondoi-ce. 
193 
The cause of this cusp and connected bar was for long time a 
puzzle to me, as the direction and force of the feeble currents and 
prevailing winds did not seem to offer a satisfactory explanation. 
Finally, however, the true cause seemed to be found in the waves 
formed four times a day by the passage of the regular steamers upon 
the lake. The waves formed in this way were by far the heaviest 
waves that struck this shore during the summer, far exceeding in their 
action those produced by the hardest winds during that period. 
As will be seen from the accompanying sketch (Fig. i). the course 
of the steamers makes a shaip bend of nearly ninety degrees just 
•about opposite the angle of the cusp, in order to get into and away 
from the Hague landing. From observation it was seen that while a 
steamer was on the course from A to B the waves reached the shore 
as breakers moving along the lines r, s, t, picking up and carrying 
inward the fine bottom material upon the shelf surrounding the delta. 
Soon after these waves reached the shore and while they were still 
running near their greatest bight, the waves from the steamer on the 
course B to C. after turning at B, reached the shore along the lines 
m, n, o, at an angle of nearly ninety degrees with the first set of waves, 
producing an interference along the line of the straight bar running 
out from the angle of the cusp. This retarding of "the waves al- 
