18 F. D. Chester—Bowlder Drift in Delaware. 
effects of a heavy rain-fall in southern Europe, and in the 
southern part of the United States. In both countries the 
influence of a great rain-fall upon a center of low pressure is 
generally not very decidedly marked; while in the northern 
part of the United States, this influence is generally quite 
obvious and decided. In the United States, the parallel of 36° 
generally forms a satisfactory dividing line between these two 
classes of cases; but in Europe this dividing line is found in a 
of the center of low pressure more than four times as frequently 
as it did on the west side; the rain-center was found in the 
northeast quadrant as frequently as in the southeast quadrant ; 
the cases of one inch rain-fall in the northwest quadrant were 
only three in number, and in neither of these cases was the 
rain-center distant from the center of low pressure more than 
150 miles. For all the cases in 1880 in northern Europe, the 
average distance of the rain-center from the center of low pres- 
sure was 420 miles, and the average pressure at the center was 
740 millimeters or 29°13 inches. 
Art. I.—On Bowlder Drift in Delaware; by F. D. CHESTER. 
ABOUT two miles to the south of Newark, Delaware, on the 
line of the Baltimore & Philadelphia Railroad, there rise above 
the level of the plain two hills, which, uniting with each other, 
trend in a nearly east and west direction. Their total length 
is about two miles, their breadth one mile, and their height 
between two and three hundred feet. 
glacial field. 
From Newark to Wilmington, running across the northern 
part of Delaware, is a chain of hills made up of the highly 
tilted gneissic rocks ; this chain marks the southern boundary 
