228 E. S. Snell on the Waterfall at Holyoke. 
place, ca also these fragments, almost as firmly fixed by frost 
s themselves. On examination, a few of the pieces 
were fond to be jeunes on the under surface also. In one or 
two cases the strie on opposite sides were nearly parallel, but 
generally inclined at a considerable angle. 
Probably these fragments were at first embedded in the glacier 
and received, while in that position, the scratches on their under 
surface, but were subsequently detached from the glacier, em- 
bedded and frozen in the clay, where they were reduced to the 
condition in which they were found. 
t may not be amiss to remark in conclusion, that strize are 
abundant upon the surface rocks of this region, their direction 
varying from 1° to 11° east of south. The most durable bould- 
ers generally exhibit upon one or more of their surfaces distinct 
traces of the same abrading ue 
Miami University, June 11th, 1 
ART. nig a age in the Waterfall at aoe Mass.; by 
Prof. E. S. SNELL, Amherst College 
AT the meeting of the American Scientific Association held in 
Montreal, August, 1857, I read a paper on the vibrations of the 
fall at Holyoke, in which I attributed the movement to the rare- 
faction of air in the tube behind the sheet, this ty nto being 
Since the ~euiitie of the rrerat mentioned paper, I have ob-’ 
served the condition of the fall at four different times. In Octo- 
very nearly, which I had previously reported. But on the 16th 
of April, 1859, I found the water four or five feet deep on the 
edge of the dam, the temperature of the air about 45°, and the 
number of oscillations only eighty-two per minute. Again, on 
the 25th of July last, I found the water lower than I had seen it 
before, (less than three inches deep,) and no vibrations, either in 
‘the Sie or the air at the end of the cavity behind it. 
are, therefore, at least three very different rates. of vibra- 
mane the slowest when the depth of water is 
