CO. G. Rockwood—Notes on Earthquakes. 257 
Art. XX V.—On Sandstones having the grains in part Quartz 
Crystais; by Rev. A. A. Youne, of New Lisbon, Wisconsin. 
In the Potsdam sandstone of the ents of New Lisbon, 
Wisconsin, and the St. Peters sandstone of Grant County in 
the same State, I have found many of the quartz grains to be 
true quartz cry stals with polished faces. On mounting some of 
the grains in pang and then examining them with the micro- 
scope, many were f ound to have well-defined nuclei of varying 
sizes, proving that the crystalline form was produced by the 
. finishing out of original irregular grains of the sand-bed, auch 
are now the kernels of the crystals, thus according with obser- 
vations by Mr. Sorby, as described in his Presidential address, 
of 1880, before the Geological Society. Some of tlie kernels are 
quite translucent, others nearly opaque, and occasionally one 
has a needle of rutile (?) which does not extend beyond. 
XXVIL—WNotes on American Earthquakes: No. by 
se rca C. G. Rockwoop, Jr., Ph.D., Princeton, N. ‘S 
THIS article embodies such information as the author has 
obtained in regard to the earthquakes which occurred upon the 
American continent and adjacent islands during the year 1881, 
with notice of some earlier shocks not previously reported. 
Items which depend upon single sources of information have 
their source indicated, and if regarded as doubtful are printed 
in smaller t type. 
or assistance in collecting information the author is 
indebted to J. M. Batchelder, Esq. of Boston, to President J. 
W. Dawson, of Montreal, and to the Superintendent of the 
Meteorological Service at Parone. The Monthly Weather 
Review of the U. S. Signal Service has also furnished valuable 
information. 
1880. 
Sept. 28.—6 p. . . Mah shocks on the island of Uka- 
mok, Alaska (55° 48’ N., 4’ W.); the first in north-south 
direction, the others westeast; 4 p. M., severe shock from W. to 
K. th, 3 A. M. and 1 heavy shocks tie W. to E. 
e commencement es this phenomend, Sept. 28th, until 
its eubaidenog Oct. 16th, there was an ep hencht tremblin ng 
motion of the earth, interspersed with heavy, subterranean, rum- 
bling sounds. During a short trip over a portion of the island, 
on Sept. 29th, ancy fissures, a width ie from ee. to 
twenty inches s were found to be very numer The abov 
pels ae ee sae ae tomate at that time a dat of the a 
