C. G. Rockwood—Notes on Earthquakes. 289 
discovered vast lakes and waters which have proved to be those 
of the higher Congo. Burton and Speke opened the way from 
the West Coast, which Speke and Grant pursued into and down 
the Nile, and Stanley down the course of the middle and lower 
Congo; and the vast extension of Egyptian dominion has 
brought a huge slice of equatorial Africa within the limits of 
semi-civilization. The western side of Africa has been attacked 
at many points. Alexander and Galton were among the first 
to make known to us its western tropical regions immediately 
to the north of the Cape Colony ; the Ogowé has been explored ; © 
the Congo promises to become a center of trade, and the nayi- 
gable portions of the Niger, the Gambia, and the Senegal are 
familiarly known. 
he progress of discovery in Australia has been as remark- 
able as that in Africa. he interior of this great continent 
was absolutely unknown to us fifty years ago, but is now 
crossed through its center by the electric telegraph, and no 
Inconsiderable portion of it is turned into sheep-farms. It is 
an interesting fact that General Sabine, so long one of our most 
active officers, and who is still with us, though, unfortunately, 
his health has for some time prevented him from attending our 
meetings, was born on the very day that the first settler landed 
in Australia. 
[To be continued. ] 
Art. XL.—WNotes on Earthquakes; by C. G. Rockwoop. 
= an extended series of shocks. This Island lies off the 
ulf of Smyrna in the Grecian Archipelago and is about 
thirty-two miles long north and south, by about eighteen miles 
wide. It is separated from the mainland by a strait seven or 
eight miles wide and had about 50,000 inhabitants. The first 
and most violent shock occurred at 1.40 Pp. M. on Sunday, April 
3d, and lasted ten seconds. It was followed by a second at % 
P.M. and a third at 3 P. M. of the same day. The ground was 
then quiet until sunset, when the shaking recommenced and 
continued with such frequency that up to April 5th two hun- 
dred and fifty shocks had been counted; of which thirty or 
forty were of sufficient strength to overthrow walls. Other 
Shocks, often severe, occurred from time to time up to May 
20th. An especially severe one, lasting four seconds, occurred 
on April 11th. The violent shoeks with which the disturbance 
