37 
Feb. 6.—Matthew Dawes, Esq. of Southwield, Bolton ; Capt. 
Alexander, H. P. Royal Staff Corps, Acre’s Fold, Suffolk; John 
Cunningham, Esq., Hope Street, Liverpool; and S. R. Pattison, 
Launceston, were elected Fellows of this Society. 
A paper ‘“‘ On a probable Cause of certain Earthquakes,” by 
M. Louis Albert Necker, For. Mem. G. S., was read. 
The object of this memoir is to show, that some earthquakes may 
be due to the falling in of the roof of cavities, produced by the sol- 
vent or erosive powers of subterranean bodies of water on beds 
and masses of gypsum, rock salt, limestone, marl, clay or sand. 
M. Necker was induced to enter upon the inquiry in conse- 
quence of the earthquake which desolated, in 1829, a considerable 
part of the country on the banks of the Segura, in Murcia, having 
occurred in a district, which is stated to contain no volcanic or trap- 
pean rocks; and because the event was unaccompanied by any of 
those phenomena which, he conceives, precede, attend, or follow 
true volcanic earthquakes. 
Of the places where earthquakes have been felt without there 
being any traces of volcanic or trap rocks, but where gypsum is 
known to occur, and in which, from that mineral being, in his opi- 
nion, of comparatively easy renewal, he supposes, caverns exist, M. 
Necker more particularly mentions Bale, Nice, Navarroux, Oleron, 
Maulen, Bagnorre de Bigorre, and the Gave Maulen, in the Py- 
renees ; he also alludes to the shocks which were felt at Clanssaye, 
near St. Paul-trois-Chateaux; in the department of the Drome, 
from the Ist of June, 1772, to the end of December, 1773, and he 
states, that though Clanssaye stands upon a tertiary deposit, yet 
it is probable that the gypseous formation of the hills to the east- 
wards having a westerly dip may pass beneath it: likewise to the 
earthquakes which affected Kronstadt in Transylvania, Odessa, 
Bucharest, Lembourg in Gallicia, and Kieff, with other towns in that 
part of Russia, early in 1838, and in the vicinity of which gypsum 
is believed to exist. Among the limestone tracts, in which caverns 
abound, and earthquakes are not unfrequently felt, M. Necker enu- 
merates Fiume, Buchari, Trieste, Lissa in the Adriatic, and Foligno. 
In the above instances M. Necker supposes, that cavities having 
been formed by the action of bodies of water, the roof gave way, 
and, falling upon a solid floor, produced in the strata a motion 
which extended laterally and vertically, and gave rise to the pheno- 
menon of an earthquake. He is further of opinion, that air con- 
fined in the caverns being also set in motion by the subsidence of the 
roof, would cause undulations in the overlying strata. To illustrate 
his views, M. Necker described the vibrations produced in the walls 
of a house which he occasionally inhabits at Geneva, by the blows 
of a blacksmith’s hammer upon an anvil placed in a vault, and 
these vibrations always appeared to him completely analogous to 
the motion which he experienced in the same room during the earth- 
quake on the 19th of February, 1812. He likewise stated, that M. 
Virlet perceived, in a coal-mine, a shock resembling that of an 
