88 Notices of Memoirs—W. P. Jervis—On Earthquakes. 
Genoa,—the sinking of Roman buildings below the sea-level at the 
coast-line near the former mouth of the Rhone,—and the fact of 
stone-boring Molluses being found many metres above the sea-level 
in other parts—led Issel to say that this coast-line is subject to 
slow upheavals and depressions; and these Mr. Jervis believes to 
be due to the district being the area of repeated earthquakes similar 
to that of last spring. But as the earthquakes seem to be due to 
the descent or sinking of mountain-masses towards the centre of the 
globe, it would seem that they could not be repeated without the 
gradual lowering of the mountains. Mr. Jervis, however, proposes 
the hypothesis that there is an extra-mundane cause of upheaval of 
certain mountain-groups. Referring to Flammarion as being probably 
correct on the whole, though very poetic and too much of a scenic 
artist to follow details patiently, Mr. Jervis proceeds with the idea 
that the sun and moon, in certain positions, may be able to attract 
a given mountain-mass very gradually, and to an exceedingly 
small extent,—such process being repeated again and again, each 
time causing a still further elevation of insensible height. In time, 
unstable equilibrium having been produced (especially at given 
moments following the transient recurrences of celestial attraction), 
terrestrial gravitation interferes, and the upheaved masses settle 
down, in some instances with rupture of the strata. Thus there are 
two phases of the disturbance ;—first, a gentle and imperceptible 
upheaval, so gradual as to be unappreciable by our senses, and 
never yet established, except on a coast-line where the sea-level 
gives a fixed point of comparison. This might, however, be as fully 
proved inland, were the heights of fixed objects on mountains (such 
as the summit of a building, a signal stone, etc.) determined with 
mathematical precision, instead of the ever-varying mountain-top (as 
Mont Bianc) being taken, which may be worn down one to twenty 
feet in a century by frost and rain, and possibly be again upheaved 
from time to time so as to restore the geographical relief. 
The earthquake, as it is called, would then be the phenomena 
caused by the influence of terrestrial gravitation,—the fall by which 
stable equilibrium is secured. In the author’s opinion the elevatory 
process by far exceeds that of depression, allowing full play for the 
ever-active erosion, by which the Alps, for instance, may have been 
worn down even hundreds of feet in historic times. Are not earth- 
quakes, then, absolutely necessary for restoring in some parts of the 
globe the equilibrium of certain forces and agents, as electricity ? 
Do they not help to maintain the balance between the heights of 
mountains and the depths of seas ? 
The defective method of buildings, especially with vaults, allow 
of much of the disasters in earthquake-areas, and the author points 
out some practical technical precautions and the building-materials 
most fit for use in these places. 
