Notices of Memoirs—W. P. Jervis—On Earthquakes. 87 
NOTICES OF MEMOTRS. 
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W. P. Jervis on EartaqQuakes. 
L CAY. W. P. JERVIS, F.G.S., Keeper of the Royal Industrial 
Museum of Italy, has published his Lecture to the Philotechnic 
Society, Turin, on the nature and causes of Earthquakes, with 
especial reference to that of February last at and near Mentone. 
This is a careful study of the earthquake of 1887 in North-western 
Italy and the neighbouring parts of France and Switzerland, estab- 
lishing certain facts and advancing some possibly new hypotheses. 
An earthquake-area being regarded as that in which the shocks have 
sufficient force to be sensible to man, this earthquake had no con- 
nection with any volcanic action, and the movements were not 
propagated to the volcanic region of Central and Southern Italy. An 
outward external area, including the parts where the seismic disturb- 
ance was manifested by very delicate instruments and magnetized 
bars, would, however, bring us nearer to the region of extinct 
volcanoes in Central Italy. 
After a close examination of the disturbance of springs and 
fountains, caused by the sliding or derangement of strata close to 
the surface, the result arrived at was that Mont Mercantour in the 
Maritime Alps, west of the Col di Tenda, was the centre of seismic 
action. That mountain and others associated with it seem to have 
been the foci of an elliptical, but nearly circular, area of shocks, 
with its greater axis of about 485 kilometres. The length of the 
axes of the outer area of shocks perceptible only by seismic or other 
instruments cannot be determined, the movements depending on the 
nature of the rocks; probably they were twice the length of the 
other axes. The summit of the Maritime Alps, from a short distance 
N.W. of the Mercantour to the junction of the Alps and Apennines 
above Savona, seems to have divided the earthquake-area. That part 
towards the Mediterranean and the bed of the sea itself were subject 
as well to vorticose as to undulatory and subsultory shocks. The 
lateral boundaries were defined by slight fissures (from one to two 
or three millimetres wide) in the rocks or soil, in a direction 
perpendicular to the Maritime Alps, from near the Mercantour to 
the vicinity of Mentone, and from the mountains to near Savona. 
The vorticose action was most curious, especially near Mentone, 
where crosses and upper stones or statuettes of marble were turned 
round 30° or 45° in the Protestant cemetery. Elsewhere only 
undulatory and subsultory shocks were apparent. A table of places 
affected, duration of shocks, and geological nature of the ground is 
given. Some of the physiological effects before and during the 
earthquake are noticed, also the hearing of strange sounds in the 
stillness of the night, as if at a great depth underground. 
The slow changes of level along the coast from Marseilles to 
