FOREIGN CORRESPONDKNOH. 205 
FOREIGN CORRESPONDENCE. 
By Dr. T. L. Phipson, of Paris. 
Earthquake at Pavia — A Lesson to Astronomers — Suirposed Relation 
betiveen Earthquakes and the Phases of the Moon — Desclokeaux on the 
Optical Properties of Cri/stals — Delesse on Metamorphism by Granite- 
RocTcs. 
A LETTER to the editor of the Corrispondenza Scientifica in Roma, by 
Sig. Zantedeschi, dated 20th January, 1859, informs us that on that 
day, at fifty-seven minutes past eight in the morning, three shocks of an 
earthquake were felt at Pavia. The undulatory movement of the 
ground was very great. Various objects in the houses were set in 
motion, bells were rung, doors burst open, &c. The duration of the 
plienomenon was about seven seconds. The undulations of the ground 
were nearly due north and south. The pendulum of a clock belonging 
to Sig. Zantedeschi, which oscillates from north to south, was not 
stopped by the earthquake ; but the clocks of the observatory, the 
pendulums of which oscillate east and west, were all stopped. This 
is a timely warning to astronomers, in countries where earth- 
quakes are common phenomena. It is of no little importance that 
tiie pendulums of clocks belonging to astronomical observatories 
should be placed in such a manner that they may oscillate in different 
directions ; so that, if a sudden commotion of the earth take place, 
one or two clocks at most will be stopped by the undulations of the 
ground. 
At Pavia, during the earthquake of which we speak, the atmosphere 
was calm and the sky serene. The moon was full on the 18th, two 
days before the earthquake. This is another obsei'vation to be added 
to those already collected by M. Perrey, of Dijon, with a view of 
proving that earthquakes are more frequent at the periods of the new 
and full moon than at the quadratures. According to M. Perrey, the 
greatest tides of the internal liquid mass of the globe must correspond 
with those of the waters on the surface of the earth. Apropos of this, 
Madame Cateriua Scarpellini, who is at present occupied with meteor- 
ological observations on the Capitol at Rome, has attentively observed 
earthquakes throughout the year 1858, and writes to M. Elie de 
Beaumont that her observations, as far as they go, confirm the idea 
brought forward by M. Perrey, that there exists a certain relation 
between these phenomena and the phases of the moon. The question 
of the "internal liquid mass" of the globe we feel inclined to leave 
alone for the present. 
