FOREIGN CORRESPONDENCE. 



205 



FOREIGN CORRESPONDENCE. 



By Dr. T. L. Phipson, of Paris. 



Earthquake at Pavia — A Lesson to Astronomers — Supposed Relation 

 hetioeen Earthqualces and the Phases of the Moon — Descloizeaux on the 

 Optical Pi'operties of Crystals — Delesse on Metamorphism hy Granite- 

 Pocks. 



A LETTER to the editor of the Corrispondenza Scientif ca in Rorna, 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 

 phenomenon 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 

 the 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 observation 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 Caterina 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. 



