58 Report on A. Perrey’s Researches relative to Earthquakes. 
This general law, although distinctly observable in the series 
of results, is however obscured by many anomalies. In order to 
eliminate these anomalies as far as possible, Prof. Perrey divides 
the 29°531 days of a lunar month into twelfths, sixteenths and 
eighths, and obtains, by proportional calculations applied to the 
number of the different tables constructed according to the solar 
ays, the numbers which correspond to each fraction of lunation. 
In his new tables thus constructed, excepting some minor anom- 
alies, the law above stated is more fully confirmed, that for a half 
century earthquakes have been more frequent at the syzygies 
than at the quadratures. 
M. Alexis Perrey has also enquired whether a relation exists 
between the frequency of earthquakes and the distances, at the 
time, of the moon from the earth. For this purpose he has tabu- 
lated according to the different methods of tabulation pointed out, 
the number of times the earth has been shaken, on the day of the 
perigee and apogee of the moon, the day before, night before, the 
following day, and the next following ; he has hence ascertained, 
by the groups of numbers thus formed, the total corresponding to 
the perigee, and also to the apogee. In order to facilitate a eom- 
parison of the results, he has taken the difference of the totals | 
thus obtained and divided by their sum, whence he has found | 
the quotients 
git) EB Ron ons ee eee | 
165) 26, 935, B44; 292, 186) 212; 1075, 
which are all, above ;,, and the last nearly equals j,. It ap; 
pears therefore that the unequal attractions of the moon on the 
earth at its greatest and least distance from the earth, has a sensi- 
ble influence on the production of earthquakes. 
In the Note of Jan. 2, On the frequency of earthquakes as re- 
lated to the passage of the moon over the meridian, the author 
aims to discover whether the repetition of the shocks of earth- 
quakes during a lunar day, has, like the tides, a relation to the 
moon’s passing the meridian. He has submitted to this investi- 
gation, 824 shocks observed at Arequipa, registered by M. Castel- ( 
nau, after calculating the hour of each, with reference to the | 
oon. He has thus made ont a table, which he afterwards di- 
vided into 16 equal parts, and then grouped these by twos into 8 
parts, using the mean lunar day of 24 hours 503 minutes. In this 
way, notwithstanding some large anomalies which cannot fail to | 
be presented in so small a number of cases, the number obtained = * 
by each mode of grouping, gave evidence of the existence in the | 
course of the lunar day, of two epochs of maximum number of 
shoeks and two of minimum, the former at the times of pe: 
moon’s passing the meridian—the superior and inferior—and t 
latter at intermediate intervals. 
