Report on A. Perrey’s Researches relative to Earthquakes. 59 
M. Alexis Perrey, by discussing the catalogues which he had 
formed, thus shows by three ways independent of one another, 
the influence of the course of the moon on the production of 
earthquakes. 
1. That the frequency augments in the syzygies. 
2. That the frequency augments in the vicinity of the moon’s 
perigee, and diminishes towards the apogee. 
3. That the shocks of earthquakes are more numerous when 
the moon is near the meridian than when 90 degrees from it. 
The tables still present more anomalies, and the author has 
omitted nothing which should remove them, so as to bring out 
the law in all its purity. 
He at first thought of representing the frequency by diagrams 
like those for barometrical observation, a process by which the 
general march of phenomena is perceived amid the anomalies 
which tend to mask it. -We regret that this has not been done, 
as it speaks at once to the eye. M. Alexis Perrey has endeavored 
i 
to obtain his results by calculation, and has devoted to this sub- 
ject the second chapter of his principal memoir, and the second 
part of his Note of Jan. 2, 1854. 
Without attempting to follow the author in these analytical 
iscussions, we simply state here that, in order to represent the 
results of observation, he employs a formula of interpolation of 
the form, 
y= m--A sin (¢+-«)-+B sin (2¢-+-2)+C sin (8¢+7)+... 
in which m, A, B, C, &c., are constant coefficients of the same 
nature with 9; «@, 8,7, &c., are constant angles; and ¢a variable an- 
gle dependent on the lunar motion, which is equal to 0 degree 
for the new moon, 90 degrees for the first quarter, and 180 de- 
grees for full moon, &c. He then adapts the formula by known 
methods to each of his tables deduced from observation, by de- 
terminiug the constants which it includes. 
the law is expressed fully and clearly. All the curves have a 
marked resemblance, although not wholly similar :—an iden- 
tity could not be, for the results are only approximative and 
take a special impress from the groups of numbers which they rep- 
resent. The resemblance in the curves leads to two principal 
maxima, corresponding to the syzygies, and two minima for the 
quadratures ; and sustaius the general deduction, that for half a 
century earthquakes have been most frequent at the syzygies. 
