32 REPORT—1858. 
There remains to be noticed, of M. Perrey’s labours, his discussion of the 
periodicity of the earthquakes of his annual catalogues for 1844, 1845, 
1846, and 1847, with reference to the phases of the moon’s motions, published 
in ‘ Mém. de |’Académie des Sciences de Dijon,’ 1848, 1849, part. des 
Sciences, p. 105, &c., and also presented to the Institute of France at a 
later period. 
The result he arrives at, as respects these four years, is, that the number of 
earthquakes occurring at the Perigees (when the tides are highest and 
lowest) are, to those occurring at the Apogees, as 47 : 39,—a conclusion 
which, independently of the assumptions by which it is arrived at, must be 
as yet accepted with caution upon so narrow a base of induction, although 
possessing more than enough probability, from physical considerations, to 
induce further inquiry. 
The Academy of Sciences (Paris) appointed a commission to report upon 
M. Perrey’s communication; and the following translation of its report 
(‘Comptes Rendus,’ tom. xxxviii. 12 Juin, 1854) will give a tolerably clear 
notion of his views, which here rest upon a larger base than in his Memoir 
as first published :— 
“ The Academy has commissioned us, MM. Liouville, Lamé, and myself, to 
draw up a report ona paper presented by M. Alexis Perrey, Professor in the 
Faculty of Sciences at Dijon, on the 21st March 1853, ‘On the Connexion 
which may exist between the occurrence of Earthquakes and the Moon’s 
Age,’ and on a note also presented by him on the 2nd January last, ‘On 
the occurrence of Earthquakes in connexion with the Moon’s passing over 
the Meridian.’ 
“ At the time of the presentation of the paper of March 1853, M. Arago 
had been appointed a member of the commission. The lamented death of 
our illustrious associate, since that date, left a vacant place in our commis- 
sion ; and before the presentation of the note of the 2nd January 1854, M. 
Lamé was appointed to it. 
“ M.Arago, whose attention nothing escaped which relates to the physics of 
the globe, pursued with sustained interest the researches of M. Alexis Perrey. 
The Academy has not forgotten the care which he constantly took to draw 
its attention to the notes which the learned Professor at Dijon addressed to 
him from time to time within the last few years, in consequence of the in- 
quiries he was engaged in on the subject of earthquakes. M. Arago made 
particular mention, at several meetings, of the connexion which the author 
had already traced between the occurrence of earthquakes and the moon’s 
age. ‘ 
“ The cause of the interest which belongs to this subject is easily explained. 
If, as is generally believed in the present day, the interior of the earth is, 
owing to its high temperature, in a liquid or melted state, and if the globe 
has but a comparatively thin solid crust, the interior, being deprived of 
solidity, is compelled to yield, like the superficial mass of the ocean waters, 
to the attractive force exercised by the sun and moon, and it acquires a 
tendency to swell out in the direction of the rays of these two bodies; but 
this tendency meets with a resistance in the rigidity of the solid crust, which 
occasions shocks and fractures of the latter. The intensity of this force 
varies, like the tides, according to the relative position of the sun and moon, 
and consequently according to the moon’s age; and we must also observe — 
that as the tides ebb and flow twice in the course of a lunar day, at those 
hours which agree with the passing of the moon over the meridian, so the — 
direction of the attraction exercised upon a point of the interior globe must 
change twice a day, according as the point recedes or approaches the 
