137 



*' The Academy has charged us with reporting on a memoir, 

 presented March 21st, 1853, by M. Alexis Perrey, Professor in 

 the Faculty of Sciences, at Dijon, On the Relations ivhich may 

 exist beticeen the Frequency of Earthquakes and the Age of the 

 Moon, and on a nole presented the 2d of January, On the Fre- 

 quency of Earthquakes relatively to the times of the Moon^s 

 fassing the meridian. 



" If, as is now generally supposed, the interior of the earth is 

 in a liquid or pasty state, through heat, and if the globe has, for 

 its solid part, only a crust comparatively very thin, the interior 

 liquid mass must tend to yield, like the surface waters, to the 

 attractive forces exerted by the sun and moon, and there must 

 be a tendency to expansion in the direction of the radius vectors 

 of these two bodies; but this tendency encounters resistance in 

 the rigidity of the crust, which is the occasion of fractures and 

 shocks. The intensity of this cause varies, like that for the tides 

 of the ocean, with the relative position of the sun and moon, and 

 consequently with the age of the moon ; and it should also be 

 noted, that as the ocean's tides rise and fall twice in a lunar day, 

 at periods dependent on the moon's passing the meridian, so in 

 the internal fluid of the globe, there should be two changes a 

 day, the time varying with the same cause. 



" Without entering now into more details, it will be easily con- 

 ceived, that if the mobility of the internal mass of the globe 

 plays a part in the production of Earthquakes, there must be 

 some dependence, admitting of study, between the occurrence of 

 an Earthquake and the circumstances which influence the action 

 of the moon on the whole globe, or on any place or portion of 

 it; that is, the angular distance with the sun, its actual distance 

 from the earth, and its distance from the meridian of the place; 

 or, in other terms, the age of the moon, the lime of perihelion, 

 and the hour of the lunar day. 



" These considerations, which have not escaped M. Perrey, 

 have, beyond doubt, inspired the idea of the twofold work which 

 we have been charged to examine ; and they have obtained for 

 the views, the interested attention of M. Arago and many other 

 men of science. They have involved on the part of the author, 

 the determination of the precise date and period of the moon, 



