Scientific Intelligence, '^G eology, 189 



and astronomical operations undertaken for the basis of this map have 

 been collected and discussed by M. Puissant, in a work in two quarto 

 vols., entitled Desa-iption Geometrique de la France. It appears from 

 calculation that the surface of our country (France) cannot be repre- 

 sented by that of an ellipsoid of revolution, flattened at the poles, what- 

 ever value be assigned to the compression. The parts situate to the 

 west of the meridian of Paris are placed on elongated ellipsoids, while 

 those situate to the east, on the contrary, are placed on oblate ellip- 

 soids, the compression of which is more considerable than that generally 

 admitted. This indicates, at least in relation to France, great irregu- 

 larities in the structure of the globe. 



Availing himself of the labours of Italian engineers and astronomers, 

 as well as Gennan and English, M. Rozet states that he has ascertained 

 that it is the same with Italy, certain parts of Germany, and of Eng- 

 land. 



These irregularities, he says, are elevations and depressions which 

 extend over a considerable portion of the surface of our planet, but 

 which never amount to the 12,000th part of its radius, so that, taken 

 as a whole, it may be considered as an ellipsoid whose flattening at 

 the poles is j^g. These elevations appear in the hilly regions of 

 continents, leaving out the consideration of what we call mountains ; 

 while the depressions are observed in the spaces contained between the 

 chains of mountains, in the places adjoining the coasts, and, in general, 

 in the vast extent of the basin of the sea. 



Observations of the seconds pendulum, made at a great number of 

 points on the surface of the globe, by MM. Arago, Biot, Mathieu, 

 Duperrey, Freycinet, Kater, Sabine, &c., confirm the results of astro- 

 nomy and geodesy. In such places as astronomical and geodesical ob- 

 servations indicate depressions, the pendulum lengthens ; it shortens, 

 on the contrary, in those where they indicate elevations. 



Observations by the barometer, collected and aiTanged by M. Schouw, 

 professor of botany at Copenhagen, entirely agi-ee with the preceding. 

 In every place where geodesy, astronomy, and the pendulum indicate 

 depressions, the mean height of the barometrical column, deduced from 

 many years* observation, is greater than in those where these three 

 kinds of operations indicate elevations. 



These in*egularities in the structure of the globe producing notable 

 anomalies in the direction of the plumb-line in passing from one place 

 to another, on the surface of seas as well as on that of continents, it 

 follows that the sea, every part of whose surface is perpendicular to the 

 vertical point, presents irregularities similar to those of the land ; a fact 

 perfectly demonstrated by observations of the pendulum and barometer. 



