30 NECESSITY OF GENERAL 



doubt that the -uniformity of figure observed in the distribu- 

 tion of our continental masses, by which they taper towards 

 the south, and spread out in breadth towards the north 

 (a fact or law on which the distribution of climates, the 

 prevailing direction of atmospheric and oceanic currents, and 

 the great extension of tropical forms into the southern tem- 

 perate zone so materially depend), may be fully apprehended, 

 together with its consequences, without any acquaintance 

 with those geodesical and astronomical determinations, by 

 means of which the precise forms and dimensions of the 

 continents have been delineated in our maps ? Thus, too, 

 the physical description of the earth teaches us that the 

 length of the equatorial axis of our planet exceeds that of 

 its polar axis by a certain number of miles, and informs us 

 of the mean equality of the compression of the northern 

 and southern hemispheres, without the necessity of relating 

 in detail the measurements of degrees and the pendulum 

 experiments, by means of which we have arrived at the 

 knowledge that the true figure of the earth is that of an irre- 

 gular ellipsoid of revolution, and is reflected in the irregu- 

 larity of the movements of the earth's satellite, the moon. 



Enlarged views of physical geography have been essen- 

 tially advanced by the appearance of the admirable work 

 (" Erdkunde im Yerhaltiiiss zur Natur und zur Geschichte 

 des Menschen, oder allgemeine vergleichende Geographic") 

 in which Carl Bitter has characterized so powerfully the phy* 

 giognomy of our globe, and has shewn the influence of its 

 external configuration, both on the physical phaenomena which 

 take place on its surface, and on the migration of nations, 

 their laws, their manners, and their history. 



France possesses an immortal work, Laplace's " Exposir 



