of the Surface of (he Earth. 123 



the progress of civilization on the formerly more prosperous 

 shores of the Mediterranean Sea.* 



Since immense and lofty chains of mountains occupy our 

 imaginations, by presenting themselves as evidences of vast 

 terrestrial revolutions, as the boundaries of climates, as great 

 water-sheds, or as the bearers of different vegetable Avorlds ; 

 it becomes so much the more necessai^y to shew, by a correct 

 numerical estimate of their volume, how small the whole 

 quantity of the elevated masses is in comparison with the 

 area of entire countries. The mass of the Pyrenees, for ex- 

 ample — a chain, the mean height of whose summits, and the 

 superficial extent of whose base, are known by accurate mea- 

 surements — would, if distributed over the area of France, in- 

 crease the height of that country only 115 English feet. 

 The mass of the eastern and Avestern chains of the Alps 

 would, in the same manner, raise the height of the flat country 

 of Europe by only 21'3 English feet. By means of a laborious 

 investigation, t which, from its very nature, only gives the 

 upper limit, i. e., a number which maybe smaller, but cannot 

 be larger, I have ascertained that the centre of gravity of 

 the volume of the land which rises above the present level of 

 the sea, is situated at a height of 671 and 748 English feet 

 in Europe and North America, and 1131-8 and 1151 English 

 feet in Asia and South America. These calculations indicate 

 the lowness of the northern regions : the great steppes of the 



* Ade Cnitrak, t. i., pp. 284-286. The Adriatic Sea has also a SE.- 

 NW. direction. 



t De la Hauteur Moyenne dcs Continents in Asie Ccntrale, t. i., pp. 82-90 

 and 165-189. The results which I obtained are to be regarded as 

 nomhrcs-limites. Laplace estimated the mean height of continents at 

 3280 English feet, which was at least three times too high. Tliat immor- 

 tal geometrician {Mecaniquc Ceksti-, t. v., p. 14) was led to this conclu- 

 sion by hypotheses regarding the mean depth of the sea. I have shewn 

 (^Asie Ccntrale, t. i., p. 93) that the Alexandrine mathematicians, accord- 

 ing to the testimony of Plutarch (ui ^milio Paulo, cap. 15.), believed 

 that tlie depth of the sea was dependent on tlie height of the mountains. 

 Tlie height of the centre of gravity of the volume of the continental 

 masses has probably been subjected to small changes in the course of 

 thousands of years. 



