2 M. Ami Boue on the Palceohydrography 



in Europe, instead of the 105 toises of Humboldt, 671 feet; 

 for North America, instead of 117 toises, 748 feet ; for Asia, 

 instead of 180 toises, llf>2 feet; for South America, instead 

 of 177 toises, 1151 feet. We arrive in this way at the 

 probability that Humboldt and Johnston's estimations are 

 still too high ; but as in our way of reasoning, we must 

 also take into consideration all the parts of the earth's crust 

 which form submarine protuberances, and add this value to 

 the one admitted in continental parts above the sea level ; in 

 this way we must arrive evidently at a higher estimation of 

 middle height or thickness, and this will not be far from 

 1500 to 2000 feet in height for the last wrinkled pellicle of 

 our globe under and above the sea level, which we thought to be 

 able to establish for our whole water-covering of the oceans. 



On the other side, the values of the elevations and sub- 

 sidences, or high and low parts of the earth's surface, being 

 equal, an estimation of the maximum for the middle height 

 of continents gives us the means to calculate the whole 

 quantity of sea water through the mutual surface contents 

 of land and water. The mutual relations of these is said 

 to be about 1 : 3 or 2$, but according to Lyell, it is 1 : 4, 1 : 3. 

 lie admits for the whole earth's surface 148,522,000 square 

 miles, with 37,673,000 square miles dry land, and 110,849,000 

 square miles of water (Principles, 1835, vol. i., p. 216). In 

 following Laplace's old error of giving to the middle depth 

 of the seas 2 miles or 4 leagues (Mem. Acad, de Sc. Paris, 

 1776), we arrive at a quantity of water of 55,091,600 cubic 

 leagues, or even for all waters on the earth's surface 1 10,183,200 

 cubic leagues of Breislak (Institut. Geol., 1818, vol. i., p. 48). 

 If Kant fixed the middle depth of seas to half a geographical 

 mile, and Keil to a quarter of a mile, old De la Metherie was 

 still more near the truth in admitting only 1200 to 1500 feet 

 for this value ; and by that way he was able to calculate the 

 quantity of the sea water to 1,530,320 cubic leagues. He 

 &d< ltd also that if the whole earth's surface were iiat and covered 

 entirely with water, the depth of it would be only 700 feet, 



■ •rding to the admission of the mentioned value of the 

 quantity [fheorie de la Terre, 1795, vol. ii., p. 347). 



De la Mctherio's estimation of the quantity of water must 





