On the Level of the Sea. 



into this subject. By taking the present height of tlie flo<xls, 

 at the Nilometers of Elephantina, and of the Island of Rondah, 

 and comparing it with what it formerly was, he found the mea^ 

 sure of the elevation of the gi'ound, which he estimates at 126 

 millimetres in the century. Considering it as such, it would 

 still require many centuries to bring Lower Egypt merely to the 

 level of the Red Sea *. 



In the course of the operations for measuring the meridian in 

 France, M. Delambre calculated the height oi Rodez above the 

 level of the Mediterranean Sea at Barcelona, and its height above 

 the ocean, which washes the foot of the tower of Dunkirk. These 

 two heights are equal to a fraction of a metre ; whence it follows 

 that if there does exist some difference of level between the Me- 

 diterranean Sea at Barcelona, and the Atlantic Ocean at Dun- 

 kirk, the difference is at least very small. 



M. de Humboldt, in his journey in America, made barome- 

 trical observations on the shores of the Atlantic Ocean, and on 

 those of the South Sea, from which some knowledge may be de- 

 rived respecting the relative height of these two seas. From ba- 

 rometrical means taken on the one hand at Carthagena, Cumana, 

 and Vera Cruz, on the east coast of Mexico, and on the other 

 hand, at Callao and Acapulco, on the shores of the South Sea, 

 it would result that the South Sea is about seven metres higher 

 than the Atlantic. Other observations made by M. Humboldt 

 would give a somewhat greater difference ; but that celebrated 

 traveller gives the above results only as a first approximation, 

 supposing that the unequal heights of the tides, the different 

 hours in harbours, and the greater or less extent of the horary 

 variations of the barometer, are so many causes which may have 

 an influence upon such delicate measurements. 



The level of the Caspian Sea has been the object of several 

 recent inquiries. It was determined in 1818, by MM. d'Eiigle- 

 Imrdt and Parrot, in their curious journey to Caucasus and in 

 the Crimea; by M. Pansner, in 1816; and about the same time 

 by M. Wisniewski, who published, in the Petersburg MefnoirSy 



• In a former number of this Journal, there is an interesting view of the 

 French okservations on the comparative level of the Red Sea, and the Medi- 

 terranean Sea. 



1 y2 



