334 On the Comparathe Level of Lakes and Seas. 



France, from Amsterdam to Marseilles.* Geographers and natural plii- 

 losopliers who do not rest satisfied with vague approximative methods, 

 know not how much the admirable labours of M. Delcros have advanced 

 at once hypsometry, geodees}', and barometrical mensuration. 



" Comparison hy the Pyrenees. — Colonel Coraboeuf, starting from Fort 

 St Ange, upon the shores of the Mediterranean near Perpignan, and 

 from the Fort Socoa, near Bayonne, on the Atlantic, reached the sum- 

 mit of Crabere by four series of points, and found that this point is ele- 

 vated — 



Metres 

 the Southern Series, 2633.37 



{tne oouinern isenes, :iDcJo.c>/ n 

 ttm^Ss : S:f Mean =2033.50 metres, 

 the Diagonals . 2632.79 ) 

 Prnm +>io ( tlie Southern Series, 2632.95 



aZuc 'l!!S?:'"?":?. • ?f??-S? \ Mean = 2632.77 metres. 



From the 

 ;errane 



^ \ the Diagonals 



{ine ooutnern iseries, :iDc>:i.yo n 



the Northern . 2632.02 I 



the Diagonals . 2633.61 ( 



the Diagonals . 2632.49 J 



^ \ the Diagonals 



Difference of mean results = to the different levels of the two seas = 0.73 metres. 



" This mean discordance in the level of the two seas, being within 

 the limits of probable errors, it may be concluded that the mean levels 

 are nearly identical. 



(b) Comparison through Germany and Holland. — M. Delcros having mea- 

 sured a geodsesical chain from the Mediterranean to Darmstadt, by Stras- 

 burg and Geneva, found— 



The height of the gallery of the tower of Darmstadt ahove the Mediterra- 

 nean, ...... metres 187.39 



Same height by German mensuration, above the Northern Ocean 

 (Zuider-Zee). near Amsterdam, . . . 187.30 



Whence it follows that the difference of the mean levels of the two 

 seas, . . . . . . • ^ + 0.09 



By the parallel of Bourges from the ocean to Noirmoutiers, mea- 

 sured by Colonel Coraboeuf, the difference is, . . ^ + 0.30 



Colonel Broussaud, by the mean parallel proceeding from the ocean 

 to Cordouan, near Saintes, is . . . . = -j- 0.52 



*' These discordances being all comprised within the limits of the pro- 

 bable errors of geodsesical levellings, prove that no difference exists in 

 the sensible level between the surfaces of equilibrium of these two seas." 



We have still to add, and also from a note supplied by M. Delcros, 

 some considerations concerning the rise which recently is alleged to have 

 taken place in the northern part of the Adriatic Gulf. '^ The Command- 

 ant Delcros and Captain Choppin having connected the geodtesical 

 operations executed in France and Switzerland with those effected in 

 Bavaria by General Bonne, have determined the altitudes of Hornliberg, 

 Rigiberg, &c., above the level of the Mediterranean. The Swiss en- 



* Taken from a Note which the Commandant M. Delcros has been so kind as 

 give me. 



