134 On the Importance of Geological Information, 8fc, 



valuable labours of Lt. Col. Long, much has already been done ; 

 but the time has arrived, when this science demands accuracy, 

 and this can be given to us only by actual admeasurements. 

 Perhaps at some future day, Congress may authorise a general 

 trigonometrical survey, which will include all these objects ; in 

 the mean time, much may be effected through the influence of 

 the commander in chief.* 



Of some parts of this continent we are almost without details : 

 of California, we know little or nothing, and of that extensive 

 territory north of 50° N. latitude, we have scarce any geological 

 information. The chain of high lands, which branches from the 

 Chippewayan mountains there, and which runs N. E., between 

 lake Winnepec, and the great Slave lake, appears to be the 

 water shed of that region. It is said to connect itself with the 

 highlands, running north of lakes Superior and Huron. It would 

 be a great service rendered to science, if some of the British 

 gentlemen, familiar with that part of the physical geography 

 of the British dominions, would give us some accurate informa- 

 tion of the country. In giving an account of the elevation of 

 countries, it is best to state the general height of the table lands, 

 distinct from that of the mountains which are based upon them : 

 in the following table, the elevations of the table lands, above 

 the level of the sea, are alone expressed. 



. Table Idnd of Irun, in Persia, 

 Moscow, in Russia, 

 Swabia, in Germany, 

 Lombardy, in Italy, ^ 

 Auvergne, in France, 

 Schweitz, 

 Bavaria, 

 Spain, 



Plains of the Rocky mountains, 

 The following table expresses the most authentic elevations 

 above the level of the sea, which we possess. Many of them have 

 been admeasured : others, no doubt, are mere approximations. 



* It would be an act of injustice to Peter A. Browne, Esq., of this city, not to notice 

 his indefatigable endeavours to interest the government of this State, in the geology 

 of Pennsylvania, with a view to the construction of an accurate geological map. The 

 disinterested and useful labours of that gentleman in the cause of geology, do him 

 great honour. 



Toises. 



Feet. 



650, or 



3900. 



67, 



402. 



150, 



900. 



80, 



480. 



174, 



1044. 



220, 



1320. 



260, 



1560. 



350, 



2100. 





3000. 



\ 



