ILLUSTRATIONS (5). MOUNTAIN-CHAIN. 39 



according to Lyell, to the respective heights, of 6652 and 

 5400 feet,) we see the richly watered, fruitful, and thickly- 

 inhabited basin of the Mississippi, at an elevation of from 

 four to six hundred feet, or more than twice that of the 

 plains of Lombardy. The hypsometrical character of this 

 eastern valley, or in other words, its relation to the sea's 

 level, has only very recently been explained by the ad- 

 mirable labours of the talented French astronomer Nicollet, 

 unhappily lost to science by a premature death. His great 

 chart of the Upper Mississippi, executed between the years 

 1836 and 1840, was based on two hundred and forty astrono- 

 mical determinations of latitude, and one hundred and seventy 

 barometrical determinations of elevation. The plain which 

 encloses the valley of the Mississippi is identical with that 

 of northern Canada, and forms part of one and the same 

 depressed basin, extending from the Gulf of Mexico to the 

 Arctic Sea.* Wherever the low land falls in undulations, and 

 slight elevations which still retain their un-English appellation 

 of coteaux des prairies, coteaux des bois, occur in connected rows 

 between the parallels of 47° and 48° north lat., these rows and 

 gentle undulations of the ground separate the waters between 

 Hudson's Bay and the Gulf of Mexico. Such a line of sepa- 

 ration between the waters is formed, north of Lake Superior 

 or Kichi Gummi, by the Missabay Heights, and further west 

 fev the elevations known as Hauteurs des Terres, in which are 

 situated the true sources of the Mississippi, one of the largest 

 river? in the world, and which were not discovered till the 

 year 1832. The highest of these chains of hills hardly 

 attains an elevation of from 16Uu tC ! 6 0° feet. From its 

 mouth (the old French Balize) to St. Louis, somewutvu 12 

 the south of its confluence with the Missouri, the Missis- 

 sippi has a fall of only 380 feet, notwithstanding that the 

 itinerary distance between these two points exceeds 1280 

 miles. The surface of Lake Superior lies at an elevation 

 of 618 feet, and as its depth in the neighbourhood of the 

 island of Magdalena is fully 790 feet, its bottom must be 

 172 feet below the surface of the ocean. f 



Beltrami, who in 1825 separated himself from Major Long's 



* Compare my Relation Historique, t. iii. p. 234, and Nicollet, 

 Report to the Senate of the United States, 1843, pp. 7, 57. 

 t Nicollet, op. cit. pp. 99, 125, 128. 



