80 TRANS. OP THE ACAD. OP SCIENCE. 



diagram exhibits in several instances; but the Mississippi, 

 with its long course and the immense area it drains, is not 

 subject to such sudden and irregular floods as, for example, 

 the Ohio or other smaller streams. Its great and regular 

 rise takes place in April, May, and June, usually reaching its 

 greatest height in the latter month, whence it is popularly 

 known as the " June rise ;" last year, however, it reached its 

 highest point on May 15. 



The ordinarily received opinion is, that the melting snows 

 in the Rocky Mountains and on the northern plains at the 

 head waters of the Missouri and the Mississippi rivers are the 

 principal source of this great periodical rise. But though 

 they may not be without some, and perhaps a considerable, 

 influence, this rise too clearly coincides in time, and in 

 amount, with our rainy season, not to be more immediately 

 referable to the heavy rains which just then deluge the great 

 extent of country drained by the confluents of our river. 



In the table, Vol. I., p. 666, of these Transactions, the fol- 

 lowing errors will have to be corrected : 



« " « " " 0.09 " 0.005 



The editor of Silliman's Journal, vol. 30, p. 394, copying 

 part of my paper on the elevation of St. Louis, refers to the fol- 

 lowing as further sources of information on the natural his- 

 tory of the Mississippi River: 



Marr's Report of Observations at Memphis, made in 1849. 



Ellet's Work. 



Measurements of Riddell, Forshey and Dickenson, in the 

 Acts of the American Association. 



Lyell in Silliman's Journal, vol. 3, pp. 36 and 118. 



