420 TRANS. OF THE ACAD. OF SCIENCE. 



The Variations in the Stage of the Blississippi River at 

 St. Louis. 



By George Engelmann, M.D. 



The desire expressed in our Transactions (Vol. I., p. 667> 

 note) to have official observations made on the daily changes 

 of the stage of the Mississippi river at this point was realized 

 soon afterwards. From January 7, 1861, the efficient city en- 

 gineer, T. J. Homer, Esq., has been making these observa- 

 tions, and publishes them in the daily city papers. With these 

 measurements, now carried on during five years, I have incor- 

 porated guage results obtained during 24 months (from May, 



1843, to May, 1845) at the St. Louis Arsenal, just below the 

 city, by Capt. T. J. Cram, Top. Eng., which I find in the 

 highly valuable "Report on the Physics and Hydraulics of 

 the Mississippi River, by Capt. Humphreys and Lieut. Abbot." 

 Philadelphia, 1*61, Appendix B., p. 24. As these observa- 

 tions embrace the year of our great flood, 1844, they are of 

 particular importance to us. Including these, we have now 

 tables comprising a period of seven years from which to 

 draw general conclusions. 



The 1st diagram on Plate XII. gives a general view of the 

 stage of the river from January, 1861, to December, 1864; 

 as it was engraved a year ago, it does not include the year 

 1865, which, as the tables below will show, varied considera- 

 bly from the four preceding ones. 



On the diagram, the level of the so called City Directrix — 

 the top of the curbstone at the intersection of Market street 

 and the Levee— is marked 33 feet 9£ inches, or 33.8 ft. above 

 the low water mark established December 21, 1863 ; to this 

 low water mark all the observations made before that date 

 have been reduced, Above the line of the City Directrix, the 

 diagram exhibits the highest point reached by the flood of 



1844, on June 27. 



The curve above the shaded line of the stage of the river 

 indicates the quantity of rain which fell in every month dur- 

 ing those four years. Comparing both lines, it becomes evi- 

 dent that the quantity of rain at St. Louis has very little to 

 do with the stage of the river there, as very little correspond- 

 ence between them can be recognized. The quantity of rain 

 in the upper countries, drained by the affluents of the Missis- 

 sippi, on which the stage of the river here and below must 

 depend, does not therefore correspond with that falling here; 

 or, rather, some of the rains must extend over a large district 

 of country, while others, especially those of the latter part of 

 summer and autumn, are more local, not materially affecting 

 the height of water here. 



