GAEDXEE.] GEOGKAPHY ELEVATION OF DATUM-POINTS. 



647 



ELEVATION OF THE SAINT LOUIS DrRECTMS-Continued. 





Feet. 



Various datum-planes. 



Elevation in feet 

 above mean sur- 

 face of Atlantic 

 Ocean. 



Argenta 







304. 65 



Saint Xouis directrix, by C. & P. and St. L. & Q. M. 



119. 00 



Above Little Eock 



E. Es. 

 (Assuming that the tracks are same height on both 

 sides of the river at Little Eock :) 





423 65 



Eighth determination. 

 Cairo city-datum, ordinary L. W 



291. 13 

 123. 70 

 12.2 



Above New Orleans M. T. 

 Above Cairo city-datum 





Carmi, by C. & V. E. E. and city-engineer 





Saint Loiiis directrix, by St. L. & S. E. E. E 



Above Carmi 





Saint Louis directrix 





407 n« 



Ninth determination. 



Cairo H. TT., by M. & 0. E.E., preliminary line 



Saint Louis directrix, by C. & V. and St. L. &S. E. E. Es 



318. 30 

 93.4 



i 



i 



Above M.T.Mobile Bay..! 



Above H. W. Cairo i. . 







411. 70 



Saint Louis directrix, by 111. Cent, to Vandalia, thence 



96.6 



Above Cairo H. W 





by St.L. &T.H.E.ES. 





414 90 



Final results. 



Saint Lonis directrix : 



(1) First determination 



433. 15 

 430. 79 







(1) Second determination 







Third determination 







(1) Fourth determination 



426. 85 

 423. 62 

 419.41] 

 423. 65) 



427. 03 

 S [411. 70J 

 I [414. 90J 



428. 29 













(0) Sixth determination 



Above New Orleans M. T. 

 do 





(0) Seventh determination 





(1) Eighth determination 



do 





(0) Ninth determination 



\ Above Mobile M. T 





Mean of five 







Adopted results. 

 Saint Louis directrix 





428. 29 



Saint Louis H. "W. 1844 







435. 87 



Saint Louis H. W. 1858 







431. 57 



Saint Lonis H.W. 1851 







431. 17 



Saint Louis L. W., extreme 







394. 48 









I have rejected tlie sixth determination because of the uncertainty of 

 the connection at Belmont, and the seventh from the uncertainty of the 

 connection at Little Eock. The two results of the ninth are rejected 

 because they are the results of a mere preliminary survey on a line about 

 five hundred miles long. The remainder are given equal weight because 

 Cincinnati and Chicago are about equally distant from Saint Louis, and 

 the connections equally good. The best result on the elevation of Saint 

 Louis will be obtained when the C. A. & St. L. E. E. rerun their levels ; 

 their own engineer making the connection with the city-directrixes at 

 both termini. If these levels are run with care, the elevation of Saint 

 Louis, as- deduced by them from the Chicago directrix, should, I think, 

 suxjersede the one I have adopted. The elevation of the Saint Louis 

 directrix, as given in Humphreys and Abbot's Eeport on the Hydrau- 

 lics of the Mississippi Eiver, is 405 feet. The causes of their error were 

 the adoption of the elevation of Cairo H. W. above Mobile Bay, as de- 

 termined by the preliminary line of the M. & O. E. E., and of the eleva- 

 tion of Saint Louis above Cairo, as reported by Gen. G. B. McCIellan. 

 His report was based on a connection of the L C. E. E., and the O. & 

 M. E. E. This part of the O. & M. E. E. profile cannot now be had. 



