Vol. 65.] ANNIVERSARY ADDKESS OF THE PRESIDENT. xciii 



composition has been determined by systematic observations ex- 

 tending over a whole year, yet these observations have not been 

 made at, stations near the mouth but at others situated up-stream, 

 far away from it. The composition of a river at one part of its 

 course affords no information, germane to this enquiry, as to 

 its composition at any other part; and consequently we cannot 

 apply the analytical results obtained at any up-stream station to 

 the volume of water passing out to sea near the mouth, but only 

 to that volume which passes the station where the analysis was 

 made. 



In a number of other cases we are still worse off, and must 

 trust to isolated analyses, which, even if trustworthy, only inform 

 us of the composition of the stream on a particular day ; and this 

 may be very different from the average. 



The cases which afford the keenest disappointment to the in- 

 vestigator are those in which all the data are perfect except one, 

 the analyst, for some unknown reason, having failed to separate 

 the sodium from the potash, the two being given lumped together 

 as alkalies. 



Prom such material as I have been able to gather together, 

 I have obtained the results given in the following table : — 



Table II. 



'River. Area of Basin. Discharge. Sodium. 



St. Lawrence 240,000 70-591 1,480,200 



Androscoggin 2,090 "652 7,277 



Merrimac 2,340 "911 39,080 



Croton 339 -122 1,024 



Mohawk 1,306 P289 19,010 



Potomac 9,650 1722 23,900 



James 6,230 2-144 21,820 



Cahaba 1,040 "395 6,139 



Mississippi 1,257,545 132-355 4,764,140 



Grande del Norte 38,000 -298 70,315 



Pecos ? -083 135,100 



Colorado 225,049 5"746 3,262,000 



Cedar ? -144 148 



Snake 17,900 1-557 242,300 



Sacramento 9,300 7-613 350,950 



Total 1,810,789 x 225-622 10,423,403 



1 The area of the basin, given in square miles, is the area of that portion 

 of it which lies above the station where the discharge was measured: the 

 discharge, stated in cubic miles, is the discharge at the station of observation, 



