THE MISSISSIPPI VALLEY. 43 



AVERAGES OP THE PRECEDING RESULTS. 



In collecting the foregoing results, we obtain the following averages for a 

 period of six years : 



The total discharge of the Ohio in — 



1843 was - - - - . - 961,382,000,000 cubic feet. 



1844 " 650,982,000,000 " " 



1845 " 555,482,000,000 " " 



1846 " 879,119,000,000 " " 



1847 " 1,142,258,000,000 " " 



1848 " 822,719,000,000 " " 



Total for six years - - - -5,011,942,000,000 " " 



Annual average 835,323,000,000 '^ " ' 



Daily average, for six years - 2,287,000,000 " " 



By applying the formula, or Table IV, we find that this quantity is just suffi- 

 cient to have maintained the river at an uniform height of StA feet during this 

 entire period of six years. 



The annual drainage, as we have seen, in — 



1843 

 1844 

 1845 

 1846 



1847 

 1848 



17 



inches. 



11 



iVt " 



9 



iV\ " 



15 



tVv 



20 



-^s " 



14 



T^ff " 



Total drainage for six years ------ 88 -j%\ " 



Annual average ---------- 14f^Vir " 



The average annual fall of rain at the head of the Ohio is about 36 inches. 

 The discharge is therefore about 40 per cent, of the total fall ; showing that 60 

 per cent, of all the rain and snow that come to the earth in this latitude is car- 

 ried back to the clouds in vapor, and never reaches the Ocean. 



There arc, doubtless, meteorological records which would enable us to state 

 the average annual fall of rain in the district of country which is drained by the 

 upper Ohio, more accurately than it is here given, for these six years ; but the 

 engagements and present position of the writer have not permitted him to pursue 

 that subject minutely. 



The average result here stated, however — 40 per cent, for the drainage, and 

 60 per cent, for the evaporation and vegetable consumption — will be found to be 

 very nearly the proportions in which the total fall of rain, in this climate, is 

 actually divided. 



