Geology. 121 
hibit the States and individuals above from deluging the country below. 
Third. The formation of an outlet of the greatest attainable capacity, 
from the Mississippi to the head of Lake Borgne, with a view, if posst- 
ble, to convert it ultimately into the main channel of the river. 
Fourth. The enlargement of the Bayou Plaquemine, for the purpose 
of giving prompt relief to that part of the coast which now suffers 
most from the floods, viz.: to the borders of the Mississippi from above 
Baton Rouge to New Orleans. 
Fifth. The enlargement of the channel of the Atchafalaya, for the 
purpose of extending relief higher up the coast, and conveying tot 
pre by an independent passage, the discharge from Red River and the 
ashita. 
the Mississippi, while affording relief to the suffering and injured popu- 
lation of the delta. ae ae 
t will be seen that these several plans harmonize with each other, 
As we have not space to follow the author through his argument, 
we only cite in this place a few from among the many valuable facts 
brought out by the author. 
“To be able to form a just conception of the present physical con- 
Stitution of the delta, and the causes of its overflow, we must imagine 
a great plane sloping uniformly from the mouth of the Ohio, in a di- 
rection deviating but little from a due southerly course, to the ulf of 
Mexico. The length of this plane, from the mouth of this river to the 
waters of the gulf, is miles. Its northern extremity is elevated 
275 feet above the surface of the sea, and is there and every where 
nearly level with low water in the Mississippi River. _ Its total descent, 
following the highest surface of the soil, is about 320 feet, or at the 
rate of 8 inches per mile. coe 
The breadth of this plane, near the mouth of the Ohio, in an east 
d at the Gulf of 
Mexico it spreads out to a width of about one hundred and fifty miles. 
Sxconp Series, Vol. XVI, No. 46.—July, 1853, 16 
