Several causes are assigned for the excessive rise of water in the Ohio valley.  This water-shed is accredited with an area of two hundred thousand square miles, and it lies upon the border-line of hot and cold temperatures.  It is subject to heavy storms, and sometimes, in winter, to large accumulations of snow.  It is presumable also, the rainfall is greater than the average of the country.  When, following great deposits of snow, warm, heavy, and prolonged rains occur, excessive floods must be the result.  Add to these coincidents the fact that forests, once existing, are now so nearly annihilated that little protection is offered against a rapid dissolution of the snow, and the sudden freezing of the earth in an interval of the late storm preventing absorption of rain falling thereafter.  The waters thus produced fall into the main streams without hindrance, like rain from roofs of buildings.  An aggregation of waters in this valley, rising from fifty to seventy-one feet, is of annual occurrence, intensified according to excesses and completeness of coincidents.

The damage arising from the Ohio flood of 1882 has been estimated at twelve millions of dollars; that of 1883 at thirty-five to forty millions of dollars.  If these estimates are approximately correct, what must have been the damage from the flood of 1884!

There are other causes for the floods in the Ohio valley, and in all Southern streams, that have been but little considered, which exercise undoubted and immense influence in solving the peculiarities of the question under consideration, and afford striking contrasts in different sections of this country.

There are two water systems presented in North America.  North of about the forty-first degree of latitude probably the southern limit of the once glacial region—­a reservoir system prevails toward the headwaters of all the streams.  It includes New England, New York, Michigan, Wisconsin, Minnesota, Dakota, and to the Rocky Mountains divide, and all of the British Provinces to the Arctic Circle.  It also somewhat occurs on the western slope of the Rockies.  This region is notable for the great lake system, and the immense number of smaller lakes and ponds—­natural inland reservoirs, supposed to be largely of glacial formation to hold back considerable portions of the cumulative waters upon any given water-shed, and serving to restrain the outflow, even after they are filled.  These basins exercise a happy and protective influence in many ways.

South of the forty-first parallel, the rivers have no reservoirs to hold any part of the flow from their water-shed.  Within this vast area few lakes or ponds exist.  The superabundance of water has no restraint, but at once takes to the bottom lands.  To this southern system the Ohio River notably belongs, with all its tributaries.  Within its two hundred thousand square miles of area, scarcely a natural reservoir is to be found.  No other