Thick fogs continue over the river in the mornings, till eight or nine o'clock. These are no doubt occasioned by the water being hotter than the air. The radiant heat passing upward, necessarily carries humidity with it, which is immediately condensed, and rendered visible by the colder air. Whenever the heat of the air is of a temperature equal to that of the water, the phenomenon disappears. The same principle may be {72} very plausibly applied, in explaining the autumnal risings of the Ohio. The great and long continued heats of summer in this country, render the air capable of accumulating a great quantity of moisture. It is not till the sun recedes considerably to the southward, and till a great portion of the atmosphere is cooled, that rains are precipitated over any great extent of the country. The Allegany mountains, and other high parts, are soonest cooled, and first produce a deposition of rain. Hence autumnal floods occur, which proceed from the higher country alone, without corresponding risings in the lower tributaries of the Ohio. In seasons when the heat continues long, the flood occurs late. With such hot days as we now enjoy, a rising in the river is not to be expected.
26th. Went up Beaver Creek.[43] This is a large stream, with a rapid descent over a sandstone bottom. Within three miles of its mouth there are three saw-mills, a grist-*mill(**should be hyphenated? ; (P3) not necessarily), an iron furnace and forge, a fulling-mill, a carding-*mill, (**should remain hyphenated?) and a mill for bruising flax-seed. At the iron furnace, cast goods are fabricated, the coarsest that I have ever seen. Coal is abundant, but not used in reducing the ores.
It has been suggested, that a navigation connecting Cay-*
