NOTES:

1. The amount of obstructions arising from the casual fixing of trees in the bottom of the river, may be estimated from the proportion of steamboats destroyed by running upon them. The subjoined statement is taken from the American Almanack for 1832.

Between the years 1811 and 1831, three hundred and forty-eight steamboats were built on the Mississippi and its tributary streams. During that period a hundred and fifty were lost or worn out.

Of this hundred and fifty: worn out 63
                           lost by snags 36
                           burnt 14
                           lost by collision 3
                           by accidents not ascertained 34
Thirty six or nearly one fourth, being destroyed by accidental
obstruction.

Snag is the name given in America to trees which stand nearly upright in the stream with their roots fixed at the bottom.

It is usual to divide off at the bow of the steamboats a watertight chamber, in order that when a hole is made in it by running against the snags, the water may not enterthe rest of the vessel and sink it intantly.