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140 have exceeded one hundred and fifty, carrying thirty tons each, and making one trip from Pittsburg to Louisville and back in two months, or about three voyages in the season. The tonnage of all the boats ascending the Ohio and Lower Mississippi was then about sixty-five hundred.

In 1811 the first steamboat was constructed at Brownsville, Pennsylvania, on the Monongahela. Several others were built soon after, but it was probably fifteen years before steamboats came into such general use as to cause any diminution in the flat- and keel-boat navigation. These first boats were built after models of ships, with deep holds. They also were constructed with low pressure engines and heavy machinery. Hence they were useless in low water, very hard to propel against the current, and their carrying capacity was greatly reduced. In order to attain greater speed, the builders soon made the boats long and narrow but it was not until they came to the decision that boats would run faster on the water than in it, and began making them flat and broad, that they finally got a boat capable