By good luck there was one man there who knew what to do. He was a lieutenant-colonel from Wisconsin, named Joseph Baily. He had been a log-driver before the war and knew what was done when logs got jammed in a stream.
When he told his plan he was laughed at by some who thought it very foolish, but Porter told him to go ahead. So, with 2,000 soldiers from Maine, who knew all about logging, he went into the woods, chopped down trees, and built a dam below the falls.
The men worked so hard that it took them only eight days to build the dam; which was wonderfully quick work. A place was left open in the center, and there four barges loaded with brick were sunk.
When the dam was finished it lifted the water six feet higher, and down in safety went three of the steamers, while the army shouted and cheered. But just then two of the sunken barges were carried away, and the water poured through the break in a flood.
The gunboat Lexington was just ready to start. Admiral Porter stood on the bank watching.
"Go ahead!" he shouted.
At once the engines were started and the Lexington shot down the foaming rapid. There were no cheers now; everybody was still.
Down she went, rolling and leaping on the wild waters; but soon she shot safe into the still pool below. All the other vessels were also safely taken down.