Most interesting of all, however, were the Government snag-boats, which constantly patrolled the river, on the lookout for obstructions that they might remove. These boats were doubled-hulled; and when one of them straddled a snag, no matter if it was the largest tree that ever grew, it was bound to disappear. With great steam-driven saws it would be cut into sections, that were lifted and swung aside by powerful derricks planted near the bows. These useful snag-boats also gave relief to distressed craft of all kinds; blew up or removed dangerous wrecks; dislodged rafts of drift that threatened to form inconvenient bars; and in a thousand ways acted the part of an ever-vigilant police for this grandest of American highways. And the great restless river needed watching. It was as full of mischievous pranks as a youthful giant experimenting with his new-found strength. It thought nothing of biting out a few hundred acres of land from one bank and depositing them miles below on the other. If these acres were occupied by houses or cultivated fields, so much the more fun for the river. For years it would flow peacefully in a well-known channel around some great bend, then decide to make a change, and in a single night cut a new channel straight across the loop of land. By such a prank not only were all the river pilots thoroughly bewildered, but a large slice of one State, with its inhabitants and buildings, would be transferred to another. If at the same time an important river-town could be stranded and left far inland, the happiness of the mischief-making giant was complete; and for many miles it would swirl and eddy and boil and ripple with exuberant glee over the success of its efforts. Above all it delighted in secretly gathering to itself from tributary streams their vast accumulations of protracted rains or melting snows, until it was swollen to twice its ordinary size, and endowed with a strength that nothing could withstand. Then with mighty leaps it would overflow its banks, cover whole counties with its tawny floods, burst through levees, and riot over thousands of cultivated fields, sweep away houses, uproot trees, and drown every unfortunate creature on which it could lay its clutching fingers. Whenever its fleeing victims managed to reach some little mound or bit of high land that it could not climb, then it found equal pleasure in surrounding them and mocking them with its plashing chuckles, while they suffered the pangs of slow starvation.