the teeth we saw, but we suddenly became conscious of unseen teeth that lay in wait to lacerate the boats under the water-line.
The whole bed of the river is formed of a rock that is worn and wasted in a strangely horrible way, as if it were pitted with a hideous smallpox. Round and oval holes are seen everywhere In the rock, some of them as much as two feet deep and three feet across; and the upper edges of these bowls are as sharp as scythes.
We saw the process of this singular pitting. Heavy stones are caught on an angle of the bottom and rolled over and over without proceeding, till they wear out these cup-like holes, and are buried deeper and deeper in their ceaseless industry. As the bowl increases in size, it catches two workers instead of one, and these grind each other and grind the matrix till the very heart of Nature must admit their toil, and pity their restlessness.
Some of these great stone cups were high out of water, empty and dry; and their round tormentors lay in peace on the bottom. Some were above the surface, but still half full of water that had dashed into them from the rapid.
But there was a keener evil than the circular knife tops of these vessels; and it was their broken edges.
When the torrents of winter and spring thun-
