It was attached to a tree, and had been cut.

It was a bit of the line that had held the raft, and the raft was gone.
The blow was a heavy one, and for a few minutes Grimshaw stood like one who is stunned.

The loss of that raft, under the circumstances, meant ruin.

It meant the loss of everything he had or cared for in the world.

At first the realization of this loss rendered him speechless.
Then he began to rave and revile his own carelessness.