"Well?" Jerry said.

I didn't understand for a minute, then I whispered:

"Do--you mean--"

"A wave just hit my foot," said Jerry in a low voice.

The first thing that we did was a lot of quick figuring. We thought
fearfully hard and remembered that Turkshead Rock was just coming
out of water when we left Wecanicut at four o'clock, so that the
tide must have been within about an hour of ebb. Therefore full
flood would be at eleven o'clock. But we hadn't any idea of whether
it was ten or eleven or twelve, because there was no light to see
Jerry's watch by. He had just an ordinary Ingersoll, not the grand
Radiolite kind that you can see in the dark and it was perfectly
maddening to hear it ticking away cheerfully, and no good to us at
all. Just then something cold wrapped itself around my ankle. It was
the edge of another wavelet.

We knew that if the cave was going to be flooded we must get Greg
out of it before the water came much higher, but it was still
raining pitch-forks outside, and we didn't know whether to risk
waiting a bit longer or not.

"Perhaps there's sea-weed and we can feel high watermark," I said.
"Try, Jerry."

We felt all the way around the sides of the cave toward the bottom,