ening din in that place of echoes. They
appeared to stir the Indians into a perfect frenzy, and it was evident,
by the sounds, that the islanders had not much liberty of movement on
the narrow strips of land they occupied on both sides of the gorge.

Elsie caught some significant splashing behind her.

"They are swimming towards the canoes," she screamed.

Telling Suarez to pull for all he was worth, Gray, clambered to the
stern of the boat and emptied the revolver at what he took to be the
black heads of the swimmers.

"Quick! Load it again," he said, and Elsie obeyed with a nimbleness
and certainty that were amazing.

The American fired three more shots before he was satisfied that the
canoes were untenanted and not cut adrift. They were now leaving the
pandemonium behind, and Elsie, bethinking herself of the dog, freed him
from that most objectionable muzzle. Joey forthwith awoke the welkin
with his uproar, but, although the girl strained her ears for some
answering hail, she could detect nothing beyond the bawling of Indians
at each other across the narrow creek, and the repeated echoes of the
dog's barking.

About this time Gray began to suspect that the tide was bearing them
onward at a remarkable rate. In the somber depths of the cleft or
canon it was difficult to discern stationary objects clearly enough to
obtain a means of estimating the pace of the stream. But the rapid
dying down of the hubbub among the savages gave him cause to think. He
asked Suarez to cease pulling. The canoes behind came crowding in on
the more solid boat, and an oar held out until it encountered some
invisible branch was rudely swept aside. In a word, they were being
impelled towards an unknown destination with the silence and gathering
speed of a mill-race.

An expert engineer, though his work may have little to do with sea or
river, cannot fail to accumulate a store of theoretical knowledge as to
the properties and limitations of water in motion. Gray knew that the
quickened impulse of the stream arose from the tidal force exerted in a
channel which gradually lessened its width. The boat was traveling at
sea level. Therefore, there could be neither rapids nor cataract in
front; but the steady rush of the current, now plainly audible, could
not be accounted for simply by the effort of the tide to gain a passage
through a mere by-way, as the boat was now nearly half a mile from the
estuary, and the velocity of the cu