They had gone, but there had been wrathful mutterings among many of the workmen.
The camp was a half mile back from the water's edge, on a low hillside.
Here the men of the outfit were settled.

There had been mutinous mutterings among some of the men, but so far there had been no open revolt.
Tom, however, who had had considerable experience in such matters, looked for some form of trouble before the smouldering excitement quieted.

So did Harry.
On this dark night Tom had proposed that he and his chum take a stroll down to the shore front to see whether all were well there.

Soon after leaving camp behind, the young engineers had started on a jog-trot.

Just before they reached the water's edge the wind had borne to their ears the faint report of what must have been an explosion out over the waters of the gulf.
"Trouble!" Tom whispered in his chum's ear.