To satisfy his curiosity on that point he wasted ten precious minutes, only to be ocularly assured that the tide was on the flood, and that there was no possible chance of going further.
Again he passed the cylindrical object. By this time it was within a few feet of one of the ledges of rock.
"When the waves throw it against those rocks it will explode," commented Mr. Greenwood. "How dangerous! Thank goodness I have yet time to put a safe distance between me and that infernal machine."
Thirty seconds later he "brought up all standing." Where a short time previously had been an expanse of hard sand, the waves were lapping against the cliff. His retreat was cut off.
Even then, at the expense of wet feet, he might have negotiated the passage, since the water was only about a foot or eighteen inches in depth; but Mr. Greenwood hesitated and, figuratively, was lost.
Step by step he retreated before the rapidly rising tide, each step taking him nearer again to the object of his apprehension. A belt of seaweed rising six or seven feet from the sand marked the limit of mean high tides on the face of the cliffs. It was evident that nowhere within the arms of the bay was safety to be found except by scaling the frowning precipice.
Discarding his umbrella—he wedged it tightly into a crevice in the granite in the hope that he might be able to retrieve his trusty friend—Mr. Greenwood sought for a suitable spot at which to commence his hazardous feat. At the same time he kept an anxious watch upon the derelict mine, which, having escaped being cast upon the ledge, was now being carried close to the main wall of rock.
In his heated imagination he fancied himself fifty or a hundred feet up the cliff with the powerful explosive going off and hurling him to a terrible death upon the rocks beneath. He shouted, but only the echoes of his own voice mocked his appeal for aid. In vain he looked seaward, where the mists of evening were already creeping over the wild North Sea. Not a sail was visible.
Mr. Greenwood was one of those men who, by disposition timid and unassuming, possessed a great reserve of courage and determination when called upon to extricate themselves from a tight corner. And, having found himself in a tight corner, he acted accordingly.
After a brief search he discovered a rift in the cliff, which at this point was not so sheer as it appeared at first sight. In any case the footholds obtainable extended sufficiently high to enable him to climb above high-water mark. Here he could wait until the tide fell and take his chance with the mine.