"Pompey" to be lying; but headland after headland was passed without any satisfactory result.

Presently he arrived at a little bay. The distance between the two enclosing promontories was less than a hundred yards apart. The shore was of sand, but, unlike the rest of the beach, was interrupted by a series of low ledges of rock. Between the water's edge and the base of the cliffs the distance averaged twenty yards, although the waves were almost washing the wall of granite at either end of the bay.

Suddenly Mr. Greenwood caught sight of a cylindrical object lying on the shore. It was a little larger than a football and glistened in the dull light. At every undulation it was flung upon the sand, whence it receded in the undertow until thrown back by the succeeding wave. Attached to it was a short length of frayed rope.

"That must be a mine," decided the alarmed man. "The authorities must be informed."

Although half inclined to retrace his steps, he walked cautiously past it, keeping as close to the cliffs as possible, until he gained the furthermost headland. Here, to his dismay, he found the distant aspect was a misleading one, for his progress was barred by a deep gulley through which the tide was surging right up to the wall of granite.

"I hope the tide is going down," thought Mr. Greenwood.

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.

The first six feet gave him great trouble, for the weed and kelp afforded little foothold, but beyond this height he was able to maintain a steady progress. Up and up he climbed, not daring to look down, although the attraction of that deadly cylinder was almost irresistible. He wanted to watch its progress towards the base of the solid rock.

At length, fifty feet above the sea, he gained a fairly broad ledge, the presence of which was invisible from the beach. Nor could it be seen from the top of the cliffs, for higher up they projected well beyond the ledge, the face being so smooth that further climbing was a matter of sheer impossibility.

"At any rate, I am safe for the time being," soliloquised Mr. Greenwood. "That is something to be thankful for, although I would infinitely prefer the comfort of a bed to the prospect of spending a winter's night less than halfway up a wall of rock. And even if that mine explodes I think this ledge will provide sufficient protection to minimise the force of the detonation."

Cautiously extending himself, he peered over the edge. In the fast-gathering gloom he could just discern the mine as it rolled to and fro on the shelving sand. The waves had almost borne it to the base of the rocks.

A new danger now confronted the stranded man. Perilous as the climb had been, the descent was doubly dangerous. When the time came, he could no more essay the feat of regaining the beach than he could hope to clamber up the remaining two hundred feet of beetling cliff. Unless aid were forthcoming, he was in danger of perishing of cold and hunger.

Mr. Greenwood's next step was to prepare for his approaching vigil while there was yet light enough for him to see. The ledge was almost twelve feet in length and five in its widest part, gradually diminishing to nothing at either end. One portion was covered by a withered bush, a circumstance that aroused the investigator's curiosity, since it seemed remarkable that vegetation could grow on the face of a granite cliff.

"Thank goodness I have pipe, matches, and tobacco," he thought philosophically. Now that the immediate danger was past, he determined to make the best of things.

He again directed his attention upon the bush. To use it as a seat would be preferable to sitting on the hard, cold rock.

As he sat the bush gave way. In vain he clutched wildly for support. Toppling backwards, he disappeared into what appeared to be the solid rock.

For some moments he lay helpless, too dazed to realise what had occurred. He was almost in darkness. A peculiar pungent smell assailed his nostrils. Could it be possible that he owed his present predicament to the explosion of the derelict mine?

After a while Mr. Greenwood raised himself. Grimly he reflected that his visit to Auldhaig had not been uneventful. Adventures were crowding upon each other's heels. His zest for excitement was increasing.

The bush had broken his fall. He found himself on a flat floor of what appeared to be a cavern. Where the foliage had been, appeared an irregular opening through which the dim twilight filtered without sufficient intensity to reveal his surroundings.

"One thing, I've a roof over my head," he soliloquised. "Now I am getting on. But I really cannot understand this peculiar odour. It reminds me very forcibly of a garage. Yes, petrol fumes. To be on the safe side I don't think I'll smoke just at present. In fact, I think it would be well to investigate."

Cautiously and on all-fours Mr. Greenwood commenced his tour of discovery, crawling lest there should be a hole in the floor.

Soon his head came in contact with a metallic object. It was a filled petrol tin, one of dozens, possibly hundreds, stacked in orderly manner against one wall of the cave.

"Now, that's strange," murmured Mr. Greenwood "It is pretty certain that that lot would not have been brought into this place from the cliff, so there must be an outlet besides the hole through which I tumbled. Why should a place like this be chosen to store petrol? And why was the hole so carefully hidden with a dead