Chapter XVII.The Clay-pitDr. Priestley walked out of the inn, and down through the village towards the ruined castle, standing upon its curiously artificial-looking mound. He had attained one of the objects of his visit, corroboration of the story of the death of Dr. Morlandson, and that without asking questions which might have suggested that he had any interest in the matter. Since the landlord had himself volunteered the information, there could be no reason for his having distorted the truth. Morlandson, by the evidence of those best qualified to speak, was dead, and his charred bones were resting in the quiet churchyard which the Professor was at that very moment passing.He felt a great desire to see the site of the tragedy, but his natural caution prevented him from walking to it immediately. He was most anxious to avoid any suspicion that Mr. Deacon, the City merchant, was in any way interested in the fate of the ex-convict. But, on the other hand, there was no reason why he should not visit the ruins of the castle, the scene of the murder of King Edward the Martyr, three-quarters of a century before the Conquest. It was the show place of the district, the natural magnet for any casual visitor like himself.The Professor climbed slowly up the steep slopes of the natural earthwork, which stands like a fortress guarding the only gap in the long range of the Purbeck hills, and listened attentively while the guide, delighted at finding a sympathetic audience so early in the year, recounted the history of the stronghold and indicated its more prominent features. Then, his inspection over, he sat down on the grass on the north-eastern slope of the hill, and drew his ordnance map from his pocket.His horizon was bounded by the high land on the southern side of the River Stour. At his feet was a rolling, sandy plain, diversified here and there by clumps of trees, but mostly covered with gorse and heather. This plain stretched away into the distance, and beyond it an occasional silvery gleam betrayed the winding channels of Poole harbour. Here and there across the plain he could see evidences of human occupation, the white surface of a clay-pit or the roof of a tiny isolated cottage. But, apart from these, the tract of country over which he looked appeared utterly deserted, abandoned to a great silence disturbed only by the note of some hovering bird.His map told him that no road traversed this expanse. Only a few winding paths, trodden by the feet of rare wayfarers, led away from where he stood in the direction of the thin whisps of smoke which indicated human habitation. Here and there he could see traces of the railway of which the landlord had spoken, which led from the hidden quarries behind him to a pier built upon one of the secluded arms of the harbour. It seemed to be but little used. The Professor, enjoying the quiet of the fine afternoon, sat for hour after hour, his eyes absorbing the subtle beauty of this unharassed land. And, except for the solitary figure of a labourer, tramping stolidly across the waste towards some unknown destination, he saw no sign of life in all the wide extent of country laid out before his eyes. Yet, somewhere, lost among the lonely solitudes of gorse and heather, lay the solution of the mystery which he had set himself to solve.Dr. Priestley smiled as the conviction that this was so came back to him with redoubled force. Utterly contrary to his usual methods of procedure, he had formed a theory based entirely upon conjecture. So far, these facts by which it must be tested seemed to point to the incorrectness of this theory. Yet, were they facts? Was it not even yet possible that some master brain had arranged these seeming facts in order purposely to mislead an investigator like himself? And, if so, what unknown dangers might he not be incurring by the attempt to prove them false?The Professor had never shirked danger throughout the whole course of his career. And in this case, as he reflected, he already stood in such imminent danger that his present actions could hardly increase it. If his theory were correct, a determined and unknown assassin held in his hand already the weapon which was aimed against his life. Why had he not struck, months ago, when the Professor was in blissful ignorance that his life was threatened? This was one of the aspects of a case which, in spite of the perils which it held for himself, thrilled him as no case had ever thrilled him before.Sitting here, contemplating the peaceful afternoon, the Professor reviewed his theory for the last time, testing it with all the apparatus of probability. Itmustbe correct, there was no other theory which would fit in with all the data before him. Yet, how could it be correct, in the face of the formidable array of facts which seemed to disprove it? This seeming contradiction it must be his task to unravel, and that alone.For he had realized at once that it was no good calling in the aid of the police, even of Hanslet, whose experience had taught him that the Professor’s most extraordinary statements had a way of justifying themselves. The police would merely confront him with their so-called facts, and seek to prove to him that his theory was utterly untenable. He could give them nothing tangible to go upon, could give them no clue which would lead to the capture of the undetected criminal he knew to be at large. Even if they accepted his theory in its entirety, how could they protect him from the dangers which encompassed him? Sooner or later, in some unguarded moment, the shadow would leap out upon him, and the Professor’s theory would be proved upon his own body.No, physical precautions were useless. It must be a battle of wits between them—himself and this mysterious killer. How far had a watch been kept upon his own actions, the Professor wondered? He was almost certain that he had not been followed to Corfe Castle, but he was by no means so certain that his pretended departure from England had imposed upon his adversary.The Timesof Friday had contained the paragraph mentioning his visit to Australia. So far, so good. But it was almost with surprise that he had failed to find the message in the personal column, which should inform him that the letter which he daily expected had arrived.The Professor rose to his feet, and walked slowly back to the inn. He had ordered dinner at seven o’clock, and it was already past six. The landlord was standing at the door, and the Professor nodded pleasantly to him as he entered.“What a beautiful afternoon!” he said. “I have been admiring the view from the Castle. A very fine prospect indeed, is it not?”“Well, sir, some admires it and some don’t,” replied the landlord. “I fancies something with a bit more life in it myself. But I dessay it’s a change to you after London.”“It is, indeed,” agreed the Professor. “Indeed, I am so taken with the look of the heath, that I propose to take a walk across it after dinner.”“Well, don’t lose your way, sir. It’s a bit lonely out there. You aren’t likely to meet anyone who’ll put you right, either.”“Oh, it is not really dark till ten o’clock,” replied the Professor cheerfully. “I have my map, and the Castle ruins must be visible from a long way off. You need have no fears of my getting lost.”“There’s no danger, sir,” the landlord hastened to agree. “Only you might happen to wander a bit further afield than you meant to. The bar closes at ten, but if you happen to be later than that, you’ve only got to knock on the door. I shan’t be abed afore eleven.”The Professor’s dinner was served punctually at seven, and by eight o’clock he was well on the road of which the landlord had told him, and which his map showed him led in the direction of the railway. A short distance beyond the village he found a narrow lane, which, after a few twists and turnings, brought him out upon the track. There was a narrow path beside it, and along this he stepped out, anxious to reach his destination while it was still broad daylight.The track followed a devious path across the heath, which, viewed from near at hand, was more undulating than at first appeared. The track had been built to avoid the steeper gradients, but every now and then it ran upon a low embankment or through a shallow cutting. On either side the heath spread out, silent and mysterious, sometimes bare and sandy, with twisted pine trees standing above it at intervals, sometimes covered with low, dense thickets, in which the general silence seemed to be accentuated. When the line rose slightly to cross one of the lesser eminences, the Professor caught a fleeting glimpse of still water, the wandering arm of some unfrequented lagoon among the islands of the harbour. Behind him the sun hung low over the long range of the Purbeck hills, which changed from green and gold to blue and purple as the sun sank ever lower. Against them, the sharp outlines of the ruined Castle stood out clear cut like a beacon.As the Professor strode on through the silence, devoid of any vestige of human habitation, he noticed how admirably adapted was this barren heath to purposes of concealment. Spread over its surface were a series of shallow depressions, shaped like a saucer, and sometimes holding an abandoned gravel pit, now half filled with stagnant water after the winter rains. A man might lie concealed in one of these, secure from observation, for as long as he could keep himself supplied with food. There would be no risk of discovery, those whose business led them to cross the heath kept strictly to the narrow paths, barely a foot wide, which meandered at wide intervals through the close growth of heather. A living man, so long as he avoided observation from these paths, might lie hidden for as long as he chose. And if a living man, why not a dead body? How easy to drag the damning evidence of crime into one of those dark thickets, to sink it into the silent depths of one of those black, unruffled pools!The Professor shuddered, and increased his pace. This lonely heath was no place in which to indulge in morbid thoughts. His life might be in danger, but somehow he felt that it was not here that the blow would fall. If his theory were correct, if he had gauged aright the psychology of his adversary, it would not be thus that he would meet his death, here where there was none to witness the blow. Despite the almost threatening aspect of the country, deepening in tone every instant as the sun sank lower behind the distant hills, there was no vestige of any real danger. The shadows that lurked amid the gorse and heather were but the shadows of his own fears.So the Professor reasoned with himself. It would have been folly for him, wishing as he did to avoid any suspicion of his interest in Dr. Morlandson, to approach the scene of his death during the day. The very track by the side of which he was walking contained a potential risk of discovery. It must be used sometimes, the rails showed signs that wagons had passed over them not so very long ago. They led only to a pier, or rather jetty, upon which the contents of the wagons were unloaded into a waiting barge. The pier was utterly unfrequented except by these barges. The track, in fact, was a dead end as far as any casual wayfarer was concerned. There could be no rational excuse for following it.He topped a slight rise, and saw in the distance the white surface of the clay-pit which was to be his guide. From where he stood, he could see a considerable distance on either side of him. There was no sign of life upon the heath, except that far away, perhaps a couple of miles, the outlines of a cottage stood out against the grey background.The Professor reached the clay-pit, and searched the undulating surface of the heath for some sign of the remains of Dr. Morlandson’s laboratory. For some moments he failed to find it, and then, at last, he made out the jagged tooth of a broken wall thrust upwards from behind a clump of gorse bushes. This, no doubt, must be his goal. There was no path leading to it from the track, but the Professor, using his stick to feel the way, stepped out boldly across the heather, which yielded like a cushion to his footsteps.The distance from the track to the ruin must have been six or seven hundred yards. It took the Professor some little time to cover it, since he was obliged to make several detours in order to avoid clumps of gorse. But he reached it at last, and stood on the edge of what had once been a clearing, surveying the scene that lay before him.The cottage itself had completely vanished. All that remained of it was a mound thickly overgrown with weeds and coarse grass, from which protruded here and there fragments of charred beams and rafters. The encroaching heath had hidden any signs of any garden there might once have been, and it was impossible for the Professor to form any idea of what the place had looked like while it was still standing. But the laboratory, having been built of concrete, had defied the utter obliteration to which the rest of the premises had succumbed. Its broken walls, rough and jagged, stood up in a gaunt rectangle, roofless, their foundations hidden deep in the all-effacing vegetation, but still marking without fear of error the site upon which the building had stood.The Professor pushed through the weeds and undergrowth until he reached the gap in the wall where the door had been. The door was still there, rusty and twisted, lying almost hidden at the base of the wall, where it had been thrown by Dr. Morlandson’s would-be rescuers. It was a plain sheet of iron, fitted with hinges and a lock. The Professor glanced at it, then passed through the door-way into the space enclosed between the walls. Something, perhaps a grass-snake, rustled among the grasses as he entered.The laboratory had been a fairly spacious room, about thirty feet by fifteen. Of its interior fittings nothing whatever remained. As the Professor advanced into the interior of the space his boots struck metal at every other step. He stooped and probed with his stick, and brought to light a twisted and shapeless tangle of iron, which might once have been the frame of a skylight. He examined it for a moment, and then cast it aside, with a nod of comprehension. The walls themselves still showed upon their interior surface the signs of having been subjected to an enormous heat. He poked about inside the laboratory for a short while longer, then came out and sat down upon the mound which had once been a cottage.There could be no doubt that the fire which had destroyed the laboratory had been far fiercer than that which had burnt down the cottage. The charred beams of the latter still existed, while nothing whatever remained of the wooden fittings of the former. And yet, in case of a concrete-built laboratory, one would have expected a fire merely to have burnt out the interior without doing much damage to the structure. The place must certainly have contained a large quantity of substances whose combustion produced great heat, such as thermite. And Dr. Priestley knew enough of the methods of research chemists, who as a rule deal in very small quantities, to wonder why Dr. Morlandson required such large quantities, and why, even supposing that his isolated situation made it necessary for him to obtain his supplies in bulk, he should store them in the laboratory itself. The suspicion that Dr. Morlandson’s activities had not been solely concerned with researches into the properties of medicinal drugs seemed to the Professor to be thoroughly well grounded.To the Professor’s mind, there was even something suspicious about the origin of the fire itself. Dr. Morlandson had been aware of the danger of such an outbreak; he had warned the police superintendent against smoking in the laboratory. This being so, was it likely that he would lock himself into what had proved to be a regular death-trap, and leave himself with no means of escape? The doubt raised by these queries set the Professor’s mind to work upon an entirely fresh train of thought. Had Dr. Morlandson’s death been as accidental as it had appeared? Or was it possible that he too had had an enemy, who had somehow contrived the whole affair? And, if so, what became of the theory which had brought the Professor to the Isle of Purbeck?The Professor awoke with a start from his meditations, suddenly conscious that the light was failing rapidly. It was already past sunset, the ruined Castle which was to be his landmark was now indistinguishable against the universal grey of its background. A faint, silvery mist was rising above the heath, wreathing every object within sight with a curious opalescent halo. The Professor realized that he had already spent long enough contemplating this deserted heap of ashes. Their secret, did they hold one, was not to be wrested from them by further study that night.He turned his back upon the gaunt skeleton of the laboratory, and walked round to the further side of the mound. Here the stumps of a rotten post or two showed where a fence had probably surrounded the front garden, now long since overgrown. Beyond the posts a white thread caught the Professor’s eye, and he made his way up to it. It was a narrow track, apparently disused for years, and had no doubt once been the path by which the cottage was approached.In one direction it led towards the railway line by which the Professor had approached the place, and rejoined the line lower down than the point at which he had left it. He started to walk down the track, with a muttered exclamation of satisfaction. By following it he might add a yard or two to his journey, but it would save him a slow and tiresome trudge through the heather in the gathering darkness. Of his ability to find his way back to the inn he had no doubt. He had only to follow the railway line backwards until the lights of the village came in sight, and then strike across country till he reached them, even if he missed the lane by which he had come.The Professor had not gone very far before he stopped dead, and bent down to examine the narrow white strip beneath his feet. He felt in his pocket, and struck a match, which he held close to the surface of the path. It was a still, windless evening, and the flame of the match burnt clear and unflickering, illuminating a narrow circle of fine, white sand. Across the centre of this patch, following the path upon which the Professor stood, ran the sharp and unmistakable imprint of a bicycle tyre.Somehow the discovery made the Professor’s pulses beat quicker than before. This apparently deserted track was in use, then, despite its overgrown appearance. No doubt it formed a short cut between two spots upon the heath, such as a pit and a clay-worker’s cottage. This was the obvious explanation, but to the Professor’s mind it seemed unsatisfactory. He had studied the map very carefully that afternoon, and knew roughly the location of every human habitation marked upon it. And this particular track seemed to run in the wrong direction to connect up with any of these. Was it possible that somebody beside himself was interested in the ruined cottage which he had just left?He threw the match away, and strode forward briskly in the direction of the railway line, which he calculated must now be less than a quarter of a mile ahead. He had an uncanny feeling that the rider of the bicycle might have been concealed close at hand while he was investigating the ruins, that he himself might have been the object of close observation all the time he had believed himself to be alone in the vast emptiness of the heath. It was an uncomfortable and a disturbing thought, and the Professor pushed on rapidly, grasping his stick tightly. Of course it was absurd, he was not the least likely to be molested. But he could not keep his mind from drawing ugly pictures of the dark thickets, of those deep, black pools, so admirably adapted as a hiding place for a murdered body——And then, all of a sudden, with an abruptness which fell upon his ears like a blow, the Professor heard a bell ring sharply behind him. He spun round in his tracks, raising his stick instinctively, as though in self-defence. Coming along the path behind him was a tall figure on a bicycle, indistinguishable but for its outline in the swiftly-falling night. The slight mist magnified it to inhuman proportions.Dr. Priestley stepped back into the heather, and waited for the figure to approach him. As it came nearer he began to distinguish details one by one. It was a man, dressed apparently in trousers and jersey, with a seaman’s cap upon his head. The Professor felt a sudden feeling of relief. No doubt this was a man from one of the stone barges which came up to Goathorn Pier to load stone or clay. He would no doubt join the railway, and follow the track beside it down to the pier. He could see the man’s features by now, or such of them as were not hidden by the mass of black beard, which grew up in whiskers on either side of his face until it was lost beneath his cap. And then, with a sudden recollection of a certain vivid description which Hanslet had given him, the Professor realized that the man had an angry-looking scar extending the whole length of his right cheek. Even as he realized the significance of the man’s appearance, he had dismounted from his bicycle, and stood confronting the Professor.“Good evening, Dr. Priestley,” he said pleasantly, but in a curiously harsh and strained voice. And, at the words, the Professor knew that this was indeed the Black Sailor.
Dr. Priestley walked out of the inn, and down through the village towards the ruined castle, standing upon its curiously artificial-looking mound. He had attained one of the objects of his visit, corroboration of the story of the death of Dr. Morlandson, and that without asking questions which might have suggested that he had any interest in the matter. Since the landlord had himself volunteered the information, there could be no reason for his having distorted the truth. Morlandson, by the evidence of those best qualified to speak, was dead, and his charred bones were resting in the quiet churchyard which the Professor was at that very moment passing.
He felt a great desire to see the site of the tragedy, but his natural caution prevented him from walking to it immediately. He was most anxious to avoid any suspicion that Mr. Deacon, the City merchant, was in any way interested in the fate of the ex-convict. But, on the other hand, there was no reason why he should not visit the ruins of the castle, the scene of the murder of King Edward the Martyr, three-quarters of a century before the Conquest. It was the show place of the district, the natural magnet for any casual visitor like himself.
The Professor climbed slowly up the steep slopes of the natural earthwork, which stands like a fortress guarding the only gap in the long range of the Purbeck hills, and listened attentively while the guide, delighted at finding a sympathetic audience so early in the year, recounted the history of the stronghold and indicated its more prominent features. Then, his inspection over, he sat down on the grass on the north-eastern slope of the hill, and drew his ordnance map from his pocket.
His horizon was bounded by the high land on the southern side of the River Stour. At his feet was a rolling, sandy plain, diversified here and there by clumps of trees, but mostly covered with gorse and heather. This plain stretched away into the distance, and beyond it an occasional silvery gleam betrayed the winding channels of Poole harbour. Here and there across the plain he could see evidences of human occupation, the white surface of a clay-pit or the roof of a tiny isolated cottage. But, apart from these, the tract of country over which he looked appeared utterly deserted, abandoned to a great silence disturbed only by the note of some hovering bird.
His map told him that no road traversed this expanse. Only a few winding paths, trodden by the feet of rare wayfarers, led away from where he stood in the direction of the thin whisps of smoke which indicated human habitation. Here and there he could see traces of the railway of which the landlord had spoken, which led from the hidden quarries behind him to a pier built upon one of the secluded arms of the harbour. It seemed to be but little used. The Professor, enjoying the quiet of the fine afternoon, sat for hour after hour, his eyes absorbing the subtle beauty of this unharassed land. And, except for the solitary figure of a labourer, tramping stolidly across the waste towards some unknown destination, he saw no sign of life in all the wide extent of country laid out before his eyes. Yet, somewhere, lost among the lonely solitudes of gorse and heather, lay the solution of the mystery which he had set himself to solve.
Dr. Priestley smiled as the conviction that this was so came back to him with redoubled force. Utterly contrary to his usual methods of procedure, he had formed a theory based entirely upon conjecture. So far, these facts by which it must be tested seemed to point to the incorrectness of this theory. Yet, were they facts? Was it not even yet possible that some master brain had arranged these seeming facts in order purposely to mislead an investigator like himself? And, if so, what unknown dangers might he not be incurring by the attempt to prove them false?
The Professor had never shirked danger throughout the whole course of his career. And in this case, as he reflected, he already stood in such imminent danger that his present actions could hardly increase it. If his theory were correct, a determined and unknown assassin held in his hand already the weapon which was aimed against his life. Why had he not struck, months ago, when the Professor was in blissful ignorance that his life was threatened? This was one of the aspects of a case which, in spite of the perils which it held for himself, thrilled him as no case had ever thrilled him before.
Sitting here, contemplating the peaceful afternoon, the Professor reviewed his theory for the last time, testing it with all the apparatus of probability. Itmustbe correct, there was no other theory which would fit in with all the data before him. Yet, how could it be correct, in the face of the formidable array of facts which seemed to disprove it? This seeming contradiction it must be his task to unravel, and that alone.
For he had realized at once that it was no good calling in the aid of the police, even of Hanslet, whose experience had taught him that the Professor’s most extraordinary statements had a way of justifying themselves. The police would merely confront him with their so-called facts, and seek to prove to him that his theory was utterly untenable. He could give them nothing tangible to go upon, could give them no clue which would lead to the capture of the undetected criminal he knew to be at large. Even if they accepted his theory in its entirety, how could they protect him from the dangers which encompassed him? Sooner or later, in some unguarded moment, the shadow would leap out upon him, and the Professor’s theory would be proved upon his own body.
No, physical precautions were useless. It must be a battle of wits between them—himself and this mysterious killer. How far had a watch been kept upon his own actions, the Professor wondered? He was almost certain that he had not been followed to Corfe Castle, but he was by no means so certain that his pretended departure from England had imposed upon his adversary.The Timesof Friday had contained the paragraph mentioning his visit to Australia. So far, so good. But it was almost with surprise that he had failed to find the message in the personal column, which should inform him that the letter which he daily expected had arrived.
The Professor rose to his feet, and walked slowly back to the inn. He had ordered dinner at seven o’clock, and it was already past six. The landlord was standing at the door, and the Professor nodded pleasantly to him as he entered.
“What a beautiful afternoon!” he said. “I have been admiring the view from the Castle. A very fine prospect indeed, is it not?”
“Well, sir, some admires it and some don’t,” replied the landlord. “I fancies something with a bit more life in it myself. But I dessay it’s a change to you after London.”
“It is, indeed,” agreed the Professor. “Indeed, I am so taken with the look of the heath, that I propose to take a walk across it after dinner.”
“Well, don’t lose your way, sir. It’s a bit lonely out there. You aren’t likely to meet anyone who’ll put you right, either.”
“Oh, it is not really dark till ten o’clock,” replied the Professor cheerfully. “I have my map, and the Castle ruins must be visible from a long way off. You need have no fears of my getting lost.”
“There’s no danger, sir,” the landlord hastened to agree. “Only you might happen to wander a bit further afield than you meant to. The bar closes at ten, but if you happen to be later than that, you’ve only got to knock on the door. I shan’t be abed afore eleven.”
The Professor’s dinner was served punctually at seven, and by eight o’clock he was well on the road of which the landlord had told him, and which his map showed him led in the direction of the railway. A short distance beyond the village he found a narrow lane, which, after a few twists and turnings, brought him out upon the track. There was a narrow path beside it, and along this he stepped out, anxious to reach his destination while it was still broad daylight.
The track followed a devious path across the heath, which, viewed from near at hand, was more undulating than at first appeared. The track had been built to avoid the steeper gradients, but every now and then it ran upon a low embankment or through a shallow cutting. On either side the heath spread out, silent and mysterious, sometimes bare and sandy, with twisted pine trees standing above it at intervals, sometimes covered with low, dense thickets, in which the general silence seemed to be accentuated. When the line rose slightly to cross one of the lesser eminences, the Professor caught a fleeting glimpse of still water, the wandering arm of some unfrequented lagoon among the islands of the harbour. Behind him the sun hung low over the long range of the Purbeck hills, which changed from green and gold to blue and purple as the sun sank ever lower. Against them, the sharp outlines of the ruined Castle stood out clear cut like a beacon.
As the Professor strode on through the silence, devoid of any vestige of human habitation, he noticed how admirably adapted was this barren heath to purposes of concealment. Spread over its surface were a series of shallow depressions, shaped like a saucer, and sometimes holding an abandoned gravel pit, now half filled with stagnant water after the winter rains. A man might lie concealed in one of these, secure from observation, for as long as he could keep himself supplied with food. There would be no risk of discovery, those whose business led them to cross the heath kept strictly to the narrow paths, barely a foot wide, which meandered at wide intervals through the close growth of heather. A living man, so long as he avoided observation from these paths, might lie hidden for as long as he chose. And if a living man, why not a dead body? How easy to drag the damning evidence of crime into one of those dark thickets, to sink it into the silent depths of one of those black, unruffled pools!
The Professor shuddered, and increased his pace. This lonely heath was no place in which to indulge in morbid thoughts. His life might be in danger, but somehow he felt that it was not here that the blow would fall. If his theory were correct, if he had gauged aright the psychology of his adversary, it would not be thus that he would meet his death, here where there was none to witness the blow. Despite the almost threatening aspect of the country, deepening in tone every instant as the sun sank lower behind the distant hills, there was no vestige of any real danger. The shadows that lurked amid the gorse and heather were but the shadows of his own fears.
So the Professor reasoned with himself. It would have been folly for him, wishing as he did to avoid any suspicion of his interest in Dr. Morlandson, to approach the scene of his death during the day. The very track by the side of which he was walking contained a potential risk of discovery. It must be used sometimes, the rails showed signs that wagons had passed over them not so very long ago. They led only to a pier, or rather jetty, upon which the contents of the wagons were unloaded into a waiting barge. The pier was utterly unfrequented except by these barges. The track, in fact, was a dead end as far as any casual wayfarer was concerned. There could be no rational excuse for following it.
He topped a slight rise, and saw in the distance the white surface of the clay-pit which was to be his guide. From where he stood, he could see a considerable distance on either side of him. There was no sign of life upon the heath, except that far away, perhaps a couple of miles, the outlines of a cottage stood out against the grey background.
The Professor reached the clay-pit, and searched the undulating surface of the heath for some sign of the remains of Dr. Morlandson’s laboratory. For some moments he failed to find it, and then, at last, he made out the jagged tooth of a broken wall thrust upwards from behind a clump of gorse bushes. This, no doubt, must be his goal. There was no path leading to it from the track, but the Professor, using his stick to feel the way, stepped out boldly across the heather, which yielded like a cushion to his footsteps.
The distance from the track to the ruin must have been six or seven hundred yards. It took the Professor some little time to cover it, since he was obliged to make several detours in order to avoid clumps of gorse. But he reached it at last, and stood on the edge of what had once been a clearing, surveying the scene that lay before him.
The cottage itself had completely vanished. All that remained of it was a mound thickly overgrown with weeds and coarse grass, from which protruded here and there fragments of charred beams and rafters. The encroaching heath had hidden any signs of any garden there might once have been, and it was impossible for the Professor to form any idea of what the place had looked like while it was still standing. But the laboratory, having been built of concrete, had defied the utter obliteration to which the rest of the premises had succumbed. Its broken walls, rough and jagged, stood up in a gaunt rectangle, roofless, their foundations hidden deep in the all-effacing vegetation, but still marking without fear of error the site upon which the building had stood.
The Professor pushed through the weeds and undergrowth until he reached the gap in the wall where the door had been. The door was still there, rusty and twisted, lying almost hidden at the base of the wall, where it had been thrown by Dr. Morlandson’s would-be rescuers. It was a plain sheet of iron, fitted with hinges and a lock. The Professor glanced at it, then passed through the door-way into the space enclosed between the walls. Something, perhaps a grass-snake, rustled among the grasses as he entered.
The laboratory had been a fairly spacious room, about thirty feet by fifteen. Of its interior fittings nothing whatever remained. As the Professor advanced into the interior of the space his boots struck metal at every other step. He stooped and probed with his stick, and brought to light a twisted and shapeless tangle of iron, which might once have been the frame of a skylight. He examined it for a moment, and then cast it aside, with a nod of comprehension. The walls themselves still showed upon their interior surface the signs of having been subjected to an enormous heat. He poked about inside the laboratory for a short while longer, then came out and sat down upon the mound which had once been a cottage.
There could be no doubt that the fire which had destroyed the laboratory had been far fiercer than that which had burnt down the cottage. The charred beams of the latter still existed, while nothing whatever remained of the wooden fittings of the former. And yet, in case of a concrete-built laboratory, one would have expected a fire merely to have burnt out the interior without doing much damage to the structure. The place must certainly have contained a large quantity of substances whose combustion produced great heat, such as thermite. And Dr. Priestley knew enough of the methods of research chemists, who as a rule deal in very small quantities, to wonder why Dr. Morlandson required such large quantities, and why, even supposing that his isolated situation made it necessary for him to obtain his supplies in bulk, he should store them in the laboratory itself. The suspicion that Dr. Morlandson’s activities had not been solely concerned with researches into the properties of medicinal drugs seemed to the Professor to be thoroughly well grounded.
To the Professor’s mind, there was even something suspicious about the origin of the fire itself. Dr. Morlandson had been aware of the danger of such an outbreak; he had warned the police superintendent against smoking in the laboratory. This being so, was it likely that he would lock himself into what had proved to be a regular death-trap, and leave himself with no means of escape? The doubt raised by these queries set the Professor’s mind to work upon an entirely fresh train of thought. Had Dr. Morlandson’s death been as accidental as it had appeared? Or was it possible that he too had had an enemy, who had somehow contrived the whole affair? And, if so, what became of the theory which had brought the Professor to the Isle of Purbeck?
The Professor awoke with a start from his meditations, suddenly conscious that the light was failing rapidly. It was already past sunset, the ruined Castle which was to be his landmark was now indistinguishable against the universal grey of its background. A faint, silvery mist was rising above the heath, wreathing every object within sight with a curious opalescent halo. The Professor realized that he had already spent long enough contemplating this deserted heap of ashes. Their secret, did they hold one, was not to be wrested from them by further study that night.
He turned his back upon the gaunt skeleton of the laboratory, and walked round to the further side of the mound. Here the stumps of a rotten post or two showed where a fence had probably surrounded the front garden, now long since overgrown. Beyond the posts a white thread caught the Professor’s eye, and he made his way up to it. It was a narrow track, apparently disused for years, and had no doubt once been the path by which the cottage was approached.
In one direction it led towards the railway line by which the Professor had approached the place, and rejoined the line lower down than the point at which he had left it. He started to walk down the track, with a muttered exclamation of satisfaction. By following it he might add a yard or two to his journey, but it would save him a slow and tiresome trudge through the heather in the gathering darkness. Of his ability to find his way back to the inn he had no doubt. He had only to follow the railway line backwards until the lights of the village came in sight, and then strike across country till he reached them, even if he missed the lane by which he had come.
The Professor had not gone very far before he stopped dead, and bent down to examine the narrow white strip beneath his feet. He felt in his pocket, and struck a match, which he held close to the surface of the path. It was a still, windless evening, and the flame of the match burnt clear and unflickering, illuminating a narrow circle of fine, white sand. Across the centre of this patch, following the path upon which the Professor stood, ran the sharp and unmistakable imprint of a bicycle tyre.
Somehow the discovery made the Professor’s pulses beat quicker than before. This apparently deserted track was in use, then, despite its overgrown appearance. No doubt it formed a short cut between two spots upon the heath, such as a pit and a clay-worker’s cottage. This was the obvious explanation, but to the Professor’s mind it seemed unsatisfactory. He had studied the map very carefully that afternoon, and knew roughly the location of every human habitation marked upon it. And this particular track seemed to run in the wrong direction to connect up with any of these. Was it possible that somebody beside himself was interested in the ruined cottage which he had just left?
He threw the match away, and strode forward briskly in the direction of the railway line, which he calculated must now be less than a quarter of a mile ahead. He had an uncanny feeling that the rider of the bicycle might have been concealed close at hand while he was investigating the ruins, that he himself might have been the object of close observation all the time he had believed himself to be alone in the vast emptiness of the heath. It was an uncomfortable and a disturbing thought, and the Professor pushed on rapidly, grasping his stick tightly. Of course it was absurd, he was not the least likely to be molested. But he could not keep his mind from drawing ugly pictures of the dark thickets, of those deep, black pools, so admirably adapted as a hiding place for a murdered body——
And then, all of a sudden, with an abruptness which fell upon his ears like a blow, the Professor heard a bell ring sharply behind him. He spun round in his tracks, raising his stick instinctively, as though in self-defence. Coming along the path behind him was a tall figure on a bicycle, indistinguishable but for its outline in the swiftly-falling night. The slight mist magnified it to inhuman proportions.
Dr. Priestley stepped back into the heather, and waited for the figure to approach him. As it came nearer he began to distinguish details one by one. It was a man, dressed apparently in trousers and jersey, with a seaman’s cap upon his head. The Professor felt a sudden feeling of relief. No doubt this was a man from one of the stone barges which came up to Goathorn Pier to load stone or clay. He would no doubt join the railway, and follow the track beside it down to the pier. He could see the man’s features by now, or such of them as were not hidden by the mass of black beard, which grew up in whiskers on either side of his face until it was lost beneath his cap. And then, with a sudden recollection of a certain vivid description which Hanslet had given him, the Professor realized that the man had an angry-looking scar extending the whole length of his right cheek. Even as he realized the significance of the man’s appearance, he had dismounted from his bicycle, and stood confronting the Professor.
“Good evening, Dr. Priestley,” he said pleasantly, but in a curiously harsh and strained voice. And, at the words, the Professor knew that this was indeed the Black Sailor.