"As to the particular method, the question was of no great importance. Still, my friend considered it. The idea of a dene-hole was at once excluded on geological grounds. Dene-holes are peculiar to the chalk. But this was not a chalk district.
"The cess-pit was possible but not very probable; for if in use, it would be subject to periodical clearance, which would make it quite unsuitable as a hiding-place, while cess-pits which become superseded by drainage are usually filled in and definitely covered up. A well, on the other hand, is often kept open for occasional and special use after the laying on of a pipe service."
"Your friend", remarked Pottermack, "seems to have taken it for granted that a well actually existed."
"Not entirely", said Thorndyke. "He looked up an older map and found that this house had formerly been a farm-house, so that it must once have had a well; and as it now fronts on a road in which other houses have been built and which is virtually a street, it is pretty certainly connected with the water-service. So that it was practically certain that there was a well, and that well would almost certainly be out of use.
"And now, having deduced a reason why the counterfeit soles should have been necessary, he had to consider another question. If the original shoes were inaccessible, how could it have been possible to make the counterfeits, which were, apparently, casts of the originals? At first it looked like an impossibility. But a little reflection showed that the footprints themselves supplied the answer. Mr. Black's own footprints on the path were such perfect impressions that a little good plaster poured into selected samples of them would have furnished casts which would have been exact reproductions of the soles and heels of Mr. Black's shoes. Possibly there were equally good footprints inside the premises, but that is of no consequence. Those on the footpath would have answered the purpose perfectly.
"I may say that my friend tested this conclusion and got some slight confirmation. For if the false footprints were impressions of reproductions, not of the original shoes but of some other footprints, one would expect to find the accidental characters of those particular footprints as well as those of the shoes which produced them. And this appeared to be the case. In one of the points of the star on the left heel a small particle of earth seemed to have adhered. This was not to be found in Black's own footprints, but it was visible in all the footprints of the second series, from the gate to the heath. And the fact that it never changed along the whole series suggested that it was really a part of the cast, due to an imperfection in the footprint from which it was made.
"That brings us to an end of my friend's train of reasoning in regard to the actual events connected with Mr. Black's disappearance. His conclusions were, you observe, that Mr. Black went in at the gate; that he was thereafter made away with by some person inside whom we have called the tenant; that his body was deposited by the tenant in some inaccessible place, probably a disused well; and that the tenant then made a set of false footprints to disguise the fact that Mr. Black had gone in at the gate.
"The questions that remained to be considered were; first. What could be the tenant's motive for making away with Mr. Black? and second, Who was the tenant? But before we deal with his inferences on those points, I should like to hear any observations which you may have to make on what I have told you."
Mr. Pottermack pondered awhile on what he had heard, and as he reflected, he laid a disparaging hand on the teapot.
"It is rather cool", he remarked apologetically; "but such as it is, can I give you another cup?"
"Prolonged exposition", Thorndyke replied with a smile, "is apt to have a cooling effect upon tea. But it also creates a demand for liquid refreshment. Thank you, I think another cup would cheer, and we can dispense with the inebriation."
Mr. Pottermack refilled both the cups and put down the teapot, still cogitating profoundly.
XVIII. THE SUN-DIAL HAS THE LAST WORD
"Your legal friend", Mr. Pottermack said at length, "must be a man of extraordinary subtlety and ingenuity if he deduced all that you have told me from the mere peculiarities of a set of footprints, and only photographs at that. But what strikes me about it is that his reconstruction was, after all, pure speculation. There were too many 'ifs'."
"But, my dear Mr. Pottermack", exclaimed Thorndyke, "it was all 'ifs'. The whole train of reasoning was on the plane of hypothesis, pure and simple. He did not, at this stage, assume that it was actually true, but merely true conditionally on the facts being what they appeared to be. But what does a scientific man do when he sets up a working hypothesis? He deduces from it its consequences, and he continues to pursue these so long as they are consistent with the facts known to him. Sooner or later, this process brings him either to an impossibility or a contradiction—in which case he abandons the hypothesis—or to a question of fact which is capable of being settled conclusively, yes or no.
"Well, this is what my friend did. So far we have seen him pursuing a particular hypothesis and deducing from it certain consequences. The whole thing might have been fallacious. But it was consistent, and the consequences were compatible with the known facts. Presently we shall come to the question of fact—the crucial experiment which determines yes or no, whether the hypothesis is true or false. But we have to follow the hypothetical method a little farther first.
"The questions that remained to be considered were: first, What could have been the tenant's motive for killing Mr. Black? and second, Who was the tenant? My friend took the questions in this order because the motive might be arrived at by reasoning, and, if so arrived at, might throw light on the personality of the tenant; whereas the identity of the tenant, taken by itself, was a matter of fact capable of being ascertained by enquiry, but not by reasoning apart from the motive.
"Now, what motives suggest themselves? First, we must note that my friend assumed that the homicide was committed by the tenant himself, that is, by the proprietor of the premises and not by a servant or other person. That is a reasonable inference from the facts that the person, whoever he was, appeared to have command of all the means and materials necessary for making the counterfeits, and also that he must have had full control of the premises, both at the time and in the future, in order to hide the body and ensure that it should remain hidden. Well, what motive could a man in this position have had to kill Mr. Black?
"There is the motive of robbery, but the circumstances seem to exclude it as not reasonably probable. It is true that Black had a hundred pounds on his person, but there is no reason to suppose that any one knew that he had; and in any case, so small a sum, relatively, furnishes a quite insufficient motive for murder in the case of an apparently well-to-do man such as the tenant. My friend decided that robbery, though possible, was highly improbable.
"The possibilities that Black's death might have been the result of a quarrel or of some act of private vengeance had to be borne in mind, but there were no means of forming any opinions for or against them. They had to be left as mere speculative possibilities. But there was another possibility which occurred to my friend, the probabilities of which were susceptible of being argued, and to this he turned his attention. It was based upon the application of certain facts actually known and which we will now consider.
"First, he noted that Mr. Black came to this place voluntarily, and that he came expressly to visit the premises within the gate is proved by the fact that this is the last house on that path. Beyond it is the country. There is no other human habitation to which he could have been bound. Now Mr. Black was, at this moment, in acute financial difficulties. He had borrowed a hundred pounds from the bank's money, and this hundred pounds he was about to pay away to meet an urgent demand. But that hundred pounds would have to be replaced, and it was of the utmost importance that it should be replaced without delay. For if a surprise inspection should have occurred before it was replaced, he stood to be charged with robbery. The circumstances, therefore, seemed to suggest that he had taken it with the expectation of being able to replace it
almost immediately.
"Now, you will remember that it transpired after his disappearance that Mr. Black had some mysterious unknown source of income; that he had received on several occasions large sums of money, which had apparently come to him in the form of cash and had been paid away in the same form—always in five-pound notes. These monies did not appear in his banking account or in any other account. They were unrecorded—and, consequently, their total amount is not known. But the sums that he is known to have received were ascertained by means of the discovery of certain payments that he had made. I need not point out to you the great and sinister significance of these facts. When a man who has a banking account receives large payments in cash, and when, instead of paying them into his account, he pays them away in cash, it is practically certain that the monies that he has received are connected with some secret transaction, and that transaction is almost certainly an illicit one. But of all such transactions, by far the commonest is blackmail. In fact, one would hardly be exaggerating if one were to say that evidence of secret payments of large sums in coin or notes is presumptive evidence of blackmail. Accordingly my friend strongly suspected Mr. Black of being a blackmailer.
"And now, assuming this to be correct, see how admirably the assumption fits the circumstances. Mr. Black is at the moment financially desperate. He has taken certain money, which is not his, to pay an urgent and threatening creditor. Instead of going direct to that creditor, he comes first to this house. But he does not enter by the front door. He goes to a gate which opens on an unfrequented lane and which gives entrance to a remote part of the grounds, and he does this late in the evening. There is a manifestly secret air about the whole proceeding.
"And now let us make another assumption."
"What, another!" protested Pottermack.
"Yes, another; just to see if it will fit the circumstances as the others have done. Let us assume that the tenant was the person from whom Mr. Black had been extorting those mysterious payments; the victim whom he had been blackmailing. That he had called in on his way to his creditor to see if he could squeeze him for yet another hundred, so that the notes could be replaced before they could be missed. That the victim, being now at the end of his patience and having an opportunity of safely making away with his persecutor, took that opportunity and made away with him. Is it not obvious that we have a perfectly consistent scheme of the probable course of events?"
"It is all pure conjecture", objected Pottermack.
"It is all pure hypothesis", Thorndyke admitted, "but you see that it all hangs together, it all fits the circumstances completely. We have not come to any inconsistency or impossibility. And it is all intrinsically probable in the special conditions; for you must not forget that we are dealing with a set of circumstances that admits of no normal explanation.
"And now for the last question. Assuming that Mr. Black was a blackmailer and that the tenant was his victim, was it possible to give that victim a name? Here my friend was handicapped by the fact that Mr. Black was a complete stranger, of whose domestic affairs and friends and acquaintances he had no knowledge. With one exception. He had knowledge of one of Mr. Black's friends. That friend, it is true, was alleged to be dead. But it was by no means certain that he was dead. And if he were not dead, he was a perfectly ideal subject for blackmail, for he was an escaped convict with a considerable term of penal servitude still to run. My friend was, of course, thinking of Mr. White. If he should have attained to something approaching affluence and should be living in prosperous and socially desirable circumstances, he would allow himself to be bled to an unlimited extent rather than suffer public disgrace and be sent back to prison. And the person who would be, of all others, the most likely to recognize him and in the best position to blackmail him would be his old friend Mr. Black.
"Bearing these facts in mind, my friend was disposed to waive the prima facie improbability and assume, provisionally, that the tenant was Mr. White. It was certainly rather a long shot."
"It was indeed", said Pottermack. "Your friend was a regular Robin Hood."
"And yet", Thorndyke rejoined, "the balance of probability was in favour of that assumption. For against the various circumstances that suggested that the tenant was Mr. White there was to be set only one single improbability, and that not at all an impressive one: the improbability that a body—found drowned after six weeks' immersion and therefore really unrecognizable—should have been wrongly identified. However, my friend did feel that (to continue the metaphor, since you seem to approve of it) the time had come to step forward and have a look at the target. The long train of hypothetical reasoning had at length brought him to a proposition the truth of which could be definitely tested. The tenant's identity with Mr. White was a matter of fact which could be proved or disproved beyond all doubt. Of course, the test would not be a real experimentum crucis, because it would act in only one direction. If it should turn out that the tenant was not Mr. White, that would not invalidate the other conclusions, but if it should turn out that he was Mr. White, that fact would very strongly confirm those conclusions.
"My friend, then, left his photographs and his ordnance map and made a journey to the scene of these strange events to inspect the place and the man with his own eyes. First he examined the path and the exterior of the premises, and then he made a survey of the grounds enclosed by the wall."
"How did he do that?" enquired Pottermack. "It was a pretty high wall—at least, so I understand."
"He made use of an ancient optical instrument which has been recently revived in an improved form under the name of 'periscope.' The old instrument had two mirrors; the modern one has two total-reflection prisms in a narrow tube. By projecting the upper or objective end of the tube above the top of the wall, my friend was able, on looking into the eye-piece, to get an excellent view of the premises. What he saw was a large garden, completely enclosed by four high walls in which were two small gates, each provided with a night-latch and therefore capable of being opened only from within or by means of a latch-key. A very secure and secluded garden. On one side of it was a range of out-buildings which, by the glazed lights in their roofs, appeared to be studios or workshops. Near one end of the lawn was a sun-dial on a very wide stone base. The width of the base was rather remarkable, being much greater than is usual in a garden dial. A glance at it showed that the dial had been quite recently set up, for, though the stone pillar was old, the base stones were brand new. Moreover, the turf around it had been very recently laid and some of the earth was still bare. Further proof of its newness was furnished by a gentleman who was, at the moment, engaged, with the aid of Whitaker's Almanack and his watch, in fixing the dial-plate in correct azimuth.
"This gentleman—the mysterious tenant—naturally engaged my friend's attention. There were several interesting points to be noted concerning him. The tools that he used were workmen's tools, not amateurs', and he used them with the unmistakable skill of a man accustomed to tools. Then he had laid aside his spectacles, which were 'curl-sided' and therefore habitually worn. It followed, then, that he was near-sighted; for if he had been old-sighted or long-sighted he would have needed the spectacles especially for the close and minute work that he was doing.
"When he had made these observations, my friend proceeded to take a couple of photographs—a right and a left profile."
"How did he manage that?" demanded the astonished Pottermack.
"By placing his camera on the top of the wall. It was a special, small camera, fitted with a four-point-five Ross-Zeiss lens and a cord release. Of course, he made the exposure with the aid of the periscope.
"When he had exposed the photographs, he decided to have a nearer view of the tenant. Accordingly he went round and knocked at the gate, which was presently opened by the gentleman of the sun-dial, who was now wearing his spectacles. Looking at those spectacles, my friend made a very curious discovery. The man was not near-sighted, for the glasses were convex bi-focals, the upper part nearly p
lain glass. Now, if he had not needed those spectacles for near work, he certainly could not need them for distance. Then, obviously, he did not need them at all. But, if so, why was he wearing them? The only possible explanation was that they were worn for their effect on his appearance; in short, for the purpose of disguise.
"As this gentleman was answering some questions about the locality my friend handed him a folded map. This he did with two objects: that he might get a good look at him unobserved, and that he might possibly obtain some prints of his finger-tips. As to the first, he was able to make a mental note of the tenant's salient characteristics and to observe, among other peculiarities, a purplish mark on the lobe of the right ear of the kind known to surgeons as a capillary naevus."
"And the finger-prints?" Pottermack asked eagerly.
"They were rather a failure, but not quite. When my friend developed them up, though very poor specimens, they were distinct enough to be recognizable by an expert.
"Now you will have noticed that everything that my friend observed was consistent with, and tended to confirm, the conclusions that he had arrived at by hypothetical reasoning. But the actual test still remained to be applied. Was the tenant Mr. White or was he not? In order to settle this question, my friend made enlargements of the photographs of the tenant and also of the finger-prints, and, with these in his pocket, paid a visit to Scotland Yard."
At the mention of the ill-omened name Pottermack started and a sudden pallor spread over his face. But he uttered no sound, and Thorndyke continued:
"There he presented the finger-prints as probably those of a deceased person, photographed from a document, and asked for an expert opinion on them. He gave no particulars and was not asked for any; but the experts made their examination and reported that the finger-prints were those of a convict named White who had died some fifteen years previously. My friend had, further, the opportunity of inspecting the prison photographs of the deceased White and of reading the personal description. Needless to say, they agreed completely in every particular, even to the capillary naevus on the ear.
Dr. Thorndyke Omnibus Vol 5 Page 53