of the foot has given way; the plantar ligaments have become stretched and the deep calf muscles weakened. Then, since bending of the weakened arch causes discomfort, the feet have become turned outwards, by which the bending of the foot is reduced to a minimum; and as the left foot is the more flattened, so it is turned out more than the right. Then the turning out of the toes causes the legs to splay outward from the knees downwards—a very conspicuous condition in a tall man like this one—and you notice that the left leg splays out more than the other.
"But we know that depression of the arch of the foot is brought about by standing for long periods. Continuous pressure on a living structure weakens it, while intermittent pressure strengthens it; so the man who stands on his feet continuously develops a flat instep and a weak calf, while the professional dancer or runner acquires a high instep and a strong calf. Now there are many occupations which involve prolonged standing and so induce the condition of flat foot: waiters, hall-porters, hawkers, policemen, shop-walkers, salesmen, and station officials are examples. But the waiter's gait is characteristic—a quick, shuffling walk which enables him to carry liquids without spilling them. This man walks with a long, swinging stride; he is obviously not a waiter. His dress and appearance in general exclude the idea of a hawker or even a hall-porter; he is a man of poor physique and so cannot be a policeman. The shop-walker or salesman is accustomed to move in relatively confined spaces, and so acquires a short, brisk step, and his dress tends to rather exuberant smartness; the station official patrols long platforms, often at a rapid pace, and so tends to take long strides, while his dress is dignified and neat rather than florid. The last-mentioned characteristics, you see, appear in the subject of our analysis; he agrees with the general description of a stationmaster. But if we therefore conclude that he is a stationmaster, we fall into the time-honoured fallacy of the undistributed middle term—the fallacy that haunts all brilliant guessers, including the detective, not only of romance, but too often also of real life. All that the observed facts justify us in inferring is that this man is engaged in some mode of life that necessitates a good deal of standing; the rest is mere guess-work."
"It's wonderful," said Polton, gazing at the now distant figure; "perfectly wonderful. I should never have known he was a stationmaster." With this and a glance of deep admiration at his employer, he took his departure.
"You will also observe," said Thorndyke, with a smile, "that a fortunate guess often brings more credit than a piece of sound reasoning with a less striking result."
"Yes, that is unfortunately the case, and it is certainly true in the present instance. Your reputation, as far as Polton is concerned, is now firmly established even if it was not before. In his eyes you are a wizard from whom nothing is hidden. But to return to these little pieces, as I must call them, for the lack of a better name. I can form no hypothesis as to their use. I seem to have no 'departure,' as the nautical phrase goes, from which to start an inquiry. I haven't even the material for guess-work. Ought I to be able to arrive at any opinion on the subject?"
Thorndyke picked up one of the pieces, fingering it delicately and inspecting with a critical eye the flat base on which it stood, and reflected for a few moments.
"It is easy to trace a connection when one knows all the facts," he said at length, "but it seems to me that you have the materials from which to form a conjecture. Perhaps I am wrong, but I think, when you have had more experience, you will find yourself able to work out a problem of this kind. What is required is constructive imagination and a rigorous exactness in reasoning. Now, you are a good reasoner, and you have recently shown me that you have the necessary imagination; you merely lack experience in the use of your faculties. When you learn my purpose in having these things made—as you will before long—you will probably be surprised that their use did not occur to you. And now let us go forth and take a brisk walk to refresh ourselves (or perhaps I should say myself) after the day's labour.
The Ambush
"I am going to ask for your collaboration in another case," said Thorndyke, a day or two later. "It appears to be one of suicide, but the solicitors to the 'Griffin' office have asked me to go down to the place, which is in the neighbourhood of Barnet, and be present at the post-mortem and the inquest. They have managed to arrange that the inquest shall take place directly after the post-mortem, so that we shall be able to do the whole business in a single visit."
"Is the case one of any intricacy?" I asked.
"I don't think so," he answered. "It looks like a common suicide; but you can never tell. The importance of the case at present arises entirely from the heavy insurance; a verdict of suicide will mean a gain of ten thousand pounds to the 'Griffin,' so, naturally, the directors are anxious to get the case settled and not inclined to boggle over a little expense."
"Naturally. And when will the expedition take place?" I asked.
"The inquest is fixed for to-morrow—what is the matter? Does that fall foul of any arrangement of yours?"
"Oh, nothing of any importance," I replied hastily, deeply ashamed of the momentary change of countenance that my friend had been so quick to observe.
"Well, what is it?" persisted Thorndyke. "You have got something on."
"It is nothing, I tell you, but what can be quite easily arranged to suit your plans."
"Cherchez la—h'm?" queried Thorndyke, with an exasperating grin.
"Yes," I answered, turning as red as a pickled cabbage; "since you are so beastly inquisitive. Miss Gibson wrote, on behalf of Mrs. Hornby, asking me to dine with them en famille to-morrow evening, and I sent off an acceptance an hour ago."
"And you call that 'nothing of any importance'!" exclaimed Thorndyke. "Alas! and likewise alackaday (which is an approximately synonymous expression)! The age of chivalry is past, indeed. Of course you must keep your appointment; I can manage quite well alone."
"We shouldn't be back early enough for me to go to Kensington from the station, I suppose?"
"No; certainly not. I find that the trains are very awkward; we should not reach King's Cross until nearly one in the morning."
"Then, in that case, I shall write to Miss Gibson and excuse myself."
"Oh, I wouldn't do that," said Thorndyke; "it will disappoint them, and really it is not necessary."
"I shall write forthwith," I said firmly, "so please don't try to dissuade me. I have been feeling quite uncomfortable at the thought that, all the time I have been in your employ, I seem to have done nothing but idle about and amuse myself. The opportunity of doing something tangible for my wage is too precious to be allowed to slip."
Thorndyke chuckled indulgently. "You shall do as you please, my dear boy," he said; "but don't imagine that you have been eating the bread of idleness. When you see this Hornby case worked out in detail, you will be surprised to find how large a part you have taken in unravelling it. Your worth to me has been far beyond your poor little salary, I can assure you."
"It is very handsome of you to say that," I said, highly gratified to learn that I was really of use, and not, as I had begun to suspect, a mere object of charity.
"It is perfectly true," he answered; "and now, since you are going to help me in this case, I will set you your task. The case, as I have said, appears to be quite simple, but it never does to take the simplicity for granted.
