“‘That is quite correct,’ I answered; ‘but you will excuse me if I say that I cannot see how all this bears upon my professional qualifications. I understand that it was on a professional matter that you wished to speak to me?’

“‘Undoubtedly so. But you will find that all I say is really to the point. I have a professional commission for you, but absolute secrecy is quite essential—absolute secrecy, you understand, and of course we may expect that more from a man who is alone than from one who lives in the bosom of his family.’

“‘If I promise to keep a secret,’ said I, ‘you may absolutely depend upon my doing so.’

“He looked very hard at me as I spoke, and it seemed to me that I had never seen so suspicious and questioning an eye.

“‘Do you promise, then?’ said he at last.

“‘Yes, I promise.’

“‘Absolute and complete silence before, during, and after? No reference to the matter at all, either in word or writing?’

“‘I have already given you my word.’

“‘Very good.’ He suddenly sprang up, and darting like lightning across the room he flung open the door. The passage outside was empty.

“‘That’s all right,’ said he, coming back. ‘I know the clerks are sometimes curious as to their master’s affairs. Now we can talk in safety.’ He drew up his chair very close to mine and began to stare at me again with the same questioning and thoughtful look.

“A feeling of repulsion, and of something akin to fear had begun to rise within me at the strange antics of this fleshless man. Even my dread of losing a client could not restrain me from showing my impatience.

“‘I beg that you will state your business, sir,’ said I; ‘my time is of value.’ Heaven forgive me for that last sentence, but the words came to my lips.

“‘How would fifty guineas for a night’s work suit you?’ he asked.

“‘Most admirably.’

“‘I say a night’s work, but an hour’s would be nearer the mark. I simply want your opinion about a hydraulic stamping machine which has got out of gear. If you show us what is wrong we shall soon set it right ourselves. What do you think of such a commission as that?’

“‘The work appears to be light and the pay munificent.’

“‘Precisely so. We shall want you to come to-night by the last train.’

“‘Where to?’

“‘To Eyford, in Berkshire. It is a little place near the borders of Oxfordshire, and within seven miles of Reading. There is a train from Paddington which would bring you there at about 11:15.’

“‘Very good.’

“‘I shall come down in a carriage to meet you.’

“‘There is a drive, then?’

“‘Yes, our little place is quite out in the country. It is a good seven miles from Eyford Station.’

“‘Then we can hardly get there before midnight. I suppose there would be no chance of a train back. I should be compelled to stop the night.’

“‘Yes, we could easily give you a shake-down.’

“‘That is very awkward. Could I not come at some more convenient hour?’

“‘We have judged it best that you should come late. It is to recompense you for any inconvenience that we are paying to you, a young and unknown man, a fee which would buy an opinion from the very heads of your profession. Still, of course, if you would like to draw out of the business, there is plenty of time to do so.’

“I thought of the fifty guineas, and of how very useful they would be to me. ‘Not at all,’ said I, ‘I shall be very happy to accommodate myself to your wishes. I should like, however, to understand a little more clearly what it is that you wish me to do.’

“‘Quite so. It is very natural that the pledge of secrecy which we have exacted from you should have aroused your curiosity. I have no wish to commit you to anything without your having it all laid before you. I suppose that we are absolutely safe from eavesdroppers?’

“‘Entirely.’

“‘Then the matter stands thus. You are probably aware that fuller’s-earth is a valuable product, and that it is only found in one or two places in England?’

“‘I have heard so.’

“‘Some little time ago I bought a small place—a very small place—within ten miles of Reading. I was fortunate enough to discover that there was a deposit of fuller’s-earth in one of my fields. On examining it, however, I found that this deposit was a comparatively small one, and that it formed a link between two very much larger ones upon the right and left—both of them, however, in the grounds of my neighbors. These good people were absolutely ignorant that their land contained that which was quite as valuable as a gold-mine. Naturally, it was to my interest to buy their land before they discovered its true value, but unfortunately I had no capital by which I could do this. I took a few of my friends into the secret, however, and they suggested that we should quietly and secretly work our own little deposit and that in this way we should earn the money which would enable us to buy the neighboring fields. This we have now been doing for some time, and in order to help us in our operations we erected a hydraulic press. This press, as I have already explained, has got out of order, and we wish your advice upon the subject. We guard our secret very jealously, however, and if it once became known that we had hydraulic engineers coming to our little house, it would soon rouse inquiry, and then, if the facts came out, it would be good-bye to any chance of getting these fields and carrying out our plans. That is why I have made you promise me that you will not tell a human being that you are going to Eyford to-night. I hope that I make it all plain?’

“‘I quite follow you,’ said I. ‘The only point which I could not quite understand was what use you could make of a hydraulic press in excavating fuller’s-earth, which, as I understand, is dug out like gravel from a pit.’

“‘Ah!’ said he carelessly, ‘we have our own process. We compress the earth into bricks, so as to remove them without revealing what they are. But that is a mere detail. I have taken you fully into my confidence now, Mr. Hatherley, and I have shown you how I trust you.’ He rose as he spoke. ‘I shall expect you, then, at Eyford at 11:15.’

“‘I shall certainly be there.’

“‘And not a word to a soul.’ He looked at me with a last long, questioning gaze, and then, pressing my hand in a cold, dank grasp, he hurried from the room.

“Well, when I came to think it all over in cool blood I was very much astonished, as you may both think, at this sudden commission which had been intrusted to me. On the one hand, of course, I was glad, for the fee was at least tenfold what I should have asked had I set a price upon my own services, and it was possible that this order might lead to other ones. On the other hand, the face and manner of my patron had made an unpleasant impression upon me, and I could not think that his explanation of the fuller’s-earth was sufficient to explain the necessity for my coming at midnight, and his extreme anxiety lest I should tell anyone of my errand. However, I threw all fears to the winds, ate a hearty supper, drove to Paddington, and started off, having obeyed to the letter the injunction as to holding my tongue.

“At Reading I had to change not only my carriage but my station. However, I was in time for the last train to Eyford, and I reached the little dim-lit station after eleven o’clock. I was the only passenger who got out there, and there was no one upon the platform save a single sleepy porter with a lantern. As I passed out through the wicket gate, however, I found my acquaintance of the morning waiting in the shadow upon the other side. Without a word he grasped my arm and hurried me into a carriage, the door of which was standing open. He drew up the windows on either side, tapped on the wood-work, and away we went as fast as the horse could go.”

“One horse?” interjected Holmes.

“Yes, only one.”

“Did you observe the color?”