"Look here, sir, what I have just picked up," he said; "it's something he has dropped, I reckon."
As Jimmy spoke he held out a square leather case: there was a monogram on it. I took it in my hand and pressed the lid; it flew open, and inside, resting on its velvet bed, lay the glittering circlet of diamonds. I held Lady Ridsdale's lost bracelet in my hand. All my suspicions were confirmed: Vyner was the thief.
Without saying a word I shut the box and despatched the old man at once for the doctor, bidding him go as fast as he could. Then I sat down by the prostrate man and waited. I knew that Jimmy could not be back for at least two hours. The grey dawn was beginning to steal in through the little latticed window when Vyner moved, opened his eyes and looked at me. He started as his eyes fell on the case.
"You are Mr. Bell," he said slowly. "Ridsdale told me that you were coming to the Theodora on purpose to discover the mystery of the lost diamonds. You didn't know that I should give you an opportunity of discovering the truth even before you arrived at the house-boat. Bend down close to me — you have injured me; I may not recover; hear what I have to say."
I bent over him, prepared to listen to his words, which came out slowly.
"I am a forger and a desperate man. Three weeks ago I forged one of Ridsdale's cheques and lessened my friend's balance to the tune of five thousand pounds. He and his wife were old friends of mine, but I wanted the money desperately, and was impervious to sentiment or anything else. On that first day when you met me, although I seemed cheery enough, I was fit to kill myself. I had hoped to be able to restore the stolen money long before Ridsdale was likely to miss it. But this hope had failed. I saw no loophole of escape, and the day of reckoning could not be far off. What devil prompted Ridsdale to bring those diamonds on board, Heaven only knows. The moment I saw them they fascinated me and I knew I should have a try for them. All during that evening's festivity I could think of nothing else. I made up my mind to secure them by hook or by crook. Before we retired for the night, however, I thought I would give Ridsdale a chance. I asked him if he would lend me the exact sum I had already stolen from him, five thousand pounds, but he had heard rumours to my discredit and refused point-blank. I hated him for it. I went into my tent under the pretence of lying down, but in reality to concoct and, if possible, carry out my plot. I waited until the quietest hour before dawn, then I slipped out of my tent, waded into the water, approached the open window of the Countess's cabin, thrust in my hand, took out the case, and, going down the river about a quarter of a mile, threw the diamonds into the middle of the stream. I marked well the place where they sank; I then returned to my tent and went to bed.
"You know what occurred the following morning. I neither feared Ridsdale nor his wife, but you, Bell, gave me a considerable amount of uneasiness. I felt certain that in an evil moment on the night before I had given you a clue. To a man of your ability the slightest clue was all-sufficient. I felt that I must take the bull by the horns and find out whether you suspected me or not. I talked to you, and guessed by the tone of your remarks that you had your suspicions. My relief was immense when that telegram arrived which hurried you away from the Theodora. On the following day I returned to my own little place on the banks of the river four miles below this lock. I knew it was necessary for me to remain quiet for a time, but all the same my plans were clearly made, and I only waited until the first excitement of the loss had subsided and the police and detectives were off their guard. In the meantime I went to see Ridsdale almost daily, and suggested many expedients for securing the thief and getting hold of the right clue. If he ever suspected me, which I don't for a moment suppose, I certainly put him off the scent. My intention was to take the diamonds out of the country, sell them for all that I could get, then return the five thousand pounds which I had stolen from his bank, and leave England for ever. As a forger I should be followed to the world's end, but as the possessor of stolen diamonds I felt myself practically safe. My scheme was too cleverly worked out to give the ordinary detective a chance of discovering me.
"Two days ago I had a letter from Ridsdale in which he told me that he intended to put the matter into your hands. Now this was by no means to my mind, for you, Bell, happened to be the one man in the world whom I really dreaded. I saw that I must no longer lose time. Under my little boat-house I had a small submarine boat which I had lately finished, more as a hobby than anything else. I had begun it years ago in my odd moments on a model I had seen of a torpedo used in the American War. My boat is now in the lock outside, and you will see for yourself what ingenuity was needed to construct such a thing. On the night before the one which has just passed, I got it ready, and, as soon as it was dark, started off in it to recover the diamonds. I got through the lock easily by going in under the water with a barge, but when I reached the spot where I had sunk the diamonds, found to my dismay that my electric light would not work. There was no help for it — I could not find the bracelet without the aid of the light, and was bound to return home to repair the lamp. This delay was fraught with danger, but there was no help for it. My difficulty now was to get back through the lock; for though I waited for quite three hours no boats came along. I saw the upper gates were open, but how to get through the lower ones I could not conceive. I felt sure that my only chance was to frighten the lock-keeper, and get him to open the sluices, for I knew I could pass through them unobserved if they were open, as I had done once before.
"In my diver's helmet was a thick glass face-piece. This had an opening, closed by a cap, which could be unscrewed, and through which I could breathe when above water, and also through which my voice would come, causing a peculiar hollowness which I guessed would have a very startling effect, especially as I myself would be quite invisible. I got into the lock, and shouted to Pegg. I succeeded in frightening him; he hurried to do what I ordered. He wound up the lower sluice, I shot through under water, and so got back unseen. All yesterday I hesitated about trying the experiment again, the risk was so great; but I knew that Ridsdale was certain to see his bank-book soon, that my forgery was in imminent danger of being discovered, also that you, Bell, were coming upon the scene.
"Yes, at any risk, I must now go on.
"I repaired my light, and again last night passed through the lock on my way up, by simply waiting for another boat. As a matter of fact, I passed up through this lock under a skiff about eleven o'clock. My light was now all right, I found the diamond case easily, and turned to pass down the stream by the same method as before. If you had not been here I should have succeeded, and should have been safe, but now it is all up."
He paused, and his breath came quickly.
"I doubt if I shall recover," he said in a feeble voice.
"I hope you will," I replied; "and hark! I think I hear the doctor's steps."
I was right, for a moment or two later old Jimmy Pegg and Dr. Simmons entered the cottage. While the doctor was examining the patient and talking to him, I went out with Jimmy to have a look at the submarine boat. By fixing a rope round it we managed to haul it up, and then proceeded to examine it. It certainly was the most wonderful piece of ingenious engineering I had ever seen. The boat was in the shape of an enormous cigar, and was made of aluminium. It was seven feet long, and had a circular beam of sixteen inches. At the pointed end, close to where the occupant's feet would be, was an air chamber capable of being filled or emptied at will by means of a compressed air cylinder, enabling the man to rise or sink whenever he wished to. Inside, the boat was lined with flat chambers of compressed air for breathing purposes, which were governed by a valve. It was also provided with a small accumulator and electric motor which drove the tiny propeller astern. The helmet which the man wore fitted around the opening at the head end.