"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.
"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."
"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.