"The idea of an unearned increment given to private properties by the social organism was talked of in my day," I said, "but only, as I remember, with reference to land values. There were reformers who held that society had the right to take in taxes all increase in value of land that resulted from social factors, such as increased population or public improvements, but they seemed to think the doctrine applicable to land only." "Yes," said the doctor, "and it is rather odd that, having hold of the clew, they did not follow it up." CHAPTER XIV. WE LOOK OVER MY COLLECTION OF HARNESSES. Wires for light and heat had been put into the vault, and it was as warm and bright and habitable a place as it had been a century before, when it was my sleeping chamber. Kneeling before the door of the safe, I at once addressed myself to manipulating the dial, my companions meanwhile leaning over me in attitudes of eager interest. It had been one hundred years since I locked the safe the last time, and under ordinary circumstances that would have been long enough for me to forget the combination several times over, but it was as fresh in my mind as if I had devised it a fortnight before, that being, in fact, the entire length of the intervening period so far as my conscious life was concerned. "You observe," I said, "that I turn this dial until the letter 'K' comes opposite the letter 'R.' Then I move this other dial till the number '9' comes opposite the same point. Now the safe is practically unlocked. All I have to do to open it is to turn this knob, which moves the bolts, and then swing the door open, as you see." But they did not see just then, for the knob would not turn, the lock remaining fast. I knew that I had made no mistake about the combination. Some of the tumblers in the lock had failed to fall. I tried it over again several times and thumped the dial and the door, but it was of no use. The lock remained stubborn. One might have said that its memory was not as good as mine. It had forgotten the combination. A materialistic explanation somewhat more probable was that the oil in the lock had been hardened by time so as to offer a slight resistance. The lock could not have rusted, for the atmosphere of the room had been absolutely dry. Otherwise I should not have survived. "I am sorry to disappoint you," I said, "but we shall have to send to the headquarters of the safe manufacturers for a locksmith. I used to know just where in Sudbury Street to go, but I suppose the safe business has moved since then." "It has not merely moved," said the doctor, "it has disappeared; there are safes like this at the historical museum, but I never knew how they were opened until now. It is really very ingenious." "And do you mean to say that there are actually no locksmiths to-day who could open this safe?"