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Neither I nor anyone in any of the caverns know why these things work, but we do know how to operate some of them. However, there are a great many evil people here who create many unpleasant things for both us and the surface people. They are safe because no one on the surface believes us or them.

That is why I am telling you this. No one would believe that we exist. We would not care, but there are many things here that the outer world must not have until they are ready to receive them, as they would completely destroy themselves, so we must be sure that they do not find them. As for the machine, I don't know how it works. But I know some of the principles of it.

   It works simply by gravity. And it is capable of reverse. The bottom plate of it always is raised about four inches from the surface of the floor.

   That is why there is no friction and has such a smooth operation. This object suspended from this chain is pure carbon. It is the key to the entire operation. As I told you before, I cannot explain why it runs, but it does. We want you two to return to where you came and forget about us. We will show you how to operate the sled and we want you never again to enter the cave. If you do and you do not encounter the horloks, we will have to do something about you ourselves, so it would not be advisable to try to return at all events. One thing I can tell you. We never could permit you to leave another time."

   He explained to us the operation of the machine and in some way reversed its direction. So thanking them, we seated ourselves in the sled, as he had called it, and were soon on our way back.

   Our return trip was really something we enjoyed as I was sure not to advance the carbon far enough on the dial to give us such terrific speed, but we soon found ourselves where we started from. The sled slid to a smooth stop and we jumped out and