"Three men! How on earth did you do it?"
"Two men and one mole. We did it with a ray, the secret of which only the Selom and Saranoff know."
ou have told me a disintegrating ray is an impossibility," objected Carnes.
"It is. This was not a disintegrating ray. Carnes, either I am crazy or the Selom have solved the secret of time, the fourth dimension. I haven't been able to grasp the whole thing yet. What I think we did was to remove that rock a distance, perhaps only a millionth of a second, forward or back into time. At any rate it ceased to exist, yet they can bring it back unchanged at will. That was the way they captured our plane. They sent out a magnetic ray of such power that it stopped our plane in midair and brought it to the ground. They removed the rock from beneath us and lowered us into the hole. By reversing the process they restored things to their original condition. All of these tunnels and rooms were made in that way."
"I still don't understand how they did it."
"I don't either, but I hope to in time. Now let's go to bed. It's late. To-morrow you will start your lessons with Captain Garland as an instructor. He won't know you for he was operated on this afternoon. Do your best to become a pilot. When I get ready, I want you with me in full possession of all your faculties."
The next morning the two prisoners separated and went to their duties. In the cavern which Dr. Bird had described, Captain Garland was waiting beside the plane he had flown. He did not know Carnes, but he still knew how to fly. Declining to enter into any conversation, he started expounding the theory of flying to the detective. Carnes remembered Dr. Bird's words and applied himself wholeheartedly. For four hours they worked together. At the end of that time the light faded in the cavern and Carnes was led by an unseen guide back to his cell. He threw himself on a bed and awaited Dr. Bird's return.
"I have learned a few more things about the Selom," said the doctor when he entered the cell several hours later. "We are in their largest community. They have cities or warrens scattered all over the world. Each city has its own ruler, but the whole race are ruled by an overlord or king who habitually lives here. He is away visiting a community under northern Africa just now, but he will be back in a few days. The Selom are sincere in their desire to help the upper world. They feel great pity for mankind in view of the conditions Saranoff has described to them. When the king returns. I plan to make a direct appeal to him. In the meantime, go on with your flying lessons. How did you make out to-day?"