It was not until Jason and Tarzan were enjoying their coffee that evening that the ape-man reverted to the subject of the American's visit.
"And now," he said, "what has brought you all the way from Southern California to the heart of Africa?"
Gridley smiled. "Now that I am actually here," he said, "and face to face with you, I am suddenly confronted with the conviction that after you have heard my story it is going to be difficult to convince you that I am not crazy, and yet in my own mind I am so thoroughly convinced of the truth of what I am going to tell you that I have already invested a considerable amount of money and time to place my plan before you for the purpose of enlisting your personal and financial support, and I am ready and willing to invest still more money and all of my time. Unfortunately I cannot wholly finance the expedition that I have in mind from my personal resources, but that is not primarily my reason for coming to you. Doubtless I could have raised the necessary money elsewhere, but I believe that you are peculiarly fitted to lead such a venture as I have in mind."
"Whatever the expedition may be that you are contemplating," said Tarzan, "the potential profits must be great indeed if you are willing to risk so much of your own money."
"On the contrary," replied Gridley, "there will be no financial profit for anyone concerned in so far as I now know."
"And you are an American?" asked Tarzan, smiling.
"We are not all money mad," replied Gridley.
"Then what is the incentive? Explain the whole proposition to me."
"Have you ever heard of the theory that the earth is a hollow sphere, containing a habitable world within its interior?"
"The theory that has been definitely refuted by scientific investigation," replied the ape-man.