"You mean it is—"
"A solemn secret. I want secure your services in a desperate and daring adventure that will mean a great deal to me—and a great deal to you."
"Certainly," was the boy's response. "I give you my pledge on that."
A look of relief came into the old soldier's face.
"If I furnished you the money," went on Major Honeywell suddenly, "could you produce in a short time a practical and manageable balloon?"
Before the boy could answer the old soldier continued: "I don't mean one of those affairs in which ascensions of an hour or so are made. I mean one in which you could travel for several days—perhaps a week?"
"No," said Ned, "it can't be done. No one has yet remained in the air in a balloon over fifty-two hours."
Major Honeywell said nothing, but Ned could see that what he had told the Major had dashed some budding hope.
"That is," Ned hastened to explain, "you couldn't do it unless you periodically renewed your supply of hydrogen. I really believe," continued Ned, "that I ought to know more about what you are planning to accomplish."
Again the white-mustached man was silent a few moments, and then he told without reserve the great secret. He began with an account of himself. Until three years before he had been an officer in the United States cavalry, stationed in the southwest. Then the President had assigned him to ethnological work. His special work was in the ruins of the Sedentary Pueblos. While scaling a cliff in this work he fell and permanently injured his left knee.