R. CURTIS let his hands drop helplessly by his side.

"So you actually think," said he, "that you can construct machinery that can work unharmed through lakes of molten matter?"

"Yes," answered Dr. Giles, "I am convinced that I can."

"And that you will be able to find, for workmen, human salamanders who can flit about in the fire unharmed by the scorching heat?"

Dr. Giles broke into a hearty laugh. "No," said he, shaking his head emphatically; "I claim no such power as that. I am convinced that I shall be able to construct fire-proof machinery, and that will be all I shall require. Of what use would it be to secure fire-proof workmen? If I were obliged to send my men down into the tube, I