"It is faster than almost anything except light," went on Mr. Roumann.
"Light travels one hundred and eighty–six thousand miles a second," stated Mark, who remembered his physics. "That's more than seven times around the earth in a second."
"Correct," said Mr. Roumann with a smile. "But sound, as you know, only goes a little over a thousand feet a second, at a temperature of thirty–two degrees above zero. In a warmer atmosphere it travels slightly faster. We are going much faster than sound ever travels. A cannon ball will travel about three thousand feet per second, so we are even going to beat cannon balls. At least, we hope we are, when we get beyond the earth's atmosphere."
"That's going to be terrific speed," remarked Jack dubiously, as if there was some risk in it.
"You need not worry," said Mr. Roumann. "You know we are building the Annihilator with a double shell, with a space between the two walls."
"Yes?" said Jack questioningly.
"Well, in that space I intend to put a new kind of gas, that will absorb all the heat that may be generated by our flight through space," went on Mr. Roumann. "Now that you know you have nothing to fear, let us go on with the work."
CHAPTER VIII
A MYSTERIOUS THEFT
"Would yo' kindly permit me t' prognostigate yo' attention fo' de monumental contraction of impossibilitiness in de circomlocution ob attaining de maximum nutrition ob internal combustion?" asked Washington White about an hour later, as he poked his head into the workshop, where the professor, the boys and Mr. Roumann, together with the machinists, were busily engaged.