houses for your workmen. There does not seem the slightest reason for incurring this extra expense, and yet you claim that these constructions are absolutely necessary, and that without them the lives of the workmen would be imperiled. Really, I am all at sea. I cannot in the least understand what your object is."
"You will understand soon enough," said Dr. Giles, grimly—"in fact, all too soon, for, unless I am much mistaken, these submarine houses will be required within less than a month from to-day."
After taking rapid note of the progress of the work, Dr. Giles bade adieu to his guests and returned to his private office. He never left this long under any circumstances, for here it was that he kept himself informed of the progress of the work of boring the tunnel. Instruments of the greatest delicacy indicated just how the work was progressing and what were the conditions at the bottom of the hole, the fluctuations in the currents of electricity showing as plainly as articulate speech the changes that occurred every minute.
By means of these instruments the doctor knew to within a fraction of an inch the exact depth that had been reached, the temperature at that depth, the pressure on the walls of the tube, and
