"No doubt, my lad. A continuous struggle against the dangers of landslips, fires, inundations, explosions of firedamp, like claps of thunder. One had to guard against all those perils! You say well! It was a struggle, and consequently an exciting life."

"The miners of Alva have been more favored than the miners of Aberfoyle, Mr. Starr!"

"Ay, Harry, so they have," replied the engineer.

"Indeed," cried the young man, "it's a pity that all the globe was not made of coal; then there would have been enough to last millions of years!"

"No doubt there would, Harry; it must be acknowledged, however, that nature has shown more forethought by forming our sphere principally of sandstone, limestone, and granite, which fire cannot consume."

"Do you mean to say, Mr. Starr, that mankind would have ended by burning their own globe?"

"Yes! The whole of it, my lad," answered the engineer. "The earth would have passed to the last bit into the furnaces of engines, machines, steamers, gas factories; certainly, that would have been the end of our world one fine day!"