"What's to be done, Tom?" repeated the contractor.
"Well, Mr. Titus," was the answer, "the only thing I see to do is to make a new explosive."
"Can you do it, Tom?"
The reply was characteristic.
"I can try."
And in the days that followed, Tom began work on a new line. He had brought from Shopton with him much of the needful apparatus, and he found he could obtain in Lima what he lacked.
A message to his father brought the reply that the new ingredients Tom needed would be shipped.
"The kind of explosive we need to rend that very hard rock," the young inventor explained to the Titus brothers, "is one that works slowly."
"I thought all explosions had to be as quick as a flash," said Walter.
"Well, in a sense, they do. Yet we have quick burning and slow-burning powders, the same as we have fuses. A quick-burning explosive is all right in soft rock, or in soil with rock and earth mingled. But in rock that is harder than flint if you use a quick explosive, only the outer surface of the rock will be scaled off.