“I think you have something there,” Salt observed. “Obviously, they’re going to doctor it in some way. We’ll see what happens.”
Webb unlocked the door of the shack and the two men carried the mine inside. Creeping still closer to the building, Salt and Penny heard Mr. Johnson say:
“Just a minute. I see you have other mines stored here. How am I to be sure that the one exploded will be the mine I have provided?”
“You may mark it if you wish,” the professor replied. “In fact, we prefer that you do, so there can be no possible doubt in your mind. Take this pocket knife and scratch your initials on the covering of the mine. Then tonight, before it is dumped in the lake, you may check again to see there has been no substitution.”
“You understand, I don’t distrust you,” Mr. Johnson said, ill at ease. “But so much money is at stake—”
“I understand your attitude perfectly,” the professor replied. “Certainly you are entitled to take every precaution.”
A silence ensued, and Penny and Salt assumed that Mr. Johnson was scratching his initials on the mine.
“Now suppose we have dinner at the village inn,” the professor presently suggested. “Then we will have the demonstration.”
“Must we wait so long before setting off the mine?” Mr. Johnson inquired.
“Yes, village authorities gave permission for the test to be held at nine o’clock,” the professor explained. “My own preference would be to get it over immediately, but I dare not disobey their orders.”