"In an hour," replied Mr. McKay promptly.
"Bursting open the door will be a tough job," remarked Andy. "How do you propose to do it?"
"I hope to manage it by means of an explosive," replied his father.
"Dynamite?"
"No, there's too much risk in carting a few sticks of that stuff through a tunnel a hundred yards in length or more. One slip and it would mean sudden death to the lot of us. I want a couple of fuses, however, so while we are getting ready you can run up to the magazine and obtain them."
While Andy was away on his errand, Mr. McKay opened a few cartridges and extracted the cordite.
"This stuff is safe enough with reasonable precautions," he remarked to Ellerton, who was watching Mr. McKay with no little fear. "So long as it is not under compression cordite can be lit without the faintest danger. In the open air it merely fizzles like a damp squib."
"Couldn't we smash the door with an axe?" asked Ellerton.
"We could, but I prefer not to. In the first place there's not much room to wield an axe; in the second, as I mentioned before, I have my suspicions regarding that door."
"What suspicions, sir?"