"I don't quite catch on," grumbled Emu Bill. "I'm hanged if I see what difference it should make; an' we doesn't know how far we'd have to dig into the blasted rock afore we hit the tunnel—if it's where you say."
Mackay took up a pick, and, proceeding along the base of the mountain away from the fissure, struck at the rocky wall repeatedly, with the result that a deep, hollow rumbling issued forth at each stroke, until a point had been reached some thirty yards distant from the tunnel entrance, when only the solid diorite formation gave back the sound.
"I calculate we'd have less than five feet to drive, Bill," said he. "About a couple o' long shots in from the top would do it. You can trace the passage as plainly as if you were looking at it. I don't know what the idea was in making it like a boomerang; but we'll soon find out. Now, Bob, you're better at explaining than me. Try an' convince Bill o' the advantages we may derive from making a new hole into the mountain."
"I reckon I can see it all right," cried the Shadow. "Oh, it are a daisy——"
"Shut up, Shad," growled Emu Bill. "Now, Bob, for any sake, tell me your plan. Of course I'm with you, whether I understand or not; but, blow me if I can see the force o' doing extra work in the niggers' mountain fur nothin'."
Then Bob endeavoured to elucidate the ideas which had been taking shape in his brain all through the night, since Mackay and he had come to a conclusion as to the origin of the warning sounds and the proximity of the passage for some distance to the outer air.
"If we don't tamper with the old door, boys," said he, earnestly, "we can block up the hole we make by some bagging, and so will always have a chance of escape if the natives are too many for us. They will guard their own entrance only, for they probably will never see ours; and it's just as well to take precautions. The darkness of the tunnel will help our plan; and if we succeed without having to trouble about getting back, so much the better——"
"And there are a few more arguments in favour o' the scheme, Bob," added Mackay; "but we may see the excellence o' them later."
"But they'll hear us firing the charges, won't they?" said Jack.