Storri, who had been studying London Bill as hard as ever that cracksman was studying him, re-began in earnest. He now laid bare the proposal in its every corner, and showed London Bill the plans and maps, including the valuable cross-section drawing that displayed the relation of the Treasury Building to street levels. London Bill, who appeared to have gifts as an engineer, bent over the maps and drawings, considering and measuring distances.
"What sort of ground is this?" said London Bill, laying a finger on the cross-section drawing, where it was painted dove-color as showing the earth beneath the street; "is it clay or sand?"
"Gray clay," returned Storri, "and fairly hard and dry."
"Good," remarked London Bill; "no fear of caving." Recurring to the drawings, London Bill proceeded: "It'll take two months to dig that tunnel. I'll have to dip as I go in, in order to creep beneath the footstones of the sidewall; then I'll bring the tunnel up on a long slant. The tunnel should be four feet high and about three wide; the earth I'd throw into the sewer, the water would wash it away. There's no risk in digging the tunnel, as no one would get an inkling of what's afoot until the last shove, when we made direct for the money. On that point let me ask: How long can we count on being undisturbed after we've got to the gold? Now if it was a bank, we'd time the play for Saturday afternoon after closing hours; that would give us until Monday morning at nine before they'd tumble."
"It'll Take Two Months to Dig that Tunnel."
"We can do better than that," returned Storri. "Saturday, May twenty-eighth, is the anniversary of the death of a former Secretary of the Treasury, and a special holiday has been already declared for that day. Monday, May thirtieth, is Decoration Day, a general holiday. We should have, you see, from Friday at four o'clock until Tuesday at ten; time enough to carry out several fortunes in twenty-pound packages worth five thousand dollars each."