Where the slip led through a fence with a board missing, a long slat was so arranged that the ignorant wayfarer could not fail to strike against it.

This slat was the spring of the trap.

A light touch upon it was sufficient to disconnect a heavy stone from a barrel perched overhead and nicely balanced.

The disconnecting of the stone permitted the barrel to turn over and spill its contents on the one beneath who touched the slat.
The boys examined the arrangement with keen appreciation.

Luckily for them, the barrel was overturned, or they too would have received a ducking, for Joe, who was in advance, had blundered against the slat.
"I wonder if this is Simpson's back yard ?" he queried softly.
"It must be," Fred concluded, "or else the back yard of some member of his gang." Charley put his hands warningly on both their arms.
"Hist! What 's that ?" he whispered.
They crouched down on the ground.