He kneeled before a porthole through which he pushed the long black barrel of his rifle.

Silas and Sullivan followed him and looked in the direction indicated by his weapon.

It pointed toward the bushy top of a tall poplar tree which stood on the hill west of the Fort.

Presently a little cloud of white smoke issued from the leafy branches, and it was no sooner seen than Wetzel's rifle was discharged.

There was a great commotion among the leaves, the branches swayed and thrashed, and then a dark body plunged downward to strike on the rocky slope of the bluff and roll swiftly out of sight.