inconspicuously as to make the act undiscoverable by anyone not looking for that precise move, repeated the operation. With the next truck they saw it again. The psychologist turned to the others. Rentland, too, had been watching through the pane and nodded his satisfaction.
Immediately Trant dashed open the door of the scale house, and threw himself bodily upon the checker. The man resisted; they struggled. While the customs men protected him, Trant, wrenching something from the post beside the checker's left knee, rose with a cry of triumph. Then the psychologist, warned by a cry from Rentland, leaped quickly to one side to avoid a blow from the giant negro. His quickness saved him; still the blow, glancing along his cheek, hurled him from his feet. He rose immediately, blood flowing from a superficial cut upon his forehead where it had struck the scale-house wall. He saw Rentland covering the negro with a revolver, and the two other customs men arresting, at pistol point, the malignant little dock superintendent, the checker, and the others who had crowded into the scale house.
"You see!" Trant exhibited to the customs officers a bit of bent wire, wound with string, precisely like that the girl had given him that morning and he had used in his test of Welter the hour before. "It was almost exactly as we knew it must be! This spring was stuck through a hole in the protecting post so that it prevented the balance beam from rising properly when bales were put on the platform. A little pressure just at that point takes many pounds from each bale weighed. The checker had only to move
