Had a chipmunk raised his head, Jimmie would have seen him.

So, when from the stone wall, like the reflection of the sun upon a window-pane, something flashed, Jimmie knew he had found his spy.

A pair of binoculars had betrayed him.
Jimmie now saw him clearly.

He sat on the ground at the top of the hill opposite, in the deep shadow of an oak, his back against the stone wall.
With the binoculars to his eyes he had leaned too far forward, and upon the glass the sun had flashed a warning.
Jimmie appreciated that his attack must be made from the rear.

Backward, like a crab he wriggled free of the golden-rod, and hidden by the contour of the hill, raced down it and into the woods on the hill opposite.