He could not defend himself, but he made a clutch to save himself, caught something, swung in, struck against the iron ladder, and went tumbling and sliding downward.
At the moment when Frank was attacked, a glare of light had filled the pit.

One of the stokers had turned his back to the gleaming mouths of the furnaces and looked upward, as if to relieve his aching eyes.
He saw everything that occurred on the grating.

He saw a man slip down the ladder behind Frank and spring on his back.

He saw that man hurl Frank from the grating.
The stoker uttered a shout and ran toward the foot of the ladder, expecting to find Frank laying there, severely injured or killed.

He was astounded when he saw the ready-witted youth grasp the grating, swing in, strike the ladder, cling and slide.
Down Frank came with a rush, but he did not fall.