The "roller" rolls backward
because of the following sequence: As the container moves forward, the rubber band untwists, Some of the stored energy gets converted into energy of motion.
The first girl rolls backward
, and the sleek ribbon of bodies glides under itself and along the 40-foot length of the pool before the swimmers resurface one by one.
There they are so crowded that Malton's chair rolls backward
along the wall right up to the ceiling, where it remains.