For accelerating dynamic trolleys.With the length of elastic
cords with brass eye let at each end. In use cord is attached
with the trolley by slipping one of the eye lets over the
front dowel peg. ( One or more cords may be used simultaneously
depending upon the acceleration required) Constant acceleration
will arise if the cord is stretched a constant amount, say,
to length of the trolley. The cords are packed in tens mounted
on a card fore easy storage.