The dandy cart was developed by George Stephenson for use on the Stockton and Darlington Railway, during its early years, when locomotive engines were scarce.  The horse would haul a heavy train of wagons up a rise, and once at the summit would be unhitched and would jump in a cart of its own, to be transported down the hill.  This allowed the horse a period of rest prior to pulling another train.  Hay in the cart was always an incentive for the horse to jump onto the moving train! A novel way of getting more mileage out of horses, the light cart opened at one end with a low level sturdy floor.  In this was the mileage of the horse was increased from 175 to 240 miles.  The carts were in general use until 1833/4.