House of Commons, Great Britain, Report from the Select Committee on Steam Carriages… (1831)
“ The following Scale of proportions is taken from a Trust where the Tolls fixed are Three-pence for every horse drawing, and One-peony not drawing; and may be applied to determine the Tolls on any other Trust, where the Tolls are fixed at a higher or lower rate:— N.B.—The Carriage and Load drawn by the Steam Carriage, shall not exceed double the weight of the Drawing Carriage. ”
