that this was a rope-worked incline with the wagons on rails, but this is not supported by any contemporary document. The limited financial and technical resources available at this time (Watt had long since departed) suggest that this might have been simply a sloping causeway on which boxes of coals were dragged down loaded, and back up empty. Alternatively it may have had rails—not necessarily metal—with single wagons making the transit. Hutton (page 42) refers to rails at this time. A set of locks Leslie continues: About the year 1788, a set of locks was constructed at Blackhill ... The set of locks at Blackhill consists of four double locks , having each two lifts of , the whole height from reach to reach being generally , but varying a few inches according to the supply of water and to the state of the winds. At the same time there were provided two locks to raise the level at Sheepford. Leslie's date seems to be premature; Martin states August 1793 for the opening of the Blackhill locks, apparently quoting the Glasgow Mercury for 20 August 1793 and the Glasgow Courier for 15 August 1793. The locks duplicated Leslie goes on: In the year 1837 the two uppermost locks were so much out of repair that it became necessary either to rebuild them or to construct two new ones ... It was resolved to proceed immediately with the construction of two new double locks by the side of the old ones. These were to replace, and not duplicate, the upper locks only. However: By the time that the new locks were finished, it had become evident, from the great increase in the trade, that either an entire second set of locks must be constructed, or some other means must be devised for passing a greater number of boats than could be accommodated by one set of locks. The "other means" was some kind of inclined plane in which canal boats could be lowered and raised to accommodate the vertical interval between the two sections of the canal. At that time, systems of this kind had already been installed in the Shropshire Canal in 1788 and 1790, where 5 tonne boats were hauled up inclines dry, on cradles. In 1798 there had been an attempt on the Somerset Coal Canal to use a system in which 20 tonne boats could rise and