Dorset and Somerset Canal - Construction

Construction

Construction began on the branch line, and about 8 miles (13 km) of canal was built, from Stratton Common towards Frome, passing through Coleford and Vobster. The works included the three-arched Murtry Aqueduct over the Mells River near Hapsford, a smaller aqueduct at Vallis Vale, near Coleford, and a tunnel at Goodeaves Farm, which was not completed.

Both the main line and the branch involved significant changes in level, and the act had specified that conventional locks would be used on the main line, but that "caissons" would be used on the branch, which rose by 264 ft (80.5m) over its length. The idea of using vertical boat lifts was proposed by James Fussell, owner of the nearby Mells ironworks, and his particular design, known as a balance lock, was patented in 1798. It consisted of two tanks, joined by chains which passed over large wheels. Boats entered one or both of the caissons, which each had an extra chamber below the main caisson, and the chamber of the top caisson was filled with water to provide the extra weight needed to cause the lift to operate. Although different in detail to those later used successfully on the Grand Western Canal, it was essentially very similar.

Fussell built the first boat lift at Barrow Hill. It was designed to take 10-ton boats, lifting them by 20 feet (6.1 m), and was tested during September and October 1800. It was formally demonstrated on 13 October 1800, and the Bath Chronicle carried a glowing report 3 days later.

Five more lifts were to be built on the Barrow Hill section, and works started on the pits for four of them, but the company ran out of money in 1802, with 1.7 miles (2.7 km) of canal still to be excavated and the boat lifts unfinished. Having consulted an engineer called Underhill, the company obtained a second act of parliament in 1803, to allow them to raise more money and to build railways instead of the canal if this would reduce the cost, but they were unable to raise any more finance. Construction ceased in 1803, and the canal was never completed.