The Tavistock Canal is a canal in the county of Devon in England. It was constructed early in the 19th century to link the town of Tavistock to Morwellham Quay on the River Tamar, where cargo could be loaded into ships. The canal is still in use to supply water to a hydro-electric power plant at Morwellham Quay, and forms part of the Cornwall and West Devon Mining Landscape World Heritage Site. It is unusual for a canal, as it has a gentle slope over its length, resulting in a considerable flow of water.
Morwellham Quay is on the River Tamar, about 23 miles (37 km) from the sea, and was the furthest point inland to which the river was navigable. It had served Tavistock as a port since before 1200, but the final overland route to Tavistock was difficult, particularly in winter. John Taylor, a local civil engineer with interests in the mining of metal ores, conceived the plan for a canal.
An Act of Parliament was obtained in 1803 which gave the proprietors the power to raise £50,000 in £50 shares for the construction of the canal. Work started on 29 August 1803, and part of the canal was opened in 1805. From here to Morwellham a tunnel was needed under Morwell Down; its construction and the completion of the canal took a further thirteen years. The 2,540 yard (2.32 km) tunnel was cut through rock, was of small bore, and required Taylor to construct two types of pump, one to keep the workings drained, and the other to clean the air. Both were powered by water wheels, driven by the canal water. The tunnel, which was driven through elvan rock and killas clay-slate, is 360 ft (110 m) below Morwell Down at its deepest point, and it was finished in 1816.
At the tunnel's southern end, the canal was on the 250 ft contour, and Taylor constructed an inclined plane to drop the level by 237 ft (72.3 m) to the quay at Morwellham. This was powered by a large pitchback waterwheel, alongside the winding house at the head of the incline, which was fed with water from the canal. Four-wheeled tipping wagons ran initially on cast iron plate rails and later on wrought iron edge rails, and the system was controlled by a declutchable winch driven by the water wheel. Chains, later replaced by cables, were used for haulage on two separate lines, one down to the river quays, the other to ore-chutes above the Lower Copper Quay. A contemporary account by two Prussian mining engineers who visited the canal in 1826/7 describes goods being transferred from the barges by crane to railway wagons.
The main line of the canal was formally opened on 24 June 1817, which was marked by ships on the River Tamar firing a 21-gun salute. It is stated that much of the construction work had been done by French prisoners of war. The canal is unusual in that it was built with a gentle slope of about 1 ft per mile (20 cm per km). This was designed to attract industry to its banks, as it resulted in a flow of water along the canal, which aided the passage of boats towards the quay, and also enabled the powering of waterwheels along the route. Between 1817 and 1819, a 2 mile (3.2 km) extension was constructed to slate quarries and a general wharf at Mill Hill. This lasted until 1846, when it was converted into a tramway.
Despite its modest length, the canal's design and execution was a remarkable achievement, owing much to the foresight and determination of John Taylor. Driving a tunnel of such length through solid and often hard rock required new drainage techniques, and finishing it off with "the greatest inclined plane in Southern England" required great boldness. It carried slate, silver-lead ore and copper ore from the Tavistock area to the quay, and general goods including limestone, coal, iron and timber for Tavistock in the reverse direction. For nearly 40 years it was a profitable concern. carrying over one million tons of cargo during this period.
The main line of the canal starts at the Abbey Weir in Tavistock, where water is taken from the River Tavy. Passing through wharfs in Tavistock, it proceeds towards Morwellham Quay in a fairly straight line, with a large horseshoe loop when it meets the valley of the River Lumburn, which it crosses by a large aqueduct. The two mile Mill Hill branch turned off immediately after the aqueduct. After about 3 miles the main line reaches the northern portal of the Morwell Down tunnel, which emerges 1.5 miles later above the quay. A short length of canal after the tunnel brought boats to the top of the inclined plane.
After the canal closed to navigation it continued to be used to supply water to various industrial activities at Morwellham Quay. The last of these was to operate a tin and wolfram mill at the Bedford United Mine, a supply which ceased in 1930. In 1933 the canal was purchased by the West Devon Electric Supply Co. Ltd, who constructed a hydro-electric power plant at Morwellham Quay utilising the canal and tunnel as a water supply. The power plant and canal now belong to South West Water, and still feed power to the UK National Grid.
A programme of archaeological survey of the canal commenced in 2004 and as of 2007 is still underway. Excavations in 2006-2007 uncovered the tunnel on the second inclined plane, part of which is now being restored. Morwellham Quay is now an open air museum.
