When the 87 mile long Kennet and Avon Canal, opened in 1810, it created a navigable waterway connecting Bristol to the River Thames and London using parts of the River Avon (Bath to Bristol), a 57 mile (92km) long canal section, and part of the river Kennet (Reading to Newbury).
Designed by the famous engineer John Rennie, it had taken 16 years to complete the canal and included some major engineering structures such as the Dundas and Avoncliff aqueducts, the Bruce Tunnel under Savernake Forest, and the Caen Hill flight of 29 locks at Devizes.
The locks were built in three groups, 7 locks at Foxhangers, 16 at Caen Hill and 6 at Devizes. Boats travelling through the locks moved 237 feet (72m) vertically in a horizontal distance of 2 miles (3.2km).
As with any canal, ensuring there was enough water in the summit level and sections which were above local water sources was a problem. To solve this two pumping stations were built.
The Claverton pump, at the Bath end of the canal, uses a 24 foot (7m) wide wooden breastshot water wheel, powered by the River Avon, to drive two lift pumps via Boulton and Watt 18 foot (5m) long cast iron beams raising water 48 feet (14.6m) into the canal. This Grade I listed (1214608) pump still works and can be seen operating on special open days - visit the Claverton Pumping Station website for details.
When the canal was built there was no reliable source of water for the 2 mile (3km) long summit pound, but there were several springs near the canal about a mile (1.6km) east of the summit. Unfortunately they were about 40 feet (12m) below it! Rennie diverted these springs into the canal pound below lock 60 (later known as 'Engine' pound) at Crofton and built a pumping station to lift water via a culvert and well from there into a feeder channel or leat to the summit pound above lock 62.
Rennie designed the pumping station to house two steam engines, although initally only one was installed. This was a second-hand Boulton and Watt obtained from the West India Dock Company. It had a wooden beam and a 36-inch (0.914m) diameter cylinder.
In 1810 the Kennet and Avon Canal Company ordered a new engine from Boulton and Watt in Birmingham, who delivered the engine parts to the site by canal. This engine, now known as 'Number 1', started work in 1812 and became the main engine, until replaced by electric pumps in the 1950s.
In the 1840s it was rebuilt to operate on the 'Cornish Cycle' and became a single-acting, condensing engine with an internal cylinder diameter of 42¼ inches (1.073m). It has a pumping stroke of 7 feet (2.134m), with an indicated power of 38.6 horsepower (28.8kW), driving a 30inch (0.762m) lift pump capable of lifting over one tonne of water, per stroke, at a rate of 11 strokes per minute.
In 1846 the original 1809 West India Dock Company Boulton and Watt engine was replaced by a new one made by Harvey and Co. of Hayle, Cornwall. It was originally built as a double-acting Sims patent combined cylinder engine. However it proved difficult to work so they stopped using it.
In 1903 it was rebuilt and brought back into use as a single-acting, condensing engine working on the 'Cornish Cycle'. It has a 42 inch diameter cylinder (1.067m), a pumping stroke of 7 feet 8 inches (2.337m), with an indicated power of 42 horsepower (31kW). It drives a 30inch (0.762m) force pump capable of lifting approximately one tonne of water, per stroke, at a rate of 10.2 strokes per minute.
As more boats used the canal the increased use of the locks at either end of the Summit pound meant that there wasn't enough water in the Engine pound to meet demand. To solve this, in 1926 Wilton Water was built on land owned by the Marquis of Ailesbury by damming the valley south-east of the pumping station. As part of the deal it was agreed that Crofton would supply the Marquis's Tottenham House, 1¼ miles (2km) away, with fresh water so a subsidiary pump was installed on each engine. The pump on the No.2 engine has been removed, but the No.1 engine subsidiary pump still works and is now used to prime the main No.2 pump which is difficult to prime on its own.
Both steam engines were in regular use until the 1950s, when the poor condition of the boiler house chimney forced the removal of the top 36 feet (11m). The shorter chimney didn't provide sufficient draught for the boiler, so the steam engines were retired and electric pumps installed.
In 1968 the pumping station was bought by the Kennet and Avon Canal Trust who have restored the building and both engines. No.1 engine was successfully brought back into steam on 4th April 1970 and the No.2 engine on 15th November 1971. In 1985 the pumping station was Grade I listed by Historic England. The chimney has also been restored to its original height of 82 feet (25m).
If you want to visit Crofton and see the engines in steam please visit the Crofton Beam Engines website for details.