The Combe Hay Locks is a derelict
flight of locks on the
Somerset Coal Canal
The Somerset Coal Canal (originally known as the Somersetshire Coal Canal) was a narrow canal in England, built around 1800. Its route began in basins at Paulton and Timsbury, ran to nearby Camerton, over two aqueducts at Dunkerton, through a ...
near
Combe Hay
Combe Hay is a village and civil parishes in England, civil parish in the England, English Ceremonial Counties, county of Somerset. It falls within the Cotswolds, Cotswolds Area of Outstanding Natural Beauty. The parish has a population of 147.
...
,
Somerset
( en, All The People of Somerset)
, locator_map =
, coordinates =
, region = South West England
, established_date = Ancient
, established_by =
, preceded_by =
, origin =
, lord_lieutenant_office =Lord Lieutenant of Somerset
, lord_ ...
, England. Twenty two locks raised the canal over approximately . The lock flight was predated in the immediate area by two other methods of canal lifts—first by a series of
caisson lock
The caisson lock is a type of canal lock in which a narrowboat is floated into a sealed watertight box and raised or lowered between two different canal water levels. It was invented in the late 18th century as a solution to the problem posed ...
s, then by an
inclined plane
An inclined plane, also known as a ramp, is a flat supporting surface tilted at an angle from the vertical direction, with one end higher than the other, used as an aid for raising or lowering a load. The inclined plane is one of the six clas ...
. The lock flight opened in 1805, and was in operation until 1899.
History
The route of the
Somerset Coal Canal
The Somerset Coal Canal (originally known as the Somersetshire Coal Canal) was a narrow canal in England, built around 1800. Its route began in basins at Paulton and Timsbury, ran to nearby Camerton, over two aqueducts at Dunkerton, through a ...
, after leaving its junction with the
Kennet and Avon Canal
The Kennet and Avon Canal is a waterway in southern England with an overall length of , made up of two lengths of navigable river linked by a canal. The name is used to refer to the entire length of the navigation rather than solely to the cent ...
at
Limpley Stoke
Limpley Stoke is a village and civil parish in Wiltshire, England. It lies in the Avon valley between Bath and Freshford, and is both above and below the A36 road.
The parish is surrounded to the north, west and south by the Bath and North E ...
, roughly parallels that of the
Midford Brook
Midford Brook is a small river in Somerset, England.
It is formed by the convergence of the Wellow Brook and Cam Brook at Midford. It passes Tucking Mill and joins the River Avon, Bristol, River Avon close to the Dundas Aqueduct and the remains ...
. At Midford, the canal followed the valley of the
Cam Brook. At
Combe Hay
Combe Hay is a village and civil parishes in England, civil parish in the England, English Ceremonial Counties, county of Somerset. It falls within the Cotswolds, Cotswolds Area of Outstanding Natural Beauty. The parish has a population of 147.
...
, the steep valley required the canal to climb a significant height—
—over a distance of .
Caisson locks
![Coombe Hay Lock](https://upload.wikimedia.org/wikipedia/commons/c/c3/Coombe_Hay_Lock.png)
The first proposed solution to overcoming the
gradient
In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gradi ...
was by the use of three
caisson lock
The caisson lock is a type of canal lock in which a narrowboat is floated into a sealed watertight box and raised or lowered between two different canal water levels. It was invented in the late 18th century as a solution to the problem posed ...
s.
Adverts were printed in
Bath periodicals in January 1796 to recruit stonemasons for building the locks.
Construction of the first caisson lock began in 1796. The masonry chamber, known as the cistern, was long and at its widest, and had a depth of . The wooden caisson—the moving box within the cistern—was long, wide and tall. Each of the three caisson locks was planned to provide a lift of .
Trials of this first lock took place between November 1797 and June 1798.
These showed that it could be traversed in 7 minutes; on 9 June 1798, a reporter for the ''
Bath Herald'' wrote that:
The same publication wrote the following year that the system was so simple that a boat could traverse the caisson in just 10 minutes under the operation of a 12-year-old boy.
The report identified problems with the caisson's ability to remain watertight,
and hypothesized that the only solution would be to rebuild the chamber.
A second caisson was started and construction of the third was probably never begun.
Surveyor
William Smith visited the site at least twice, in 1798 and 1799.
The
geology
Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other Ear ...
of the area, with substantial deposits of
fuller's earth
Fuller's earth is any clay material that has the capability to decolorize oil or other liquids without the use of harsh chemical treatment. Fuller's earth typically consists of palygorskite (attapulgite) or bentonite.
Modern uses of fuller's ea ...
,
proved unsuitable for the caisson chambers—in May 1799 the masonry of the lock chamber bulged under pressure and the caisson was immovable. Repairs were quoted at £16,000——which was in addition to the £75,167 (£) already invested in the caisson project.
In January 1800, the caissons were abandoned and an alternative sought.
In May 1801, having moved to Bath upon her father's retirement,
Jane Austen
Jane Austen (; 16 December 1775 – 18 July 1817) was an English novelist known primarily for her six major novels, which interpret, critique, and comment upon the British landed gentry at the end of the 18th century. Austen's plots of ...
wrote to her sister
Cassandra
Cassandra or Kassandra (; Ancient Greek: Κασσάνδρα, , also , and sometimes referred to as Alexandra) in Greek mythology was a Trojan priestess dedicated to the god Apollo and fated by him to utter true prophecies but never to be believe ...
about plans with her uncle to "take the long-planned walk to the Cassoon";
the short trip was a popular excursion at the time.
The same year,
Richard Warner wrote of the then-state of the caisson lock in his ''Excursions from Bath'':
The precise location of the caisson locks (or their intended location) is in doubt.
General consensus is that the completed caisson lock was accessed east of the basin near Caisson House. The second caisson was likely a short distance to the east,
with the third a considerable distance downstream (near the site of Locks 19 and 20).
Inclined plane
The canal company investigated alternatives to the caisson locks, and a lock flight was chosen as the appropriate method. To achieve this, in June 1800 the company made the decision to build a temporary
inclined plane
An inclined plane, also known as a ramp, is a flat supporting surface tilted at an angle from the vertical direction, with one end higher than the other, used as an aid for raising or lowering a load. The inclined plane is one of the six clas ...
to transfer cargo,
although this method for climbing the hill proved slow.
The inclined plane was only ever intended to avoid further delays to the canal's construction,
and would only be in operation while the flight of locks was built.
To reduce the length (and gradient) of the inclined plane, three pound locks were built to the east of Combe Hay. The inclined plane began operation in November 1801.
Lock flight
In addition to the three extant locks below the inclined plane, a further 19 locks were built to supersede the plane.
Fundraising began in February 1800, initially via shareholder donations totalling £20,000 (). In 1802, a fund established by the canal company along with the proprietors of the
Wilts and Berks and Kennet and Avon canals sought to raise a further £45,000 ().
Construction began on the flight in November 1802, with the first lock (lock 19) being completed in June 1804. During the works, the caisson lock was demolished and it is likely that the significant amount of masonry was reclaimed for use on the lock flight as
coping stones and possibly on the later building of Caisson House.
The engineer of the flight was probably
William Bennet.
The flight of 22 locks fully opened in April 1805.
These all had the same specification—a rise of approximately , a
beam
Beam may refer to:
Streams of particles or energy
*Light beam, or beam of light, a directional projection of light energy
**Laser beam
*Particle beam, a stream of charged or neutral particles
**Charged particle beam, a spatially localized grou ...
of , and a length to fit a narrowboat. These locks were half as wide as those on the connecting Kennet and Avon Canal, thus two vessels from the Somerset Coal Canal could fit side by side in the broad Kennet and Avon locks.
To achieve the climb in the available area, the lock flight diverted north of the caisson and inclined plane routes,
before turning 170° and rejoining the route to the south. This
hairpin bend
A hairpin turn (also hairpin bend or hairpin corner) is a bend in a road with a very acute inner angle, making it necessary for an oncoming vehicle to turn about 180° to continue on the road. It is named for its resemblance to a bent metal hai ...
became known as the "Bull's Nose".
Speed of traversing the flight was a priority, and the
lock paddle
A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water lev ...
s and culverts were made as large as practicable to empty and fill the locks as quickly as possible. To avoid damage to the locks caused by carelessness,
wrought iron
Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag Inclusion (mineral), inclusions (up to 2% by weight), which give it a ...
plates and
cast iron
Cast iron is a class of iron–carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured: white cast iron has carbide impuriti ...
slabs were installed on the lock flight.
In 1805, the locks opened.
Decline
In 1881, the
Camerton Branch of the
Bristol and North Somerset Railway
The Bristol and North Somerset Railway was a railway line in the West of England that connected Bristol with Radstock, through Pensford and further into northern Somerset, to allow access to the Somerset Coalfield. The line ran almost due so ...
opened through the Cam valley, crossing the lock flight at lock 16.
Like many canals, the arrival of rail transport began the decline of the waterway's use.
The canal was put up for sale in 1894. The backpumps on the flight ceased operation in November 1898;
transport would continue to operate until August 1899 when the water levels became insufficient for navigation.
Legacy
After the abandonment of the canal in 1899, the flight was left to become derelict. The chamber of lock 16, beneath a railway arch of the Camerton railway branch, was infilled.
In 1982, 10 of the extant locks—those in the parish of Combe Hay—were given
Grade II listed
In the United Kingdom, a listed building or listed structure is one that has been placed on one of the four statutory lists maintained by Historic England in England, Historic Environment Scotland in Scotland, in Wales, and the Northern Irel ...
status. The survey for the listing found that the locks'
ashlar
Ashlar () is finely dressed (cut, worked) stone, either an individual stone that has been worked until squared, or a structure built from such stones. Ashlar is the finest stone masonry unit, generally rectangular cuboid, mentioned by Vitruv ...
retaining walls
Retaining walls are relatively rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides.
Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to ...
survive to a height of , and some of the lower lock gates were still in situ.
In 1984, a further five locks of the flight—those in
South Stoke parish—were also listed as Grade II. This survey found similar survival of the retaining walls, although it described some as being in a poor condition. A
milestone
A milestone is a numbered marker placed on a route such as a road, railway line, canal or boundary. They can indicate the distance to towns, cities, and other places or landmarks; or they can give their position on the route relative to so ...
is extant near Lock 4, although its cast iron plaque (reading "4/MILES") is missing. It was identified that four locks in the 1805 flight of 19 had been buried or otherwise destroyed.
A building near the summit of the flight, Caisson House, is named for its proximity to the first caisson lock. The building is likely a former terrace of cottages built for the canal company in the 1830s (and therefore the removal of the caisson lock predates the cottages' construction).
Restoration
General restoration work began on the lower lock flight (below the Bull's Nose) in 2000. This work was expanded to cover the upper flight in 2011, as landowner permission needed to be sought. This work was undertaken alongside the
Inland Waterways Association
The Inland Waterways Association (IWA) is a registered charity in the United Kingdom and was formed in 1946 to campaign for the conservation, use, maintenance, restoration and sensitive development of British Canals and river navigations.
No ...
's Waterway Recovery Group.
Locations
Footnotes
References
{{reflist
Canals in Somerset
Lock flights of England
1805 establishments in England
1899 disestablishments in England
History of Somerset
Grade II listed buildings in Bath, Somerset