The Hydraulic engine house is part of the "Underfall Yard

Underfall Yard

The Underfall Yard is a historic boatyard on Spike Island serving Bristol Harbour, the harbour in the city of Bristol, England.Underfall Yard was commonly referred to as "The Underfalls" and takes its name from the underfall sluices...

" in Bristol Harbour

Bristol Harbour

Bristol Harbour is the harbour in the city of Bristol, England. The harbour covers an area of . It has existed since the 13th century but was developed into its current form in the early 19th century by installing lock gates on a tidal stretch of the River Avon in the centre of the city and...

 in Bristol

Bristol

Bristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

.

The octagonal brick

Brick

A brick is a block of ceramic material used in masonry construction, usually laid using various kinds of mortar. It has been regarded as one of the longest lasting and strongest building materials used throughout history.-History:...

 and terracotta chimney

Chimney

A chimney is a structure for venting hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. Chimneys are typically vertical, or as near as possible to vertical, to ensure that the gases flow smoothly, drawing air into the combustion in what is known as the...

 of the engine house dates from 1888, and is grade II* listed, as is the hydraulic engine house itself. It replaced the original pumping house which is now The Pump House

Pump House, Bristol

The Pump House is an historic public house situated in Hotwells on Bristol Harbour, Bristol, England.It was built around 1870 by Thomas Howard as a Hydraulic Pumping House to provide power to the bridges and machines of Bristol Harbour. It was replaced by the current Hydraulic engine house in the...

 public house

Public house

A public house, informally known as a pub, is a drinking establishment fundamental to the culture of Britain, Ireland, Australia and New Zealand. There are approximately 53,500 public houses in the United Kingdom. This number has been declining every year, so that nearly half of the smaller...

. It is built of red brick with a slate roof and originally contained two steam engine

Steam engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...

s. These were replaced in 1907 by the current machines from Fullerton, Hodgart and Barclay of Paisley. It powers the docks' hydraulic system of cranes, bridges and locks.

The tower houses a hydraulic accumulator

Hydraulic accumulator

A 'hydraulic accumulator' is an energy storage device. It is a pressure storage reservoir in which a non-compressible hydraulic fluid is held under pressure by an external source. That external source can be a spring, a raised weight, or a compressed gas...

which stores the hydraulic energy ensuring a smooth delivery of pressure and meaning that the pumps do not need to be running the whole time. The external accumulator was added about 1920. The water is pumped from the harbour into a header tank and then fed by gravity to the pumps. The working pressure is 750 lbs/square inch.