Reasons for Designation
Gunpowder was the only explosive available for military use and for blasting
in mines and quarries until the mid-19th century. Water-powered manufacturing
mills were established in England from the mid-16th century, although powder
had been prepared by hand for at least 200 years. The industry expanded until
the late 19th century when high explosives began to replace gunpowder. Its
manufacture declined dramatically after the First World War with British
production ceasing in 1976. The technology of gunpowder manufacture became
increasingly complex through time with the gradual mechanisation of what were
essentially hand-worked operations. Waterwheels were introduced in the 16th
century, and steam engines and water turbines from the 19th century. Pressing
and corning were also introduced between the 16th and 19th centuries to
improve the powders. Pressing improved the explosive power of the mill cake
and corning broke the pressing cake into different sizes and graded it with
respect to its fineness. Additional techniques were developed throughout the
17th, 18th and 19th centuries to improve the quality and consistency of the
finished product, and this in turn resulted in a variety of types of powders;
ranging from large coarse-grained blasting powders used in mines and quarries,
to fine varieties used, for example, in sporting guns.
Gunpowder manufacturing sites are a comparatively rare class of monument with
around 60 examples known nationally. Demand for gunpowder centred on the
London area (for military supply), other ports (for trade), and the main metal
mining areas. Most gunpowder production was, therefore, in Cumbria, the south
west, and the south east around the Thames estuary. The first water-powered
mills were established in south east England from the mid-16th century
onwards, and many of the major technological improvements were pioneered in
those mills. All sites of gunpowder production which retain significant
archaeological remains and technological information and survive well will
normally be identified as nationally important.
Despite conversion of the monument into an operational fisheries site, many of
the original features associated with the incorporating of gunpowder survive
well. It remains one of the better preserved late 18th to early 20th century
gunpowder works in northern England and a rare example of a gunpowder
incorporating plant divorced from the other stages of the gunpowder
manufacturing processes. Many of the monument's structural components still
survive, including remains of all the incorporating mills and a charge house,
together with virtually all of the water management system which powered the
waterwheels. Many of the surviving mills preserve technological information
relating to their use from the late 18th century until closure in 1935.
Details
The monument includes the ruins, earthworks and buried remains of Basingill
gunpowder works, located on the east bank of the River Kent approximately 700m
WSW of Sedgwick village. The site is unusual in that it was not a
self-contained gunpowder works, but was instead established in 1790 to provide
additional incorporating mills for Old Sedgewick gunpowder works located a
short distance upstream of Basingill. Later, once Old Sedgwick closed in
1850, it performed a similar role for a milling annexe to Gatebeck gunpowder
works some 4km away, a function it performed until closure in 1935. The
gunpowders incorporated at Basingill mainly comprised coarse powders used for
mining, quarrying and other blasting activities, and the remains include three
sets of incorporating mills with architectural features and a small amount of
original timberwork, the water management system constructed to provide power
for driving the machinery in these mills, the remains of a green charge house
and the sites of a wrought charge house and watch house.
At the northern end of the site, a short distance downstream from Force
Bridge, stand the remains of three incorporating mills which were the first to
be constructed at Basingill. Here the gunpowder ingredients of charcoal,
saltpetre and sulphur were crushed and ground together under heavy edge
grinding runners to form mill cake. Large waterwheels powered the grinding
stones, so that the design of an incorporating mill is instantly recognisable
as being identical structures either side of a waterwheel, with a tail race
taking used water away. All the mills were deliberately burned at the closure
of the works to ensure no explosive powder nestled in crannies and, as a
result, the light wooden-framed huts that enclosed each mill were destroyed,
leaving only the thick stone-built three-sided outer blast walls. These
early mills were powered conventionally by a waterwheel located between the
central and northern mills. Water to turn the wheel was channelled off the
Kent a short distance upstream and taken along a leat; once it reached the
mills some of the water was diverted 90 degrees to power the waterwheel, after
which it flowed back into the Kent via a short tail race, while the remainder
of the water flowed along an underground tunnel towards the other sets of
incorporating mills. Immediately south of these early incorporating mills lie
the ruins of the green charge house where unincorporated powder was stored,
and south of this, close to the river, lie a pair of incorporating mills with
a short tail race. The third set of incorporating mills stand on a terrace a
short distance to the south east and comprises a set of three. The large
waterwheel pit lies between the central and northern mills and water to power
the wheel exited the underground leat through a semi-circular opening known as
a Rennie's Hatch. A tail race then took the waste water southwards for
approximately 100m to empty into the river. Although no surface evidence
remains, site plans show that a wrought charge house stood on a flat terrace
near to the site entrance; here the ripe or incorporated mill charge would be
stored prior to transportation. A pathway with a stone retaining wall on its
western side runs southwards from this terrace to two freshwater wells. The
site plans also show that a watch house was situated near to the entrance,
but a modern store now overlies remains of the watch house.
A number of features are excluded from the scheduling; these include fish
hoarding tanks, a fish counter hut and counter weir, the modern store near to
the site entrance and the platform on which it stands, and all modern walls,
fences, seats, sluice gates, telegraph poles and gateposts; the ground beneath
all these features, however, is included.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
