Grade II* Listed Building
An 1859 inventory of Saltford mill lists two waterwheels driving a rolling mill, the entry stating:
- Waterwheel, 15 ft x 3 ft 6 in, and
- Waterwheel, 15 ft x 3 ft 6 in, driving
- 2 pairs rolls, 5 ft 6 in and 3 ft 6 in wide.
(15 ft = 4.6 m. 5 ft 6 in = 1.7 m. 3 ft 6 in = 1.0 m)
In an interview with Joan Day in the late 1960s, George Shellard, who had worked in the mill as a boy before the First World War, described the rolls as he remembered them in operation in the early C20th. The rolling mill contained two set of rolls: a heavier set of 'breaking-in' rolls and a lighter set of 'finishing-rolls'. The replica rolls on display at Saltford (Fig 1) show the arrangement of the 'breaking-in' rolls, with the upper and lower rolls being driven by separate waterwheels to provide the power needed for the first pass of rolling the cast metal slabs, initially 6 to 8 mm thick.
The replica is based upon evidence of a set of rolls that were installed at the Avon Mill, Keynsham; Saltford Mill and Avon Mill being operated by the same company and employing similar technology.
The photograph at Fig 2, taken in 1928 as the Avon Mill rolls were being dismantled, clearly shows the tandem drive. The lower roll was driven a shaft connected to a waterwheel to the left of the photograph. The upper roll was driven by the shaft connected to the large gear-wheel, turned by a second waterwheel behind the wall on the right of the photograph.
As both waterwheels turned in the same direction, it was necessary to employ a reversing gear to one of the rolls to enable the two rolls to rotate in counter directions. This was achieved by means of the two large gear wheels on the left of the photograph at Fig 3. The right-hand wheel is mounted on the waterwheel shaft which runs in a leat behind the wall to the left of the picture. A replica of the reversing gear has been constructed at Saltford, shown at Fig 1.
Avon Mill specialized in the manufacture of wire. The Avon Mill rolls were therefore relatively narrow, being only 1 ft 6 in (0.45 m) wide. These were designed to produce long lengths of brass strip, 10 cm wide, seen coiled up in the foreground of the photograph at Fig 3, before being slit into strings and then drawn into wire.
Saltford's rolling mill specialized in the production of metal sheet requiring much wider rolls. Fig 4 shows an artist's impression of what the wide, 'breaking-in', rolls would have looked like, the rolling bed width being 5 ft 6 in (1.7m).
Angerstein describes Saltford in 1754 as being purely a Battery Mill, but this was to change later in the century as the demand for sheet grew, not only for the production of brass pans for the Guinea trade, but also to produce copper sheet for the sheathing of merchant ships built in Bristol for trade with West Africa, the Caribbean and America. Copper sheathing of merchant ships to protect them from the teredo navalis shipworm starting in the 1780s, by which time the brass company had expanded and was known at the United Brass Battery, Wire & Copper Company of Bristol.
Techniques for rolling brass were introduced into the Avon valley around 1709, when the Bristol Brass Company entered into a partnership with the Esher Brass Wire Company, which was eventually to lead to the Bristol company being named the Bristol Brass & Wire Company. The types of rolls were probably very similar to those shown in Figs 2 and 3.
In 1754, the Swedish industrial spy, RR Angerstein, reported observing:
“By the town of Keynsham, five miles from Bristol on the way to Bath, there are two specially-built brass-works, belonging to the Bristol Brass Wire Co, comprising rolling and slitting mills for brass wire, and rolling mills for large brass sheets for Guinea pans and kettles. There is also a wire drawing mill for brass wire here.”
A. RR Angerstein's Illustrated Travel Diary. 1753-1755. Industry in England and Wales from a Swedish Perspective.
B. Bristol Brass: A History of the Industry. Joan Day. 1973