The term 'Battery' is derived from the latin 'Battere', meaning to beat (Old French - 'Batteria'). A 'Brass Battery Mill' is therefore a mill adapted for the manufacture of brass products (hollow-ware) by the beating of brass slabs (called naps) using water-driven hammers.
Little evidence above ground of the battery hammers survives today (Fig 1) although the leats that contained the waterwheels which drove the battery hammers are very much in evidence. So how do we know what was here? We have a number of sources of evidence:
- The location of the waterwheels, visible today;
- An archaeological excavation conducted in 1986;
- A contemporary description of the Saltford battery hammers from c.1905;
- A photograph of a similar mill in Stolberg, Germany, taken in 1905;
- An inventory of Saltford mill, compiled in 1859;
- A description of Saltford mill in 1754; and
- A description of a similar mill in Namur, written in 1749.
The working conditions in Saltford battery mill are likely to have been similar to the conditions shown in the photograph at Fig 2, taken in Stolberg c.1905. Several workers are shown manipulating slabs of brass beneath water driven trip-hammers to produce hollow-ware basins, bowls and pans, seen stacked on the working floor next to each artisan.
The makings on the floor in Fig 1 indicate the location of the large oak piles driven into the ground on which the anvils were wedged for working the brass plate, as clearly seen in Fig 2.
Fig 3 is based on George Shellard's description of Saltford battery mill.
Born in 1896, George was the son of Tom Shellard, one of the last people to produce battery pans at Saltford. George, who was 14 when the hammers last worked in 1908, remembered the hammers and described the arrangement to Joan Day in the late 1960s.
The drawing shows three hammers and their related anvils, the heavy frame driven into the ground into which were wedged the pivots for the hammer shafts (helves) and the large, waterwheel-driven, rotating shaft on which is mounted three sets of cams to lift and trip the battery hammers. A replica, truncated, drive shaft is shown in Fig 1.
George's description mirrors the 1859 inventory of the mill which describes two battery mills at Saltford, each consisting of a waterwheel, 15 ft x 3 ft 6 in, driving three hammers.
The arrangement of hammers in sets of three also mirrors the description by Galon of a brass mill at Namur in 1749.
Fig 4 shows a cross-section of a battery hammer, based upon the various descriptions that have been obtained by the Saltford Brass Mill Project, the key aspects of which are:
- The anvil and toe-plate piles, sunk approx. 1 m in to the ground.
- The hammer frame, sunk approx. 2 m into the ground.
- The hammer shaft (helve) approx. 2 m long.
- The cams mounted on the waterwheel-driven shaft.
As the waterwheel turned, the cams drove the heal of the helve on to the toe-plate. The heal bounced on the toe-plate, causing the hammer to strike the anvil. This action was repeated at high speed - the waterwheel turned at approx. 12 to 18 rpm, there were 20 cams on the shaft; hence the hammer struck between 4 and 6 blows per second.
This operation was not the slow steady beat used when working iron, but a rapid hammering. People who have witnessed the operation describe the working of the brass as being akin to a potter working clay.
Saltford mill was leased by the Bristol Brass & Wire Company in 1721 and adapted to operate as a battery mill, adding to the company's other battery mills at Keynsham (Chew Mill), Woollard (Woodborough Mill), and Weston. Angerstein described Saltford mill in his diary of 1754:
On the road between Keynsham and Bath there is... (a mill), comprising three workshops and twelve hammers
Fig 5 shows a postulated layout of the mill when Angerstein visited the site in 1754.
Later in the 18th century, two sets of hammers were replaced with rolls for the manufacture of copper or brass sheet, the inventory of 1859 identifying:
Battery Mill No 1: Waterwheel, 15 ft x 3 ft 6 in, driving three hammers.
Battery Mill No 2: Waterwheel, 15 ft x 3 ft 6 in, driving three hammers.
Rolling Mill: 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.
The battery mill ceased operation in 1908; rolling, however, continued until 1925.
A. The Art of Converting Red Copper to Brass by means of Calamine Stone, its Casting into Slabs and Battery under Hammer. Messers Galon and Du Manceau. 1749
B. RR Angerstein's Illustrated Travel Diary 1753 - 1755. Industry in England and Wales from a Swedish perspective.
C. Bristol Brass: A History of the Industry. Joan Day. 1973
Grade II* Listed Building