The original 1849 pumps were upgraded and modified as water demand increased, finally being retired and replaced by the present beam engine in 1904.
It is a Woolfe compound rotative beam engine of 140 indicated horsepower and it can run between 9 and 16 revolutions per minute. During its working life supplying the town it will have averaged about 12 rpm giving a total of 140 million revolutions. At that speed it would deliver 1900 gallons (8640 litres) of river water into the filters and 1700 gallons (7730 litres or 21 standard bath tubs) into the town every minute.
The cast iron beam is 30 feet 3 inches (9.2 metres) long and weighs 25 tons. The flywheel is also made of cast iron and is 21 feet (6.4 metres) in diameter and weighs 14.5 tons.
The Beam Hall