Pump and Glamorganshire canal

The History of Melingriffith Pump by Steve Rowson

How old is it?
The water-driven pump at Melingriffith dates from 1795. In its early years there may have been several alterations to the design and position in order to improve its efficiency. This culminated in 1806 with proposals that included replacing the water wheel with a ‘fire engine’ i.e. a steam engine. Although the scheme did not go ahead it has led certain historians to suggest that the surviving design dates from 1806 and not from 1795.

The original 1795 design was by Watkin George, the renowned innovative engineer from Cyfarthfa Ironworks whose 50 ft water wheel drove the blast engine there. By 1806 George had left the district and the canal company’s engineering consultant was John Rennie. If the surviving water engine at Melingriffith is a Rennie replacement then one wonders how it would have differed from George’s original design. Its old-fashioned simple appearance contrasts with Rennie’s sophisticated design of Claverton engine (near Bath) on the Kennet and Avon Canal, erected in 1811 which performed a similar function and which also survives. The evidence points towards the surviving structure not being by Rennie but being substantially what George had designed in 1795.

Why was the pump needed?
Canals need a regular supply of water. They not only use water to pass boats down (and up) the locks but they also lose a considerable amount from leakage and evaporation. When the Glamorganshire Canal was built there were many industries competing to use the waters of the Taff valley

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One of the few photos showing the 'trough' of water brought up via the pistons which had leather valve flaps. The water then ran toward the photographer, into the canal.
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The canal’s promoters needed an Act of Parliament to allow them to build the canal. This gave the proprietors of existing industries the opportunity to oppose the Bill until their water rights were safeguarded. One of those industries was the Melingriffith Tinplate Works. The canal company had to include a clause in the Bill stating that all excess water in the canal at Melingriffith would be made to overflow into the tinplate works’ feeder upstream of the works. [This overflow weir still exists underneath the cast iron towpath bridge at the beginning of the Long Wood.]


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However, this meant that the canal became short of water below Melingriffith. This became apparent as soon as the canal was opened and so the engine was built in 1795, with the agreement of the Melingriffith Tinplate Works, to pump water back into the canal after the water had been used to drive the machinery in the works.

The pump was so important that it continued in use at least until the late 1920s to provide a water supply for canal traffic from Maindy and Blackweir to Cardiff docks.

[A full account of the pump can be found in Stephen Rowson and Ian L Wright The Glamorganshire and Aberdare Canals Vol 2 (2004).]

Steve Rowson is the author of The Glamorganshire and Aberdare canal: Pontypridd to Cardiff Vol 2. To purchase the books at a reduced rate, please contact us.

Rubbing post, right. Located next to oak cottage. NB the rope marks worn into the metal.