Princess May Water Balance, Penrhyn Quarry

Princess May Water Balance


29 January 2011

Penrhyn Quarry, Bethesda

SH 62154 65387; 53.16768°N, 4.06354°W

Further Information

Princess May is one of the two surviving water balances at Penrhyn Quarry; the other is called Sebastopol and has been restored. Originally there were eight at the quarry.

The water balance was used to lift quarried slate from a lower level to a higher one and employed water to counteract the weight of the payload. Two wagon platforms with water tanks on top were connected by a cable running over the top of a large wheel. When one platform was ready at the bottom with a full wagon and an empty water tank, the other platform, at the top with an empty wagon, had its tank filled and was allowed to descend under the weight of the water, thereby lifting the other platform to the top.

Sebastopol Water Balance (

Princess May Water Balance, Penrhyn Quarry

Princess May Water Balance

Main water tank and wheel

Water tank

Main structure supporting the wheel

Wheel enclosure

Wagon platform

Braided cable supporting the platforms

Platform position indicator

Brake control


Penrhyn Quarry. Princess May is at the bottom left. Above and to the right of this, the Sebastopol water balance can just be seen.

2 thoughts on “Princess May Water Balance, Penrhyn Quarry

  1. Pingback: Dereliction « GeoTopoi

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