Cwm-y-glo explosion memorial, near Llanberis

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This memorial plaque was unveiled in 2008 to commemorate the six people who died as a result of an explosion near this spot in 1869. One was a boy who happened to be leading his blind father past the village at the time.

In the afternoon of 30 June 1869, an extremely hot day, two carts set out from Caernarfon. Each was laden with a ton of nitroglycerine, manufactured by Alfred Nobel in Germany and destined for the Glynrhonwy slate quarries, Llanberis. The canisters containing the liquid explosive had been carefully packed into boxes containing sawdust and loaded onto the carts. The boxes were then covered in straw to prevent movement during the journey.

The cargo exploded at about 5.50pm, as the carts had just passed the railway station goods shed outside Cwm-y-glo (now the site of Gwynedd Council’s storage yard). The explosion was probably the loudest man-made explosion which had ever occurred. The press reported that it was felt in Holyhead (37km away as the crow flies).

Both of the carters were killed, as well as three others. Eight other people were seriously injured, one of whom died six weeks later from his injuries. See the Footnotes for their details.

The chief constable, based in Caernarfon, quickly impounded three other cartloads of nitroglycerine until “further precautions” were taken.

No trace of horses or carts remained at the site, where there were two deep craters approximately 3.3 metres (10ft) deep. Of the people killed immediately, quarryman Robert Morris was the only one whose remains which could be identified. Human and animal parts were spread far and wide. Some of the debris was found in the neighbouring village of Brynrefail. The human remains were collected and taken to the nearby Craig y Don tavern to await the inquest, held the following day.

Many of the injured suffered broken bones. One had his arm amputated. Scarcely a house in Cwm-y-glo escaped damage, including those high on the hill above the main street.

An X inscribed on a dry stone wall at Clegyr, on the old road from Bryn Bras to Llanberis, is now the only physical indication of where a wheel and the harness of one of the carts were found, more than 800 metres (over half a mile) away.

The inquest jury agreed that the carters had not been drunk, although they had stopped at the Blue Bell pub in the village. The verdict was “accidental death”. The reasons for the accident were unknown, nitroglycerine being a relatively new material.

As a result of the explosion, an Act of Parliament prohibited the import of nitroglycerine and regulated its carriage. As a result, quarries and other industries replaced it with dynamite, a more stable material manufactured for the first time by Alfred Nobel in 1866 (in whose name Nobel Prizes are awarded annually).

With thanks to Martin Kressman, who also paid for the commemorative plaque

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Footnotes: The casualties

The following people died as a result of the explosion at Cwm-y-glo in 1869.

Evan Jones, aged 20, lived at Tyddyn Llwydyn.
John James Jones, aged 11, of Cwm-y-glo.
Robert Morris, quarryman, aged 26, of Cae’r Bronydd, Llanllechid. He had recently returned from the USA.
Griffith J Prichard, aged 11, of Penyclegir, Brynrefail. He was leading his blind father, John, home after buying a sheep at Bryn Bras. John, who lost his sight while working in Dinorwig quarry, was uninjured (as was the sheep) and left with nobody to guide him.
David Roberts, carter, who hailed from Denbighshire and left numerous children.
Owen Roberts, aged 15.