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Results of the Great Blasting Operation at Holyhead, North Wales, 1856. Building a new harbour and breakwater. '...in the lower quarries of the mountain a most stupendous and successful blasting operation took place, when the enormous quantity of 13,000 lb. of powder, contained in four separate chambers, were simultaneously exploded by means of the galvanic battery, producing upwards of 70,000 tons of the hardest schistus quartz, of which the Holyhead mountain is composed. The respective chambers...were so judiciously charged that the rock, after the explosion, fell in blocks of a size not larger than from one to twenty tons; thus enabling the contractors, without further expense for reducing the stone, to lift the blocks into the iron waggons; and so to convey them from the quarries over the staging, and thence tipped into the sea, or to build them into the Cyclopean structure'. From "Illustrated London News", 1856.