page_title: Slate industry in Wales
section_title: Mechanization and increased production
hierarchical_section_title: Slate industry in Wales / Peak production (1831–1878) / Mechanization and increased production
caption_attribution_description: English: Drumhouse at Dinorwig Quarry
context_page_description: The existence of a slate industry in Wales is attested since the Roman period, when slate was used to roof the fort at Segontium, now Caernarfon. The slate industry grew slowly until the early 18th century, then expanded rapidly until the late 19th century, at which time the most important slate producing areas were in northwest Wales, including the Penrhyn Quarry near Bethesda, the Dinorwic Quarry near Llanberis, the Nantlle Valley quarries, and Blaenau Ffestiniog, where the slate was mined rather than quarried. Penrhyn and Dinorwig were the two largest slate quarries in the world, and the Oakeley mine at Blaenau Ffestiniog was the largest slate mine in the world. Slate is mainly used for roofing, but is also produced as thicker slab for a variety of uses including flooring, worktops and headstones.
  Up to the end of the 18th century, slate was extracted on a small scale by groups of quarrymen who paid a royalty to the landlord, carted slate to the ports, and then shipped it to England, Ireland and sometimes France. Towards the close of the century, the landowners began to operate the quarries themselves, on a larger scale.
context_section_description: In 1843, the Padarn Railway became the first quarry railway to use steam locomotives, and the transport of slate by train rather than by ship was made easier when the London and North Western Railway built branches to connect Port Penrhyn and Port Dinorwic to the main line in 1852. The Corris Railway opened as the horse-worked Corris, Machynlleth & River Dovey Tramroad in 1859, connecting the slate quarries around Corris and Aberllefenni with wharves on the estuary of the River Dyfi. The Ffestiniog Railway converted to steam in 1863, and the Talyllyn Railway was opened in 1866 to serve the Bryn Eglwys quarry above the village of Abergynolwyn. Bryn Eglwys grew to be one of the largest quarries in mid Wales, employing 300 men and producing 30% of the total output of the Corris district. The Cardigan Railway was opened in 1873, partly to carry slate traffic, and enabled the Glogue quarry in Pembrokeshire to grow to employ 80 men.
  Mechanization was gradually introduced to make most aspects of the industry more efficient, particularly at Blaenau Ffestiniog where the Ordovician slate was less brittle than the Cambrian slate further north, and therefore easier to work by machine. The slate mill evolved between 1840 and 1860, powered by a single line shaft running along the building and bringing together operations such as sawing, planing and dressing. In 1859, John Whitehead Greaves invented the Greaves sawing table to produce blocks for the splitter, then in 1856 introduced a rotary machine to dress the split slate. The splitting of the blocks to produce roofing slates proved resistant to mechanization, and continued to be done with a mallet and chisel. An extra source of income from the 1860s was the production of "slab", thicker pieces of slate which were planed and used for many purposes, for example flooring, tombstones and billiard tables.
  The larger quarries could be highly profitable. The Mining Journal estimated in 1859 that the Penrhyn quarries produced an annual net profit of GB£100,000, and the Dinorwig Quarry £70,000 a year. From 1860 onwards slate prices rose steadily. Quarries expanded and the population of the quarrying districts increased, for example the population of Ffestiniog parish increased from 732 in 1801 to 11,274 in 1881. Total Welsh production reached 350,000 tons a year by the end of the 1860s. Of this total, over 100,000 tons came from the Bethesda area, mainly from the Penrhyn Quarry. Blaenau Ffestiniog produced almost as much, and the Dinorwig Quarry alone produced 80,000 tons per year. The Nantlle Valley quarries produced 40,000 tons, while the remainder of Wales outside these areas produced only about 20,000 tons per year. By the late 1870s, Wales was producing 450,000 tons of slate per year, compared with just over 50,000 tons for the rest of the United Kingdom, which then included Ireland. In 1882, 92% of the United Kingdom's production was from Wales with the quarries at Penrhyn and Dinorwig producing half of this between them. Alun Richards comments on the importance of the slate industry:
  It dominated the economy of the north-west of Wales, where, by the middle of the 19thC. it accounted for almost half the total revenues from trade, industry and the professions, and in Wales as a whole, its output value compared with that of coal.
  The prosperity of the slate industry led to the growth of a number of other associated industries. Shipbuilding increased at a number of coastal locations, particularly at Porthmadog, where 201 ships were built between 1836 and 1880. Engineering companies were set up to supply the quarries, notably De Winton at Caernarfon. In 1870, De Winton built and equipped an entire workshop for the Dinorwig Quarry, with machinery powered by overhead shafting that in its turn was driven by the largest water-wheel in the United Kingdom, over 50 feet in diameter.
caption: The drumhouse at the top of an incline housed the winding gear used to lower the loaded slate waggons down the slope. The weight of the loaded waggons would pull up empty waggons. This drumhouse is at Dinorwig Quarry
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