Slate Splitting and Dressing
It was in the quarry itself, in the gwalia — the open-sided sheds — that splitting and dressing was actually done; it is now carried out in the yard, but we still have three slate sawing tables. The power from the water wheel drives all three by means of the line shafting. The two smaller tables come from Dinorwig Quarry itself, but the largest comes from Penyrorsedd quarry in the Nantlle valley and dates from 1876.
Slate sawing is a heavy, dusty and noisy task. A trough of water under the table cools the wheel as it cuts through the slab of slate, and damps down some of the dust produced. When a hundred or more tables were at work at the same time, there would be so much dust in the air that the other end of the shed would be invisible. The effects of this dust were very damaging to the quarrymen's health, leading to chest diseases and silicosis.
You can also see a number of slate dressing machines: two guillotines worked by a drop lathe, to trim the slate, and three machines to dress the slate, one from Dorothea quarry, one from Penyrorsedd and the third from Dinorwig. But remember that, although machine and electrical means have been devised to facilitate the work of sawing and dressing slates, they are still split by hand.
In their leisure hours, quarrymen were proud of their ability to work slate, fashioning it into beautiful objects as well as roofing slates. There are many examples in the quarrying areas of fireplaces, trays and panels delicately carved with all kinds of symbols.
Slate of Different Sizes
The slates were called by different names according to their sizes — and highly select names they were, too, varying from the 'Ladies' (16 inches by 12 inches) through 'Countesses' (20 inches by 12) and up through the 'Duchesses' and 'Princesses' to the 'Queens', which were 42 inches by 27.
It's difficult to know why men who spoke only Welsh gave the slates such very English names. It seems that the practice began at the end of the 18th century at the Penrhyn quarry in Bethesda, introduced by a man called GeneralWarburton.