English: A slate saw Prior to the introduction of steam powered saws at the Feiar Injan steam mill in 1849, slate blocks were reduced to a manageable size using large wooden mallets, made of African oak. Such a mallet was called a 'rhys'. The progress of mechanisation proved slow. It took another sixty years for the first two large mills to be built at Dinorwig, which together had a total of 58 sawing machines. Between 1920 and 1935, a further 422 sawing tables were added. These saws were responsible for the creation of a very dusty atmosphere in the sheds leading to a widespread incidence of pneumoconiosis amongst shed workers. To the bitter end the company fought paying compensation to the men. It was only in 1979, ten years after the company had gone out of existence, that the Pneumoconiosis (Workers' Compensation)Act was passed by a Labour government in its death throws as a trade-off for the support in the lobbies of Plaid Cymru. This legislated for a one-off lump sum to sufferers, or their dependents if they had died.