1907 Minutes of the Proceedings of the Institution of Civil Engineers  
THE slate-mines and quarries of Wales are situated, almost without exception, in the mountainous regions of Merionethshire and Carnarvonshire, and their working forms the staple industry of these counties. The form of the country, in which high hills alternate with deep valleys, greatly facilitates mining and quarrying, inasmuch as it enables the slate beds, which usually incline at relatively high angles, to be approached and worked by adit-levels and horizontal galleries directly from the
more » ... sides, natural ventilation being also available. These advantages of position, by dispensing to a large extent with the necessity for powerful winding-, pumping-and ventilatingmachinery, such as is generally required in collieries and metalliferous mines, have caused the amount of power in use to be small, relatively t o the magnitude and importance of the undertakings generally. There is little doubt that it is due to this fact that the mechanical equipment of slate-mines and quarries-particularly in connection with the generation and distribution of power-has not kept pace with the progress made in other industries. The conditions under which the slate is being worked tend, however, to become less favourable every year, for, as the workings become deeper, natural drainage is no longer possible, winding from the lower galleries becomes necessary, and satisfactory ventilation is more difficult of attainment. Moreover, mechanical aids in the manufacture, 3s well as in the mining and quarrying, of slate, tend to become more universal every year. These changing conditions, by involving an increasing use of power, Proceedings.] HYDRO-ELECTRIC POWEE TO SLATE-BIISIKG. 51 render the question of the best means of generating and distributing it of considerable importance, especially at the present time, when the stress of foreign competition is so great that the very existence of the industry requires that advantage should be taken of every aid to effective working and cheap production. By reason of its situation on the west coast, and the high altitude of the mountains comprising the Snowdonian range, which intercept the moisture-laden west and south-west winds, the locality has an exceptionally high rainfall, ranging from 90 inches to as much as 170 inches per annum. The large volume of water which this implies is moreover generally available for storage a t a high elevation, so that the two conditions of volume and head, essential to the production of hydraulic power, are present. There is no doubt that, properly developed and applied, there is an abundance of water-power available in the two counties for all the needs of the slate industry, At present, though in some instances water-power is applied, the bulk of the power for working machinery in the slate mines and quarries is being derived from steam. The disadvantages attendant upon the use of steam-engines, as regards expense and inconvenience, when they are distributed in small units, and especially when situated underground, are so well known to engineers that it is unnecessal-y to enlarge upon them.
doi:10.1680/imotp.1907.17245 fatcat:475o2phj6vambo4gu2wohfv2yy