The Park and Croesor Quarries The Park and Croesor Slate Quarries Co. Ltd. Park and Croesor Quarries, Penrhyndeudraeth, N. Wales Telegrams: Kellow, Porthmadoc Telephone: P.O. No. 10 Portmadoc The Croesor Quarries 1 This article, specially written for the SLATE TRADE GAZETTE, will no doubt prove of the greatest interest to slate quarry proprietors. It is scarcely necessary to say that a personal inspection of the Park and Croesor Quarries would more clearly demonstrate the efficiency of electric power in its application to slate quarrying. Where a visit is not possible, the following description will serve to give our readers some idea of what has been accomplished in the early stages of a new era in roofing slate production. The properties of the Park and Croesor Slate Quarries Company, Limited, are upwards of 2,000 acres in extent, and have a length of 312 miles on the finest range of slate-bearing strata in the world. They lie in a direct line from the mouth of the London and North Western Railway Tunnel at Blaenau Festiniog to Portmadoc. The Company are in membership with the Festiniog District Slate Quarry Proprie- tors’ Association, and its quarries form part of the Festiniog group. The Croesor Narrow Gauge Railway - 8 miles in length - was constructed, and still serves, to convey the produce of the Park and Croesor Quarries to the shipping wharves of Portmadoc, and to the junction with the Cambrian Railway at the Croesor siding, Portmadoc, where a large assortment of slates is always kept in stock ready for dispatch by rail or water. The Festiniog series of veins, comprising in ascending order The New " or "Deep Vein,"The Old Vein," "The Small Vein," "The Back Vein," and "The North Vein," and lying imme- diately on a thick stratum of felspathic porphyry, known locally as "The GlanypwIl Trap," traverses the properties for their entire length, and repre- sents a slate reserve which, at a conservative computation, amounts to over two thousand millions of tons, of which over six hundred mil- lions consist of the world-famous "Old Vein" slate. It is sad to reflect that the British building industry should use inferior slate from foreign and distant countries while a practically inexhaustible source of supply of the finest slate in the world is available in their own country, and at their very doors. The Moelwyn and Cynicht mountains, which are well-known landmarks in the country, and are veritably mountains of slate, are included in the properties. The Croesor Quarry was first opened about 55 years ago, and has since been worked on an extensive scale exclusively for " Old Vein " roof- ing slates. The Park Quarry was opened about 10 years later, and has been chiefly worked The Croesor Quarries 2 for slate for manufacturing purposes, such as slate ridg- ing, slabs, etc., the perfect straightness of the cleavage which characterises the rock of this quarry rendering it specially suitable for this class of work. The two quarries are, in fact, the complement of one another, enabling the Company to supply its customers' needs in either roofing slates, slate ridging, slabs, or any other variety of article produced in slate. Both Quarries are worked entirely below ground, and are, therefore, more correctly describable as "mines" rather than by their usual designation of quarries. At the Croesor mine or quarry, the plan of development pursued has been that now recognised as standard in the underground quarries of the Festiniog neighbourhood, i.e., the alternation of chambers in which the slate is quarried, with walls of solid rock left to support the roof. The chambers and walls follow, approximately, the line of dip of the strata (averaging about 27°), with horizontal galleries, or floors, at convenient intervals, along which the traffic is conveyed to the haulage inclines, and thence elevated to the surface of the ground. The unusual thickness of the "Old Vein" in this Quarry - upwards Of 40yds. at right angles to the bedding, and over 110 yards on the horizontal - in conjunction with the fact that it has been frequently possible to work chambers up to 16 or 17 yards in width without endangering the roof, has resulted in openings of abnormal size being produced. To the layman, the existence of these enormous caverns in the very heart of a mountain is strange and startling, and few people, who have not personally visited the quarries, realise even to a faint degree the conditions under which slate is ob- tained. At the Park Quarry owing to a peculiarity in the dip of the pillaring or grain of the rock, it has been possible to reverse the ordinary order of underground quarrying, commencing at the bottom instead of the top; working the galleries in ascending order, and leaving the rubbish behind to support the roof and walls, instead of conveying it to the surface at great expense, there to become an unsightly blemish on the landscape. The various parts of the properties range froul 2560 feet in elevation to practically sea level, and, being situated near the Atlantic coast, have a heavy rainfall; this, with unique storing facilities, provides all the conditions for the production of hydraulic power to almost any required extent. One artificial reservoir, of about 12 acres in extent, has been constructed at an elevation of 1460 feet, and another, of about 5 acres, at an elevation of about 1650 feet, in addition to which there are natural lakes, of about 6 acres, which are likewise utilised, at an elevation of about 1750 The Croesor Quarries 3 feet. The waters from these (besides from various other sources) are applied to the driving Of 4 high pressure turbines (aggregating about 500 H.P.) to an 80 H.P. engine, and to the work- ing of two Overshot Water Wheels (one Of 40 feet and the other of 20 feet in diameter) and these, in turn, are utilised for hauling, driving slate mills, pumping, and the production of electric power on the three-phase system. The electric power is applied to all the various requirements of slate quarrying and manufacturing where direct driving is not feasi- ble. The electric plant comprises machines aggregating about 775 H.P. In addition to the use of electric current for power purposes, it is also utilised for lighting the quarries underground, and for lighting the mills; the latter being so efficient that it would be possible to carry on the manufacture of slate continuously throughout the 24 hours if so desired. The Hydro-Electric system in use at these quarries contained when first erected many features of novelty among these being: (1) That the head of water utilised was the highest of any in the British Isles. (2) That the turbines were of a special, and exceedingly efficient type. (3) That it was the first application of the three-phase electric system to slate mining. (4) That it involved the use for the first time in Great Britain of an electric mining loco- motive. (5) That it afforded the first example of the application of the multi-stage, electrically- driven, centrifugal pumps to slate-mine drainage. The Hydro-Electric system here installed was the subject of a paper read by Mr. M. Kellow (the General Manager and Engineer of the Company) before the Institution of Civil Engineers, and it will be within the recollection of our readers that extracts from this paper appeared some time ago in the SLATE TRADE GAZETTE. Compressed air has been in use for upwards of 30 years for the transmission of power, and, to a small extent, the working of rockdrills. For the transmission of power it has, however, been almost entirely placed, and for rockdrilling entirely so, by the very much more effective and convenient electric and hydrau- lic systems. The Croesor Quarries 4 The utilisation of compressed air as a means of transmitting power, though still in extensive use through- out the world, is exceedingly inefficient, the power ob- tained from the executive engines being rarely in excess of 10 per cent. of that applied to the driving of the com- pressor, no less than 90 per cent. being wasted in me- chanical, compression, heat, and transmission losses, which are inherent in the system. When applied to rock-drilling, the result is even less satisfactory, being of the order of 1 per cent. of the input to the compressor. In comparison with these figures, it may be stated that, with electric transmission at this Company's quarries as much as 78 per cent. is being delivered by the motors of the HP. applied to driving the electric generators at the power station (one mile distant), and in the case of hydraulic transmission, approximately 50 per cent. of the power is usefully applied to rockdrilling and channelling, in comparison with about 1 per cent. in the pneumatic system. Until recently, and as a result of the inefficiency and many limitations of pneumatically-operated drills, the boring of rock for blasting purposes was done almost entirely by manual labour in slate quarries throughout the world; but Mr. M. Kellow, who has been associated with the slate industry all his life- time, and who has made a deep study of the various mining and mechanical problems connected with it, has invented, and patented, a Rock Drill, which can be operated by hydraulic power, with a view to over- coming the objections and limitations in the pneu- matic system. A limited company, viz., The Kellow Rock Drill Syndicate, Limited, has been formed to manufacture and exploit these drills, and already they have found their way into various important quarries of the locality.