816 KEPORT — 1888. 



These actuate electric generators, from wliich the currents are sent along a circuit 

 of eighteen miles, driving Sprague motors at fourteen different points where power 

 is required in a mining district for pumping, hoisting, &c. 



The falls at Roaring Fork, Grand River, are utilised for driving an electric 

 generator, from which the power is convej'ed across country over a mile to Aspen 

 Mines, Colorado, where a 10 horse-power Sprague motor is driving the mine 

 machinery, replacing steam power with considerable economy. 



A gold mine in New Zealand has recently been made valuable by transmitting 

 the power from a waterfall two miles away. The conductors, supported on poles, 

 are carried direct over the mountains, two thousand feet intervening between the 

 fall and the mine. Obviously, where water power can be thus applied, the 

 saving as compared with using fuel is considerable, especially m metal or dia- 

 mond-mining districts, where coal is expensive. The ease with which the power 

 can be conveyed over hill and dale and into the intricacies of the mine is also a 

 factor of no mean importance. 



It will be seen from the above how meagre are the results in transmission of 

 power up to the present, and yet in every case where it has been adopted it has 

 proved economically successful. 



Possibly in fiery mines some are afraid of the sparks. There is no danger 

 whatever on this head, as all the machinery can be enclosed in an air-tight 

 chamber. It may be that want of familiarity hinders others ; they fear to embark 

 capital in plant of which they cannot speak from their own expevience. 



The failures in the history of electric lighting have no doubt prejudiced some, 

 and they look upon the electric light and all akin to it with suspicion. The 

 writer will be amply repaid if he can by means of this brief paper so interest some 

 mining engineers as to cause them to take up the matter for themselves. He is 

 satisfied that, under many conditions common in colliery working, electricity can 

 and will be applied successfully and economically. 



8. Miners' Electric Safety Lamps. ^ 

 By Nicholas Watts, Assoc. M.Inst.G.E. 



After referring briefly to the but partial success attained in modifying miners' 

 oil-lamps to adapt the same to the currents now obtaining in collieries, and noticing 

 the apparent suitability of the incandescent lamp as a substitute, the author described 

 the following miners' portable electric safety lamps, some of which he exhibited : — 



The Stoan Lamp. — Secondary battery. Four cells grouped together in a block 

 of gutta-percha which is enclosed in a wooden case. The elements are lead oxide 

 and lead. Luminosity, 1 to 1^ candle for ten hours' duration. Weight, 7 lbs. 

 Price, 27s. Cost of maintenance, 2>hd. per week. In extensive use in South 

 Wales. 



The Schanschieff Lump. — Single liquid primary battery. Four zinco-carbon 

 cells, the carbon non-porous. The peculiar novelty is the nature of the exciting 

 liquid, which is a solution of the basic sulphate of mercury, about u6 per cent, of 

 the salt being held in S(;ilution. The solution is sold at 4s. per gallon, of which 

 3s. 7d. is allowed for the same quantity of the spent liquid with its solid residue 

 and free mercury precipitated by the cells. Luminosity (with reflector), 2 to 3 

 candles for nine hours' duration. Weight, about 5 lbs. Price, 30s. Cost of 

 maintenance, '3^d. per week. Tested at Cannock Chase, Mardy, Merthyr, and 

 elsewhere. 



The Pitkin Lamp. — Secondary battery. Four cells. Luminosity (with re- 

 flector), 4 to 5 candles for ten hours' duration. The lamp is fitted with a switch 

 and resistance to regulate the expenditure of the electro-motive force, which, if 

 allowed to act without check, would, when the battery was started, destroy the 

 filament. Weight, 8 lbs. Price, 21. 2s. Used at Llwynypia, Ocean Colliery, 

 Treviky, and elsewhere. 



T/ie Walker Lamp. — Primary battery. Three carbon-zinc cells in a strong 



' Printed in extenso in Electrical Engineer, vol. ii. (N. S.), p. 226. 



