SIR WILLIAM ARMSTRONG AND THE ELECTRIC LIGHT.

Daily Telegraph (Napier), Issue 3057, 13 April 1881, Page 4

SIR WILLIAM ARMSTRONG AND THE ELECTRIC LIGHT.

Sir William G. Armstrong has forwarded to a recent number of the Engineer the particulars of the successful application of bwan's electric lamps to the lighting of his country residence at Cragside, Bothbury. The cast he says, possesses novelty, not only in the application of this mode of lighting to domestic use, but also in the derivation of the producing power from a natural source—a neighbouring brook being turned to account for that purpose. The brook, in fact, lights the house, and there is no consumption of any material in the process. The generator used is one of Siemens's dynamo-electrio machines, and tho motor is a turbine which gives off six-horse power, the distance of the turbine and generator from the house is 1,500 yards. The conducting wire is of copper, and its section is that of No. 1 Birmingham wire gauge. A return wire of the same material and section is used, so that the current has to pass through 3,000 yards of this wire to complete the circuit. The number of lamps in the house is 45, but as he can switch off the current from room to room, he never requires to have more than 37 in light at once. Por this number of lamps six-horse power proves to be amply sufficient, notwithstanding the great length of the conducting wire. The library, which is a room of 33ft. by 20ft., with a largo recess on one side, is well lighted by eight lamps. The dining room is also lighted by eight lamps. A picture gallery, which is also used as a drawing room, is lighted by twelve over head lamps ; but when the eight lamps in the dining room are no longer wanted, the ourrent supplying them is shunted to the gallery for lighting eight additional lamps, making twenty in all. The gallery is agreeably lighted even with the twelve lamps, and with the full illumination the pictures are seen as distinctly as in daylight. In the passages and stairs the lamps are for the most part used without glass shades, and present a very beautiful star-like appearance, not so bright as to pain the eye in passing, and very efficient for lighting the way. Each single lamp is about equal to a duplex korosene lamp well turned up, and this, he believes, is equivalent to 25 candles, so that the 6-hovse power in supporting 37 lamps, gives an illuminating effect equal to 925 candles. Sir William states that he has not yet had sufficient experience of Mr Swan's lamps to judge of their durability, but, with the exception of a few that failed by over-heating in his first trials, he has lost none since he began to use them about a month ago. Thoy have not, however, been in constant use during that time, and the test of their duration remains incomplete. But whatever their durability may be at f resent, it is almost certain to be increased y progressive improvement in manufacture, and when they aro systematically made in large numbers, the oost of renewing them will probably be small. The lamps are connected with the main leading wires, in what is called " multiple are," so that if one fails the others are unaffected.