October 8, 1891] 



NATURE 



54. 



of putting them under the streets and himself under the 

 control of the authorities. 



But every corner at the Bond Street central station 

 had soon to be utilized ; a dynamo weighing tons had on 

 one occasion to be lifted into position over a steam- 

 engine necessarily kept always running to maintain a 



existing^ overhead mains, and again reduced to loovoks 



on entering the houses, as before. 



The scheme was a far-reaching one ; permission was 

 asked from the Board of Trade by the London Electric 

 Supply Corporation, the outcome of the original Gros- 

 venor Gallery Syndicate, to run wires along 27 railways 



Fig. 4.— Two 1250 horse power dynamos (opened for inspect! jn) at D-ptford. 



constant supply of current to the houses. New customers 

 were added daily to the list, more and more current had 

 to be generated nightly, in the face of engineering diffi- 

 culties, and in the teeth of injunctions against smoke, 

 injunctions against dust, and injunctions against noise. 



A fresh start became imperative, so it was decided to 

 build at Deptford, 6 miles away from Bond Street, a vast 



and through 30 parishes; two dynamos, each to furnish 

 1250 horse- power at 10,000 volts, were built with special 

 engines to drive them, as seen in Fig. 4, and a cable laid 

 to London. But on starting the dynamos, when they 

 were completed, it was found that the insulation of the 

 cable would not stand 10,000 nor even 5000 volts ; and 

 for a time power was supplied direct from Deptford to 



Fi?- 5. — Longitudinal section of the Ferranti main. 



V, inner copper lube ; b, outer copper lube ; d, i 

 shaded black- 



protecting lube ; waxed parer insulation 



generating station, which should be the largest in the 

 world, and to use the Grosvenor Gallery, and probably 

 fresh sites to be obtained in town, merely as transforming 

 stations. In the mains between Deptford and London it 

 was decided to employ 10,000 volts, to be reduced to 

 2400 in London, and the power then distributed by the 



NO. I 145, VOL. 44] 



the houses in London, one transformation at the houses 

 themselves being alone effected. 



Then Mr. Ferranti carried out his original intention of 

 constructing the main of two concentric copper tubes, to 

 serve respectively as the going and return conductor. 

 The inner copper tube, 20 feet long, seen in section, A, 



