October 8, 1891] 



NA TURE 



545 



Finally, in March of this year, current was again 

 turned on from Deptford, at the pressure originally pro- 

 posed, viz. 10,000 volts. It was not, however^ supplied 

 from the dynamos illustrated in Fig. 4 ; but, instead, 

 Messrs. Deprez and Carpentier's plan of transforming 

 up and transforming down again, illustrated in Fig. i, 

 p. 522, was employed. For, by this time, two dynamos, 

 formerly at the Grosvenor Gallery, each of 600 horse- 

 power, had been taken to Deptford and erected there, as 

 seen in Fig. 9 ; new steam-engines, more powerful than 

 those formerly employed at the Grosvenor Gallery, having 

 been constructed to drive them. 



These dynamos generate the current at 2400 volts, 

 then, by means of transformers at Deptford, this is raised 

 to 10,000 volts. On the power arriving in London, the 



London at a pressure which, even at the end of last year, 

 was deemed simply visionary. 



i But as a commercial undertaking the Deptford trans- 

 mission is a dreary failure, since what is the advantage of 



j tiansmitting the current 6 miles that is in any way com- 



( mensurate with the capital already expended t When 

 power can be obtained very cheaply, from a rapid river 



j for example, it may be highly remunerative to transport 

 it in some such way as is now being done between 

 Lauffen and Frankfort. But can power be obtained so 

 much more cheaply at Deptford than in London to make 

 it worth while transmitting it over 6 miles ? Land un- 

 doubtedly costs much less down the river than in the 

 heart of London, coal can be very easily brought to a 

 generating station on the banks of the Thames, and the 



Fig. 9. — Two of the Grosvenor Gallery dynamos re erected at Deptford and driven by new steam-engines. T«-o 1250 horse-power dynamos at the back. 



pressure is transformed down again to 2400 volts, and at 

 the houses there is a further transformation of this 2400 

 volts to 100 volts. There are, therefore, no less than 

 three transformations of pressure between the dynamo 

 terminals at Deptford and the lamps in the houses in 

 London. 



Regarded as a gigantic experiment in electrical engi- 

 neering, the Deptford scheme has achieved a gallant 

 victory, for, with a buoyancy that no disaster could crush, 

 and with the determination of a Napoleon to conquer 

 every mechanical and electrical obstacle in the way, Mr. 

 Ferranti has step by step succeeded in distributing current 

 to quite distant parts of London at a pressure which in 

 1885 was regarded as quite impracticable, and for the 

 last seven months he has been sending the power to 



NO. I 145, VOL. 44] 



water might perhaps be employed to work condensing 

 steam-engines ; but such economies can only compensate 

 for a fraction of the yearly interest on the capital ex- 

 pended on the Deptford scheme. Indeed, even if the 

 station at Deptford had been built with rigid economy, 

 and only large enough for the present demand, it is 

 questionable whether the loss of power in three trans- 

 formations of the pressure would not eat up much of the 

 saving that could be effected by having the generating 

 station quite out of London. 



As it is, however, the London Electric Supply Company 

 have been so engrossed with the electric lighting of 

 London in the future, that they have practically ignored 

 the present wants of the householder ; the vast building 

 at Deptford has been constructed to carry a second story 



