!7o 



SCIENTIFIC NEWS. 



[Oct. 5, iS 



a small potential difference and a large current, and an 

 electric transformer is for the purpose of effecting the 

 transformation with as little loss of power as possible, so 

 that what is lost in potential difference may be all gained 

 in current. 



Electrical transformation may be effected by 



(i) Alternate current transformers, 



(2) Motor-dynamos, 



(3) Accumulators, or secondary batteries, 



(4) Direct current transformers. 



Of these apparatus the oldest by far is the alternate 

 current transformer, as it is merely the development of 

 the classical apparatus invented by Faraday in 1831, and 

 familiar to many of you as the Ruhmkorff or induction coil. 

 A combination of a motor and dynamo was suggested 

 by Gramme in 1874. Accumulators are the outcome of 

 Plant's work, while direct current transformers are quite 

 modern and not yet out of the experimental stage. 



After studying the literature on the subject, it appears, 

 as far as I have been able to judge, that the first definite 

 proposal to use a high potential difference in the street 

 mains and transform down to a low potential difference 

 in the houses, was made in the lecture given by me at the 

 meeting of the British Association in Sheffield in 1879, on 

 which occasion I explained and showed in action the motor- 

 dynamo principle suggested by Professor Perry and my- 

 self. The apparatus on the platform is not unlike that 

 shown on the former occasion ; an Immisch motor work- 

 ing at 500 volts and with a current of 6 '8 amperes is 

 geared direct to a Victoria brush dynamo giving five 

 times that current, and we will now use this larger 

 current to produce an electric fire. Messrs. Paris and 

 Scott have combined the motor and dynamo into one 

 machine, which they have kindly lent me, and by means 

 of which we are now transforming about 700 volts and 

 6'8 amperes into 100 volts and about 40 amperes used to 

 light that group of incandescent lamps and work these 

 motors. 



Lastly, here is a working illustration of the double 

 transformation proposed by M. Deprez and Carpentier in 

 1 88 1, by means of which, while the potential difference 

 between the mains may be two or ten thousand volts if 

 you like, not merely is the potential difference in the 

 house so low that you could hardly feel anything if you 

 touched the wires, but in addition there is the same 

 security against shocks in the dynamo-room. This alter- 

 nate current machine is producing about 50 volts, which 

 is transformed up to 2,000 volts by means of this trans- 

 former. At the other end of the platform, by means of 

 a similar transformer, the 2,000 volts is transformed down 

 again to 50 volts employed to light that cluster of low 

 voltage incandescent lamps. 



In this experiment there is, as a matter of fact, still 

 more transformation than that I have yet mentioned, 

 because, whereas in actual practice the alternate current- 

 dynamo, as well as the small dynamo used to produce 

 the current for magnetising the electro-magnets in the 

 alternate current-dynamo, would be worked by a steam, 

 gas, or water engine, I am working them both by 

 electro-motors, since a steam engine or a water wheel 

 would be an unsuitable occupant of the Drill Hall. 

 Practically then, a steam-engine on the land belonging to 

 the Midland Railway Company, on the other side of the 

 lower Bristol road, is driving a Thomson-Houston 

 dynamo ; this is sending a small current working these 

 high voltage, constant-current Immisch motors. The 

 motors being geared with lew voltage dynamos, the 



potential difference is transformed down, the first alter- 

 nate current transformer transforms it up again, and the 

 second alternate current transformer transforms it down, 

 so that there are, in fact, three transformations taking 

 place in this experiment on the platform before you. 

 {To be continued.) 



*-^t^>"^*<^- — 



of ^apttg, flectute^, etc* 



SOCIETY OF ENGINEERS. 

 On Tuesday, 25th September, this Society visited the 

 London and South-Western Railway Locomotive 

 Carriage and Waggon Works at Nine Elms. 



These famous works, which were originally designed 

 by the late Mr. Joseph Beattie, and at that time con- 

 sidered very complete, have been, owing to the increase 

 of traffic and stock, considerably altered and enlarged by 

 Mr. William Adams, the present superintendent. 



The works, which cover 45 acres of ground, are 

 situated at Nine Elms, which is on the south-east side 

 of the main line after leaving Vauxhall station ; and 

 between 2,000 and 2,500 men are employed. 



The locomotive department consists of machine, 

 erecting, wheel, smiths', fitters, cylinder, brass, copper- 

 smiths, boiler, tender-fitters', mounting and pattern 

 shops, grindery, iron and brass foundries, and running 

 sheds. The "short" machine shop is a large brick 

 building, well lighted, and is 164 ft. long by 57 ft. wide. 

 It is well fitted with the most modern classes of machine 

 tools, milling machines being conspicuous by their large 

 numbers, notably an horizontal milling machine by 

 Messrs. Muir, of Manchester. These machines leave the 

 work in such a state of perfection, that further attempt 

 at finishing with a file would only spoil it. On leaving 

 the " short " machine shop the cylinder shop is entered, 

 which is provided with a very useful overhead travelling 

 crane, made at Nine Elms. Here there are two very 

 fine vertical milling and drilling machines, which are 

 used for machining the valve faces of cylinders. This 

 shop is 57 ft. long by 29 ft. wide. In the fitting shop, 

 which is 118 ft. long by 58 ft. wide are several "vortex 

 blast pipes," the invention of Mr. W. Adams. There 

 is no doubt that when this pipe is designed on thoroughly 

 scientific principles that a great saving of fuel is effected, 

 and this has been proved by the gradual decrease of 

 coal consumption during the last three years on the 

 South Western Railway. We may here mention that 

 the average consumption of fuel in 1885 was 30 lbs. per 

 engine mile, which has now been reduced to 26| lbs. 

 per mile. This has effected a total saving, since June, 

 1885, of nearly ^34,000. In the brass shop is made 

 the white metal piston and valve rod packing, which is 

 a standard now with all new engines of the South 

 Western Railway, and is giving the greatest satisfaction. 

 The millwrights' shop is 85 ft. long by 58 ft. wide, and 

 is fitted with very modern machinery. The " long " 

 machine shop is 300 ft. long by 57 ft. wide — the standard 

 width of the shops at Nine Elms. A piston-rod grinding 

 machine is here in use. The rods are first roughed 

 down in the lathe and finished off here. 



The erecting shops consist of two bays, each 500 ft. 

 long by 57 ft. wide, and which have accommodation for 

 seventy engines. There are three roads in each bay. 



