Sept. 20, 1888] 



NA TURE 



497 



scattered over a very wide area of London. The glow-lamp of 

 Edison, which in 188 1 required 5 watts per candle, has been so 

 far improved that it now consumes but z\ watts per candle. The 

 dynamo, which in the same year weighed 50,000 pounds, absorbed 

 150 horse power, and cost ^'4000 for 1 000 lamps, now weighs 

 14,000 pounds, absorbs 1 10 horse-power, and costs ^500 for the 

 same production of external energy ; in other words, its com- 

 mercial output has been increased nearly six times, while its 

 prime cost has been diminished eight times. 



The steam-engine has received equal attention. The economy 

 of the electric light when steam is used depends almost entirely 

 on the consumption of coal. With slow-speed low-pressure 

 engines one kilowatt (1000 watts, 1^ horse-power) may consume 

 12 pounds of coal per hour ; in high-speed high-pressure triple- 

 expansion engines it need not consume more than I pound of 

 coal per hour. Willans and Robinson have actually delivered 

 from a dynamo one kilowatt by the consumption of 2 pounds of 

 coal per hour, or by the condensation of 20 pounds of steam. 



There is a great tendency to use small economical direct-acting 

 engines in place of large expensive engines, which waste power 

 in countershafting and belts. Between the energy developed in 

 the furnace in the form of heat, and that distributed in our rooms 

 in the form of light, there have been too many points of waste 

 in the intermediate operations. These have now been eliminated 

 or reduced. Electricity can now be produced by steam at 3^. 

 per kilowatt per hour. The kilowatt-hour is the Board of Trade 

 unit as defined by the Act of 1882, for which the consumer of 

 electric energy has to pay. Its production by gas-engines costs 

 6d. per kilowatt hour, while by primary batteries it costs 35. per 

 kilowatt-hour. The Grosvenor Gallery Company supply currents 

 at 7j</. per kilowatt-hour ; a 20 candle-power lamp consuming 3 

 watts per candle, and burning 1200 hours per annum, expends 

 82,000 watt-hours or 82 kilowatt-hours, and it costs, at 7\d. per 

 unit, 50^. per annum. If the electricity be produced on the 

 premises, as is the case in the Post Office, in the House of 

 •Commons, and in many large places, it would cost 20s. di. per 

 annum. I have found from a general average under the same 

 circumstances and for the same light in the General Post Office 

 in London that an electric glow-lamp costs 22^. and a gas-lamp 

 i8x. per annum. The actual cost of the production of one candle 

 .light per annum of 1000 hours is as follows : — 



Sperm candles 

 Gas (London) 

 Oil (petroleum) . 

 Electricity (glow) 

 Electricity (arc) . 



The greatest development of the electric light has taken place 

 ■on board ship. Our Admiralty have been foremost in this work. 

 All our warships are gradually receiving their equipment. Our 

 ocean-going passenger ships are also now so illumined, and per- 

 haps it is here that the comfort, security, and true blessedness of 

 the electric light are experienced. 



Railway trains are also being raoidly fitted up. The express 

 trains to Brighton have for a long time been so lighted, and now 

 several northern railways, notably the Midland, are following 

 suit. Our rocky coasts and prominent landfalls are also having 

 their lighthouses fitted with brilliant arc lamps, the last bein^ 

 St. Catherine's Point, on the Isle of Wight, where 60,000 candles 

 throw their bright beams over the English Channel, causing many 

 an anxious mariner to proceed on his way rejoicing. 



Eontaine showed in Vienna, in 1873, that a dynamo was re- 

 versible — that is, if rotated by the energy of a moving machine, 

 it would produce electric currents ; or, if rotated by electric cur- 

 rents, it would move machinery. Amelectric current is one form 

 -of energy. If we have at one place the energy of falling water, 

 we can, by means of a turbine and a dynamo, convert a certain 

 portion of the energy of this falling water into an electric current. 

 We transmit this current through proper conductors to any other 

 place we like, and we can again, by means of a motor, convert 

 the energy of the cunent into mechanical energy to do work by 

 moving machinery, drawing tram-cars, or in any other'way. We 

 can in this way transmit and utilize 50 per cent, of the energy of 

 the falling water wherever we like. The waste forces of Nature 

 are thus within our reach. The waterfalls of Wales may be 

 utilized in London ; the torrents of the Highlands may work the 

 tramways of Edinburgh ; the wasted horse-power of Niagara may 

 light up New York. The falls of Bushmills actually do work 



the tramway from Portrush to the Giant's Causeway, and those 

 of Bessbrook the line from Newry to Bessbrook. 



The practicability of the transmission of energy by currents is 

 assured, and the economy of doing this is a mere matter of 

 calculation. It is a question of the relative cost of the trans- 

 mission of fuel in bulk, or of the transmission of energy by wire. 

 Coal can be delivered in London for 12s. per ton. The mere 

 cost of the up-keep of a wire between Wales and London to 

 deliver the same amount of energy would exceed this sum ten- 

 fold. For long distances the transmission of energy is at present 

 out of the question. There can be no doubt, however, that for 

 many purposes within limited areas the transmission of energy by 

 electricity would be very economical and effective. Pumps are 

 worked in the mines of the Forest of Dean, cranes are moved in 

 the works of Easton and Anderson at Erith, lifts are raised in 

 banks in London ; water is pumped up from wells to cisterns in 

 the house of Sir Erancis Truscott, near East Grinstead ; ventila- 

 tion is effected and temperature lowered in collieries ; goods, 

 minerals, and fuel can be transmitted by telpherage. 



The transmission of power by electricity is thus within the 

 range of practice. It can be distributed during the day by the 

 same mains which supply currents for light by night. Small 

 industries, such as printing, watch-making, tailoring, boot- 

 making, can be cheaply supplied with power. It is thus brought 

 into direct competition with the distribution of power by steam 

 as in America, or by air-pressure as in Paris, or by high-pressure 

 water as in London ; and the relative advantages and economies of 

 each system are simple questions of calculation. When that evil 

 day arrives that our supply of natural fuel ceases, then we may 

 look to electricity to bring to our aid the waste energies of 

 Nature — the heat of the sun, the tidal wave of the ocean, the 

 flowing river, the roaring falls, and the raging storm. 



There is a mode of transport which is likely to create a revolu- 

 tion in the method of working tramways. A tramcar carries a 

 set of accumulators which supplies a current to work a motor 

 geared to a pair of wheels of the car. The weight, price, day's 

 work, and life of the accumulator is curiously the same as the 

 weight, price, day's work, and life of horseflesh ; but the cost of 

 maintenance, the liability to accident, and the chances of failure 

 are much less. Although very great improvements in batteries 

 have been made, and they are now really practical things, 

 sufficient experience in tramcar working has not yet been obtained 

 to say that we have reached the proper accumulator. Nor have 

 we yet acquired the best motor and mode of gearing ; but very 

 active experiments are being carried out in various countries, 

 and nothing can prevent their ultimate success. 



The property which the electric current possesses, of doing 

 work upon the chemical constitution of bodies so as to break up 

 certain liquid compounds into their constituent parts, and 

 marshal these disunited niDlecules in regular order, according to 

 a definite law, upon the surfaces of metals in contact with the 

 liquid where the current enters and exists, has led to immense 

 industries in electro-metallurgy and electro-plating. The extent 

 of this industry may be gathered from the fact that there are 

 172 electro-platers in Sheffield and 99 in Birmingham. The 

 term electro-metallurgy was originally applied to the electro- 

 deposition of a thin layer of one metal on another ; but this is 

 now known as electro-plating. 



1° '^39> Jacobi in St. Petersburg and Spencer in Liverpool laid 

 the foundations of all we know of these interesting arts. Copper 

 was deposited by them so as to obtain exact reproductions of 

 coins, medals, and engraved plates. The first patents in this 

 country and in France were taken out by Messrs. Elkington, 

 of Birmingham, who still occupy the foremost position in the 

 country. 



The fine metals, gold and silver, are deposited in thin layers 

 on coarser metals, such as German silver, in immense quantities. 

 Christofle, of Paris, deposits annually six tons of silver upon 

 articles of use and of art. and if the surfaces so electro-plated were 

 spread out continuously they would cover 140 acres. 



The whole of the copper plates used in Southampton for the 

 production of our splendid Ordnance Survey maps are deposited 

 by copper on matrices taken from the original engraved plates, 

 which are thus never injured or worn, are always ready for 

 addition or correction, while the copies may be multiplied at 

 pleasure and renewed at will. 



Nickel-plating, by which the readily oxidizable metals like iron 

 are coated with a thin layer of the more durable material nickel, 

 is becoming a great industry ; the trappings of harness, the 

 exposed parts of machinery, the fittings of c) cles and carriages, 



