1 
 
 fornia 
 aal
 
 THE 
 
 HOUSE-TO-HOUSE 
 
 Eleetrie Light Supply 60,, Ld, 
 
 (MODEL CENTRAL ELECTRIC LIGHTING STATION, KENSINGTON, 
 
 ADJOINING THE WEST BROMPTON STATION ON THE 
 
 METROPOLITAN DISTRICT RAILWAY) 
 
 Are prepared to assist the formation 
 
 of 
 
 LOCAL ELECTRIC LIGHT COMPANIES, 
 
 and to erect 
 
 CENTRAL STATIONS 
 
 for the distribution of Electricity in 
 any part of the Kingdom. 
 
 j£0timate0 for Complete Seta of plant 
 furniabeb free of cbaroe* 
 
 WILLIAM UyNR\^, Engineer. 
 
 H. St. JOHN WINKWORTH, ^Secretary, 
 117, Bishopsgate Street, London, 
 
 E.C.
 
 DISTRICT ELECTRICITY SUPPLY. 
 
 CENTRAL SUPPLY STATIONS WORKED ON 
 THE 
 
 E. P. S. 
 
 AUTOMATIC SYSTEM FOR THE PUBLIC SUPPLY OF 
 ELECTRICITY FROM 
 
 STORAGE^IATTERIES. 
 
 Epitome of the System. 
 The generating plant is all placed in a con- 
 veniently situated building within or without 
 the District to be Lighted. 
 
 Convenient Sub- or Storage-Stations are 
 selected throughout this District, and con- 
 tain sufficient Accumulators to supply the 
 maximum demand. 
 
 The Batteries in each of these Storage- 
 Stations are recharged in series, one half at 
 a time, throughout the System during the 
 period of minimum demand, and by the 
 evening are all full and ready to cope with 
 the heavy night work. 
 
 The whole of the charging, discharging, 
 and regulating apparatus is worked auto- 
 matically. 
 
 Advantages of the System. 
 r Reliability. — The Light is solely de- 
 rived irom Storage, and is absolutely steady. 
 There is no connection whatever between the 
 Lamp and Moving Machinery. 
 
 The Supply is continuous day and night. 
 
 Economy in Prime Outlay. — 
 The proportion of Engine Power in use to the 
 power required for maximum supply is only 
 about one third, while any system, if running 
 direct, requires a large portion of the plant 
 to be duplicated. 
 
 Economy in "Working. — The gene- 
 rating station is only at work a definite 
 number of hours during the daytime, after 
 which period the plant may be let out or 
 utilized for other purposes, such as motive 
 power, &c. 
 
 Electro Motors for all purposes can 
 be driven from the ordinary discharge mains. 
 This is impossible where alternating currents 
 are employed. 
 
 GUARANTEE.— The E.P.S. Co. undertake to supply all the necessary 
 renewals for the Storage Batteries in use in the above system at the rate 
 of 12% per annum on the actual first cost of the Batteries. 
 
 E.P.S. Accumulators are already in use at the following Central Stations : — 
 Vienna ; Berlin ; Cadogan (London) ; Norwich ; Taunton ; Leamington j 
 St. Austell; Detroit, U.S.A.; Allentown, U.S.A.; Blenheim, U.S.A.; 
 Haverford, U.S.A. ; Delaud, U.S.A. 
 
 Districts Surveyed, Flans, Specifications and Tenders submitted by the 
 
 ELECTRICAL POWER STORAGE COMPANY, LTD, 
 
 4 GREAT WINCHESTER STREET, LONDON, E.G. 
 
 Telegrams, "Storage, London." Telephone No. 338.
 
 ANGLO-AMERICAN 
 
 Brush Electric Light Corporation, Ltd. 
 
 MANUFACTURERS OF 
 
 BRUSH ARC DYNAMOS AND LAMPS. 
 
 Victoria Incandescence Dynamos and Lamps. 
 ALTERNATE CURRENT DYNAMO MACHINES. 
 
 Ml FITTINGS FOR ARC AND INCANDESCENCE LIGHTING, Etc- 
 
 CONTRACTORS FOR 
 
 PRIVATE INSTALLATIONS OF ELECTRIC LIGHT. 
 
 CENTRAL ELECTRIC LIGHT STATIONS. 
 
 INSTALLATIONS ON SHIPBOARD, 
 
 ELECTI^ICTIIi R^mW^Yg ^j^D ¥]R^MW^Yg. 
 
 Railway Train Lighting by Electricity. 
 
 INSTALLATIONS FOR TRANSMISSION OF 
 POWER, Etc. Etc, 
 
 The Corporation are prepared to undertake the establishment of Central 
 Electric Lighting Stations on the high or low tension continuous current 
 systems, with or without accumulators, or on the alternating current system 
 with transformers, as may be best suited to the requirements of each 
 particular case. 
 
 The Corporation invite enquiries from ^Municipalities, Local Gas or 
 Electrical Companies, or owners of Blocks of Houses or Shops, for the 
 erection of Central Generating Stations, and the supply of Electricity, 
 either on their own account, or upon such terms and conditions as may 
 be agreed upon. 
 
 Full particulars on application to — 
 
 THE SECRETARY, 
 
 112, BELVEDERE ROAD, LONDON, S.E.
 
 CENTRAL-STATION 
 
 ELECTRIC LIGHTING,
 
 BV THE SAME A UTHOR, 
 
 PRECAUTIONS TO BE ADOPTED ON 
 INTRODUCING 
 
 THE ELECTRIC LIGHT. 
 
 INSURANCE RULES, &»€., 
 
 WITH 
 
 NOTES ON THE PREVENTION of FIRE RISKS. 
 Illustrated. Price 2S. od. 
 
 THE SUPPLY OF ELECTRICITY 
 BY LOCAL AUTHORITIES. 
 
 Demy 8vo. Illustrated. Price is.
 
 CENTRAL-STATION 
 
 ELECTRIC LIGHTING 
 
 WITH 
 
 NOTES ON THE METHODS USED FOR THE 
 DISTRIBUTION OF ELECTRICITY. 
 
 BY 
 
 KILLINGWORTH HEDGES, 
 
 MEMBER OF THE INSTITUTION OF CIVIL ENGINEERS, AND OF THE 
 SOCIETY OF TELEGRAPH ENGINEERS AND ELECTRICIANS. 
 
 LONDON: 
 
 E. & F. N. SPON, 125, STRAND, 
 
 NEW YORK: 12, CORTLANDT STREET. 
 
 [All rights reserved.^
 
 PREFACE 
 
 The art of lighting by Electricity practically dates 
 from ten years ago, and it has during that period 
 received the constant attention of both Electrical 
 Engineers and others, who have applied the greatest 
 scientific knowledge. The result of all this energy 
 appears to be discouraging. Five hundred thousand 
 pounds have been subscribed to carry on the business, 
 and it is doubtful whether the companies which 
 survive have a market value of one-tenth of that 
 sum. The experience may have been bought too 
 dearly, but the era of Central-Station Electric Light- 
 ing, which has now commenced, ought to re-establish 
 the position of Electricity in financial circles, and afford 
 a safe and profitable outlet for the surplus capital of 
 the investor who buys gas and water shares to pay 
 four per cent. 
 
 The distribution of electricity from a central-station, 
 which was the subject of Sir William Siemen's Pre- 
 sidential Address at the Society of Arts in 1882, is not 
 only accomplished from the scientific point of view, 
 but is also a commercial success : the power of flowing 
 water, or the potential energy stored up in coal, wood.
 
 vi PREFACE. 
 
 or other fuel, can be utilised for lighting our streets 
 and houses at night, and during the day may be trans- 
 mitted by means of electricity in the easiest possible 
 way, and supplant the gas-engine for driving small 
 machinery. 
 
 A paper entitled " Central-Station Electric Light- 
 ing " was contributed by the Author to the Institution 
 of Civil Engineers, and was published in Part II. of the 
 Minutes, iZZ^-'^y \ the subject-matter has been ex- 
 tended and brought up to date, with the object of 
 giving a description of the systems which are prac- 
 tically employed in Central-Station Lighting at home 
 and on the Continent. Details respecting the gene- 
 rating plant at these stations are omitted on purpose ; 
 technical terms would also be avoided if possible ; 
 failing this, it is hoped that the accompanying Glos- 
 sary will explain what is unfamiliar. 
 
 The amendment of the Electric Lighting Act of 
 1882 has given a fresh stimulus to the industry, and 
 many new enterprises for distributing electricity from 
 Central-Stations are being prepared, and it is to be 
 hoped that the public will profit by former experience, 
 and will discriminate between the good and the bad 
 schemes which will be offered to them. 
 
 The organizing facilities possessed by Gas Com- 
 panies make it desirable that they should follow the 
 example of the American Companies, and take up 
 the business of supplying electricity. The- existing 
 powers of private companies might have to be altered,
 
 PREFACE. vii 
 
 but those municipal authorities who own the gas- 
 works could certainly distribute electricity from a 
 central-station, which might be installed at the 
 present works. Local authorities have certain advan- 
 tages over private companies owing to the purchasing 
 clause of the Electric Lighting Act, also the power to 
 borrow money under this and the Local Loans Act 
 of 1875 ; should there be no department to carry out 
 the business of supplying electricity, the generating 
 plant could be maintained and worked by a contractor 
 for a fixed annual sum. 
 
 The remarks of Lord Herschell that the "electric 
 light is more used in the South Sea Islands than in 
 this country " ought to be taken as not so much 
 referring to want of enterprise on the part of capitalists 
 and engineers, but to the Electrical Facilities Act of 
 1882, which has been appropriately termed a very 
 " boa-constrictor." 
 
 KILLINGWORTH HEDGES. 
 
 25, Queen Anne's Gate, 
 Westminster, S.W. 
 Sepfe?nber, 1888.
 
 INDEX OF TERMS. 
 
 Ampere-hour. — A current of one ampere strength for one hour. 
 
 Current, Continuous.— The flow of electricity in one direction. 
 
 Current, Alternating. — The intermittent flow in two directions. 
 
 Conductor. — The wire through which the current passes. 
 
 Circuit, Primary. — With transformers, the conductor or leads 
 attached to the dynamo. 
 
 Circuit, Secondary. — ,, ,, the conductor from the 
 
 transformer to the lamps. 
 
 C. P. — Abbreviation of Candle-power. 
 
 E. M. F. — Abbreviation of Electro-motive force. 
 
 Life of Incandescent Lamps. — The duration of the filament which 
 produces the light. 
 
 Potential. — Difference of E. M. F., or High and Low Tension. 
 See also Glossary ^ or Explanation of Terms, page 107.
 
 AN 
 
 ELECTRICAL CENTRAL -STATION. 
 
 m 
 
 S the term "central-station" associates itself 
 with some pretentious building, such as a 
 railway terminus, it may be advisable to 
 remark that the similarity is only in the 
 words, and that central-station is an abbreviation of 
 central-generating station, or building designed to 
 contain the plant for the public supply of electricity. 
 In the early days of electric lighting the transmission 
 of electricity to a distance was considered an im- 
 possibility ; we find the late Sir William Siemens, 
 in his Presidential Address at the Society of Arts on 
 the occasion of the opening of the session in 1882, 
 stating "that a quarter of a mile in every direction 
 from the lighting station was the area which would be 
 as much as could be economically worked ;" and, in 
 order to tap the most paying district, it was proposed 
 to establish a station in the most central spot. Sir 
 William Siemens suggested the utilisation of the 
 public squares, which could be excavated to a depth 
 of twenty-five feet, and then arched over to the 
 
 B
 
 2 CENTRAL-STA TION LIGHTING. 
 
 existing ground level, and in this covered space the 
 engines, boilers, and dynamos were to be fixed ; the 
 only erection above the surface was the chimney, 
 which was to be of ornamental design and combined 
 with the ventilating arrangements of the subterranean 
 chamber. The great inventor, who so ably filled the 
 presidential chair at the meeting where these words 
 were spoken, would be astonished to find that in 
 London one electric-lighting company has already 
 erected seventy miles of overhead wire, and that 
 customers are supplied miles away from the so-called 
 central-station. The changed position of electricity 
 is due to the introduction of the transformer by Gou- 
 lard, who showed, at the Turin Exhibition of 1884, 
 that a high-tension current could be transformed into 
 a low-tension working current of safe potential, fifty 
 miles away from the generator, in a successful and 
 economical manner, and that the generating station 
 might, therefore, be located outside the area to be 
 lighted. In large cities this is a great advantage, the 
 value of land often precluding the erection of a 
 big station in the working area ; for this reason 
 small stations are often arranged in basements, under 
 a large building, which are, as a rule, specially de- 
 signed. This plan is somewhat similar to that adopted 
 in the United States, where it is not unusual to find 
 a successful installation in a basement and sub- 
 basement, the general arrangement being of similar 
 character to the engine-room of a steamship. 
 
 A station is being erected in Philadelphia on a 
 ground space of 72 feet X 100 feet, which is to supply 
 60,000 lights ; the building is six-storied, the dynamos
 
 CENTRAL-STA TION CONSTR UCTION. 3 
 
 are on the first floor, the boilers on third, the coal 
 stores on fourth, and the offices on the fifth. 
 
 The term " block station " is also used in the United 
 States and in Germany, and is applied to an installa- 
 tion which lights a group of buildings or block without 
 crossing any streets, and consequently without having 
 any wayleave or permission from local authorities. 
 
 Cextral-Statiox Construction. 
 
 An American electrical engineer graphically sums up 
 this question in the following manner: — "There are two 
 ways of starting a central-station for electric lighting — 
 the investment or the speculative plan, or the fair 
 means or the foul. The first has its legitimate end, 
 but the latter is the border ruffian or money-or-your- 
 life policy, which enters a territory already sufficiently 
 covered, not for fair competition, but to make money 
 by being bought out." Happily; here, we have at 
 present only to deal with the first plan, and the 
 question naturally arises. Is electric lighting a paying 
 investment? It certainly will not be if the object in 
 view is only to compete with gas in a limited district 
 where perhaps it is being sold at 2^-. 6d. per 1000 feet, 
 for, as long as there is a ready market for the coke and 
 other bye-products, gas will remain in possession of 
 the field. The heat from gas, which is found so unde- 
 sirable by the wealthier classes, is advantageous to 
 those who perhaps cannot afford a fire ; in fact, gas has 
 been truly called the " poor man's friend," and, until 
 
 B 2
 
 4 CENTRAL-STA TION LIGHTING, 
 
 electricity can be supplied at a nominal price, it will 
 be useless to expect any revenue from the poorer dis- 
 tricts of large cities. Quite an opposite result may be 
 looked for when the electric mains are laid at the doors 
 of the wealthy householder, or through the business 
 neighbourhoods. Shop-owners especially are found 
 to immediately take up electric light, from the fact 
 that no fumes are given off to destroy goods or tarnish 
 silver or gilding, and because it can be so easily 
 applied in a shop window so as to efficiently light the 
 contents without producing shadows. The great 
 object to be aimed at in selecting a district to be 
 served from a central-station is a " constant demand," 
 and for this reason it is advantageous to include a 
 business neighbourhood with shops, public-houses, and 
 restaurants, which require the light for a definite period 
 every day, and probably will each take more than 
 double the amount of an ordinary dwelling-house ; in 
 fashionable neighbourhoods especially, it is not unusual 
 to find a large number of houses vacated at the close 
 of the season, the interest on that portion of the electric 
 system which is unemployed will have to be set against 
 the profits of other periods of the year. 
 
 The number of gas lights which are actually used at 
 one time in a house is found to average only two-thirds 
 of the total number fixed, and with electric light this 
 number is reduced to one-half; economy is at once the 
 rule with electric light, partly because of the novelty 
 of the illuminant, and also on account of the facility of 
 lighting and extinguishing by simply turning a tap or 
 switch. The number of hours artificial light is wanted 
 in a residential district may be taken at about looo
 
 CENTRAL-STA HON CONSTR UCTION. 5 
 
 hours per annum, that is to say, the light is required 
 for about four hours a day in winter and two hours in 
 summer ; this amount is very much exceeded in clubs, 
 shops, and even in large houses, but 1000 hours 
 is a safe figure, and, if the supply is taken by meter, 
 an annual payment equivalent to 1000 hours' supply 
 should be a fixed amount to be paid for, whether used 
 or not. Mr. Crompton estimates that a Londoner, who 
 is a tenant or owner of a house having three reception 
 rooms, ten bedrooms, and usual offices, spends about 
 £2^ a year for his lighting, which is made up as 
 follows: — gas bill, ;^I5 ; lamp, oil, candles, matches, 
 about ;^ 10. There would be about fifty burners fixed ; 
 and, supposing fifty electric lights to be substituted, he 
 could be supplied with electricity for £2^ 2. year, at a 
 fair profit to the supply company if they charged 8^. 
 per Board of Trade Unit, as practice has shown that the 
 total number of lamp hours with fifty electric lamps is 
 not more than sixty-two, so that two Units,* or is.A^d. 
 per day, would be sufficient for the lights he would 
 require. 
 
 The diagram. Fig. i, taken from a London residential 
 district, shows how the number of lamps on at one time 
 vary ; the district is supposed to be wired for 10,000 
 lamps, and the plant as equal to the supply of 600 
 kilowatts, or 600,000 watts ; the number of lamps is 
 small until about 3 o'clock, when it gets dusk on a 
 winter afternoon ; it then increases steadily until about 
 6.30 o'clock, when the curve goes up with a rush; 
 about this time a great number of people are pre- 
 paring for dinner, and probably the lights are on 
 
 * Unit ; see page 7.
 
 CENTRAL-STATION LIGHTING. 
 
 both in the dining-room and bedrooms. The curve 
 falls, and at about 8 it begins to sink gradually until 
 lo o'clock; a great many people appear to go to 
 bed about this tim^e, but a few sit up to i o'clock ; 
 until 6 the next morning hardly any supply is taken, 
 when the ser\^ants get up and prepare the rooms for 
 the day. The diagram, Fig. 2, is taken from the 
 Edison Company's central-station at Cincinnati, and 
 agrees fairly with the London demand for light. 
 
 
 
 ^^^^^BSj^B 
 
 
 
 ^^^^^^H 
 
 
 
 
 Hm^^^^^H 
 
 
 
 ^^^^^H 
 
 
 
 ^^^^^^^^H 
 
 
 
 ^^^^^1 
 
 
 
 ^Hi^^^^^H 
 
 
 
 ^^^^^H 
 
 
 
 ^^^^^^^^B 
 
 
 
 ^^^^^1 
 
 
 
 ^hI^^^^^^h 
 
 
 
 ^^^^^^1 
 
 
 
 ^Hi^^^^^H 
 
 
 
 ^^^^^1 
 
 
 
 ^^^^^^^hI 
 
 
 
 ^^^^^1 
 
 
 
 ^^mI^^^HBhB 
 
 
 
 ^^^^^^^H 
 
 
 
 ^■^^^^■Rl 
 
 
 
 ^^^^^1 
 
 
 
 ^^^^^^^Bl 
 
 
 
 i^^^^^l 
 
 
 
 ^^^^^^9^H 
 
 
 
 ^^^^^B 
 
 
 
 
 
 
 
 mil 
 
 
 
 
 ■ 
 
 
 Fig. I. 
 
 Another interesting fact has been ascertained from 
 the observations taken at the Mauer strasse station 
 in Berlin, namely, that the output varies with the 
 temperature, it goes up or down with the thermometer. 
 The reason is easily explained ; gas is laid on side by 
 side with the incandescent lamps, and the burners are 
 first lighted when it is cold to warm the apartments ; 
 in warm weather the electric light alone is used. 
 From these and other diagrams the very important
 
 CHARGES FOR ELECTRICITY. 7 
 
 fact has been obtained, that the average daily output 
 of a station throughout the year is less than one-third 
 of the total capacity of the generating machinery, so 
 that, although the station from which the diagram in 
 Fig. I was taken could maintain 10,000 16 candle- 
 power lamps simultaneously alight, the average daily 
 
 
 Fig. 2. 
 
 output of electricity would only equal 3 500 con- 
 stantly lighted ; and, as the first cost of the station is 
 dependent on the size of the plant, the saleable output 
 is the important factor which governs the profits. 
 
 Charges for Electricity. 
 
 The well-known expression '' per 1000 Cubic Feet " 
 is not applicable to electric light, and, instead, the 
 Board of Trade Unit is employed. By this term Unit is
 
 8 CENTRAL-STA TION LIGHTING, 
 
 meant the quantity of energy contained in a current of 
 1000 Amperes flowing under an Electro-motive Force 
 of One Volt during One Hour. In the early days of 
 electric lighting the term Volt-ampere was used, and 
 has for convenience sake been shortened to Watt ; 
 that is, the Volt or Unit of Electro-motive Force (or 
 pressure) is multiplied by the Ampere or Unit of 
 current. 
 
 The Board of Trade Unit is, therefore, a Thousand 
 Volt-amperes or Watts per hour. 
 
 For example : i6 candle-power Swan lamps are 
 assumed to take 60 Watts, which, if the electrical 
 pressure is 100 Volts, would mean a consumption of 
 0'6 Ampere ; and, as an Electrical Horse-power equals 
 746 Watts, I2"4 lamps should theoretically be obtained 
 per Horse-power, which is, however, reduced in actual 
 practice to 10 at the most, often less. 
 
 The charge per Unit suppHed by meter varies in 
 England from i^. to jd. 
 
 Price for electric Equivalent price for gas of equal 
 
 light. light. 
 
 s. d. s. d. 
 
 I o ^ per Board ( 6 \o per 1000 cubic feet. 
 
 o Q I of 1 c; li 
 
 o 
 
 o 
 
 Co7nparison of Cost of Gas and Electricity. 
 
 These prices, of course, include the manufacturer's 
 profit as well as the loss in transmission through the 
 mains and expenses of connecting up to the con- 
 sumer. The actual manufacturing cost of a station
 
 ELECTRICITY AND OIL. 
 
 maintaining 10,000 lights should not be more than 
 id. per Unit, or equivalent to gas at \s. Z\d. per 1000 
 cubic feet.* 
 
 As petroleum lamps are used for the street lighting 
 of many foreign and colonial towns, the question arises, 
 Will it pay to substitute the electric light ? Comparing 
 the light given by a kerosene or petroleum lamp with 
 that from the incandescent electric lamp, the cost is 
 greatly in favour of oil ; and, in fact, where the price 
 of kerosene is under \s. per gallon, electricity cannot 
 compete if labour is cheap. On the other hand, 
 the trimming, lighting, and keeping in order of a 
 number of lamps scattered over a large area greatly 
 augments the working cost, to which must be added 
 the breakages of chimneys, expense of wicks, also the 
 danger of fire. It is the safety of electricity which 
 has caused it to supplant oil both for public and pri- 
 vate lighting in American cities ; even where the price 
 of kerosene is not more than 6d, per gallon there is a 
 demand for the electric light, which is by far the dearer 
 illuminant, after making a liberal allowance for labour 
 in cleaning, filling, and lighting the oil lamp, also for 
 depreciation of the burners. 
 
 Arc and Incandescent or Glow Lighting. 
 
 Electric lighting can be obtained by means of arc 
 or incandescent lamps. The arc light is now well 
 understood to be caused by the extremely high tem- 
 perature of the end of one or both the carbon elec- 
 trodes. The voltaic arc, Fig. 3, is formed by the 
 
 * See Table IV., page 87.
 
 I o CENTRAL-STA TION LIGHTING. 
 
 minute particles of carbon in a high state of com- 
 bustion which the current appears to break off and 
 carry from one electrode to the other, the light, 
 however, being mainly due to the incandescence of 
 the crater shown in Fig. 3 on the upper carbon. In 
 the incandescent or glow lamp light is produced by 
 the passage of a current of electricity through 
 a continuous fine thread or filament of carbon 
 which becomes white-hot, the destruction 
 of the filament being prevented through its 
 enclosure in a glass bulb from which the air 
 is exhausted. Figs. 4 and 5. 
 
 The first method is suitable for the 
 lighting of streets where a high-class illu- 
 mination is required ; also will be wanted 
 ^^r the external lighting of shops, public- 
 iouses, and places of amusement, so that 
 arrangements must be made for arc light- 
 ing. The usual plan is to charge at the 
 same rate per Unit by meter as the incan- 
 descent lamps, but to make an additional charge of 
 5^-. to Js. 6d. per lamp per quarter for rent, and a 
 further charge of 3^-. per week for cleaning and 
 trimming. 
 
 The principal types are the Edison and the Swan, 
 Fig. 4 and Fig. 5. 
 
 Incandescent lamps can be obtained to order from 
 I J candle-power upwards, but the 16 candle-power 
 (nominal 20) or the 8 candle-power (nominal 10) 
 lamps are almost invariably employed. The latter 
 give the best effect, and can be worked to 10 candle- 
 power without much risk, they take about 30 watts
 
 LIFE OF INCANDESCENT LAMPS. 1 1 
 
 as against 60 watts for the 16 candles ; and are 
 not uneconomical, for nearly double the number can 
 be worked with the same energy. A new type of 
 glow lamp, called the '' Sunbeam," has been recently 
 
 4- t^iG. 5. 
 
 introduced, which contains a thick filament, and gives 
 a light of from 200 to 1500 candle power, and can 
 be employed instead of an arc lamp with the same 
 economy as the ordinary 16 candle-power type. 
 
 Life of Incandescent Lamps. 
 
 In estimating the annual cost of lighting, the re- 
 newals of lamps must be taken into account ; and 
 although some lamps have worked 3000 or even 4000 
 hours, a life of looo working hours is the highest aver-
 
 1 2 CENTRAL-STA TION LIGHTING. 
 
 age it is safe to assume in practical work under even 
 the best conditions, that is, using secondary batteries 
 and never over running. The average life of 1 30 lamps 
 on H.M.S. troopship Malabar was 3799 hours each, 
 the shortest life being 63 8 J hours for 18 yard-arm 
 lamps of 32 candle-power. If the current is allowed 
 to fluctuate, the average life would be very much less ; 
 it is an unsettled question whether long-lived lamps 
 are really economical, by reason of the blackening of 
 the globes, which takes place after the lamp has been 
 worked some time, and is probably due to small 
 particles of carbon thrown off from the filament being 
 deposited on the glass. It has been suggested that 
 attrition of the filament is going on all the time the 
 lamp is at work, and that the heated atoms striking 
 against the filament may account for the blackening, in 
 that the mean free path of the atoms would be greater 
 in a perfect vacuum than in the air, consequently they 
 would abrade the filament with considerable force. 
 If lamps were sold at I.S-. each instead of ^s. 6d.y 
 which is now the price for not less than a thousand, 
 it would be more economical to change them at the 
 first signs of blackening, even if the life did not 
 exceed 500 hours. 
 
 The diagram. Fig. 6, has been so arranged that the 
 amount of light required in a given district can be 
 ascertained for any period of the day or night ; it has 
 been calculated from the observations taken daily at 
 one of the Berlin central-stations by the engineer to 
 the company. 
 
 Six hundred and forty watts are assumed, for the 
 purposes of the diagram, to be the equivalent of a
 
 DIAGRAM OF SUPPL Y. 13 
 
 horse-power, instead of j^^, as the German electrical 
 horse-power is 736 watts instead of 746 watts. 
 
 Fig. 6. 
 
 The table, Fig. 6, has two vertical scales, A and B, 
 each giving the kilowatts* and corresponding horse- 
 * 1000 watts. ^
 
 14 CENTRAL-STA TION LIGHTING. 
 
 power. A is drawn to a scale ten times greater than 
 B, with the object of noting the smaller amount of 
 lights required for street illumination. The horizontal 
 line is divided into hours, and represents a day's light- 
 ing in the middle of December and the end of July, 
 so as to show the maximum and minimum amount of 
 current that will be required. In the lighting of a 
 town there are two classes of illumination, the amount 
 taken by the public, which is uncertain, and that 
 employed for street lighting, which is a known 
 quantity. 
 
 The curves, 1 1 and 1 1 A, represent the private light- 
 ing of houses, hotels, theatres, and shops of different 
 kinds in December and in July, the curve, 1 1 A, being 
 in dotted lines clearly shows what a vast difference 
 there is in the amount of light, and consequently the 
 amount of energy required in the generating station, 
 as compared with curve ii, which is taken when the 
 days are longest. 
 
 The rectangles, i and i A, show the street illumina- 
 tion, and are drawn to suit scale A ; half an hour 
 after sunset all the lamps are turned on, and the work 
 reaches its maximum suddenly, and continues the 
 same until 12 o'clock, when, according to the muni- 
 cipal decrees, it either falls one or two gradations 
 until half an hour before sunrise, when all the lamps 
 are extinguished. The calculations are based on the 
 assumption of 640 watts to the horse-power, instead 
 of 736, which is the theoretical efficiency of a German 
 horse-power. 
 
 If a number of diagrams are taken on this method 
 for different periods of the year, the constant work
 
 EXPLANATION OF DIAGRAM. 
 
 15 
 
 can be ascertained. This knowledge is most valuable 
 when calculating the most economical area for the 
 mains, which is then easily accomplished by means 
 of Forbes' tables, which are based on Sir William 
 Thomson's well-known rule. 
 
 The lines, 2 and 2 A, show the constant work at the 
 same two periods of the year from which the diagrams 
 are taken. The constant work at the end of Decem- 
 ber will be found to amount to 20 per cent, of the 
 total work, and that at the middle of June to 15 per 
 cent. By summing up the average work for all the 
 days in the year we obtain the cost per annum, and 
 adding to this the expense of management, interest, 
 &c., and knowing the local conditions, we can fix 
 what proportion of the day's work is admissible as 
 loss. With the Edison system at Berlin, 5 per cent, is 
 taken as average loss ; thus, at the end of December, 
 it amounts, with the maximum number of lights, 
 to 18 '8 per cent, and with the minimum to i • I per 
 cent.; in the middle of July the maximum is 15*8 
 per cent., and the minimum 0*5 per cent. The dyna- 
 mos must, of course, be of sufficient power to be able 
 to overcome this loss, which only shows itself periodi- 
 cally ; therefore the generating plant may be con- 
 structed to give, nominally, 20 to 30 per cent, less 
 than the maximum, work, and be capable of being 
 pushed to the full amount for a short time only.
 
 1 6 CENTRAL-STA TION LIGHTING. 
 
 The Position of Central-Station Lighting. 
 
 Uncontrolled financial speculation, aided by the 
 stringent clauses of the Electric Lighting Act of 1882, 
 have been a great deterrent to the extension of old or 
 the introduction of new schemes for the supply of 
 electricity to the public in the same manner as gas. 
 The President of the Board of Trade, replying to a 
 question in the House of Commons, said that, "since 
 the passing of the Electric Lighting Act of 1882, fifty- 
 nine provisional orders and five licences had been 
 granted to companies, and fifteen provisional orders 
 and two licences to local authorities. He was not 
 aware that, in any single case where these powers had 
 been obtained, they had been exercised." Up to the 
 present time no company supplying electricity has 
 been under the necessity of applying for compulsory 
 powers, and has either obtained permission from the 
 local authorities to take up the streets, or has carried 
 the electric mains over the houses, and, regardless of 
 the question of overhead wires, has depended on way- 
 leaves granted by the too-confiding householder, who 
 has no idea that his roof is supporting a cable weigh- 
 ing if tons to the mile. 
 
 An amendment of the Act of 1882 has passed 
 both Houses without hindrance, and has received 
 the Royal assent. It provides that in the case of 
 Provisional Orders the period after which the under- 
 taking may be bought up by the Local Authority 
 shall be extended from twenty-one to forty-two years, 
 .and that portion of the previous Act which referred to
 
 DESCRIPTION OF IXSTALLATIONS. 17 
 
 the compulsory purchase of the undertaking by a local 
 authority at the end of the term has been altered, and 
 more favourable terms given to the electric companies. 
 
 On the Continent, and in the United States, where 
 each city may be said to legislate for itself in matters 
 relating to the general welfare of its citizens, the 
 electric lighting industry is in a very different position, 
 and central stations are either established or about to 
 be started in ever}- important town. There were, in 
 1887, 121 Edison central stations alone, supplying 
 over 323,000 incandescent lamps, and paying divi- 
 dends from 6 to 14 per cent. The Westinghouse Com- 
 pany, who use a transformer system which is a modi- 
 fication of the Goulard and Gibbs, have a hundred 
 stations, maintaining 191,000 lamps, although the 
 first Westinghouse plant was put down only three 
 years ago. The progress in the United States is so 
 rapid, and there are so many successful applications 
 of central-station lighting, that the subject becomes 
 too large to be even summarised, so that it is pro- 
 posed to treat in the following pages with some of the 
 principal installations on the Continent and at home. 
 
 Travellers abroad are accustomed to find electric 
 lighting installed in the most out-of-the-way places, 
 especially in Switzerland, where water power is 
 abundant and is utilised to generate electricity, so 
 that in small hamlets arc lighting is often employed, 
 and the visitors to the local hotel will find it lit 
 throughout by electricity. Electric-light stations in 
 England are, with one exception, small in comparison 
 with those on the Continent. The most important is 
 that at the Grosvenor Gallery, London, which has 
 
 C
 
 1 8 CENTRAL-STA TION LIGHTING. 
 
 increased from small beginnings until it now supplies 
 20,000 glow lamps on sixteen circuits, the total length 
 of which is seventy miles. The next largest, which 
 have been in practical work for some time, are the 
 Brighton and Eastbourne stations, from which small 
 installations of glow and arc lights are maintained in 
 various districts of the two towns. That the question 
 of cost or trouble, and the annoyance of machinery 
 when erected in a dwelling-house, do not altogether 
 prevent the adoption of a superior light, is clearly 
 proved by the increasing number of householders, who, 
 after waiting in vain for electricity to be brought to 
 their doors, have set up the plant necessary to pro- 
 duce it themselves, and find no practical difficulty in 
 doing so. There are also many important public 
 works where electric light has been exclusively 
 adopted. For instance, at the Tilbury Docks there 
 are 1350 glow and 80 arc lamps, distributed over an 
 area of 300 acres, and including the lighting of an 
 hotel, dock sheds, warehouse, signal-boxes, and offices. 
 The London, Chatham, and Dover station at Victoria 
 has also been electrically lighted for the past three 
 years, the current being obtained from a central 
 station, which was erected for the purpose of supply- 
 ing electricity to the Victoria district, and for which 
 a provisional order was obtained. This, however, has 
 since been abandoned, although ;^ 16,000 had been 
 expended on plant and buildings by the promoters, 
 who preferred to postpone the scheme rather than to 
 submit to the onerous 27th clause of the Electric 
 Lighting Act. Another still larger installation has 
 been put down to supply electricity to the Paddington
 
 PADDINGTON INSTALLA TION. 19 
 
 station and district of the Great Western Railway, as 
 far as Westbourne Park. It embraces an area of sixty- 
 seven acres, and is lighted by 41 15 glow and 98 arc 
 lamps. The system adopted is that designed by Mr. 
 J. E. Gordon, and has now been successfully worked 
 for some time ; but the many accessories which are 
 introduced, such as telephones, telegraphs, and indi- 
 cators, make it complicated in comparison with gas, 
 or even with the ordinary electric-light systems. The 
 current is generated by two dynamos, each weighing 
 45 tons, and having revolving magnet wheels 9 feet 
 8 inches in diameter, 22 tons in weight, a third 
 machine being kept in reserve. These dynamos are 
 separately excited, and produce alternating currents. 
 The electricity is led to a large switch-board for dis- 
 tribution throughout the district by means of five sub- 
 stations ; and from this board there branches a double 
 system of mains, which run everywhere side by side, 
 one-half the mains being connected to the first machine 
 and one-half to the second, so forming an excellent 
 arrangement for the prevention of total extinction of 
 the light. The mains running to the sub-stations are 
 on the divided system, which is introduced for the 
 purpose of saving copper, as in a solid cable the loss 
 of pressure is greatest when the full number of lamps 
 is on, and decreases as the lamps are extinguished. 
 With the divided main system it is intended to follow 
 out Sir William Thomson's formula, which equates 
 the value of the loss of head, and the interest on the 
 saving on the copper. If for a certain main this 
 formula shows that a fall of 20 per cent, is the most 
 economical condition for working, then, since by the 
 
 C 2
 
 20 CENTRAL-STA TION LIGHTING. 
 
 divided main the pressure can be kept within a varia- 
 tion of 2 per cent, at the distant end, it follows that a 
 considerable saving can be effected over an ordinary 
 solid main. Special arrangements are adopted at 
 Paddington to keep the pressure constant, a fall of 
 potential being allowed for ; thus at the engine-house 
 the pressure is 150 volts, in the passenger station it is 
 120 volts, and at Westbourne Park it is 100 volts. 
 The arc lamps are fed by the same mains, and are 
 arranged two in series. 
 
 A small installation at Kensington Court, erected two 
 years ago, for the purpose of supplying the houses in the 
 immediate neighbourhood, has rapidly developed, and 
 underground mains have been led in many directions 
 from the station, and a constant service of electricity is 
 provided for by means of secondary batteries. As this 
 is the first practical exposition of the secondary bat- 
 teries' system of distribution, it is proposed to describe 
 the installation under that head. Central stations are 
 also at work in Liverpool, Leamington, Taunton, 
 Exeter, and there are also five large installations nearly 
 completed in London, besides the Kensington Court 
 station, all of which will probably be in full swing 
 before the end of the year. 
 
 Electric Lighting from Central Stations is 
 now practically carried out on five different methods. 
 
 L By Secondary Generators or Trans- 
 formers, WITH alternating CURRENT. 
 
 II. The Edison or Parallel System, with 
 
 CONTINUOUS current. 
 
 III. The Series or Bernstein System.
 
 TRANSFORMER SYSTEM. 21 
 
 IV. Multiple Series. 
 
 V. Distribution with Secondary Batteries 
 OR Accumulators. 
 
 CLASS I. 
 
 Supply by Secondary Generators or Trans- 
 formers. 
 
 The problem of electric lighting from central-stations 
 is comparatively easy if an area can be obtained im- 
 mediately surrounding, and within a short distance of, 
 the station, with a right of way for laying down the 
 electric mains direct. This happy state of affairs has 
 not yet been attained, consequently the generating 
 station has more often to be in an out-of-the-way 
 corner of the district to be lighted, and it would be 
 financially impossible to use low-tension currents with 
 correspondingly large mains. The difficulty has been 
 overcome in se\ eral ways by the use of high-tension 
 currents in the mains, and has led to the adoption of 
 secondary generators or transformers of electricity, 
 which by induction supply a current of low potential 
 in the house-service. The first to make this plan a 
 practical success was Mr. Goulard, to whom the honour 
 of the introduction is due, although his claims as the 
 first inventor have been recently upset by the decision 
 of the Courts. 
 
 The relative economy of the supply of electricity 
 by the use of a transformer is clearly shown by the 
 following diagram, Fig. 7. A, B, and C give propor- 
 tionately the area of cross section of the total mass of
 
 22 CENTRAL-STA TION LIGHTING. 
 
 copper necessary to supply 5000 16 candle-power glow 
 lamps situated at a mean distance of 4000 feet from 
 the dynamo. A refers to the Edison "three-wire" 
 system/working at a potential or electrical pressure of 
 200 volts with a fall of potential or loss of energy in 
 the distributing feeders of 10 per cent, average distance 
 from dynamo 4000 feet — the usual conditions on which 
 
 Fig. 7. 
 
 this system is worked. B shows the size of conductor 
 required for the same work in an installation based on 
 the transformer system, potential 1000 volts, allowing 
 2*5 per cent, loss in the supply mains — only one- 
 fourth as much as in the direct Edison system at the 
 same average distance from dynamo. If this loss were 
 increased to 10 per cent, and made equal to that in 
 the direct system, viz. 10 per cent, the size of the 
 conductor would be that shown at C. 
 
 ' - , , - ■ ,. , , ==3 6666 
 
 853 
 
 213 
 
 Fig. 8. 
 
 The graphic diagram, Fig. 8, demonstrates what 
 the relative cost would be with each of the three con- 
 ditions just named.
 
 PRINCIPLE OF TRANSFORMERS. 
 
 23 
 
 Mr. Goulard's first practical application of the 
 secondary generator in this country was the lighting 
 of the Underground Railway Stations, in 1883, from 
 Edgware Road to High Street, the generating dynamo 
 being fixed at the former place. These experi- 
 ments, which were made by Mr. Kenneth Mackenzie, 
 attracted considerable attention at the time, but it 
 was not until the report of the jurors to the Turin 
 International Exhibition in 1885 was published that 
 companies were formed to instal the Goulard system 
 for lighting an extensive district. 
 
 I ORDINARY RUHMKORFF TYPE [ 
 
 I I 
 
 'rS R iiiliiilSR £! « " Si' r S !• R 1 s 5 :s 5 ! • !i; 1 il 
 
 TO GENERATOR 
 
 Fig. 9. 
 
 The principle underlying all transformers is that of 
 the induction coil invented by Ruhmkorff in 1842, 
 but described by Faraday in his " Experimental Re- 
 searches," published in 183 1-2. 
 
 Fig. 9 is a diagram of the ordinary induction coil ; 
 on a central core is wound a short length of thick wire 
 called the primary, and again over this is wound a 
 greater length of fine insulated copper wire which 
 forms the secondary coil. On sending a low-pres- 
 sure current from the generator round the thick
 
 24 CENTRAL-STA TION LIGHTING. 
 
 wire, a much smaller high-tension current is induced 
 in the secondary. A contact breaker is employed to 
 make and break the current, or, as in the early instru- 
 ments, a commutator may be used to produce the 
 alternations. When used as a transformer the action 
 is reversed, that is, a high-tension current is passed 
 through the primary coil, which is composed of a wire 
 of small sectional area, the high-pressure main con- 
 nected to the dynamo also being small as compared 
 with the distributing cable leading from the trans- 
 former, which, acting as a step-down induction coil, 
 converts the electricity into a safe working pressure. 
 
 Ol 
 
 Fig. 9 a. 
 
 Fig. 9 A shows the arrangement of the two separate 
 and complete circuits. D is the dynamo, P the primary 
 coil, S the secondary, and L the lamps arranged in 
 parallel. 
 
 It is hardly necessary to go into the technical 
 details of the various improvements which have 
 led up to the modern type of transformers ; they 
 are summarised by Mr. Kapp into two classes : — 
 
 I. Core transformers, one core and two sets of coils. 
 
 II. Shell transformers, two cores and one set of coils. 
 No. I. are those in which the copper coils are spread 
 
 over the surface of the iron core enveloping the latter 
 more or less completely ; and No. II. in which the
 
 DESCRIPTION OF TRAXSFORMERS. 25 
 
 core is spread over the surface of the copper coils 
 forming a shell over the winding. 
 
 The original Goulard and Gibbs secondary generator 
 was of the core transformer type, it had an open mag- 
 netic circuit and cores which could more or less be 
 inserted into the coils so as to regulate the electro- 
 motive force of the secondary circuit. The transformers 
 were constructed with a number of copper disks or 
 washers ; these were placed alternately primary and 
 secondary in a vertical frame, through the centre of 
 which an iron core was fixed, consisting of a bundle of 
 straight iron wires. The core was movable in the coil 
 in the manner of the well-known induction coils, and 
 thereby the electro-motive force of the secondary cur- 
 rent could be adjusted. In their latest design the coils 
 are circular in plan and rectangular in section and are 
 surrounded by groups of U-shaped soft iron stampings 
 slipped over from both sides and held together by two 
 circular cast-iron plates with a central bolt. The 
 magnetic lines of force pass through the core, in at 
 one end and out at the other, and are then more or 
 less disseminated through space ; it will thus be seen 
 that the path of the lines lies partly in iron and partly 
 in air, and, since air has about seven hundred times 
 more magnetic resistance than iron, it is evident 
 that the number of lines created with a given current 
 must be considerably smaller than would be the case 
 if the path of the lines contained iron only. This 
 constitutes the improvement in the Zippernowsky- 
 Deri-Blathy system of transformer, which has coils 
 similar to the Goulard, but with the iron of the core
 
 26 
 
 CENTRAL-STATION LIGHTING. 
 
 applied in the form of a ring-shaped shell, surrounding 
 both coils completely. This arrangement can best be 
 described by comparing it to a Gramme armature, in 
 which the copper and the iron have changed places. 
 Imagine what is usually the core in an armature re- 
 placed by the primary and secondary coils, and, instead 
 of the winding of insulated copper wire, wind iron wire 
 around the coils, and one of these transformers is 
 the result. In consequence of the lower magnetic 
 
 Fig. io. 
 
 resistance of the Class II. transformer, as compared to 
 that of Class L, the electrical output obtainable with 
 equal weights of copper and iron appears to be con- 
 siderably greater in the former apparatus. Professor 
 Feraris, of Turin, has published some of the results 
 of comparative experiments made with Classes I. 
 and II. and finds that the coefficient of induction is 
 yG times as great with the latter as with the former.
 
 GROSVEXOR GALLERY STATION. 27 
 
 There are many varieties of transformers in the market 
 which closely resemble each other ; one of the most 
 practical is that designed by Kapp and Snell, of which 
 Fig-. 10 is an illustration. U-shaped stampings form 
 the shell and the cores are laid in the double trough. 
 The cover of these troughs is formed from the metal 
 removed from the interior of the stampings, and the 
 whole is held together in a cast-iron frame so arranged 
 as to allow air to circulate through the core and round 
 the coils. The price of these transformers is about 
 £4. per indicated horse-power, and the efficiency under 
 the best conditions, namely, with full load, is, according 
 to Professor Ayrton, as high as 96 per cent., and when 
 it is doing one quarter of the full work 89 per cent. 
 
 Application of Transformers. 
 
 The installation at the Grosvenor Gallery, London, 
 may be taken to Illustrate Class I. or the practical 
 working of distribution by means of transformers. 
 
 Fig. 1 1 represents the arrangement of primary and 
 secondary circuits. 
 
 An alternating current Is sent through the main ll\ 
 which is a closed circuit, and a small portion is drawn 
 off wherever there is a secondary generator or trans- 
 former T ; these instruments are placed in parallel 
 between the conductors in the same manner as a glow 
 lamp ; neither main can be called positive or negative, 
 as the current flows backwards and forwards many 
 times in a second. The house wires M M are joined to 
 the secondary circuits, and are quite distinct from the
 
 28 CENTRAL-STA TION LIGHTING. 
 
 main, which they do not even touch, although suffi- 
 ciently near to receive an induced current alternating 
 the same as the primary, but of a much lower electro- 
 motive force. 
 
 The Goulard transformers were used at first, but 
 have been superseded by others designed by Mr. Fer- 
 
 D, alternating-current dynamo ; M M, secondary conductors ; 
 
 E, continuous-current dynamo for T T, transformers ; 
 
 exciting ;_ S' S= S^ S* S^ S% lamps in paral- 
 L \}, main primary conductors ; lei. 
 
 ranti ; they are of the No. 2 kind, or shell type, and 
 have a core of hoop-iron, on which the two coils are 
 wound ; the hoop-iron is then bent over, and the ends 
 joined so as to enclose the coils. The machinery is 
 fixed in a basement excavated under the Grosvenor 
 Gallery ; the foundations are of massive concrete, in
 
 GROSVENOR GALLERY STATION. 29 
 
 which stone supports for the engines and dynamos 
 are embedded ; the concrete does not touch the walls 
 of the building, but a space of about i foot is left, 
 which is filled in with clay ; and by this simple plan 
 all vibration of the machinery is isolated from the 
 building. The power is obtained from two horizontal 
 high-pressure engines, each of 600 indicated horse- 
 power, in addition to the original two horizontal high- 
 pressure non-condensing engines, each of 35 nominal 
 horse-power, running at a speed of 55 revolutions per 
 minute, which is maintained constant by means of a 
 governor directly attached to the expansion slide- 
 valve. The four engines drive on to a countershaft, 
 which is cut up into lengths ; each section is coupled 
 to a dynamo and exciter by means of a conical fric- 
 tion-disk clutch ; this permits of either length being 
 started or stopped without interfering with the other. 
 The speed of each engine is checked by means of a 
 liquid speed-indicator, designed by the author. Two 
 Ferranti alternating-current dynamos, each capable of 
 maintaining ten thousand lamps, are driven direct, 
 one dynamo by each length of shafting : they are 
 excited by two continuous-current machines, the cir- 
 cuits from which are joined to a regulating apparatus, 
 which by altering resistance keeps the electro-motive 
 force of the large machines proportional to the num- 
 ber of lamps which are to be maintained. At present 
 hand regulation is employed, but it is proposed to use 
 automatic regulation, which will increase the life of 
 the lamps, as they are severely tried by the variation 
 of the current, which is more noticeable than in con- 
 tinuous-current installations. The current from the 
 machines is at a potential of 2400 volts, and that from
 
 30 CENTRAL-STA TION LIGHTING. 
 
 the transformers is lOO volts. The primary wire 
 which carries this high electro-motive force does not 
 enter the houses, as the transformers are, as a rule, 
 fixed in the cellars, and from them the house branch 
 is led in the form of a cable of fine wires, having a 
 total diameter of -f^ inch ; the lamps, which are placed 
 in parallel across this cable, are attached to single 
 No. 1 8 or No. 20 B. W. G. wires in the usual manner. 
 When first established, the transformers presented an 
 element of danger, in that they, in common with all 
 induction coils, were also condensers, and therefore a 
 dangerous shock might be given to any one touching 
 some unguarded portion of the lighting system. This 
 has been prevented by the simple plan of connecting 
 one of the terminals of every secondary circuit to 
 earth, a method which, however, is not to be recom- 
 mended, as it throws an additional strain on the insu- 
 lation of the primary circuit ; in fact, by earthing the 
 secondary the insulation is practically reduced to one- 
 half A safety device should be inserted, which would 
 come into operation on any leakage from primary 
 to secondary, and immediately cut out the trans- 
 former. 
 
 The primary-current conductor is led overhead, and 
 still remains an objectionable feature of the system, 
 although the original trouble with the neighbouring 
 telephones and telegraphs has been overcome. The 
 primary circuit is a small carefully insulated cable 
 of high conductivity copper wire, nineteen strands of 
 No. 15 B. W. G. It weighs about i| ton per mile, 
 and is suspended, where it crosses the streets, on a 
 steel bearer whose tensile strength is i4- ton. It is so 
 arranged according to the droop of the cable that the
 
 GROSVEKOR GALLERY S2ATI0N. 31 
 
 strain of the bearer never exceeds 225 lbs., which 
 means that the factor of safety is nearly 12 to I. 
 Double cut-outs or safety fuses, in many instances of 
 the author's design, are placed on each pole of the 
 primary, at the point where it enters the house, so 
 that, in the case of an excess current, the mica-foils 
 would fuse, and all connection between that house and 
 the supply main would cease. 
 
 Much credit is due to M. Goulard, who, in spite of 
 great opposition to the use of his transformer system, 
 initiated the Grosvenor Gallery installation three 
 years ago. It has developed into not only the 
 largest and most important central station in Europe, 
 but, as regards the transformer system, it supplies 
 more lights than any in the United States. The 
 original company has been taken over by the London 
 Electric Supply Corporation, who are putting down 
 plant capable of maintaining 30,000 lights, and are 
 erecting another station at Deptford for 200,000 lights, 
 which will be distributed by means of district trans- 
 formers from mains, which it is proposed to run from 
 Deptford through the Thames Tunnel and the Under- 
 ground Railways. The electric current is supplied by 
 meter at the price of 'j\d. per Board of Trade Unit, a 
 price for light equal to gas at about 4^-. 2d. per icoo 
 cubic feet. 
 
 The Eastbourne station is also on the transformer 
 system. An alternating-current dynamo, by Ellwell 
 Parker, maintains a pressure in the primary circuit of 
 2000 volts, v/hich is reduced by means of a Lowrie 
 Hall transformer to a working pressure of 100 volts. 
 There is a special arrangement for maintaining a 
 constant electro-motive force in the mains, indepen-
 
 32 CENTRAL-STATION LIGHTING. - 
 
 dent of the number of lights in use. The mains are 
 carried underground, and have so far given no trouble 
 as regards the insulation of the high-tension current 
 which passes through them. The Eastbourne com- 
 pany commenced by lighting the parade only with 
 arc lamps, but now supply the incandescent light to all 
 parts of the town, and enjoy the unique position of 
 having obtained power from the corporation to run 
 the mains in the streets prior to the passing of the 
 Act of 1882. Another small station has been success- 
 fully worked for the last six years at Brighton ; the 
 group system was originally adopted, the lamps, both 
 arc and incandescent, being placed in series or multiple 
 series ; the high-tension current is led through over- 
 head wires in a very similar manner to the installation 
 at Temesvar, Hungary, which is described at page 58, 
 as an example of multiple-series lighting. The ex- 
 tensions at Brighton are to be carried out on the 
 transformer plan, which will necessitate the running 
 of separate circuits, the intention of the company, 
 however, being to gradually convert its whole system 
 of supply to the transformer system. The Brighton 
 Company has regularly paid dividends to its share- 
 holders since its formation. 
 
 On the Continent the Goulard transformer is largely 
 employed. 
 
 An important installation at Tours of 3500 lamps 
 has been for some time successfully working. Another 
 at Tivoli has some additional points of interest, in 
 that the natural power of a waterfall is applied to 
 generate electricity. Two turbines constructed by 
 Escher Wyss, of Zurich, having an available head of
 
 COXTIXENTAL IXSTALLATIONS. 33 
 
 29*75 feet, give 80 horse-power each, which is em- 
 ployed to drive two Siemens alternating -current 
 dynamos, separately excited by two small continuous- 
 current machines. Two distinct circuits of chromo- 
 bronze naked wire, 3*7 millimetres in diameter, are 
 run overhead, in the same manner as telegraph 
 wires, through the town for a total length of about 
 nineteen miles. The street lamps are fixed alternately 
 on each circuit, so that one-half can be extinguished 
 at a late hour without interfering with the others, or 
 having to turn out individual lamps. The number of 
 lamps used in the streets is two hundred glow lamps 
 of 50 candle-power ; also one hundred and twenty 
 glow lamps of 16 candle-power for the illumination of 
 the narrower streets. Arc lamps are also employed,* 
 as well as a large reflector lamp, the rays from which 
 are turned on the Temples of Vesta and Sibilla. A 
 house-to-house system is also being established, and 
 the company which has put up the work proposes to 
 utilise the falls of Tivoli in order to transmit 2000 
 horse-power for lighting purposes in Rome. 
 
 The firm of Ganz, of Budapest, who are the manu- 
 facturers of the Zippernowsky-Deri-Blathy system of 
 transformers, have a similar installation completed 
 in order to light a portion of Lucerne. The water- 
 power of Thorenburg 3 • i miles off, works the tur- 
 bines, which drive two self-exciting alternating-current 
 dynamos of the Ganz type, similar to those shown 
 at the Vienna Exhibition in 1884. The primary 
 current of 38 amperes, at an electro-motive force of 
 1800 volts, is led by four uncovered wires, each six 
 
 D
 
 34 CENTRA L-STA TION LIGHTING, 
 
 millimetres in diameter, to the first station, which is 
 2 '4 kilometres distant; here 1500 watts are taken 
 off, and at 2-3 kilometres further 7000 watts are 
 utilised in two of the hotels at Lucerne. A large 
 installation on the same system has been put down in 
 Rome, and several Continental cities are adopting 
 this method of supplying electric light by small over- 
 head wires. An advantage claimed by the Zipper- 
 nowsky system is the method of keeping the strength 
 of the magnetic field of the dynamos in accordance 
 with the external demand for current. The recrulatinsr 
 apparatus employed consists of a small transformer, 
 the primary coil of which is traversed by the whole, 
 or by a proportionate part, of the main circuit, while 
 the secondary coil is inserted into the exciting circuit. 
 Thus, if the main current increases, the exciting 
 current induced in the two armature coils of the 
 dynamo is reinforced by the inductive action of the 
 regulating transformer ; and the field of the dynamo 
 is strengthened when more current is required. The 
 opposite takes place when, through the extinction of 
 lamps on the external circuit, the demand for current 
 becomes less. In an experiment made with the trans- 
 formers, which supply some five hundred electric lamps 
 for the Teatro dal Verone and adjoining houses at 
 Milan from the central electrical station three-quarters 
 of a mile away, the main current was often found to 
 vary from one ampere to thirty-five amperes ; it was 
 stated that no variation in the service pressure could 
 be detected, and the lamps burnt with equal brightness 
 whatever the number in use. In the experiments at 
 the Teatro dal Verone each transformer worked its
 
 THE WESTINGHOUSE SYSTEM. 35 
 
 own independent circuit of lamps ; but, if the condi- 
 tions of the different circuits were ahke, they could 
 be coupled up together in any manner desired, and 
 thus a group of transformers could become a centre of 
 distribution. 
 
 The Westixghouse System. 
 
 The Alternating-current system of the Westing- 
 house Company has come to the front in the United 
 States with extraordinary rapidity, and, although it is 
 not three years since the first plant was erected, at 
 the present time over 190,000 incandescent lamps are 
 operated from a number of central stations. The 
 fundamental principles of the Goulard system have 
 been retained in the Westinghouse converter ; but 
 the manner in which these principles are applied has 
 been greatly modified, while most of the details have 
 undergone a radical change at the hands of the 
 engineers and electricians whose researches have been 
 utilised by the Westinghouse Company. The form of 
 converter as now designed consists of a number of thin 
 sheet-iron plates, shaped like the letter E^ they are 
 slipped alternately from opposite directions over the 
 primary and secondary coils, which are disposed side 
 by side ; the inductive core is, therefore, composed of 
 a mass of detached plates insulated from each other by 
 paper, and forming a discontinuous magnetic circuit. 
 In order to protect the converter from mechanical 
 injury as well as dampness, and also to avoid the possi- 
 bility of contact with wires carrying currents of high 
 
 D 2
 
 36 
 
 CENTRAL-STATION LIGHTING. 
 
 potential, it is enclosed in a cast-iron case or box, 
 made in two parts and adapted to be secured to any 
 convenient support. Fig. 12 is a transverse vertical 
 section of such a converter box, with the converter in 
 
 position. The terminals of the primary coil, P, of the 
 converter are led into the compartment D^, and the 
 terminals of the secondary coil into D^. The[terminals 
 are secured to bolts or couplings,//; mounted upon 
 insulating plates, e^ and r. Fusible mica-foils, g, and
 
 .^
 
 THE WESTINGHOUSE SYSTEM. 
 
 37 
 
 switch plates, k and /, with pkigs k, are provided for 
 protecting and disconnecting the circuits. The open 
 front of the compartments D^ and D^ are closed by 
 glass plates, T, which permit inspection of the con- 
 nections without entering the box. The converter 
 box occupies little space, and may be placed in any 
 convenient situation in or about the premises to be 
 lighted, much the same as a gas-meter. The practice 
 
 where overhead conductors are employed, is to mount 
 the converter box on a pole in the vicinity of the 
 premises to be lighted, as shown by Fig. 13, and 
 thus it is only necessary to lead the secondary or low 
 potential wires into the building, the high potential 
 wires remaining in an accessible position upon the 
 pole. Fig. 14 is a view of North Street, Pittsfield, 
 Massachusetts, engraved from a photograph, and shows
 
 38 CENTRAL-STA TION LIGHTING. 
 
 a very neat form of tubular pole with its converter 
 box on top. This arrangement is used throughout the 
 city, and is a great improvement on the ordinary form 
 of telegraph poles which so greatly disfigure American 
 cities, and are really the most objectionable feature of 
 the overhead wire system. 
 
 The potential ordinarily employed in the main 
 circuits of the Westinghouse installations is about 
 1000 volts, and that in the lamp circuits 50 volts, 
 the ratio of conversion, therefore, being as 20 to i ; 
 the dynamos are manufactured, as a rule, in three 
 sizes, No. I for 650, 16 candle-power lamps; Nos. 2 
 and 3 for respectively 1300 and 2500 lamps. The 
 converters are also made in three ordinary sizes to 
 supply 20, 30, and 40 lamps of 16 candle-power 
 each. A 40-light converter contains about 85 pounds 
 of iron and 25 pounds of copper, so that the total 
 weight of metal is less than 3 pounds per lamp ; 
 the electrical efficiency of the converter is said to 
 exceed 95 per cent, when the potential is reduced 
 from 1000 volts in the primary to 50 in the secondary. 
 " It is claimed that the trifling loss of energy in con- 
 version from high to low potential at the point of 
 consumption is made up for by gain at other points, 
 especially in the increased efficiency of the lamps, so 
 that an alternating current plant may be counted on 
 to give 10-16 candle-power lamps per indicated 
 horse-power, as against 7 with the direct s}^stem ; " 
 the comparative gain is doubtful, but by using 50 
 instead of 100 volts the life of the lamps is increased, 
 the former having a much stronger filament and 
 consequently a longer life.
 
 ELECTRIC MOTORS. ' 39 
 
 Electric IMotors. 
 
 Having slightly diverged from the original lines by 
 describing a system which is at present not introduced 
 into Europe, a few remarks on the subject of electric 
 motors may not be inappropriate, as they are almost 
 universally worked in the United States, from the 
 installation which supplies electric light. There is a 
 considerable profit to the electric company if electric 
 power is taken in the district, the wires conveying 
 the lighting current are thus economically employed 
 during the day. In the diagram, Fig. 15, which 
 represents a district at Boston, the curve on the right 
 principally represents the dem.and for power which 
 takes place between the hours of 8 A.M. and 3 P.M. A 
 circular was addressed to all the leading electric com- 
 panies in America a short time ago, asking if they 
 supplied power as well as light, also for what purposes 
 it was used. 
 
 Answers were received from 56 companies, who 
 stated that the motors were employed for : — driving 
 ventilator fans, collar-and-cuff machines, printing- 
 presses, various apparatus in repair-shops, sewing- 
 machines, coffee - mills, gun - shop tools, sausage- 
 machines, elevators, lathes, pumps, saws, ice-cream 
 freezers, organ-bellows, and washing-machines. The 
 size of motors varied from one-eighth to 15 horse- 
 power ; 26 companies have supplied motors from arc 
 light circuits, 14 from arc and incandescent, and 16 
 from incandescent circuits alone. The motors are 
 principally owned by the subscribers, and arc charged
 
 40 CENTRAL-STA TION LIGHTING. 
 
 for at a rate varying from £i to ^^15 per horse-power 
 
 ^^SB^^HBSSBHH^^^^^^H 
 
 Jr'lG. I' 
 
 per month. The motor business is still in its infancy, 
 but is cited to show how Electric Power can supplant
 
 THE EDISON SYSTEM, 
 
 41 
 
 the steam-engine, especially for those purposes in 
 which the power required is small and complete 
 control is desirable. 
 
 CLASS II. 
 
 The Edison Parallel Syste^i, with Con- 
 tinuous Current. 
 
 It will be found, on examining Appendix II., that 
 in European stations by far the larger number of 
 
 ^ft 
 
 ^^ 
 
 I# 
 
 % 
 
 %. % 
 
 /J^L 
 
 ^ 
 
 Fig. 16. 
 
 lamps are maintained from installations employing the 
 Edison system ; the Ferranti plan of using transformers 
 comes next, closely followed by Goulard and Zipper- 
 nowsky ; the distribution with secondary batteries 
 follows, and the high-tension multiple series comes 
 last. 
 
 The Edison system has frequently been discussed, 
 in connection with small installations, but in magnitude
 
 42 CENTRAL-STA TION LIGHTING. 
 
 the stations in Berlin and in Milan exceed anything 
 that has been started here with continuous current. 
 
 Before describing the central electric-light station 
 at the former city, it may be well to recall to mind 
 that the Edison plan is the combination of a number 
 of machines which pump electricity into a network of 
 feeders, mains, and conductors, the lamps being placed 
 in parallel circuit, as shown at L /, Fig. 1 6, and main- 
 tained at a constant potential of no volts. 
 
 M M' are the flow and return mains, the dynamos 
 bridging them across at one end. If the mains were 
 very long, those near to the dynamos would be ex- 
 hausting the supply, and the lamps at the remote end 
 would not get the full pressure. A system of feeders 
 has been devised so that each lamp, no matter where 
 it may be, shall have approximately the full i lo volts 
 working through it. Fig. 17 shows a long circuit con- 
 sisting of two branch mains bridged by a large number 
 of lamps, / /, and D D are the dynamos at the central
 
 THE THREE-WIRE SYSTEM. 43 
 
 station. Series of feeders, //', have to be taken from 
 the dynamo mains and fed direct into the branch 
 mains at various points, d d', b b', c c\ in order to dis- 
 tribute the electrical pressure equally. 
 
 The Three-Wire System. 
 
 The ordinary parallel system is undoubtedly suit- 
 able for small installations ; but when the area to be 
 lighted is extensive, it is impossible to proportion the 
 mains, with a view to economy in the cost of copper, 
 without sacrificing energy wasted in heating the con- 
 ductors. 
 
 In Figs. 1 6, 17, the lamps are shown in simple 
 parallel ; but if two dynamos are connected together, 
 and a main wire is run from each of their two extreme 
 terminals and a third wire from the branch connecting 
 the two machines, we have what is known as the three- 
 wire system, which was invented by Edison in America, 
 and Hopkinson in England, almost simultaneously. 
 Although by using the third wire there is a saving 
 in copper over the parallel plan, the maximum gain is 
 not more than 25 per cent, under the best conditions ; 
 when the district to be illuminated is not more than 
 400 to 600 yards from the central station, the three- 
 wire system answers well, but as soon as this distance 
 is exceeded the cost of the mains begins to mount up 
 at a most alarming rate. Although there are many 
 Edison installations in the United States on this 
 system and a few on the Continent, it has only been 
 used here in a few instances for factory lighting.
 
 44 CENTKAL-STA TION LIGHTING. 
 
 The Edisox System at 3^Iilan. 
 
 The Santa Radegonda station at Milan is at the 
 present moment the second largest Edison station in 
 Europe. The building, which was formerly a theatre, 
 is well adapted for the work required ; the dynamos 
 and engines are fixed in a deep basement, while the 
 boilers are a few feet above the street-level, the upper 
 floors being used as stores and testing-rooms. The 
 dynamos, eight in number, are of the old Edison type, 
 with horizontal magnets ; seven of these machines are 
 connected to the feeders which supply the mains, and 
 these cover the district to be lighted on the Edison 
 network system. The motive power is furnished by 
 six Armington-Sims, and two Porter-Allen engines, 
 each connected direct to the armature of a dynamo, 
 the speed being maintained at the uniform rate of 350 
 revolutions per minute, except in the case of the spare 
 engine and dynamo, which is kept turning slowly, 
 ready to be switched on should occasion demand. The 
 starting or cutting - out of circuit of these large 
 machines requires some care. In the first place, to 
 start, it is necessary to insert resistance into the shunt 
 circuit of the dynamo, which is done by a switch ; but 
 to throw 1 50 horse-power into the main circuit would 
 be dangerous to the lamps, so that the current is first 
 sent into a bank of one thousand lamps used as a 
 resistance, and these are cut out step by step ; similar 
 care is taken when a machine is stopped. To control 
 the electro-motive force, which varies greatly from 
 time to time, hand regulation is used during the day, 
 with the help of the Edison tell-tale, consisting of two
 
 ELECTRIC LIGHTIXG OF MILAN. 45 
 
 lamps, a red and white one, which light up when the 
 current is high or low ; but when the night service 
 comes on, as it may happen that two thousand lamps 
 may be turned out at once, an attendant has to care- 
 fully watch the electric regulator, and be ready to 
 insert resistance into the field-magnet circuits by 
 moving a w^heel connected by a shaft and bevel-gear 
 to a system of commutators. The principal difficulty 
 to be overcome, in an installation where the current is 
 distributed over a large area, is the regulation of the 
 electro-motive force at the various points, as at Milan ; 
 there are no return galvanometer wires, which are now 
 used in both the two and the three-wire Edison 
 systems in the United States. The plan devised by 
 the company's electrician at i\Iilan is very ingenious, 
 and enables the pressure at the ends of the various 
 feeders to be kept practically the same, although they 
 are of different lengths and sectional area. In the 
 first place, resistance was added to each feeder to 
 equalise the resistance in each conductor ; and, in 
 order to provide for the varying amount of current the 
 feeder has to supply, a peculiar form of commutator, 
 having a guillotine-shaped contact-piece, was inserted 
 in the circuit. By moving this, suitable resistance is 
 inserted or cut out, and the attendant, having a series 
 of numbers, has only to set this instrument to the 
 number shown by the ampere meter. By far the 
 largest amount of current is drawn off for the lighting 
 of the Scala Theatre, the stage-lighting alone taking 
 more than one thousand lights : if these were all 
 turned on suddenly, the other lights in the district 
 would be dimmed ; to obviate this, auxiliary feeders
 
 46 
 
 CENTRAL-STATION LIGHTING. 
 
 have been run, which are used only when any great 
 increase is expected ; commutators similar to those 
 referred to above also regulate these feeders without 
 any special attention. The pressure at any point in 
 the system is by this means easily controlled, and 
 
 Fig. iS. 
 
 affords an illustration of what is perhaps not the most 
 economical, but is found to be the most practicable, 
 way of maintaining a constant potential in a district 
 where the amount of output of current is suddenly 
 doubled. Fig. i8 is a plan of the network system of
 
 ELECTRIC LIGHTING OF MILAN. 47 
 
 conductors laid through a large portion of the city ; 
 the conductors are in outward appearance similar to 
 gas-pipes, the current passing through semicircular 
 bars of copper, imbedded both for the flow and return 
 in the same iron tube, which is laid underground in a 
 shallow trench. The house-supply is drawn from the 
 mains, and these are connected to the feeders by 
 means of ordinary junction-boxes, which each contain 
 a fusible cut-out. The bridge-boxes allow of expansion 
 of the line, and have connections for testing purposes. 
 The insulation is extremely good, mainly on account 
 of the favourable nature of the ground, which \s chiefly 
 gravel ; no trouble has been experienced with leakage, 
 nor has the service ever been interrupted. The cut- 
 outs are of an improved Edison form, but have the 
 disadvantage attending all lead plugs where the 
 current is great, in that, to guard against accidental 
 melting due to the heating effect of the current, the 
 sectional area of the lead has to be much larger than 
 would be otherwise necessary. In fact, these cut-outs 
 will protect the cable against a bad short-circuit, but 
 nothing else. 
 
 In addition to the glow lamps, eighty arc lamps are 
 worked in derivation, two in series ; most of these 
 lamps require 45 volts, to which 10 per cent, of idle 
 resistance is added, constituting a total loss of current 
 which is extremely low for a combined arc and incan- 
 descent system of lighting. The service commenced 
 in 1882 with a little over one hundred lamps, and at 
 present there are over ten thousand glow lamps, and 
 two hundred arc lamps are in use. At first the new 
 enterprise had to struggle against very great diflicul-
 
 48 CENTRAL-STA TION LIGHTING. 
 
 ties ; not only the technical difficulties of distribution 
 by means of a network of feeders and mains had to be 
 overcome, but also those arising from the prejudices 
 of consumers and the competition of the gas com- 
 pany, who tried to deter consumers from introducing 
 electric light into their houses. One of these means 
 consisted in offering to the private consumers, resident 
 in the district which was threatened by competition 
 with electricity, an agreement by which the gas com- 
 pany bound itself to supply gas at 5^-. %\d. per looo 
 cubic feet, instead of Js. yd. as charged hitherto ; and 
 even now those inside the " charmed circle " of the 
 electric-light conductors get their gas cheaper than 
 the public outside. One of the reasons which accele- 
 rated the adoption of electric light was the introduc- 
 tion of the Edison meter, in consequence of which 
 consumers could be charged exactly for the amount 
 of light they had received, and were relieved from 
 paying a lump sum according to the number of lamps 
 fixed, which was customary in the early days of the 
 company. The prices at which the company now 
 provides light, at all hours of the day and night, arc 
 as under : — 
 
 Installation Charge per 
 
 Type of Lamp. charge per lamp. lamp-hour. 
 
 s. d. 
 
 lo-candle . . . i8 0*26 
 
 16- „ . . . 28 0-40 
 
 32- „ ... 56 o-8o 
 
 that is, a little over \d. per ampere-hour ; the 10- 
 candle lamps requiring o* 5, the i6-candle lamps 0*75, 
 and the 32-candle lamps 1*5 ampere.
 
 THE EDISOX METER. 49 
 
 The company lends meters for 50, 100, and 150 
 lamps, at an annual rent of 45-. \od., ys. ^d., and 
 9^. 7^. respectively, and replaces, without charge to 
 the consumer, any lamp the filament of which has 
 broken, but it does not replace lamps where the glass 
 is broken. For arc lamps requiring 9 to 10 amperes, 
 an annual rent of £2 must be paid for the lamp itself, 
 and a charge of a little over \d. per hour for every 
 ampere-hour. The carbons are charged for at \d, per 
 pair, lasting for about seven hours. Xow that the 
 installation has been in use for several years, and that 
 the company has arrived at a very accurate estimate 
 of the time during which an average consumer requires 
 the light — about one thousand six hundred lamp-hours 
 per annum — it proposes to simplify the method of 
 charging large consumers, by omitting the initial 
 charge of each lamp, and, instead, to charge 0'6d. for 
 each i6-candle lamp-hour. 
 
 The Edison meters are based on the electrolytic 
 action of a small fraction of the current which passes 
 through the meter. They are cells, with rectangular 
 zinc plates immersed in a solution of sulphate of zinc 
 of 1*054 density, the distance between the plates 
 being a little over \ inch. The proportion of the 
 current which passes through the meter to that which 
 passes directly into the consumer's house is i to 973. 
 The resistance of the shunt circuit is 9 '75 ohms, made 
 up as follows: cell, 1*75 ohm; metallic portion, 
 ohms. The resistance of the metallic portion rises 
 with the temperature, whereas that of the cells falls 
 with a rising temperature ; and in this manner the 
 small variations of resistance which might take place 
 
 E
 
 50 CENTRAJSTA 21 ON LIGHTING. 
 
 in the cell are counterbalanced by the equally small 
 variations in the resistance of the metallic portion. A 
 complete meter consists of two similar-sized cells of 
 the same resistance, placed in series. The object of 
 employing two cells is, that when little current is 
 passing, as in the summer months, one cell alone is 
 used, and when the consumption is sufficiently large 
 both cells are employed, and the mean between the 
 two indications is taken as the basis for calculation in 
 number of ampere-hours. The quantity of electricit}' 
 passed through the cell is calculated by the loss of 
 weight which has taken place in the positive plate. 
 An employe of the society visits every meter monthly, 
 taking aw^ay the old cells and substituting others 
 freshly constructed. A book is kept in which the 
 weights of the new plates and those of the returned 
 plates are entered, and on the basis of these entries 
 the accounts are made up. The largest plates are 
 those in the lOO-light meter, and are intended for a 
 maximum current of 75 amperes in the main circuit ; 
 they are 6 inches long by 2 inches wide. In cases 
 where a larger amount of current is taken, the capa- 
 city of the lOO-light meter is increased by joining two 
 or more copper strips across the terminals of the cells. 
 The weak point of the system is the removal of the 
 cells, which leaves the adjustment of the account to 
 be paid entirely in the hands of the Electric-light 
 Company ; in spite of this drawback, it is stated that, 
 there has not been a single complaint from consumers 
 during the four years in which the meter system has 
 been in use.
 
 ELECTRIC LIGHTIXG OF MILAN. 51 
 
 Discovery of Faults. 
 
 It is evident that in so extensive a system of light- 
 ing a short circuit now and then between the lamp 
 wires and the earth cannot altogether be avoided. 
 Many of the lamps have been fitted to existing gas 
 fittings, and are beyond the daily supervision of the 
 company's officers ; the faulty place is often not easily 
 accessible, so the first step taken is to discover on 
 which of the two circuits the trouble has occurred. 
 This is done at the station by joining two i6-candle 
 lamps in series across the main conductors and the 
 point of junction between the two lamps is connected 
 to earth by a stout wire. As long as both circuits 
 (positive and negative) are perfectly insulated from 
 earth no current flows through this middle wire, and 
 both lamps remain hardly incandescent ; but, if one of 
 the circuits should be in connection with the earth, 
 the lamp which is joined on the other circuit will 
 brighten up, because the potential of the middle wire 
 and that of the faulty circuit are both zero, and con- 
 sequently the lamp between the middle wire and the 
 sound circuit receives the full pressure of no volts. 
 To localise the fault, contact is made between the 
 earth and the sound circuit by means of a fusible 
 plug of known melting point, say for a thirty-lamp 
 supply. If the fault is on a portion of the external 
 circuit, supplying less than thirty lamps, its fusible 
 plug will melt as soon as the sound main is put to 
 earth. If, however, the fault is on a portion supply- 
 ing more than thirty lamps, the fusible plug which 
 has been inserted at the station between the sound 
 
 li 2
 
 5 2 CENTRA L-STA TION LIGHTING. 
 
 main and the earth will melt instead. A series of 
 fusible plugs are thus tried, increasing in melting 
 capacity until one is found that does not go : in this 
 case, the other plug on the faulty portion has melted, 
 and the consumer's lamps on that branch are extin- 
 guished ; the position of the fault is thus localised, 
 and the company proceed to remedy the defect with- 
 out interfering in the slightest degree with the rest of 
 their system. 
 
 The Electric Lighting of Berlin. 
 
 The Edison system is also employed at Berlin, in 
 fact the Deutscher Edison Gesellschaft have at the 
 present time a monopoly of the supply of the city 
 from three large central stations, each of which serves 
 the area in their immediate neighbourhood. The 
 mains differ from those used at Milan in that stranded 
 highly insulated cables, protected with steel wire on 
 the outside, are laid under the pavement in every 
 street throughout the district. With the exception of 
 the Leipziger strasse and Unter den Linden, which are 
 lit with arc lamps suspended from chains running be- 
 tween cast-iron poles 24 ft. high, about 100 to 250 ft. 
 apart, gas is used for the street lighting, and electricity 
 for the interior illumination of many public buildings 
 and private houses ; there are also a good many arc 
 lights outside the shops and restaurants. The mains 
 are on the Edison network system, the area of copper 
 being such, that when all the lamps are on there is a 
 loss of energy of 25 per cent. ; but this does not occur
 
 CHARGES TO COXSUMEJiS. 53 
 
 on an average for more than half an hour a day. No sole 
 concession is given to the company, who simply have 
 the right to take up the pavement and cross streets, 
 and for this permission they are bound to furnish any 
 consumer in the district with a constant supply of 
 electricity at the following charges : — 
 
 lo-candle lamps 2-5 pf., about 0*29 d. per hour. 
 16- „ 4-0 „ 0-48 
 
 32- „ 8-0 „ 0-96 
 
 50- » 12-5 „ 1-50 
 
 100- „ 25 „ 3-00 
 
 In addition to this an installation fee of 6s, per 
 lamp is charged, which includes one lamp. 
 Meters are charged as follows : — 
 
 10- to i6-candle power 
 
 — 3" " " 
 
 50- 
 100- „ „ 
 
 A discount is allowed off this meter charge, varying 
 with the number of hours the light is used in the 
 year. 
 
 The cost of gas is about 4^". gd. per 1,000 cubic feet, 
 so the electric light is slightly the dearer illuminant. 
 
 The Aron meter. Fig. 19, is usually employed as 
 the recorder of the electricity consumed. It consists 
 of two pendulums, controlling two distinct clockwork 
 gears. One oscillates at a regular speed, but the 
 other has a permanent magnet, instead of a weight, 
 and is variable in speed. The entire current passes 
 
 £ s. 
 
 d 
 
 16 
 
 per annum. 
 
 I 
 
 
 
 I 10 
 
 
 
 2 
 

 
 54 
 
 CENTRAL-STATION LIGHTING. 
 
 through the solencid, which is underneath the pen- 
 
 Fig. 19. 
 
 dulum, with the magnet ; the difference in speed 
 between the standard and variable clocks is gfiven in
 
 THE SERIES SYSTEM OF DISTRIBUTION. 55 
 
 direct ampere-hours by a counter-gearing similar to 
 the index of a gas-meter. An electro-magnet starts 
 each pendulum when the current begins to flow, and 
 immediately it ceases, two detents come into operation 
 and hold the pendulums stationary. 
 
 CLASS III. 
 The Series System of Distribution. 
 
 This method dates back to the introduction of the 
 incandescent light, and, although it has been fre- 
 quently demonstrated that a small current of high 
 potential could be employed to work incandescent 
 lamps, the series system has never been installed on a 
 commercial scale, and is confined to arc lighting. In 
 the United States the usual pressure for arc lighting 
 is 2,000 volts, and it is not an uncommon occurrence 
 to have forty arc lamps in series upon a line over 
 10 miles in length, carrying a current of 10 amperes. 
 To economically use this high pressure for glow lamps 
 in series, they must be of such design as to enable 
 the whole of the current to be passed through them 
 without injury. The filament of an ordinary high- 
 resistance glow lamp would be immediately destroyed, 
 so that low-resistance lamps, having a much larger 
 sectional area, must be employed. The Bernstein or 
 the Cruto lamp, which can be made to have a "hot" 
 resistance of about o"j ohm, and requires a current
 
 5 6 CENTRAL-STA TION LIGHTING. 
 
 of 9*75 amperes, could be used, and the current 
 might be economically brought from a great distance. 
 Mr. Bernstein calculates that it would be possible to 
 operate 6,ooo of these /-volt lamps from twent}' 
 dynamos, each giving a current of lo amperes at a 
 potential of 2,ooo volts, and still have a margin for 
 loss of current in the leads. An economical feature 
 of this scheme is the easy way in which power could 
 be saved when only comparatively few lights were 
 required ; for instance, in the daytime all the circuits 
 could be looped together and fed by one dynamo, and. 
 as the number of lights increased, so other machines 
 could be switched in by having an auxiliary bank of 
 lamps as a resistance. From the central station 
 twenty pairs of carefully insulated copper wires, sa}* 
 of No. 6 B. W. G., would lead to the houses ; and, as 
 a good-sized ordinary house takes on an average 
 twenty lights, the conductor would pass through 
 fifteen houses before it returned to the station. It is 
 in the house that the practical difficulty commences, 
 as in this series system the circuit must never be 
 opened, so that the switches and safety appliances 
 must be such that, whatever happens, there must 
 remain some path for the current, otherwise all the 
 lights on that particular circuit would be extinguished. 
 Mr. Bernstein gives the designation of " short closed " 
 if the current goes through the switch-lever, and 
 " long closed " if the current is led through the lamps 
 or other electrical devices. 
 
 Fig. 20 is a diagram of the lamps in any building. 
 The street main, M, enters at the main switch, S, and 
 continues from switch to switch, S^ S\ and returns to
 
 THE SERIES SYSTEM OF DISTRIBUTION. 57 
 
 S before it leaves. It is necessary, to guard against 
 any possible extinction, to construct all the switches 
 so that it would be impossible to move the lever with- 
 out a lamp was lighted ; and, should the lamp give 
 out, an equivalent resistance must be automatically 
 inserted. These details have been investigated by 
 Mr. Alexander Bernstein, who has designed a com- 
 plete system for " series " lighting, and claims for it 
 
 Fig. 
 
 special economical advantages. It is, however, very 
 doubtful if this plan can be recommended for adoption 
 in private houses ; but in public lighting, or in large 
 establishments where an electrician could be kept to 
 look after the fittings and the insulation of the con- 
 ductors, there should be no more danger, in introduc- 
 ing the high-tension continuous current of 2,000 volts, 
 than there is at present with the lOO-volt alternating
 
 5 8 CENTRAL-STA TION LIGHTING. 
 
 current, and the relative saving in weight of conductors 
 would be an important item. 
 
 Installations on this method have been erected at 
 Messrs. Brunner and Mond's alkali works, and in several 
 large factories in the United States where lights had 
 to be distributed over a considerable area ; the system 
 has not, however, come into favour for central-station 
 work. 
 
 CLASS IV. 
 
 The Multiple-series System. 
 
 This method of using a high-tension current has 
 already been referred to in connection with house- 
 to-house lighting at Brighton, it was first employed 
 for the street lighting of Chesterfield by the Brush 
 Company. The electric lighting of the town of 
 Temesvar, in Hungary, is on a far larger scale, and 
 has, from November 1884, successfully superseded a 
 combination of gas for the more important streets, 
 and petroleum for the outlying ones, the total cost of 
 which was 26,480 florins per annum. A twenty-four 
 years' concession was given to the International 
 Electric Compan}-, the plant remaining their property 
 at the expiration of the term, subject to purchase by 
 the municipality at their own valuation. The public 
 lighting is stipulated to be effected by means of 
 731 glow lamps of the intensity of 16 candle- 
 power ; but the option is given to the company of 
 switching out a fixed proportion of these lamps at
 
 THE MULTIPLE-SERIES SYSTEM. 59 
 
 11.30 P.^r., or of leaving the whole number in operation 
 with their light-intensity reduced from 16 to 8 candle- 
 power from 11.30 P.M. till dawn. The total number 
 of lighting-hours per annum is 3,597i for the lamps 
 which are in operation from dusk until dawn, and 
 1,816 for those which are extinguished at 11.30 P.M. 
 The price fixed in the concession for public lighting 
 is 1*5 kreutzer per 16 candle-power lamp per hour, 
 equal to 53 florins 95 kreutzers per lamp per annum 
 of 3o972 hours, or 27 florins 24 kreutzers per lamp 
 per annum of 1,816 hours. The company has found 
 it more convenient to exercise the option reserved to 
 it, of keeping all the 731 lamps in operation from 
 dusk till dawn, reducing their light-intensity to 
 8 candles after 11.30 P.M.; and the municipality 
 has agreed to pa}- a round sum of 29,000 florins 
 (£2,4.16 13^-. 4d.) per annum for this lighting, and 
 41-95 florins (^^3 los.) per annum for each additional 
 lamp worked in the same way. Comparing these 
 figures with what precedes, it will be found that the 
 electric lighting of the streets now in operation costs 
 2,520 florins more than it did on the former plan of 
 combined lighting, partly by gas and partly by 
 petroleum. On the other hand, the streets are lighted 
 throughout with 16 candle-power lamps from dusk 
 until 11.30 P.^I., and with 8 candle-power lamps from 
 11.30 P.M. until dawn. For electric light supplied to 
 private consumers the concession fixes the price at 
 I -81 kreutzers per 16 candle-power lamp per hour, or 
 0-1131 kreutzers per candle per hour, with the right to 
 charge 1 5 per cent, more for lamps of less intensity 
 than 16 candles. In all these prices the renewal by
 
 6o 
 
 CENTRAL-STA TION LIGHTING. 
 
 the company of lamps failing from legitimate wear is 
 included. 
 
 One central generating station has been provided 
 for the whole town, from which at present four distinct 
 
 Fig. 21. 
 
 ^G 
 
 
 Ss 
 
 8 
 J 
 
 n GROUP CUT-OUTS 
 
 • LAMPS 
 
 — WIRES CONNCCTiHO Cr.IjPS 
 
 GENERATOR STATION 
 
 Multiple-series Lighting. Temesvar. 
 
 circuits have been laid, each fed by a separate dynamo. 
 The street lamps are connected up in *' multiple series," 
 that is to say, in groups placed in series on the circuit, the 
 lamps in each group being connected up in parallel.
 
 THE MULTIPLE-SERIES SYSTEM. 6i 
 
 Fig. 21 shows the arrangement diagrammatically. 
 Each group consists of eight lamps in parallel ; at 
 present three of the circuits have twenty-four groups 
 in series, and the fourth circuit has twenty-three 
 groups in series, giving a total of ninety-five groups, 
 comprising 760 lamps, of which 731 are public lamps 
 and 29 are used at the central station. To meet the 
 risk of interruption in any circuit through the failure 
 of individual lamps, an automatic switch is arranged 
 so as to put in a reserve lamp, in the event of a whole 
 group being interrupted. Another self-acting device 
 will short-circuit the whole group, so that the other 
 groups in the circuit will be unaffected. The auto- 
 matic lamp-switch is contained, together with the 
 reserve lamp, in the lantern, and the automatic group 
 cut-out consists simply of an electro-magnet with a 
 coil of high resistance connected up in parallel with 
 the group of lamps it protects. These appliances have 
 been found to work well. The main conductors are 
 formed of insulated single copper wire, 4 • 6 millimetres 
 in diameter ; they are carried overhead on porcelain 
 insulators, fixed to telegraph posts or to wooden arms 
 let into the walls of houses ; the resistance of this 
 conductor is about I * i ohm per kilometre. The glow 
 lamps are placed in reflectors at an angle of about 
 45^ from the vertical, and are carried on brackets 
 either fixed to the walls or on special cast-iron posts. 
 Fig. 22 shows the details of street bracket and reflector 
 with automatic lamp-switch and lamps in place. The 
 brackets are for the most part fixed to the walls of 
 houses or to painted wooden posts. 
 
 The under side of the reflector, which is made of
 
 62 
 
 CENTRAL-STATION LIGHTING. 
 
 enamelled iron disposed in the form of a flat inverted 
 cone, reflects the upward rays from the lamp and 
 causes the extreme ones to strike the ground at a 
 distance of about 50 metres from the foot of the 
 lamp-post. The increase of lighting effect in the 
 streets due to those reflectors is very marked. The 
 upper part of the reflector sei-\'es the purpose of a case 
 and weather protector for the automatic lamp-switch 
 
 Lamp Bracket. 
 
 which is inserted from the top, and the lower end of 
 which is fitted with copper hooks to which the two 
 lamps arc fixed. The glow lamps are fitted with 
 holders of a type designed by the engineer, which 
 provide the lamp terminals with large and strong eyes 
 affording considerable contact surface and adapted for 
 hooking on direct to 2*5 mm. copper wire, the ends of 
 which have merely to be bent into a suitable form 
 for maintaining the lamp in any required position.
 
 THE MULTIPLE-SERIES SYSTEM. e^ 
 
 These lamps are of an improved Lane-Fox type, 
 manufactured by the Electrical Company, at their 
 works in Vienna. Although originally intended for 
 1 6 candle-power lamps they have so far been worked 
 at 1 8 candle-power, taking 53*618 volts and about 
 I "1 83 amperes, which is equivalent to 3*522 watts 
 per candle-power, or about 211 candles per horse- 
 power. The current is maintained at 10 amperes, 
 and the potential between independent groups of 
 lamps is 53*6 volts. The aggregate energy lost, 
 in overcoming the resistance of the main leads, 
 switches and cut-outs, is 12*8 per cent, of the total 
 electrical energy generated at the central-station — 
 a very satisfactory result on a system of over 
 37 miles of streets. The electro-motive force in the 
 conductors is about 1,400 volts, which is below the 
 normal capacity of a Brush machine, thus allowing 
 more lamps to be operated from the four machines. 
 The machinery is driven by a 300 horse-power hori- 
 zontal compound-condensing tandem steam-engine, 
 running at the normal speed of 100 revolutions per 
 minute. During the first 1,200 hours of lighting, only 
 three lamps out of 760 failed, and one of these had 
 been broken maliciously. The engineering arrange- 
 ments are due to Mr. C. F. de Kierskowski Steuart, 
 I\I. Inst. C.E., the various difficulties incidental to a 
 novel work having been surmounted with experienced 
 workmen. Although the system at Temesvar has 
 more complicated arrangements than are now re- 
 quired if secondary generators are used, it has shown 
 that it is quite practicable to light all the streets in a 
 town by electricity ; also it has enabled a comparison
 
 64 CENTRAL-STA TION LIGHTING. 
 
 to be made between the useful effect obtainable from 
 arc and from glow lamps. Each group of glow lamps 
 was found to absorb practically the same energy as 
 one arc lamp of from 800 to 1,000 candle-power, and 
 ninety-one or ninety-two of these could have been run 
 with the same expenditure of power as 731 glow 
 lamps. The eight glow lamps forming one group are 
 in many cases scattered in different streets, often quite 
 out of sight of each other. Under such circumstances, 
 the substitution of one light centre, however powerful, 
 for every eight could only be done by leaving many 
 spots in complete darkness. To give a usefully diffused 
 light by means of arc lamps, their number would have 
 to be considerably greater than ninety-two, or, in 
 other words, the standard of street lighting would 
 have to be raised, and for this the town was not pre- 
 pared to pay. 
 
 The business has now passed into the hands of the 
 Anglo-American Corporation of London, who are 
 extending the installation by placing alternating cur- 
 rent dynamos at the station to work transformers for 
 the supply of houses so as to utilise the original plant 
 for street lighting only, as, even with the advanced 
 knowledge of the present day, it is doubtful whether 
 for this purpose a more economical system could be 
 employed.
 
 BATTERY TRANSFORMER SYSTEM. 65 
 
 CLASS V. 
 
 The Distribution with Secondary Batteries, 
 OR THE Battery Transformer System. 
 
 Mr. Lane Fox was the first to put forward a com- 
 plete system of electrical supply on this plan, Fig. 23. 
 
 Fig. 23. 
 
 iL»-o- 
 
 G Generating station. 
 R Returns. 
 L Lamps. 
 
 A Accumulators (secondary batteries). 
 M Mains or conductors. 
 X Meters. 
 
 The system is discussed by him as follows :* — 
 "The chief points of the system is the use of a 
 generator in a central position, from one pole of which 
 
 * Hedges on the Supply of Electricity by Local Authorities. Pro- 
 ceedings of Association of Municipal and Sanitary Engineers and Sur- 
 veyors, vol. ix. (1882-83), p. 159. 
 
 F
 
 66 CENTRAL-STA TION LIGHTING, 
 
 insulated conductors or mains are led to the several 
 points where the electric energy is to be utilised, 
 being branched and sub-branched as much as required, 
 and thence back to the other pole of the generator by 
 an uninsulated conductor, such as the gas or water 
 pipes. At certain points, storage or secondary bat- 
 teries are set up in connection, on one hand, with the 
 mains, sub-mains, and branches, as the exigencies of 
 the case may require, and, on the other, with the 
 return conductor." 
 
 " The combination of generators, circuit and storage 
 batteries is such, that when the current from the 
 generators falls below the demands made on it from 
 the various outlets to the mains at which its energy is 
 utilised, the deficiency is made up from the storage 
 batteries, which act in unison to supply the requisite 
 quantity of energy. On the other hand, when the 
 current from the generator exceeds in point of quantity 
 the demands upon it at the various outlets, the excess 
 goes to charge the storage batteries and to create a 
 reserve to be called upon in case of need." 
 
 The objection to the system which prevented it 
 being put in practical operation was the use of the 
 earth as a return conductor. Besides the great danger 
 of short-circuit, the gas and the water-pipes, which are 
 so thickly laid in most cities, would conduct the 
 current and interrupt telegraphic and telephonic com- 
 munication. The experiment of using storage bat- 
 teries as reservoirs, from which a constant supply of 
 electricity could be drawn as required, was tried on a 
 considerable scale at Colchester, where a large instal- 
 lation was started in 1884, secondary batteries being
 
 BA TTER V TRANSFORMER S YSTEM. 6 7 
 
 placed in favourable positions, and charged by a high- 
 tension current. The plan adopted is shown by 
 Fig. 24. 
 
 Fig. 24. 
 
 r^D 
 
 DYNAMO 
 
 B 
 
 
 B ! 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 ^^^^i?^l?^^6^^ 
 
 o- 
 
 T. T, 
 
 A is a meter in charging circuit ; B, the batteries or accumulators ; 
 L, lamps in parallel on low-pressure service main. 
 
 The dynamos were two of the Brush type, ^each 
 
 F 2
 
 68 CENTRAL-STA TION LIGHTING, 
 
 dynamo giving a current of 9*5 amperes, with an 
 electro-motive force of 1,800 volts, when rotated at a 
 speed of 700 revolutions per minute. They were 
 driven by a semi-portable engine indicating 90 horse- 
 power. The dynamos were coupled in parallel cir- 
 cuit for quantity, and excited by a small machine 
 giving 10 amperes. The current was led some dis- 
 tance by a seven-strand 19 B. W. G. cable to the bat- 
 teries, which were charged in series, the 60-volt lamps 
 being placed in parallel on separate mains connected 
 to the batteries. The danger of introducing a high- 
 tension current of 1,800 volts into the houses was 
 obviated by a rocking-switch worked automatically, 
 so as to throw the batteries out of the charging cir- 
 cuit. The operation was accomplished by means of a 
 master cell M, C, Fig. 24, similar to the others, but 
 fitted with an arrangement to collect the gas evolved, 
 which extended a diaphragm attached to a make-and- 
 break arrangement which worked the rocking-switch. 
 The Colchester installation did not turn out com- 
 mercially successful, and has been abandoned ; but 
 the experiment has been valuable, and there is little 
 doubt that, with simplification of details, a high-tension 
 charging current could be led from a dynamo fixed in 
 any convenient site where power is available ; also in 
 very crowded districts the batteries could be placed 
 in cellars and be drawn from as reservoirs, so as to 
 furnish a constant supply of electricity. 
 
 The Kensington Court installation has been pre- 
 viously quoted as an example of what promises to be 
 one of the most successful methods of distributing a 
 constant supply of electricity through a large area,
 
 V 
 
 pTWTTffTTTnr^^
 
 KENSnYG TON CO UR T ST A TION. 69 
 
 a description of the station may therefore be inter- 
 esting. The accompanying elevation, Fig. 25,* shows 
 the unpretending design of the building, and the very 
 compact arrangement of the generating machinery 
 and batteries. When the illustration was made the 
 plant consisted of one Willan's single-crank triple- 
 expansion engine in combination with a Crompton 
 dynamo provided with vertical inverted single magnets, 
 the output being 250 amperes at 140 volts when 
 running at 500 revolutions per minute, the steam 
 pressure being 160 lbs. on the square inch. A com- 
 plete duplicate plant has already been installed, and 
 three more sets of engines and dynamos are shortly 
 to be erected. The draught from the boiler is led 
 downwards by an underground flue, with the object 
 of economising the very limited space as much as 
 possible. As a rule, the dynamo and accumulators are 
 used in parallel, the current enters and leaves the 
 regulating cells by the same contact, in other words, 
 there is only one switch which serves for charging and 
 discharging the batteries. This switch has nine con- 
 tacts, so as to give nine degrees of regulation of the 
 light ; when the dynamo and accumulators are work- 
 ing together, the lights are parallel with either 41, 
 42, or 43 cells, according to the amount of charge in 
 the cells and current required, while, when the dynamo 
 is out of circuit, the lights are worked off, 50, 51, 52, 
 or 53 cells. The current passes through the usual 
 measuring instruments, and each main conductor is 
 protected by safety fuses mounted in a Hedges duplex 
 cut-out. The accumulators are of the Plante type, but 
 
 * From Industries.
 
 70 CENTRAL-STATION LIGHTING, 
 
 instead of being plain lead are sawn out of ingots which 
 are cast porous on the Howell process. Each cell con- 
 tains 35 plates, 8 in. x 8 in., and, as each plate when 
 fully formed is said to be capable of yielding five 
 ampere-hours per pound of lead, the cell has about 
 6oo ampere-hours total capacity. In the event of a 
 serious break-down the whole of the work would fall 
 on the accumulators, which could furnish a steady 
 current for perhaps an hour or more ; and herein lies 
 the novelty of the arrangement. For the first time 
 we have an accumulator put in not only as a fly-wheel 
 to the whole system and to give the advantage of 
 supplying current throughout the day and the small 
 hours when the engine is not running, but also to act 
 as an actual reserve. The routine is as follows : — the 
 dynamo will start charging the accumulators a few 
 hours before dusk ; for a short time after lighting hours 
 commence, the dynamo alone will supply sufficient 
 current, but later on the demand will gain on the 
 dynamo, and a certain portion of the discharge will be 
 from the accumulators. At eleven o'clock at night 
 the engine will be stopped and the accumulators will 
 alone supply the demand for the rest of the night. 
 In the small area occupied by the station there is 
 ample room for a plant of six times the present 
 capacity, and it is intended to erect sub-distributing 
 stations at points at the outskirts of the district where 
 accumulators to act as transformers will be fixed, which 
 will be charged by a special main with a current of 
 500 volts, the outgoing wires from the sub-station 
 taking electricity at the usual E. M. F. pressure for 
 incandescent lamps in houses of 100 volts.
 
 SYSTEM OF DISTRIBUTION. 71 
 
 Thirteen candle lamps are used in the district, 
 having been found to be more convenient than 16 or 
 20 candle-power, the 13 candle is obtained for 36 
 watts, or 2 '75 watts per candle. The price charged 
 to consumers is Zd. per Board of Trade unit, or equi- 
 valent to gas at about 4^. jd. the 1,000 cubic feet. 
 Meters on the Aron plan, Fig. 17, ate used, a card 
 being supplied on which the readings are entered 
 exactly similar to the method adopted with gas. The 
 service mains terminate at the meter, where the com- 
 pany fix for their own purposes a double pole switch 
 of the author's design. Fig. 26, which enables both 
 wires to be disconnected, a spring shut-off, marked S S, 
 prevents the switch being left partly on. 
 
 System of Distribution. 
 
 The mains from the Kensington Court Station are 
 laid underground in a culvert 18 in. by 12 in., which 
 is built with brickwork and cement under the pave- 
 ment. A double conductor of flat copper, 0*25 square 
 inches section, is stretched from shackle insulators 
 attached to iron bars, which are firmly built into the 
 culvert ; the continuity of the circuit is provided by 
 means of stranded wire, which connects each section ; 
 the flat copper rests on the top of porcelain insulators, 
 fixed on vertical iron pieces, which are built into the 
 floor. Connections with the sewers are left for drainage, 
 and six surface boxes are provided for every hundred
 
 72 
 
 CENTRAL-STA TION LIGHTING. 
 
 yards. Where house connections have to be made, the 
 branch wires are united by soldering to the bare 
 copper mains. For crossing under the streets a heavily 
 insulated cable is employed, and is led through cast- 
 iron pipes. 
 
 Until a larger amount of mileage is actually at 
 
 Fig. 26. 
 
 work, it is difficult to express an opinion as to which 
 is the cheapest and most efficient method of laying 
 conductors in the streets. The relative cost of two 
 plans tried at Kensington Court — the insulated and the 
 bare cable in a culvert — was given by Mr. Crompton 
 in the following Tables, No. i and No. 2, which are
 
 SYSTEM OF DISTRIBUTION. 73 
 
 taken from a paper read before the Society of Tele- 
 graph Engineers and Electricians on April 12th, 
 1888. 
 
 Table No. i refers more particularly to what is 
 known as the Callender- Webber system of using bitu- 
 men concrete, which is compressed into blocks or 
 cases usually about 6 ft. long, 8 in. by 5^ in. sec- 
 tion, having two-inch holes through which the insu- 
 lated copper cable is led. 
 
 The estimates given in Table No. 2 were criticised 
 by Mr. Kapp, who thought that " a more reliable 
 conductor could be obtained by using a high-class 
 lead-covered cable, which might be laid in the ground 
 with the simple protection of a rough tarred plank to 
 cover it." The cost of digging the trench and ruiming 
 in the cable from the drum was quoted at 3^". a yard, 
 and the total cost, inclusive of ^10 for surface boxes, 
 at ;^i55 per 100 yards, instead of £1^7, as shown 
 by the Table.
 
 74 
 
 CENTRAL-STATION LIGHTING. 
 
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 SYSTEM OF DISTRIBUTION. 
 
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 7 6 CENTRAL-STA TION LIGHTING. 
 
 The Vienna Central-station. 
 
 The practical success of the Battery Transformer 
 system has been demonstrated at Vienna, where an 
 installation of five thousand lamps in the Opera House 
 and Burg Theatre was maintained for the past year 
 from a distributing station 1,400 yards away. The 
 boilers are fixed in a basement formed by excavating 
 the court-yard of a private house to a depth of 1 5 feet 
 6 in. below the street level ; the building itself is 
 utilised partly for offices and partly as a large dy- 
 namo and engine-room. Each dynamo is designed 
 to give an output of 72 kilowatts or 120 amperes, 
 at 600 volts pressure. The current is led by means 
 of a lead-covered cable underground to the accu- 
 mulators, which are erected in groups of 52 cells 
 each, so as to give 100 volts to the lamps, with a 
 comfortable margin. The total pressure required to 
 charge the four groups of batteries in series varies 
 from 430 volts at the time the batteries are giving off 
 work, to 480 volts for the short time during which the 
 charge is being completed. During five hours of 
 lighting about two-thirds of the current comes direct 
 from the dynamos ; but during this time, for short 
 periods, the demand for current often increases to 
 such an extent that these proportions may be re- 
 versed, and the batteries supply two-thirds of the 
 total. 
 
 The regulation of groups of batteries placed in 
 series is not a difficult matter, and will be understood 
 by referring to the following diagram, Fig. 27 : — 
 
 The four battery stations mentioned as arranged
 
 in series are represented. 
 The current may be sup- 
 posed to enter at the 
 right-hand corner, passing 
 through the first battery 
 with the lamps parallel 
 to it, and from that bat- 
 tery to the commence- 
 ment of the next, and so 
 on through the third and 
 fourth, the current being 
 varied at will at the cen- 
 tral station, or kept con- 
 stant by means of an 
 electrical governor. The 
 potential for each of the 
 four groups of lamps is 
 maintained in the follow- 
 ing manner : — In each 
 group one terminal is kept 
 permanently connected to 
 one of the discharge mains 
 and to one of the charging 
 mains ; the other terminal 
 can be shifted from cell 
 to cell according to the 
 E. M. F. required in the 
 corresponding lamp cir- 
 cuit by means of a contact 
 regulator. This mov- 
 able terminal is shown by 
 the bunch of lines at one 
 
 Fig. 27.
 
 78 
 
 CENTRAL-STA TION LIGHTING, 
 
 extremity of each battery group. The rule for charge 
 and discharge is, that the terminal cell at the regu- 
 lating end of the battery is so arranged that it neither 
 
 Fig. 28. 
 
 Central Station. 
 receives nor gives off current, so that there is no loss 
 of energy in the shape of E. M. F. The contact 
 regulator, which was designed by Mr. Crompton for 
 use at Kensington Court, is shown by Fig. 28 : —
 
 DYNAMOTORS. 79 
 
 The ring contacts are arranged in a line in such a 
 manner that a circular contact piece, made of thin 
 sheets of copper, can be forced through them in turn 
 by means of a central screw spindle. The mains for 
 charge and discharge are attached to the fixed disc 
 contacts on the central screws, and the regulating 
 cells of the battery are coupled to their respective 
 contact rings by sockets at the back of the board. 
 
 The difficulty with the battery transformer system 
 is the introduction of 400 to 500 volts into the houses, 
 which would be necessary without the batteries are 
 always fixed in sub-stations from which a low-pressure 
 current, say of 100 volts E. M. F., could only be dis- 
 tributed. 
 
 A method has been devised by Mr. Henry Ed- 
 munds to obviate this disadvantage. He also uses 
 the high-tension current to charge the batteries, but 
 by means of a distributor, which is automatically 
 worked by the current, each group of cells is charged 
 in turn, when it is entirely cut off from the supply 
 main to the house, through which current is perhaps 
 being taken for lighting purposes. The system is 
 now being adopted by the Cadogan Electricity Supply 
 Company, Chelsea. 
 
 Direct Current Transformers or Dyna- 
 
 MOTORS. 
 The method of transforming by direct current with- 
 out the aid of batteries is not practically at work ; but, 
 as the advantages are so obvious and its development
 
 8o CENTRAL-STA TION LIGHTING. 
 
 is only a question of time, a description of the system 
 may not be considered out of place. 
 
 The electrical exhibition at Philadelphia in 1884 
 contained a dynamotor which was exhibited by the 
 Van de Poele Electric Light Company, but, as far as 
 could be ascertained, was not worked, and, as it was 
 simply described as an induction machine for distri- 
 buting currents for the use of incandescent and other 
 lights, it attracted little attention. 
 
 The advantages of an alternating current transformer 
 system of distribution, Class II., has been put forward 
 in these pages, especially that of simplicity and cheap- 
 ness. An alternating current dynamo for a given 
 output is cheaper than a direct, and it takes less labour 
 to look after it, because it has no commutator. 
 
 An alternating transformer is also an exceedingly 
 simple piece of apparatus. If originally made with 
 due care and kept in a dry place, it never breaks down, 
 as it has no moving parts, and so there is nothing to 
 go wrong. 
 
 The alternating system of distribution has, however, 
 some very serious disadvantages. In the first place, it 
 is most important that motors should be driven during 
 the day when the lights are not in use. In the second, 
 batteries cannot be used in an alternating current 
 system, so any immunity from breakdown that they 
 might ensure is wanting ; and steam must be kept up 
 all day and all night. 
 
 If motors are wanted during the day, so that the 
 load on the engine is nearly constant, batteries are 
 not so valuable, except with a view of preventing a 
 breakdown ; but, if batteries cannot be used, the advan-
 
 DYNAMOTORS. 
 
 tage of using motors becomes enormous, as the plant 
 has to be large enough to supply the maximum load, 
 and would otherwise be idle during the day. 
 
 In alternating current systems there are two diffi- 
 culties in the way of using motors. It is difficult to 
 make an alternating current motor that will start, and, 
 if that difficulty is surmounted, it is difficult to make 
 an alternating current motor that will work on varying 
 loads without great waste of power. The question 
 of the efficiency of alternating current motors has 
 never been really practically studied yet ; and, until 
 these difficulties are overcome, we must regard al- 
 ternating current motors as non-existent. Several 
 methods of working alternating current transformers 
 off direct currents by commutating the primary^ have 
 been proposed at different times ; but they all seem 
 to be impracticable, and it seems impossible to get 
 over the difficulties that arise from sparking when it 
 is attempted to break a high-tension circuit. 
 
 One of the first methods of distribution over 
 large areas proposed was by means of motors and 
 dynamos combined. For instance, suppose, in order 
 to keep down the size of the leads, 2,000 volts are 
 used in the mains, a motor capable of working with 
 2,000 volts is put down where the lights are wanted, 
 and this is made to drive a dynamo giving 100 volts 
 and a large current. Instead of having a separate 
 motor and a dynamo connected by a belt or by coupling 
 the spindles together, it is simpler to make one machine 
 with two armatures, or to have only one armature with 
 two circuits on it. One circuit is wound with fine wire 
 and takes the 2,000 volts and tends to turn the arma- 
 
 G
 
 82 CENTRAL-STATION LIGHTING. 
 
 ture round. The other circuit is wound with thick 
 wire giving lOO volts and a large current, and tends to 
 stop the armature, thus absorbing the power supplied 
 by the high-pressure circuit. The direct current trans- 
 former or dynamotor is thus a sort of double dynamo, 
 or dynamo and motor combined. If it gets 2,000 volts 
 and 10 amperes, it would, if there were no waste, give 
 100 volts and 200 amperes ; with a waste of 10 per 
 cent, it will ^im^ 1 00 volts and 180 amperes. 
 
 In the United States it is usual to place an alterna- 
 ting current motor in each house to be lighted ; but 
 the conditions are quite different there, overhead wires 
 being used extensively. In this country this system is 
 not likely to find favour, and local sub-stations will be 
 used, the high pressure, which is always dangerous 
 to life, will thus be kept out of private houses and 
 offices. There is, then, very little difference in the cost 
 of maintenance of alternating current transformers and 
 dynamotors, and the advantages possessed by alter- 
 nating current transformers in this respect are more 
 than counter-balanced by the use of motors on direct 
 current circuits. 
 
 Dynamotors have not come into general use yet 
 because no stations have been started in this country 
 of the size which demands them. No central station 
 with sub-stations is in operation, but there is every 
 reason to expect several will be soon ; and it is very 
 necessary to discuss the various methods, not only in 
 use at this moment but coming into use in the im- 
 mediate future. The dynamotor itself needs no 
 working out, as any maker of direct-current dynamos 
 can, of course, make them. Messrs, Paris and Scott of
 
 DYNAMOTORS. 
 
 83 
 
 Norwich showed some in operation at the Newcastle 
 Exhibition in 1887; the most successful type is that 
 recently invented by Mr. J as. Swinburne, illustrated 
 by Fig. 29. The backward main round primary or 
 motor magnet is shown on the left, and the forward 
 main round the secondary or dynamo magnet on 
 
 Fig. 29. 
 
 the right, the outside coil round both magnets is the 
 shunt. 
 
 The dynamotor may be made with two circuits on 
 one armature as already explained, or it may have two 
 armatures in separate fields, still making up one 
 machine. The first arrangement has two grave dis- 
 advantages. There is difficulty about securing perfect 
 insulation between the two circuits, and this leads to 
 chances of danger in the houses. A dynamotor with 
 
 G 2
 
 84 CENTRAL-STA TION LIGHTING. 
 
 two circuits on one armature cannot be compounded, 
 that is to say, it cannot be made to give constant 
 electrical pressure on the mains if the number of lamps 
 is varied. A Swinburne double armature machine 
 can be compounded, not only to give constant pressure 
 with a varying load,, but to give constant electrical 
 pressure even if both the load and the pressure on 
 the primary circuit vary. This makes a considerable 
 difference in the copper of the primary leads, as in 
 large and complicated districts it is almost impossible 
 to arrange leads, even when working with high elec- 
 trical pressure and small currents, so that the electrical 
 pressure remains constant, or even nearly so. A very 
 small variation of the pressure on an incandescent 
 lamp makes an enormous difference in the amount of 
 light it gives, and in its duration. It is, therefore, most 
 important that the E. M. F. on the lamps should be 
 kept absolutely constant. 
 
 This difficulty is, of course, insurmountable in the 
 case of alternating current transformers. Alternating 
 current transformers cannot be made to compound, 
 and the loss in leads cannot be corrected by them, so 
 that the lamps burn dull at full load. 
 
 If secondary batteries are used at the sub-stations, 
 the reduction of pressure might be effected by them. 
 A number would be charged in series and discharged 
 in parallel. This arrangement needs at least two sets 
 of cells, and cells are expensive ; and it is difficult 
 to preserve the insulation of cells with such electrical 
 pressure as 2,000 volts. If cells are used for the pur- 
 pose of equalising the load or as a safety reserve, it is 
 better to charge them by means of a dynamotor.
 
 INSTALLATION AND WORKING COST. 85 
 
 Installation and Working Cost of Central 
 Stations. 
 
 Until the balance-sheet of some large central 
 station has been published, it is impossible to do more 
 than surmise what relation the earning power of the 
 generating plant bears to the initial cost. Those 
 central stations which are working successfully in this 
 country at the present time are either too small for a 
 reliable estimate to be formed, or, as in the case of the 
 Grosvenor Gallery, the space is too cramped for the 
 large amount of machinery which it has been found 
 necessary to add in order to meet the increasing 
 demands for light. In order to obtain an approximate 
 idea of the cost of installing a station capable of main- 
 taining 10,000 lights, the following data (Table III.) 
 given in Mr. Crompton's paper before the Society of 
 Telegraph Engineers are extremely valuable and will 
 be examined with interest. 
 
 Although the figures given are necessarily empirical 
 and open to criticism, the cost with both systems of dis- 
 tribution is approximately the same, and may be taken 
 roughly at £s,2>6o per 1,000 lights, which amount, 
 according to Professor Forbes, would be reduced to 
 ;^3,9i4 per 1,000 lights if the installation was put down 
 according to American practice, and at the initial cost 
 of the Westinghouse alternating current system. 
 
 Mr. Crompton also compares the working cost of 
 the two systems (Table IV.).
 
 86 
 
 CENTRAL-STATION LIGHTING. 
 
 
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 WORKING COST OF CENTRAL-STATIONS. 87 
 
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 88 CENTRAL-STA TION LIGHTING. 
 
 With the exception of the amount allowed for de- 
 preciation of the accumulators, which time alone can 
 show to be correct, the expenses may be said to be 
 over rather than under-estimated ; the 15 per cent, 
 depreciation given in Table IV. is under what has 
 hitherto been found necessary to allow for the renewal 
 of the plates of a secondary battery. 
 
 If the mean of the two results in Table IV. are 
 taken, the working cost per Board of Trade Unit will 
 be 3 '22^., which shows that with both systems, after 
 making due allowance for interest on capital, direc- 
 tors' fees, bad debts, and other sundries omitted by 
 Mr. Crompton, there is a probability of a very fair 
 return on the capital expenditure, and the prospect of 
 a handsome dividend for an electric-lighting company 
 who can sell electricity at the average price of "jd. per 
 Unit 
 
 The cost of maintaining and working electric-light- 
 ing plant at private installations is usually much in 
 excess of a supply from a central-station; but where 
 the installation is over 500 lights, the difference is not 
 very great. 
 
 The working cost at the Athenaeum Club of 387 
 lamps for the past year is given as follows : — 
 
 Gas for gas-engine 
 
 Oil 
 
 Water „ ,, 
 
 Wages 
 
 Sundries 
 
 Maintenance of lamps, etc. 
 
 Repairs ^ 
 
 jC9S9 
 
 £ 
 
 s. 
 
 d. 
 
 446 
 
 7 
 
 10 
 
 71 
 
 3 
 
 8 
 
 35 
 
 
 
 
 
 175 
 
 2 
 
 I 
 
 30 
 
 3 
 
 
 
 98 
 
 4 
 
 I 
 
 103 
 
 I 
 
 I
 
 COST OF ELECTRIC LIGHT. 89 
 
 Average cost of lighting by gas and oil for previous 
 years, for two-thirds number of lights £^Ap, 
 
 At the Naval and Military Club, 420 lights cost 
 ;£"82i I Si", for the same period, a steam-engine being 
 used instead of a gas-engine. 
 
 The annual report of the cost of the electric light at 
 the South Kensington Museum shows that in a larger 
 installation, consisting both of arc and incandescent 
 lamps, the annual cost of the latter is much less than 
 in either of the clubs mentioned. At the Museum 
 there are 860 16 candle-power lamps, working 65 5 J 
 hours per annum, or 562,387 lamp hours ; the total 
 cost for working last year was ^386, which includes 
 £^6 for repairs of engines, boilers, dynamos, and 
 maintenance of lamps ; but rent, interest on capital, 
 depreciation of plant, and management is not in- 
 cluded. The light is used only three evenings a 
 week, so that the wages of the attendants are pro- 
 portionately in excess of what they would be in a 
 central-station. 
 
 The cost of arc lighting for street purposes may be 
 estimated from the following tenders. At Taunton 
 the local electric-light company offered to extend the 
 lighting of streets from 29 to 60 arc lamps of 1,200 
 candle-power nominal on the Thomson- Houston 
 system, at the following rate : — 
 
 Per annum. 
 
 C s. d. 
 
 Burning on average of 6 hours per night each lamp 17 7 6 
 
 7 n » iS 12 6 
 
 8 „ „ 19 17 6 
 
 The posts and supports to be provided and fixed 
 by the company, or, if the town council found the
 
 9Q CENTRAL-STA TION LIGHTING. 
 
 same, the company would allow a deduction at the 
 rate of 5 per cent, per annum upon the outlay made 
 by the council. The lamps are usually about 400 feet 
 apart. 
 
 The actual cost of operating arc lights on this 
 system is given in the following detailed expenses of 
 a six hours' run of a 50-light plant for the street light- 
 ing of an American city : — 
 
 2,600 lb. Ind. nut and slack coal, at $i '30 per ton 
 Engineer, one night, at $50*00 per month 
 Superintendent or electrician, one night, at $50*00 
 
 per month ....... 
 
 Trimmer, one day, at $40*00 per month . 
 
 48 pairs of carbons, at $18*50 per month . 
 
 Waste, &c., at $20*00 per year 
 
 Water rent, at $40*00 per year 
 
 Half-pint cylinder oil, at 60 c. per gallon . 
 
 One pint engine and d}Tiamo oil, at 50 c. per gallon 
 
 One day repairs on machine and lamps, including globes 
 
 at $120*00 per year ..... 
 One day taxes on 50-light plant, assessed at $5,000, at 
 
 2\ per cent. ...... 
 
 One day interest on 50-light plant ($10,000), at 6 per 
 
 cent. ........ 
 
 Making a total of . . . . . . $9 * 82 
 
 \o\d. or 20 "45 cents, per lamp. ^^15 \os, per annum. 
 
 If, in addition to the 50 street lights, 33 other arc 
 lights are maintained, the total cost is reduced for a 
 six hours' run to $13*25, or £2 i^s. 2d. for the 83 
 lights, Zd. or 15 '96 cents per lamp, £\2 33*. ^d. per 
 annum. 
 
 Table V. has been calculated by M. Decker, of 
 Nuremburg, and gives the comparative cost of work- 
 ing 150 lamps by electricity and by gas. The gas 
 price (i) is that paid in Paris, namely, 6s. gd. per 1000 
 cubic feet ; column (2) is the price usually taken com- 
 mercially, which includes the fixed charges. The 
 
 |i*69 
 1*67 
 
 1-67 
 
 '■% 
 
 II 
 
 04 
 
 06 
 
 33 
 
 31 
 
 1*67
 
 COST OF GAS AND ELECTRICITY. 
 
 91 
 
 price of electricity is given : 1st, when a steam-engine 
 is available ; 2nd, when it is necessary to lay down a 
 special engine ; 3rd, when a gas-engine is used the gas 
 is charged at a trifle over the price in column (i). 
 
 Table V. 
 Total Cost per Hoiir and per Lamp. 
 
 II 
 
 S 
 
 II 
 
 ■fl 
 
 
 
 
 5 
 
 ■11 
 p 
 
 •I 
 
 c 
 
 
 6 
 
 
 
 v5 ^ 
 
 = ^ 
 
 W 
 
 
 
 
 rt 
 
 
 iz; 
 
 12; 
 
 
 K 
 
 m 
 
 
 
 
 
 
 
 
 Pence. 
 
 Pence. 
 
 Pence. 
 
 Pence. 
 
 Pence. 
 
 Pence. 
 
 IS 
 
 1-38 
 
 0-485 
 
 
 1-055 
 
 I-216 
 
 0-418 
 
 0-552 
 
 2-19 
 
 0-371 
 
 
 0-780 
 
 1-007 
 
 0*399 
 
 0'5i3 
 
 1,200 
 
 3-29 
 
 0-314 
 
 
 o-6o8 
 
 0-865 
 
 0-380 
 
 0-352 
 
 3,600 
 
 9-87 
 
 0-219 
 
 0-152 
 
 0-352 
 
 0*485 
 
 0-361 
 
 0-465 
 
 Arc Lamps. 
 
 5°° 
 800 
 
 1,200 
 
 3,600 
 
 1-38 
 
 5-235 
 
 4-246 
 
 10-459 
 
 11-485 
 
 
 2-19 
 
 3-971 
 
 3-089 
 
 7-552 
 
 9-272 
 
 
 3*29 
 
 3-087 
 
 2-441 
 
 6-004 
 
 7-581 
 
 
 9-87 
 
 2-185 
 
 1-510 
 
 3-591 
 
 5-586 
 
 
 Underground or Overhead Wires. 
 
 Apart from the unsightly appearance of overhead 
 wires, there are many reasons why any extended 
 system of supply of electricity should be carried out 
 by underground cables. It is true that there have 
 been no accidents in this country due to electric light 
 wires falling, owing to the care bestowed on their insu-
 
 9 2 CENTRAL-STA TION LIGHTING. 
 
 lation and erection ; on account of the heat generated 
 by the passage of the current through the leads no 
 snow can accumulate on them, and therefore they are 
 not subjected to the extra weight which destroyed so 
 many of the telegraph and telephone wires in the last 
 snow storm. Overhead electric light wires are exclu- 
 sively used by the largest electric-supply company in 
 London, and it is probable that, without further legis- 
 lation takes place, other companies will shirk the 
 expense of an underground system ; and even a 
 more dangerous method of running cables than that 
 which has been condemned in the principal cities of 
 the United States will become not the exception but 
 the rule. In the city of New York the process of 
 conversion of the present overhead to an underground 
 system is a fact about to be accomplished to a very 
 great extent at least, in the near future. Since July, 
 1887, the Western Union Telegraph Company have 
 occupied the conduits, which have been constructed 
 and laid with some 500 miles of wire ; also the IMetro- 
 politan Telephone and Telegraph Company have lOOO 
 miles of wire in the subways ; and the Edison Illumi- 
 nating Company, whose conductors were laid in the 
 trench at the time of construction, has more than 1000 
 miles of underground cable. The plan adopted is to 
 build conduits of section, as in Fig. 30, which shows 
 the subway in course of construction, with man- 
 hole opening and exposed ends of conduits. The 
 single tube at top is for distribution between man- 
 holes, and some wires are shown entering the vault on 
 the right from the service box in the foreground. 
 The conduits are of various types ; creosoted wooden
 
 UNDERGROUND OR OVERHEAD WIRES. 93 
 
 tubes are placed in creosoted wooden casings ; 
 wrought-iron pipes are sometimes laid in asphaltic 
 concrete with creosoted wooden box ; another arrange- 
 ment is to be of composition blocks on concrete, and 
 cover them with brick — or wrought-iron pipe is lined 
 
 Fig. 30. 
 
 with cement, and laid in hydraulic cement concrete 
 and cased with creosoted plank. About 85 per 
 cent, of all the conduits have been constructed on 
 this plan, the interior diameter of the pipes being 
 2\ inches. 
 
 Fig. 3 1 shows how the street arc lighting wires are
 
 94 
 
 CENTRAL-STATION LIGHTING, 
 
 taken, also a branch for house use, out of the man- 
 
 FiG. 31. 
 
 holes, which are placed at each street crossing. For 
 the cleaning purposes and for drawing the cable
 
 UNDERGROUND OR OVERHEAD WIRES. 95 
 
 through the conduits, these must be laid practically 
 straight. 
 
 Fig. 32 illustrates a method proposed by Mr. Ken- 
 neth Mackenzie, which is somewhat similar to the 
 system of conduit which, used at Tours for the past 
 two years, has been found most efficient for the 
 high potential supply mains to the transformers. The 
 troughs would be about 4 ft. long and 1 5 in. deep, 
 
 ./ '•' 
 
 
 Fig. 32. 
 
 having spigot and socket joints at the ends like or- 
 dinary water-pipes. Transverse pieces of wood, or 
 preferably slate, would rest upon projections, and 
 would support the mains, and a cover recessed as 
 shown would make the conduit fairly water-tight ; 
 drain holes would be provided, and the branches to 
 houses led off through glands in the side of troughs. 
 The American plan is, doubtless, the best, as there is
 
 g6 CENTRAL-SI A TION LIGHTING, 
 
 no space for moisture to collect in the conduits ; but 
 Mr. Mackenzie's system is well worth trying, and has 
 the advantage of being much cheaper in first cost. 
 
 The Edison plan is to place two solid conductors 
 in a tube which is filled up solid with an insulating 
 material, suitable bends and offsets being supplied, so 
 that the tube containing the two conductors can be 
 buried in the ground like a gas-pipe. The system is 
 very largely used both in the United States and in 
 Continental cities; but it is doubtful whether the pro- 
 tection would suffice in our towns, where the streets 
 are already at the mercy of the gas and water com- 
 panies, whose workmen, with a single blow of a pick, 
 might perforate the tube, and cause a dangerous short 
 circuit. 
 
 The Interests of Gas Companies as to 
 Electric Lighting. 
 
 The policy of gas companies with regard to electric 
 light has, with few exceptions, been a state of indif- 
 ference to the progress of things electric, with con- 
 tempt for a rival whose opposition is not sufficiently 
 powerful to be appreciated. The chairman of a well- 
 known gas company stated, what is undisputed, — 
 that the introduction of electric arc lights was ac- 
 companied by an increased consumption of gas in 
 the immediate neighbourhood where these lights are 
 used ; but it is very doubtful whether this will be 
 the case when incandescent lights are generally sup- 
 plied. The introduction of these lights into any busi-
 
 GAS COMPANIES AND ELECTRIC LIGHT. 97 
 
 ness district would mean the displacement of at least 
 as many burners as there are electric lamps ; and this 
 reduction not only means loss of income, but also loss 
 by interest on plant which is not kept at work to the 
 capacity for which it was designed. The question 
 suggests itself, Are existing gas companies more 
 favourably situated for furnishing electricity than any 
 one else ? There are many reasons in favour of the 
 supposition that the directors of gas companies have 
 at the present time an opportunity of acquiring almost 
 as complete a monopoly of lighting by electricity as 
 they have with gas. As regards central-stations, 
 everything is in their favour ; there is generally some 
 spare ground for the machinery, waste heat could be 
 utilised, and a cheap fuel in the shape of coke is ready 
 to hand. They have greater facilities for breaking up 
 streets without danger of troubles arising with the 
 local authorities, and if the Gasworks Clauses Acts, 
 which authorise their existence, tie them down to one 
 illuminant, a very little expenditure would enable them 
 to enlarge their powers. In many towns the share- 
 holders are local men who wish to use the electric 
 light, but cannot favour its introduction because they 
 think it would tend to smaller dividends or lower 
 quotations for their shares ; if, however, a scheme was 
 promoted either by the gas company, or, if that was 
 impossible, if the directors interested themselves in a 
 separate electric-light undertaking, the security which 
 the gas and water investments command would, no 
 doubt, cause a sufficient number of local subscribers 
 to come forward and make even a small installation a 
 paying concern. The Imperial Continental Gas As- 
 
 H
 
 98 CENTRAL-STA TION LIGHTING, 
 
 soclation have already taken up the supply of elec- 
 tricity in Vienna, and are likely to extend this new- 
 branch of their business to the other cities in which 
 they hold gas concessions ; also in the United States 
 the growing opposition of the electric-light companies 
 is being seriously discussed, and already several gas 
 companies are installing electric-light plants. 
 
 It is not at all probable that the scare which caused 
 such a drop in the value of gas shares when the elec- 
 tric light first appeared will be repeated, but the 
 present high price of gas shares cannot be maintained. 
 Kerosene lamps have been for some time a far greater 
 rival to gas than electricity. The cheapening of 
 petroleum, which is now shipped in bulk to this 
 country in tank steamers, will cause the consumption 
 to increase, and enable the oil to be supplied at a 
 price so that it can be used in petroleum-engines, and 
 give a motive power which will be found to be far 
 more economical than the gas-engine. The latest 
 development of petroleum-engines is that shown by 
 Messrs. Priestman at the Royal Agricultural Society's 
 Show at Nottingham. The engine in external appear- 
 ance is like the Otto gas-engine, but uses the ordinary 
 " paraffin oil " of commerce, which has a high flash- 
 ing point. The oil is simply put into a closed tank, 
 and on the top of this, air is forced which drives the 
 petroleum into a chamber heated by the exhaust 
 from the engine, where it is partially vaporised and 
 led into the cylinder with sufficient air to cause it to 
 ignite by means of an electric spark. 
 
 The report of the trials with a 5 horse-power engine 
 show that a brake horse-power was obtained for i • 7 lb.
 
 THE LUCIGEN LIGHT. 99 
 
 of oil, or at (i\d. per gallon for I • \d. per horse-power 
 per hour ; with the Spiel engine the cost is stated to 
 be • %d. per horse-power per hour. 
 
 Any serious reverse to the gas industry would 
 cause a great pecuniary loss to a large number of 
 investors. The paid-up and borrowed capital devoted 
 to the manufacture and supply of gas in the United 
 Kingdom exceeds ;^5 6,000,000, of which above 
 ;^36,ooo,ooo appertain to the companies and the re- 
 mainder to the local authorities, whose receipts in 
 respect of their gas undertakings last year exceeded 
 ;£'4,400,ooo. 
 
 The corporation of Bradford, who are owners of the 
 gasworks, have wisely foreseen that it is better to 
 keep the electric light in their own hands, and are 
 now about to erect a central-station, and will lay 
 underground wires ; the amount sanctioned for this 
 preliminary installation is ;^20,ooo. 
 
 The Lucigex Light. 
 
 A few remarks on this method of obtaining light 
 from the combustion of crude petroleum may be 
 added, as the light has been put forward as a cheaper 
 and better substitute for the electric arc. The Lucigen 
 light is produced by burning creosote oil, tar oil, or 
 other heavy hydro-carbons, by means of compressed 
 air in a special form of lamp, and consists of a cylinder 
 at the side of which a steam donkey compressing 
 pump is mounted, or in a more recent form known as 
 the Wells' light, no separate air compressor is used, 
 
 II 2
 
 I oo CENTRAL-STA TION LIGHTING. 
 
 but, instead, the pressure is obtained from the water 
 mains or from a small force pump. The cost is stated 
 to be 3<^. per hour for 2,500 candle-power, requiring 
 three gallons of oil per hour, but is in reality at the 
 present time double this owing to the price of the oil, 
 which, under the most advantageous circumstances, 
 costs on average 2d. per gallon. At the Forth Bridge 
 these lights have been found of use in illuminating 
 open spaces, but have not supplanted the electric arc 
 lights which arc universally employed for the lighting 
 of the works and the interior of the shops. The dis- 
 advantages are the noise, the oil shower which per- 
 vades the vicinity of the light causing timber staging 
 to be highly inflammable, and the difficulty of pre- 
 venting water from entering the burner, a few drops 
 sufficing to extinguish the light. The use of the 
 Lucigen light is, therefore, very limited, and it is pro- 
 bable that, in situations where shadows from the arc 
 light are found to be objectionable, large incandescent 
 electric lamps, which are supplied up to 1,500 candle- 
 power, would meet the case ; or, failing these, petro- 
 leum could be burnt in lamps similar to those used 
 in lighthouses with greater safety, and at not much 
 increased cost, than the compressed-air system.
 
 USEFUL NOTES, loi 
 
 Useful Notes. 
 
 To ascertain in what direction the electric current 
 is flowing through any wire by means of a pocket 
 compass : — 
 
 A current flowing from soiitJi to noyth will always 
 deflect the needle to the west, providing the wire in 
 which the current flows is oi;er the instrument. 
 
 The word S. N. O. W. expresses this — south north 
 over west ; and should be remembered. 
 
 Another simple plan\?>X.o hold the outstretched right 
 hand over the compass ; then, if the current flows in 
 the direction of the wrist to the fingers, the needle will 
 move towards the thumb. 
 
 To find the direction of the current in the wire of 
 an electro-magnet : 
 
 Place the palm of the hand on the coil with the 
 fingers parallel to the wires : the thumb will point to 
 the North Pole if the current is flowing as in previous 
 rule towards the fingers. Conversely : if the North 
 Pole is known, the fingers will point to the direction 
 of the current when placed parallel with the wires, with 
 the thumb pointing to the North Pole. 
 
 If no compass is available, take two pieces of lead 
 and place a few inches apart in a pot containing dilute 
 sulphuric acid, scrape the lead clean, and join a piece 
 of wire to each and connect to poles to be tested. 
 After current has passed a short time one piece of lead 
 will become brown, the other grey ; trace the former 
 to the dynamo cable, and this is the positive, and 
 should be marked with a -f- or be painted red for 
 future distinction.
 
 I02 CENTRAL-STA TION LIGHTING, 
 
 Incandescent Lights or Gloiv Lights. 
 
 The number of lights required to illuminate any 
 room would vary \<zxy much, according to the style of 
 decoration and position of the lamps. As a rule, a 
 similar number of glow lamps are required as there 
 would be gas burners. The former give a much 
 higher standard of illumination, which, curiously 
 enough, is generally expected with electric lighting 
 on account of the purity of the atmosphere when 
 the full light is being used, which is not the case with 
 gas. 
 
 One 1 6 candle-power lamp will light an area of 
 about 8 feet in diameter at 8 feet above ground ; in 
 ordinary situations allow, one lamp for 38 square feet. 
 
 A re L ighting of Works. 
 
 External. — 56. 2,000 CP. arc lights will illuminate 
 160,000 square yards, or one for each 2,800 square 
 yards. 
 
 Internal. — 43. 2,000 CP. arc lights will illuminate 
 31,500 square yards, or one for each 730 square 
 yards. 
 
 Approximate Cost of Electric Eighty JMuscnni. 
 
 Arc lighting, f gas ; with interest, f . 
 Incandescent, '^ eras ; with interest, ^. 
 
 Motive Power. 
 
 Compound engine 2 lbs. of coal per indicated horse- 
 power per hour.
 
 USEFUL NOTES. 103 
 
 Good single-acting engine 3 to 6 per indicated horse- 
 power per hour. 
 
 An indicated horse-power can be obtained in a 
 compound engine from 20 lbs. of steam per hour 
 
 A good boiler evaporates 9 to 10 lbs. of water per 
 lb. of coal. 
 
 From 21 to 28 cubic feet of gas are required in a 
 gas-engine per indicated horse-power per hour. 
 
 Incandescent Lamps, 
 
 In practice allow 9-60 watt 16 CP. lamps per in- 
 dicated horse-power of engine. 
 
 Mem. for Wire Rnnning. 
 
 Leads to the left or " low," " ligJit coloured^ 
 Returns to the right or " raised," " red'' 
 
 English and French Measures. 
 
 Millimetre =0*039 inches i mill = ' 0254 millimetres. 
 
 Centimetre = 0*393 ,, l inch = 2 '5399 centimetres. 
 
 Decimetre = 3*93 ,, i foot = 3 • 34S0 decimetres. , 
 
 Metre = 39'37 >j i yard = '91439 metres. 
 
 Cubic metre = 35*32 cubic feet or 1*31 cubic yards.
 
 I04 CENTRAL-STA TION LIGHTING. 
 
 Electrical Measurements. 
 
 The Paris Congress Units (1884) are now universally- 
 adopted and consist as follows : 
 
 Electro-motive Force, and Potential (E). — The Volt. 
 The legal volt is -926 of the E.M.F. of a DanielVs cell, 
 ivhich for rough purposes may be take7i as a volt. 
 
 Resistance (R). — The Ohm. The legal ohm is now 
 represented by the resistance of a column of mercury 
 of a square millimetre in section at the temperature of 
 zero centigrade i'o62 metres long. 
 
 Current (C). — The Ampere. This is the strength 
 of current sent through a wire having the resistance of 
 I ohm at the E. M. F. of i volt. 
 
 Quantity (Q). — The Coulomb. It is the quantity of 
 electricity given by an ampere in a second. One 
 coulomb decomposes '00142 grain of water. 
 
 Heat or Work (W). — The Joule, or Volt-Coulomb, is 
 the work done by i coulomb in i ohm. The work done 
 by any current per second is obtained in ergs by the 
 product of the current into the electro-motive force 
 producing it or W = C E or W = C ^R. The Erg is 
 the C. G. S. unit of work. 
 
 Power (Y). — The Watt, i~-y46 of a horse- power, 
 employed in doing i joule of work in i second. 
 
 HP, or the Horse-power, is found by dividing C E 
 
 ^ , C E C^K ,,^ 
 
 by 746, thus ^^^^== HP. 
 
 See also explanation of terms.
 
 BIRMINGHAM WIRE GAUGE FOR COPPER, 105 
 
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 EXPLANATION OF TERMS. 107 
 
 EXPLANATION OF TERMS. 
 
 Accumulator. — Another name for secondary bat- 
 teries. 
 
 Alternate Current Dynamo. — Produces currents 
 which are alternately positive and negative. 
 
 Amalgamation. — Zinc is protected from local action 
 by having its surface coated with mercury. 
 
 Ampere. — The Unit of current. A volt divided by 
 an ohm. (See Electrical Measurements, page 104.) 
 
 Ampere Meter. — An instrument used for measuring 
 strength of current. 
 
 A node. — The positive electrode or pole of a decom- 
 posing cell, the wire or plate connected to the copper 
 or other negative element of a battery. In electro- 
 plating, it is usually the soluble pole of the metal to 
 be deposited, {v. Cathode.) 
 
 Arc. — The air space in which the electric light 
 forms. 
 
 Armature. — The keeper of a magnet : the part 
 which closes the magnetic lines of the field magnet, 
 or the rotary part. 
 
 Battery. — A combination of two or more voltaic 
 cells coupled together. 
 
 B. A. — British Association. 
 
 Block Station. — A central-station for the supply of 
 continuous buildings. 
 
 Board of Trade Unit. — One thousand watt hours 
 equals 10 amperes at 100 volts per hour, or i -35 HP. 
 working for one hour. 
 
 Bobbin. — A coil of wire, or a number of such coils, 
 generally so mounted that they can be rapidly revolved.
 
 io8 CENTRAL-STA TION LIGHTING. 
 
 Bridge ( Wheats tone's). — An apparatus for measur- 
 ing resistances by balancing the unknown resistance 
 against one known and capable of adjustment. 
 
 B. W. G. — Birmingham wire gauge. 
 
 Candle Power. — Term used to denote the amount 
 of light as compared with a standard sperm candle, 
 which is a spermaceti candle, burning at the rate of 
 2 grains per minute. 
 
 Carbons. — The electrodes of arc lamps ; the nega- 
 tive plate of a battery. 
 
 Car eel Lamp. — The French standard, equal to 9*4 
 candles. 
 
 Capacity (K). — The power of a surface to hold elec- 
 tricity as " static charge." A coulomb divided by a 
 volt. Its Unit is the Farad. 
 
 Cathode. — The negative pole of a battery ; the wire 
 or plate connected with the zinc or positive element 
 of the battery. The object on which a metallic 
 deposit is to be formed, (y. Anode). 
 
 Centimetre. — The hundredth part of a metre. 
 
 Cell. — Each separate vessel in which a chemical 
 action occurs, by which electricity is capable of being 
 developed. 
 
 Central-station. — A building containing plant for 
 supplying electricity to the public. 
 
 C. G. S. — The centimetre -gramme- second sys- 
 tem. 
 
 Circuit Conductive. — The wires which form the path 
 for the passage of the current. 
 
 Commutator. — A circuit changer, or switch. The 
 collector of currents on a dynamo. 
 
 Compound Wielding. — A method of increasing or
 
 EXPLANATION OF TERMS. 109 
 
 decreasing the energy developed in a dynamo in pro- 
 portion to the demand. 
 
 Conductivity. — Is the reciprocal to resistance, and 
 applies to that property of any substance whereby the 
 passage of electricity through it is effected with the 
 least opposition. 
 
 Conductors. — Substances which most freely permit 
 electricity to pass. 
 
 Connections. — Wires, &c., completing the circuit 
 between different apparatus. 
 
 Co7itact Breaker. — The electric lighting equivalent 
 for a gas tap. 
 
 Coulomb (Q). — The Unit of quantity, which passes 
 in one second of an ampere current. 
 
 Cut-out. — An instrument placed in the circuit which 
 will open it automatically. 
 
 Current (C). — The Unit is the Ampere. The sup- 
 posed flow or passage of electricity or electrical force 
 in the direction from + to — , or positive to nega- 
 tive. 
 
 Current Reverse. — A current in the opposite direc- 
 tion to the normal current. 
 
 Decimetre. — The tenth part of a metre. 
 
 Deflection. — The angle or number of degrees through 
 which the needle of a galvanometer moves when a 
 current is passing through its coils. 
 
 Diaphragm. — A porous division between two liquids 
 through which electric current passes. 
 
 Duplex Cut-out. — An instrument which enables a 
 spare fuse to be immediately substituted for that 
 melted. 
 
 Duty. — A term used to denote the economy of any 
 motor.
 
 1 1 o CENTRAL-STA TION LIGHTING. 
 
 Dynamo. — A name given to machines which pro- 
 duce electricity for commercial purposes. 
 
 Dynamometer. — An instrument for ascertaining the 
 horse-power absorbed by any machine. 
 
 Dyne. — The Unit of force which gives a velocity of 
 I centimetre per second to I gramme weight after 
 acting for I second. 
 
 • Direct Current Dynamo. — An electric generator pro- 
 ducing currents passing in one direction. 
 
 Earth. — A term for the return circuit, which for 
 economy is formed through the earth in telegraph 
 work. A return conductor common to many circuits 
 is sometimes called " earth." 
 
 Electrodes. — A term for the poles or plates leading 
 the current into and out of a cell. 
 
 Electrolysis. — The act of decomposition by the elec- 
 tric current. 
 
 Electrolyte. — The liquid in a cell. 
 Electrometer. — An instrument for measuring electric 
 potential. 
 
 Electro-motive Force {E. M. F.) (E). — The electric 
 force tending to produce electric current. The Unit 
 is the volt. 
 
 £r^. — The C. G. S. Unit of energy. The work of 
 moving a body through i centimetre against the force 
 of a dyne. 
 
 Extra Current. — The induced current of higher 
 E. M. F., which appears in a wire wound in a helix 
 when the current is broken. 
 
 Farad. — The Unit of capacity : a coulomb divided 
 by a volt. 
 
 Field of Force. — The space between or around the 
 poles of a magnet.
 
 EXPLANATION OF TERMS. iir 
 
 Filament. — That part of an incandescent lamp 
 which gives out the hght. 
 
 Field Magnets. — In a dynamo the magnets between 
 which the armature revolves. 
 
 Foot Ponnd. — The British Unit of work, or i lb. 
 raised i foot high. 
 
 Galvanometer. — An instrument for measuring cur- 
 rent. 
 
 Ge7ierator. — Another term for a dynamo. 
 
 Governor. — An apparatus for controlling the speed 
 of any motor. 
 
 Horse Power (//P.)— indicated HP.— The Unit is 
 33,000 lbs. lifted i foot high per minute. The nominal 
 HP. of any motor is generally fixed considerably less 
 than the indicated. 
 
 '^ A P R S 
 
 Ind. HP. of any engine = ^ ^^ 
 
 A = Area of piston in square inches. 
 P = Average pressure of steam in lbs. per square 
 
 inch. 
 R = Number of revolutions per minute. 
 S = Length of stroke in feet (if in inches, 
 X 33,000 by 12). 
 The French " force cheval " represents 32,560 foot 
 pounds. 
 
 Horse Pozver of Water. — Indian Go\-ernment rule, 
 15 cube feet per second falling through i foot = i HP. 
 
 Indicator Diagram. — The drawing produced by an 
 instrument which is fixed to the cylinder of a steam- 
 engine for the purpose of ascertaining its duty. 
 
 Induction, — The name given to efiects produced
 
 1 1 2 CENTRAL-STA TION LIGHTING. 
 
 out of a force-exerting body or out of the circuit to 
 which the force is directly appHed. A current in a 
 wire induces currents in other conductors parallel 
 to it. 
 
 Inertia. — The resistance to change of state of rest 
 or motion. 
 
 Insiilators. — Bodies possessing high electrical re- 
 sistance. All insulating substances, however, allow 
 some electricity to pass. 
 
 hitensity. — The old term for the properties now 
 described as E. M. F. and potential. 
 
 Joide, also called Jojilad (W). — The Unit of heat 
 or work, it has also been applied to the mechanical 
 equivalent of heat, 772 foot lbs. 
 
 Kilowatt. — One thousand watts. 
 
 Knot. — The geographical and nautical mile. 
 
 Leads. — Terms usually applied to copper con- 
 ductors. 
 
 Magnetis7n. — A condition which can be highly 
 developed in iron and steel, by electric action or 
 otherwise. 
 
 Meas7irement. — See Units. 
 
 Metre. — The French standard of length = 3'28 
 feet. 
 
 Meg Ohm. — The prefix meg signifies a million. 
 
 Millimetre. — The thousandth part of a metre. 
 
 Milliampere. — The thousandth of an ampere. 
 
 Mica-foil. — The fusible portion of a Hedges cut- 
 out. 
 
 Multiple Arc. — Galvanic cells or dynamos connected 
 parallel, or lamps so arranged that each furnishes a 
 separate path for the current.
 
 EXP L ANA TION OF TERMS. i r 3 
 
 Negative. — In a machine the wire returning from 
 the lamp. In a galvanic battery the copper, carbon, 
 or platinum plate. Sign — . 
 
 Nigger. — An American term used to denote an 
 electrical fault. 
 
 Ohm. — The Unit of resistance. A volt divided by 
 an ampere. 
 
 Ohms Laws. — Laws, investigated by Ohm, regu- 
 lating electrical current magnitudes. Calling the cur- 
 rent C, electro-motive force E, and resistance R : the 
 expression is 
 
 Current E.M.F. Resistance. 
 
 E E 
 
 C = ^, amps. E = C X R, volts. R = y=^, ohms. 
 
 (See Electrical Measurements.) 
 
 Osmose. — The process of diffusion of liquids through 
 a porous division. 
 
 Pa7'affi}t. — An insulating substance much used in 
 telegraphic work. 
 
 Phmimer Block. — The bearing on which a shaft 
 revolves. 
 
 Polarity. — The distinct features of the two separate 
 poles of a magnet. 
 
 Poles. — The two ends of a magnet. The wires, 
 plates, &c., leading from a battery. 
 
 Positive. — In a machine the wire proceeding to the 
 lamp. In a battery the zinc plate. Sign -f. 
 
 Potential. — A word used to indicate a condition for 
 work. Difference of potential is a difference of elec- 
 trical condition. Potential of a battery means its 
 E.M F. 
 
 I
 
 1 1 4 CENTRAL-STA TION LIGHTING. 
 
 Power (P). — The rate of doing work. When an 
 ampere passes through an ohm, the unit power, called 
 a watt, is required. 
 
 Qtiantity (Q). — The Unit is the Coulomb. 
 
 Relay. — An electro-magnet which, receiving its 
 current from a distance, closes the circuit of a local 
 battery so as to produce the required effect of 
 strength. 
 
 Resistance (R). — The opposition presented by the 
 circuit to the development of the current. The Unit 
 of resistance is the Ohm. 
 
 Rheostat. — An instrument for inserting resistances. 
 A valuable artificial resistance employed for measur- 
 ing unknown resistances. 
 
 Return Ciirrent. — The current in the wire leading 
 to the machine. 
 
 Rigger. — The pulley or wheel by which power is 
 transmitted. 
 
 Secondary Battery, — Wrongly termed an accumu- 
 lator, is an appliance for storing energy in such a form 
 that it shall be available for the reproduction of elec- 
 tric currents. 
 
 Secondary Generator. — A transformer of a current 
 of high potential into a current of less E.M.F. 
 
 Series. — The plan of connecting lamps so that the 
 current passes one after the other. 
 
 Shnnt. — A coil of wire arranged to take a certain 
 proportion of any current. 
 
 Solenoids. — Helices of wire which act like magnets. 
 
 Switch. — An apparatus for changing one circuit on 
 to another. 
 
 Spectrum. — The elongated figure of the prismatic 
 colours.
 
 EXFLANA TION OF TERMS. 1 1 5 
 
 Torque. — Term used to express the strain on a 
 shaft due to electro-magnetic action. 
 
 Units. — The various bases of any system of mea- 
 surement. 
 
 Volt. — The Unit of electro-motive force and poten- 
 tial. An ampere multiplied by an ohm. (See Elec- 
 trical Measurements.) 
 
 Voltameter. — An apparatus for measuring the cur- 
 rent by its chemical action. 
 
 Voltmeter. — An instrument used for measuring 
 E.M.F. 
 
 Watt. — The Unit of power. A volt-ampere. The 
 horse-power electrical, taken as 746 B A watts, is 
 equivalent to only ^16 true watts. The horse-power 
 electrical is equal to 756 B A watts, which is equal to 
 746 true watts. The "force de cheval," or horse- 
 power in use abroad, is defined as 75 kilogrammetres, 
 and is, therefore, 736 true watts. 
 
 Work (W.) — Is a volt multiplied by a coulomb, or 
 amp.^ X sec x ohm or amp. X sec x volt. The Unit 
 is the Joule. 
 
 Yoke. — Is a term applied to the apparently neutral 
 mass of iron which connects the poles of a horse-shoe 
 magnet at the back. 
 
 I 2
 
 Tl6 
 
 CENTRAL-STATION LIGHTING. 
 
 Appendix I.— Principal Electric- 
 
 Name of 
 Station. 
 
 Approximate 
 Number of Lights. 
 
 Incan- 
 descent 
 or Glow 
 Lamps. 
 
 System employed. 
 
 Approxi- 
 mate 
 length of 
 longest 
 main 
 supply 
 conductor 
 
 Main 
 
 conductor 
 overhead 
 
 or under- 
 ground. 
 
 Approximate area] 
 of distribution J 
 
 Brighton 
 hltctric- 
 Light 
 Companj' 
 
 I, Fog 
 
 Cadogan 
 Electricity 
 Supply 
 Company 
 ;New Com- 
 pany' 
 
 High-tension \ 
 
 lamps in multiple 1 1 
 
 series Brush | i 
 
 Dynamos 
 
 jFdmunds' system) 
 < of Battery > 
 ( Transformers ) 
 
 Overhead 
 
 About 
 3 square miles 
 
 Overhead 
 
 Belgravia and 
 Cadogan Estate 
 
 Eastbourne 
 
 Lo«rie Hall 
 Transformers 
 
 I 7 miles 
 < under- 
 l ground 
 
 \ igh tension 
 
 with Ferranti 
 
 'J rans formers 
 
 primary 2,400 
 
 volts, secondary 
 
 100 volts, 
 
 Ferranti 
 
 dynamos 
 
 Kensington 
 
 Court 
 
 Electric 
 
 Lighting 
 
 Company 
 
 1600 
 to be ex- 
 tended 
 to 10,000 
 
 ' Crompton 105 
 I volts low tension, 
 constant supply 
 by means of 
 I accumulators 
 
 6 circuits, 
 
 total 
 
 about 
 
 70 miles 
 
 Very irregular 
 
 I district, a house 
 
 Overhead \ is lighted 2 
 
 miles from the 
 
 station 
 
 Under- 
 ground 
 
 Liverpool 
 
 Low tension 
 continuous 
 
 Current 
 dynamos 
 
 The streets 
 I adjoining the sta- 
 tion, the mains 
 to be continued 
 to another 
 station at 
 Knightsbridge 
 
 Leamington 
 
 I Chamberlain and" 
 Hookham ) 
 dynamos \vith 1 
 accumulators , 
 
 I* 
 
 Under- 
 ground 
 
 183 street lamps 
 
 iPaddington 
 
 <Electric 
 
 iLighting 
 
 jiSlU'HIf; 
 
 E. M. F. 150 
 .olts, Gordon 
 ternating cur- 
 |f I en; Dynamos 
 
 Under- 
 ground 
 
 67 acres
 
 APPENDIX I. 
 
 T17 
 
 Lighting Stations in Great Britain. 
 
 Working 
 CapitaL 
 
 Hours of 
 Supply. 
 
 Charges. 
 
 By Meter. 
 
 By yearly fixed amount. 
 
 Remarkst 
 
 ^12,000 
 
 Constant 
 
 'Glow lamps, u. per unit, or' 
 rather over \d, per lamp 
 per hour. Arc lamps, 4?. per 
 lamp per week including 
 maintenance 
 
 ;^ 20, 000 
 
 Constant 
 
 p.„, . ....... 
 
 \ averaging about 6i^. per> 
 
 jif consumption is below 
 100 units quarterly, xo\d. 
 \ discount. 
 
 A similar station at 
 Hastings. 
 
 ;^375,ooo 
 
 8a 
 to 
 
 3 
 
 M. ) 
 
 7iper 
 Board of 
 Trade 
 
 A station at Depford is 
 under erection to maintain 
 , 200,000 Hghts. 
 
 ;C2S,ooo Constant 
 
 By meter 
 and mini- 
 mum 
 charge of 
 
 xos. per 
 light per 
 
 annum 
 
 'Zd. per unit, equal to o's(>d.^ 
 per 20 C.-P. lamp per hour, 
 or o--2%d. per 10 C.-P. lamp. I 
 bhops taken at ;^2 per an-i 
 num per 20 C.-P. lamp mini- 1 
 mum of 10 lights , 
 
 {District embraces resi- 
 dences, shops, public hall, 
 and church. 
 
 ;^ 20, 000 
 
 By meter ]' (First 400 hours, i J. per unit 
 on sliding W Second ,, „ 8^. „ 
 scale ) (, Afterwards 4^/. „ 
 
 II 
 
 Board of Trade license for 
 six years, hotels, shops, 
 and residences. 
 
 Constant 
 
 meter 
 
 Street lights £1 2J. per annum 
 for 2,860 hours, including re- 
 newals. 
 
 I to 40 units per quarter 8^.1 
 per unit. 41 to 150 units per| 
 quarter, dd. per unit. 151 j 
 units per quarter ^. per unitj 
 
 Constant 
 
 Worked by G. W. Railway 
 
 (The district between Pad- 
 
 dington and Westbourne 
 
 \ Park is lighted throughout.
 
 ii; 
 
 CENTRAL-STATION LIGHTING, 
 
 Appendix I. — Prin'cipal Electric- 
 
 Name of 
 Station. 
 
 Approximate 
 Number ot Lights 
 
 Incan- 
 de cent 
 or Glow 
 Lamps. 
 
 System employed. 
 
 Approxi- 
 mate 
 length of 
 longest 
 main 
 su ply 
 conductor 
 in miles. 
 
 Main 
 condui tor 
 overhead 
 or under- 
 ground. 
 
 Approximate area 
 of distribution. 
 
 Barnet and 
 Di-t ict 
 E. Supply 
 Company 
 (New Com- 
 pany) 
 
 Chelsea 
 E. Supply 
 Company 
 (New Com- 
 pany) 
 
 Joel Dynamos 
 
 Overhead 
 chiefly 
 
 St. James 
 and Pall 
 Mall 
 
 (New Com- 
 pany) 
 
 Taunton. 
 
 Continuous 
 curicnt 
 
 Thompson 
 Houston 
 
 continuous 
 current 
 
 Overhead 
 
 Street lighting 
 
 Whitehall 
 Court 
 
 (New Com- 
 pany) 
 
 Westminster 
 
 Battery \ 
 
 Transformer \ 
 
 sy.>.tem ) 
 
 lo light hotels \ 
 in I 
 
 Northumberland 
 Avenue 
 
 West 
 
 Brompton 
 
 Ade'phi 
 Theatre 
 
 f LowTie Hall 
 I Transforme 
 
 ;i| 
 
 Continuous 
 
 current 
 
 dynamos 
 
 coupled direct 
 
 to engines 
 
 Bath (New 
 Company 
 
 86 
 
 Thomson 
 
 Houston 
 
 Dynamos and 
 
 Transformers 
 
 ID miles ] 
 
 when 
 
 completed ) 
 
 external ? 
 circuits ) 
 
 Over- 
 head I j The 1 uildings 
 and v< are dose 
 
 under- (l ( together 
 
 ground 
 
 .A.rc lights in streets
 
 APPENDIX 7. 
 
 119 
 
 Lighting Stations in Great Britain — continued. 
 
 Working 
 Capital. 
 
 £s,ooo 
 
 Hours of 
 Supply. 
 
 Charges. 
 
 By Meter. 
 
 By yearly fixed amount. 
 
 Remarks. 
 
 71 lamps in streets on posts 
 12 ft. high. 
 
 ;C20,000 
 
 Area to be ligh'ed adjoin- 
 ing station. 
 
 By yearly contract 
 
 Arc lamps of 1200-C.-P. 
 
 ^^24.753 
 
 Constant 
 
 ^,l?^.rtt 1 ■ (Proposed charge, Zd. per unit 
 < with minimum of 
 
 n.eter-rent 
 10s. per 
 quarter 
 
 per lamp per annum 
 
 Amalgamated w'th the 
 
 Metropolitan Electric 
 
 Supply Company. 
 
 New Company. 
 
 rnncfa (■ P f i/"^^^ station IS being erected by the House to House Lighting 
 
 (constant r.y me.er ^ Company, who also propose installations in other districts. 
 
 Private 
 
 The Adelphi Theatre, Adelaide Gallery, and Strand Re- 
 staurant are lit, the machinery being fixed in a basement 
 about 30 X 45 feet. No gas is laid on. 
 
 Yearly contract 
 
 The power obtained from 
 town weir supplemented 
 by steam engine.
 
 120 
 
 CENTRAL-STATION LIGHTING. 
 
 Appendix II. — Principal Electric- 
 
 Name of 
 Station. 
 
 Approximate 
 Number of Lights. 
 
 Incan- 
 descent 
 or Glow 
 Lamps. 
 
 Arc. 
 
 System employed. 
 
 Approxi- 
 mate 
 
 length of 
 
 longest 
 
 main 
 
 supply 
 
 conductor 
 
 in miles. 
 
 Main 
 conductor 
 overhead 
 or under- 
 ground. 
 
 Approximate area 
 of distribution. 
 
 Bergen 
 
 3,000 
 
 Brush 
 
 Overhead 
 
 Bellegarde . 
 
 Gramme dynamos 
 
 Overhead 
 
 Berlin 
 
 Edison lamps 
 100 volts 
 
 17.400 
 
 3,000 
 
 42,200 
 
 108 
 400 
 
 Under- 
 
 S'-o^^dM Nearly whole of| 
 business part of, 
 city 
 
 Breslau . 
 
 S,ooo 
 
 69 
 
 Siemens 
 
 Under- ■» f i, 
 ground j I 
 
 Brunswick 
 
 Edison 
 
 200 metres 
 radius 
 
 Crefeld . 
 
 1,560 
 
 Darmstadt 
 
 Dresden 
 
 Elberfeld 
 
 f Under- 
 l ground 
 
 }{ 
 
 Three-vtdre 
 system 
 
 Hamburg 
 
 Schuckert 
 
 Hemosand 
 
 Thomson 1 
 Houston i 
 
 Overhead 
 
 Halle 
 
 1.350 
 
 Edison 
 
 Under- 
 ground 
 
 Hanover. . 
 
 ! 10,000 1 
 to be in- 1 
 creased j 
 to 20,000 j 
 
 '13,000 feet radiusl 
 : from station j
 
 APPENDIX IT. 
 
 121 
 
 Lighting Stations on the Continent. 
 
 Description of 
 lighting. 
 
 Charges. 
 
 Hours of 
 
 Supply. 
 
 By Meter. 
 
 By yearly fixed amount. 
 
 Remarks. 
 
 {Street lighting 
 and public 
 buildings 
 
 )0f fr. o"4 per hour, or S| 
 francs per mondi for> Worked bywater power, 
 8-C.-P. ) 
 
 These instal- 
 lations supply 
 clubs, 
 theatres, 
 public build- 
 ings, and 
 street light- 
 ing 
 
 Railway 
 
 station and 
 
 mills 
 
 {Constant 
 service 
 
 r. per year fixed charge, 
 and \d. per hour per 
 i6 - C. - P. lamp ; arc| 
 lamps, td. and qd. perj 
 hour, and 6oJ. yearly 
 per light 
 
 (Stations at 
 Friedrich Street, 
 Mauer Street, 
 Schadou Street. 
 
 Mills and 
 factories 
 
 (Lighting of theVrDusk until J i 
 I Free Port J I dawn / 
 
 (Under construction. 2 
 block stations, i cen- 
 tral station. 
 
 (Yearly contract, which 
 I is less than former 
 ( lighting by oil. 
 
 Stadt Theatre 
 
 (Shops and pub-v 
 lie buildings / 
 
 Constant 
 
 'By meter] 
 to sub- 
 scribers 
 lor three 
 
 [ years J 
 
 \.o'ifld. per lo-C.-P. lampj 
 ( per hour ; 0*5^. per 16- > 
 I C.-P. )
 
 122 
 
 CENTRAL-STATION LIGHTING. 
 
 Appendix IT. — Principal Electric- 
 
 Name of 
 Station. 
 
 Approximate 
 Number of Lights. 
 
 
 Approxi- 
 mate 
 length of 
 longest 
 main 
 supply 
 conductor 
 in miles. 
 
 Main 
 conductor 
 overhead 
 or under- 
 ground. 
 
 Approximate area 
 of distribution. 
 
 
 Incan- 
 descent 
 or Glow 
 Lamp<. 
 
 Arc. 
 
 System employed. 
 
 
 Lucerne . 
 
 800 
 
 { Zippernowsky \ 
 1 high - ten-ion 1 
 j current withj 
 ( transformers j 
 
 4 
 
 Overhead 
 
 1 To be extended ] 
 < throughout > 
 ( Lucerne | 
 
 
 Lubeck . . 
 
 2,000 
 
 Ldison 
 
 
 " 
 
 •• 
 
 
 Milan . . 
 
 I 11,000 
 [ 1,000 
 
 210 
 
 Edison 
 Zippernowsky 
 
 i 
 
 f Under- 1 
 
 I ground j 
 
 >» 
 
 li square mile 
 
 fTheatre vidth 460 
 I lamps in houses 
 
 
 Munich . . 1 6,500 
 
 140 i Edison | ,, ,, 
 
 Two theatres 
 
 
 Rome . . 
 
 14,000 
 
 •• 
 
 Zippernowsky 
 
 4 
 
 Hotels and shops 
 
 
 Rotterdam . 
 
 1,000 
 
 . . 1 Edison 
 
 
 „ 1 
 
 
 St. Etienne . 
 
 3,000 
 
 If Edison, Three- \ 
 jl wire system ] 
 
 •• 
 
 " 
 
 
 
 Strassburg . 
 
 1,800 
 
 62 
 
 f Edison and "1 
 I Siemens / 
 
 •• 
 
 [ Under- ] 
 1 ground 1 
 jand over( 
 \ head j 
 
 Railway station, 
 and goods 
 j yards, 86 acres 
 \ area 
 
 
 Stuttgart . 
 
 1,060 
 
 •• 
 
 " 
 
 f Under- I 
 i\ ground / 
 
 Theatre 
 
 
 >chwerin . j 2,390 
 
 .. 1 
 
 .. 
 
 
 » 
 
 
 Tivoli . . 
 
 1,000 
 
 6 
 
 j Goulard high- | 
 < tension trans- > 
 ( formers ) 
 
 18 
 
 Overhead 
 
 /Principally street 
 I lighting 
 
 
 Tours . . 
 
 3.500 
 
 
 Goulard 
 
 i 
 
 3 j „ 
 
 " 
 
 
 Temi. . . 
 
 3.000 
 
 " 
 
 { Zippernowsky 1 
 I Transformers / 
 
 • • 
 
 •• 
 
 Town lighting 

 
 APPEXDIX II. 
 
 123 
 
 Lighting Stations on the Continent — contitmed. 
 
 Description of 
 Lighting. 
 
 Hours of 
 Supply. 
 
 Charges. 
 
 Remarks. 
 
 By Meter. | By yearly fixed amount. 
 
 In hotels 
 
 !f Dusk until] 
 \ midnight j 
 
 Motive power, water. 
 
 jThe district is 
 1 sened in a 
 j similar man- 
 ( ner to gas 
 
 Constant 
 
 Arc and 
 
 incan- 
 descent 
 ■^d. per 
 ampere- 
 hour 
 
 Installation charge per 
 
 lamp per 10 candles, 8.f. 
 
 „ 16 „ 2?.r. 
 
 ,, 32 „ 56J. 
 
 Arc lamp £2 per annum 
 
 rent 
 
 4 P.M. to 
 I A.U. 
 
 fOf 2 -08./. per 16 C.-P. 
 I lamp per hour 
 
 (The installation is 
 < owned by the gas 
 ( company. 
 
 Meter 
 
 hi-. 5(/. per 16 C.-P. lamp 
 , permonth,also fixed sum 
 [ of 2J. 11^. per lamp 
 
 'Also a block 
 I station fori fDusk untih' 
 I hotel and re-( I daylight / 
 staurants 
 
 Net cost o" lighting sta-' 
 tim, including 12 per 
 cent, for interest and 
 renewal. — Arc lamps, 
 2,id. per hour; 16 C.-P. 
 glow lamps, o'42^. per 
 hour; 10 C.-P. glow 
 lamps, o 32^/. per hour ; 
 8 C.-P. glow lamps, 
 o'2gd. per hour ; 
 
 Carried out by the rail- 
 way company. The 
 cost is estimated at 
 one-third less than 
 gas. 
 
 One central station. 
 One block station. 
 
 (Motive power, water ; 
 < yearly contract for 
 ( street lighting. 
 
 , c V -v .. J s (Three distnbutmg sta- 
 
 bubscnbers at 2J. qd. per) J »• „^ , .„ 1 ,„ i,„ 
 
 \ a r^ -n ^ ^u i \ tions at work, to be 
 
 I 16 C.-P. lamp per month/ ] • _„^_j ,^ ,. ' 
 
 increased to ten. 
 
 (Charge 0*4;/. to i*3(/. per 
 [l hour according to C.-P.
 
 124 
 
 CENTRAL-STATION LIGHTING. 
 
 Appendix II. — Principal Electric- 
 
 Name of 
 Station. 
 
 Approximate 
 Number of Lights. 
 
 System employed. 
 
 Approxi- 
 mate 
 length of 
 longest 
 main 
 supply 
 conductor 
 in miles. 
 
 Main 
 conductor 
 overhead 
 or under- 
 ground. 
 
 Approximate area 
 of distribution. 
 
 
 Incan- 
 descent 
 or Glow 
 Lamps. 
 
 Arc. 
 
 
 Treviso . 
 
 800 
 
 
 1 Zippemowsky \ 
 \ transformers J 
 
 
 Overhead 
 
 Town lighting. 
 
 
 Turin . . 
 
 1,000 1 100 
 
 Edison 
 
 •• 
 
 r Under. Vf Street lighting by 
 I ground / I arc lamps 
 
 
 Temesvar . 
 
 760 
 
 •• 
 
 J Brush machines ;| 
 [Lane-Fox lamps ) 
 
 3 
 
 Overhead {^^"^^7^-^'^°^ 
 
 
 Vienna . . 
 
 8,000 
 
 ! 
 
 Crompton Low- \ 
 
 tension dynamos! 
 
 with battery j 
 
 transformers j 
 
 i 
 
 1 Opera-house, 
 (■ Under- ) ) Court theatre, 
 I ground / j and municipal 
 
 1 buildings 

 
 APPENDIX II. 
 
 125 
 
 Lighting Stations on the Continent— cc7;i//««c'6!'. 
 
 
 Description of 
 Lighting. 
 
 Hours of 
 
 Supply. 
 
 Charges. 
 
 Remarks. 
 
 
 By Meter. 
 
 By yearly fixed amount. 
 
 
 ! .. ' 
 
 .. 
 
 •• 
 
 
 j .. j 
 
 f Thomson Houston arc ) 
 I lamps / 
 
 
 
 i 
 
 fStreet lighting]' fDusk until] 
 I chieriy J I dawn /j 
 
 Street lighting, 1-5 kreut- 
 zer per 16-C.-P. lamp 
 per hour 
 
 Private consumers, i'8i 
 kreutzer 
 
 •• 
 
 
 
 •• 
 
 •• 
 
 fBy contract at a price] 
 I about double gas ] 
 
 TThis installation is being 
 1 put down by the gas 
 j companywhich 
 ( lights the city.
 
 ( I2S ) 
 
 INDEX. 
 
 Arc Lamps, 
 
 places where suitable, lo. 
 
 charges for, lo. 
 
 at ^iilan, 47. 
 
 Accumulators, 
 
 at Kensington Court, 69. 
 
 at Vienna, 76. 
 
 Birmingham wire gauge resistance 
 
 table, 105. 
 in French measurements, lOO. 
 
 Central-stations, 
 
 Siemens' suggestion for, I. 
 
 at Philadelphia, 2. 
 
 block, 3. 
 
 construction, 3. 
 
 selection of district for, 4. 
 
 relation between daily output 
 
 and capacity, 7. 
 
 loss in, 15. 
 
 at Deptford, 31. 
 
 at Eastbourne, 31. 
 
 at Brighton, 32. 
 
 at Tours, 32. 
 
 at Vienna, 76. 
 
 position of, 16. 
 
 in United States, 17. 
 
 at Grosvenor Gallery, 27. 
 
 Kensington Court, 20, 68. 
 
 methods of lighting from, 20. 
 
 tables showing cost of, 86, 87. 
 
 Cost of gas compared with electri- 
 city, 8. 
 
 Cost of kerosene, 9. 
 
 Cost of arc lighting, lo. 
 
 Conductors, 
 
 relative size of, for different 
 
 systems, 22. 
 
 arrangement of, at Grosvenor 
 
 Gallery, 28. 
 
 primary conductors at Gros- 
 venor Gallery, 30. 
 
 diagram of network system 
 
 of, at Milan, 46. 
 
 diagram of multiple series 
 
 system at Temesvar, 60. 
 
 conduits for, in New York, 92, 
 
 93» 94- 
 
 Distribution of Electricity, 
 
 Edison parallel system, 41. 
 
 Edison feeders, 42. 
 
 three wire system, 43. 
 
 series system, 52. 
 
 Bernstein system, 57. 
 
 multiple series system, 58. 
 
 by means of secondary bat- 
 teries, 65. 
 
 system of, at Kensington 
 
 Court, 69. 
 
 Dynamotors, 79. 
 
 Swinburne's Compound, 83. 
 
 Electric Lighting, 
 
 as an investment, 3, 9, 97. 
 
 people who most readily take 
 
 it up, 4. 
 relation between number of 
 
 lights used and number fixed, 4, 5.
 
 INDEX. 
 
 127 
 
 Electric Lighting — continued. 
 
 cost of, to householder, 5. 
 
 diagram of, in London dis- 
 trict, 6. 
 
 diagram of, at Cincinnati, 7. 
 
 charges for, 8. 
 
 description of arc and glow, 9, 
 
 at Tilbury Docks, 18. 
 
 at Victoria Station, 18. 
 
 at Paddington Station, 19. 
 
 relative cost of, for direct and 
 
 transformer systems. 21, 27. 
 
 at Lucerne, 34. 
 
 at Milan, 34, 44. 
 
 cost of, at Milan, 48. 
 
 at Berlin, 52. 
 
 cost of, at Berlin, 53. 
 
 Bernstein system of, 55. 
 
 diagram of, system at Col- 
 chester, 67. 
 
 working cost of, at Athen^um 
 
 Club, 88. 
 
 working cost of, at Naval and 
 
 Military Club, 89. 
 
 working cost of, at South 
 
 Kensington Museum, 89. 
 
 working cost of Thomson- 
 Houston system of, in an Ameri- 
 can city, 90. 
 
 Experiment at the Teatro dal 
 Verone, 34. 
 
 Faults, discovery of, 51. 
 
 Gas Lights, 
 
 heat from, advantages and ob- 
 jections, 3. 
 
 • number used and fixed, 4. 
 
 • cost of, at Berlin, 53. 
 
 • cost of, to householder, 5. 
 
 Glossary, 107. 
 
 Incandescent Lamp" 
 number obtaincu per electri- 
 cal HP., 8. 
 
 illustration of, 1 1. 
 
 candle power of, 1 1. 
 
 consumption ofenergy in, 10,63. 
 
 ■ life of, II. 
 
 • blackening of, 1 2. 
 
 at Temesvar, 63. 
 
 Lighting, 
 
 number of hours of, per annum, 
 
 4- 
 
 cost of, to London house- 
 holder, 5. 
 
 diagram of, in London dis- 
 trict, 6. 
 
 diagram of, at Cincinnati, 7. 
 
 diagram of, 13. 
 
 relative cost of, with direct 
 
 and transformer system, 22. 
 
 relative cost of, by electricity 
 
 and gas, 91. 
 
 Lucigen light, the, 99. 
 
 cost of working, lOO. 
 
 Machinery at Grosvenor Galler)-, 
 29. 
 
 Motors, Electric, 39. 
 
 diagram showing power sup- 
 plied to, in Boston, 40. 
 
 purposes used for, in America, 
 
 39. 
 Meters, Electric, > 
 
 the Edison, 49. 
 
 the Aron, 54. 
 
 Mackenzie's conduits for electric 
 
 light cables, 95. 
 
 Priestman's petroleum engine, 98. 
 
 Regulation of E. M. F. at Gros- 
 venor Galler}', 29. 
 
 Regulation of E. M. F. at Milan, 
 44. 
 
 Rent of meters at Milan, 49. 
 
 Rent of meters at Berlin, 53. 
 
 Regulators for secondary batteries, 
 76. 
 
 Resistance of Copper Wire, 105, 
 106. 
 
 Speed indicators at Grosvenor Gal- 
 lery, 29. 
 Safety luses at Grosvenor Gallery, 
 
 31- 
 
 Safety fuses at Milan, 47. 
 Switch, double pole, 72.
 
 128 
 
 INDEX. 
 
 Table I. showing cost of laying con- 
 ductors, 74, 75. 
 
 Table II. showing cost and main- 
 tenance of plant, 86, 87. 
 
 Table showing resistance, &c., of 
 copper wire, io5» 106. 
 
 Table showing principal electric 
 lighting stations in Great Britain, 
 116-119. 
 
 Table shownng principal electric 
 lighting stations on the Continent, 
 120-125. 
 
 Terms, explanation of, 107-115. 
 
 Transformers, 
 
 application of, 27. 
 
 diagram of Ruhmkorff type of, 
 
 23- 
 
 description of Ruhmkorff type 
 
 of, 23. 
 arrangements of circuits of, 
 
 24. 
 
 two classes of, 24. 
 
 Kapp & Snell, 27. 
 
 • distribution of electricity by 
 
 means of, 21. 
 
 Transformers — continued. 
 
 prevention of shocks from, 30. 
 
 Westinghouse converters, 35. 
 
 potential used in, 38. 
 
 direct current, 79. 
 
 comparison between alternate 
 
 and direct current, 80. 
 
 Swinburne's dynamotor, 83. 
 
 advantages of Zippernowsky- 
 
 Deri system of, 34. 
 Turbines working the dynamos at 
 
 Tivoli, 32. 
 Turbines working the dynamos at 
 
 Lucerne, 33. 
 
 Useful Notes, 101-103. 
 
 incandescent lights, 102. 
 
 arc lighting of works, IC2. 
 
 approximate cost, 102. 
 
 wire running, 103. 
 
 Electrical Measurements, 104. 
 
 Westinghouse system, 35. 
 
 at Pittsfield, 37. 
 
 Wires overhead or underground, 91. 
 
 LONDON: PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, STAMFORD STREET 
 AND CHARING CROSS.
 
 UNITED 
 
 ELECTRICAL ENGINEERING 
 
 COMPANY, LIMITED. 
 
 THE COMPANY have exceptional facilities for carrying out contracts 
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 work, enabling the Company to give prompt attention to the demands of 
 their clients. 
 
 Contractors for 
 CENTRAL ELECTRIC 
 
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 Please apply for complete list of Electric Light and Poiver Supplies to— 
 
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 THE GLOBE ELECTRICAL AND 
 
 ENGINEERING COMPANY. 
 ELECTRICAL AND GENERAL ENGINEERS. 
 
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 No. I Department comprises all Electric Light Fittings, also Ornamental 
 Electroliers, Pendants, Brackets, Ceiling Plates, or Rosettes, Globe Lamps 
 and Globe Lamp Holders, also Glass Shades and Fringes in coloured glass 
 of many varieties. 
 
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 in Stock, also Cable, Silk and Cotton Covered Wire. 
 
 Address :-The MANAGER, 
 
 Offices-7, CARTERET STREET. 
 
 Supply Stores: 20, Dartmouth Street, Westminster,S.W. 
 
 Telegraphic Address, " Globulous, London."
 
 CARBON WORKS, BARNSLEY. 
 
 THE 
 
 Glohe Electrical & Engineering Company. 
 
 CARBON CUTTERS AND GRINDERS. 
 
 GO 
 (Q 
 O 
 PC 
 
 O 
 
 P^ 
 
 o 
 
 GO 
 
 ELECTRIC LIGHT CARBON RODS (Fig. 6), cored and solid, 
 coppered and plain. All sizes in stock from 4 to 40"'"^- 
 Makers of Sir James Douglas's Rods (Fig. 4), as used by the Trinity House. 
 CARBON PLATES for Leclanche Batteries, etc. (Fig. 3), Consolidated 
 Battery Plates, made to withstand nitric acid or bichromate, can be 
 supplied up to I3ins. + loins, out of stock, and larger sizes to order. 
 CARBON CELLS AND CYLINDERS (Figs, i, 2, and 5), of 
 all descriptions. 
 Experimental Carbon Goods of every description made to Order. 
 
 Offices.— 7, CARTERET ST., WESTMINSTER, S.W.
 
 THE GULCHER 
 
 ELECTRIC LIGHT & POWER CO., LTD., 
 
 BATTERSEA FOUNDRY, BATTERSEA, LONDON, 8.W. 
 
 Manufacturers of Electrical Machinery 
 
 OF EVERY DESCRIPTION. 
 
 Contractors to H.M. NAVY, H.M. WAR DEPARTMENT, 
 
 Sir W. G. ARMSTRONG & CO., 
 
 OUDH AND ROHILKUND RAILWAY CO., etc., etc. 
 
 THE COMPANY SUPPLY- 
 DYNAMOS. Series, Shunt, and Compound Wound. 
 ARC LAMPS. Projectors, Search Lights, etc. 
 SWITCH BOARDS and Fittings. 
 ALTERNATING CURRENT DYNAMOS. 
 TRANSFORMERS. 
 SECONDARY BATTERIES. 
 
 COMPLETE INSTALLATIONS for lighting TOWNS, PUBLIC 
 BUILDINGS, MILLS, FACTORIES, IRONWORKS, and 
 COLLIERIES, also PRIVATE HOUSES and MANSIONS. 
 
 SOLE CONTRACTORS for the PERMANENT LIGHTING of the 
 CRYSTAL PALACE, Sydenham, and the ROYAL AQUARIUM, 
 WESTMINSTER, also the CITY of WELLINGTON, New Zealand,
 
 WOODHOUSE & RAWSON, 
 
 XjIIMIITEID. 
 
 (Electrical dnc^inecvs anb Contractors, 
 
 FOR THE 
 
 LIGHTING OF CITIES, TOWNS, FACTORIES, MILLS, 
 
 AND 
 
 COMPLETE CENTRAL STATION PLANT. 
 
 Houses Wired and Fitted throughout for connection 
 to Central Station Circuits. 
 
 Estimates on ^Application. Pood y/oRK at JvIoderate P'rices. 
 
 11, QUEEN VI CTORIA STREET , LONDON, E.G. 
 
 Contractors to the Chief Exhibitions, Stock Exchange, Messrs. W. H. Smith &» Sons, 
 Peak, Frean &> Co., Crosse 6^ Blachwell, Grosvenor Gallery, &^c., 6^0. 
 
 THE 
 
 Orient Eleetrie Light Gompanj 
 
 I LONDON. CALCUTTA. MADRAS. RANGOON. | 
 
 Contractors for the supply of Electric Lighting Plant for Private Houses^ 
 
 Public Buildings, Factories, Towns, ^c, on the most approved 
 
 system ayid at moderate cost, 
 
 QUOTATIONS GIVEN FOR TEMPORARY INSTALLATIONS. 
 
 Central Stations Fitted Out, and Negotiations 
 carried on for same. 
 
 ESTIMATES AND QUOTATIONS FREE. 
 
 Xonbon ®fficc6 : 2, lEa^t 3nMa Hvcnue, ie,C. 
 
 ^Agents ^broad : 
 
 Messrs. QILLANDERS, AEBUTHNOT & CO. . . . Calcutta and Rangoon 
 
 Messrs. GORDON, WOODROFFE & CO Madras. 
 
 Messrs. EWART, LATHAM & CO Bombay.
 
 Crown Svo.j 12S />/>., Limp cloth^ 40 Illustrations. Price 2s. 6d. 
 
 PRECAUTIONS TO BE ADOPTED ON INTRODUCING 
 THE ELECTRIC LIGHT. 
 
 WITH NOTES ON THE PREVENTION OF FIRE RISKS. 
 
 CONTENTS. — /7>^ I^isk Co77imittee— Resistance of Conductors — Glow 
 Lamps — Sizes of Main and Branch Conductors — Standard and Birmingham 
 Wire Gauge — Factors for Calculation — Runtiing of Wires — Switches — Connectors 
 and Joints— Ifisulators — Short Circuit — Cut-out, Fusible, and Automatic — 
 Lamp Holders — Life of Lamps, Electrical Gover?ior, Speed Gauge — Testing 
 Insulation — Fires and Accidents from Electric Current — Specification for Electric 
 Lighting — Instructions for Working — Phcenix Fire Office Rules — American Fire 
 Office Rules — Electrical Measurements — Resistance of Copper and Germafi Silver 
 — English and French Measure — Rules for Fusible Mica-Foils — Rules for 
 Direction of Current — Number of Electric Lights to compare zvith Gas — Motive 
 Power, Steamy Gas — Motive Power ^ Water — Explanation of Terms — Price 
 List. 
 
 OPINIONS OF THE PRESS. 
 
 The Bicilder. 
 
 " Mr. Hedges points out clearly the risks that are inseparable from slovenly work and 
 incompetent handling, and gives clear directions for carrying the main and branch conductors 
 and the lamp wires, and for calculating the sizes of the various leads according to the 
 number of lights to be worked. He insists very properly that some regular system should 
 be followed, so that it should always be known which is the positive and which the negative 
 wire, — in other words, which wire leads from the machine to the lamps, and which is the 
 return. In addition, however, to showing this by mere position, i.e., bv placing the positive 
 wire on the left side of the negative if vertical, and under it if horizontal, we should strongly 
 recommend that the insulating covering should be of different colours on the two wires, and 
 thus any accidental displacement would not be of consequence." 
 
 Revue Internationale de PElectricite. 
 
 " Ce petit livre sans pretention contient une grande quantite de renseignements pratiques. 
 Tous ceux qui s'occupent d'cclairage electrique trouveront grand profit a le consulter. 
 
 "Dans les quatre-vingts pages que contient ce travail, I'auteur a su rassembler toutes les 
 indications necessaires et utiles pour effectuer les installations. II n'etait pas possible de 
 grouper d'une maniere plus logique, plus claire et plus concise les regies a suivre pour assurer 
 le bon fonctionnement d'une installation d'eclairage. 
 
 " L'auteur s'est etendu surtout sur la description et I'installation des appareils de surete, sur 
 la pose des conducteurs et sur les diametres a leur donner, sur I'essai des circuits, etc. . . 
 
 "Un petit dictionnaire, donnent I'e.xplication des terms tecliniques, complete d'une maniere 
 heureuse ce petit guide qui sera consulte avec autant de profit que bien d'autres ouvrages 
 plus etendus et congus dans un esprit moins pratique. 
 
 "Aug. M." 
 
 Copies of the above can be obtained from 
 
 The Glok Electrical and Engineering Company, 
 
 7, CARTERET STREET, WESTMINSTER, S.W. 
 Manufacturers of Electrical Supplies.
 
 E. AND F. N. Spon, London. 
 
 Cr(nvn %vo. 156 //. Cloth gilt. Price y. 
 
 Useful Information on Electric Lighting. 
 
 EMBODYING THE 
 
 RULES OF THE FIRE RISK COMMITTEE AND THE 
 ELECTRIC LIGHTING BILL; 
 
 PLAIN DIRECTIONS for the WORKING of ELECTRIC LAMPS 
 AND DYNAMO MACHINES. 
 
 By KILLINGWORTH HEDGES, 
 
 M.I.C.E.y M. Soc. Telegraph Engineers, F.CS. 
 
 CONTENTS.— Introductory Remarks— The Production of Electricity—The 
 Voltaic Arc — Division of the Electric Light — Machines or Generators — Power 
 required, and Motors — Application of the Electric Light — Choice of a System — 
 Electrical Measurement — Cost of Working — Result oj Various Installations — 
 Measurement of Light and Current — Storage of Electricity and Transmission of 
 Power — Conclusion — Useful Tables and Memoranda. 
 
 The Graphic^ 
 
 "At the present time, when the question of illumination by electricity is 
 fully under discussion, a third edition of Mr. Killing^vorth Hedges' Useful 
 Information on Electric Lighting is doubly welcome. The little work is now 
 fully brought up to date, and gives a plain, straightforwardly written account 
 of the various forms of the arc and incandescent lamps, and, indeed, of the 
 general system of electric lighting. Thus a very fair idea of the principle may 
 be gathered by the general reader, who will find it a welcome companion 
 when visiting the Electrical Exhibition, while the manufacturer in search of 
 a practicable light for his workshop will gain valuable information from the 
 various hints conveyed in its pages. To the scientific student also the work 
 will be exceedingly useful, if only from the handy memoranda and tables in 
 the appendix. Altogether the book is the best of the kind that we have yet seen^ 
 and we cannot refrain from hoping that Mr. Killingworth Hedges may see fit 
 to bring out a more compendious and detailed work on the subject, with 
 which he is so eminently competent to deal." 
 
 AlsOy by the same Author, demy Svo. Illustrated, 32 pp. Paper. Price \s. 
 
 The Snpply of Electricity by Local Authorities. 
 
 Read at the Annual Meeting of the Association of Municipal 
 Engineers and Surveyors, Oxford, 1883. 
 
 All Mr. Hedges' books are sent post free on receipt of postal order, by 
 the Globe Electrical and Engineering Company, Supply Stores, 
 7, Carteret Street, Westminster, S.W.
 
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 CARSON WORKS: 
 
 BARNSLEY, 
 YORKSHIRE. 
 
 LONDON OFFICE: 
 
 7, Carteret Street, 
 
 Westminster, S.W.
 
 J. EDMUNDSON & CO., 
 
 LIMITED, 
 
 Engineers & Electricians, 
 
 19, GI[EAT GEORGE ST, WESTMINSTE}[, S.W. 
 
 Electric Xigbting for Country? 
 anb Zomx fIDanaione, &c 
 
 J^ 9 EDMUNDSON & CO., invite an inspection of their Complete 
 tS)*^ System of Lighting Country and Town Mansions, by means 
 of Incandescent Electric Lights. 
 
 A COMPLETE INSTALLATION consisting of DYNAMO 
 MACHINE, ENGINE, STORAGE BATTERY and LAMPS, 
 may be seen working at J. E. & Co.'s SHOW ROOMS, ig, GREAT 
 GEORGE STREET, WESTMINSTER, where all information, 
 including Estimates of Cost, &c., may be obtained. 
 
 ESTIMATES ALSO GIVEN FOR TEMPORARY LIGHTING BY MEANS OF 
 STORAGE BATTERIES, FOR BALLS, RECEPTIONS, &.C. 
 
 SPECIAL AGENTS FOR 
 
 EDISON & SWIN LAMPS* 
 
 Special Terms to the Trade, 
 
 JVIanufactuf^er^ or E^ectrojlier^, Bracket^, 
 
 AND 
 
 All Descriptions of Electric Light Fittings.
 
 Bentral Station Lighting. 
 
 THE KAPP TRANSFORMER. 
 
 THE CONNAUGHT 
 
 XlfFPnating-OurrFnl^ Hgnarao. 
 
 (KAPP'S \ PATENT.) 
 
 SHARP AND KENT, 
 
 ENGINEERS AND ELECTRICIANS, 
 
 Connaught Mansions, Victoria St., Westminster, S.W 
 
 Telegraphic Address — 
 ''MEGAVOLT, LONDON." 
 
 TELEPHONE, 3,125
 
 DR. ARONS ELECTRICITY METERS 
 
 For Alternate and Continuous Current. Used in all the most 
 Important Central Stations in the World. 
 
 THLE OEIVERAL ELEOTPftIO CO., 
 
 (G. BINSWANGER & CO.) Mamtfactiirers and Suppliers of 
 The APOSTLE Carbons. | China and Glass Ware, I Switches, Lamps, Cables, Casings, &c. 
 The best without exception. \ In great variety.', \ Electrical Fittings of every description. 
 
 LONDON ; 
 
 THE GENERAL ELECTRIC CO. 
 
 5, Great St. Thomas Apostle, 
 
 London, E.C. 
 
 Telegravis : '^£lectriciiy." 
 
 Telephone: "1887."- 
 
 MANCHESTER: 
 
 I\L\NCHESTEK ElECTRIC WoRKS Co., 
 
 (G. BiNSWANGER, Managing Director,), 
 
 45, Chapel Street, Salford, 
 
 Manchester. 
 
 Telegrams: ^^ Induction."
 
 THE GLOBE ELECTRICAL AND 
 ENGINEERING COMPANY. 
 
 Offices:—!, CARTERET ST., WESTMINSTER, S.W. 
 
 MANUFACTURERS OF 
 
 HEDGES' PATENT SAFETY CATCHES, OR CUT-OUTS, 
 
 FUSIBLE SAFETY PLUGS AND OF ALBO METAL MICA FOILS. 
 
 Directions for inserting a Spare Mica Foil. — Undo the Contact 
 Screws, lift the Contact Pieces and place Foil fairly under, and screw down, 
 taking care not 'to jam the Mica on to the Foil, which should be loose, 
 so as to allow for expansion. 
 
 Certificate from the Vienna Exhibition^ which was protected througho7it 
 
 by ''Hedges' Patent Fuses:' 
 
 [Translation.] 
 
 THE PATENT HEDGES' CUT-OUTS have found a useful sphere 
 
 of employment in the labours of the Technical Scientific Commission, and 
 
 ,their construction has proved itself most admirably adapted to the ends 
 
 in view. 
 
 The President of the Technical Scientific Commission, 
 Vienna, lyh May, 1884. {Signed) F. STEFAN.
 
 MEMORANDA.
 
 MEMORANDA. 
 
 University of California 
 
 SOUTHERN REGIONAL LIBRARY FACILITY 
 
 405 Hilgard Avenue, Los Angeles, CA 90024-1388 
 
 Return this material to the library 
 
 from which it was borrowed.
 
 W. T. GOOLbMN TUS.; 
 
 Electrical Engineers, ^ 
 
 Contractors to Her Majesty's Govcrnjuent and the Principal Railway Companies. 
 Sole Manufacturers of the Connaught (Kapp's Patent) 
 
 Alternating (Current Dynamo and Cransformers ; 
 
 GOOLDEN-RAVENSHAW CONTINUOUS -CURRENT DYNAMO; 
 Electric Motors for all purposes ; 
 
 MEASURING INSTRUMENTS; 
 CARDEW VOLTMETERS 
 
 (The only Reliable Instruments for Alternating Currents) ; 
 
 Evershed Patent Gravity Voltmeters and Ammeters 
 
 (Not afifected by the proximity of dynamos). 
 
 Complete Estimates furnished for Central Stations, Plant for 
 
 Alternating and Direct Currents, or for Batteries, Engines, 
 
 Boilers, etc., by the Best Makers only, and of the most 
 
 economical types. 
 
 ^(^Tall plants supplied can be tested at our own works. \^ 
 
 Offices and Works : 
 
 WOODFIELD ROAD, WESTBOURNE PARK, LONDON, W.