M. GOIRAND proposed the following additional paragraph: "The dispositions which precede shall be no obstacle to the creation and working, by communes, of telephone lines serving their districts. These creations and workings will be regulated by a decree in the form of a regulation of public administration."

M. Goirand and the Reporter of the Committee having spoken, Article 3 was put and adopted. Articles 4 and 5 were also adopted, and then M. MERILLON spoke on the whole project as follows: Before voting the whole of this law, I wish to put a question to the Director-General of Posts. I wish to know whether that gentleman intends to take steps so that the telephone staff shall not be victims of the suppression of the company's service.

M. COULON, Government Commissary: The desire of the Government is to add to the staff of the Posts, if not the whole of the staff, at least the lesser staff of the telephone company. Our intention is to subject the servants whom we retain to a probationary period before employing them under the State. It is the intention of the Government to lower the tariffs; but the Chamber will understand that in this connection the Government must reserve its entire liberty of action.

M. FAURE: It could make known its intentions. M. COULON: The Government cannot fix and make known at present the precise limits in which this lowering of tariffs will be realised. The question to be solved touches upon an order of very complex considerations; it must be made the object of a preliminary examination; it must be subjected to profound study. In these conditions, the Government must limit itself to affirm-and it does so in the most formal manner that it enters absolutely into its intentions to benefit the public by a notable reduction.

M. DE KERGARIOU: What proves that the calculations of the Government repose on nothing determined is that it cannot enter into any decided engagement

now.

The PRESIDENT: I now put to the vote the whole of the project.

A demand was made for a scrutiny, and the President announced the result as follows:-Number of voters, 500; absolute majority, 251; for the adoption, 435; against, 65.

THE ELECTRIC LIGHT IN BERLIN AND AT ELBERFELD.

From "Le Bulletin de la Société Belge des Electriciens."

(Concluded from page 63.)

AT ELBERFfeld.

On arriving at Elberfeld, the railway makes a slight curve round the town, and it is thus seen as in a hollow. Seen thus at night, the town resembles one of those great factories, like that of Krupp, at Essen, for which electric lighting has become, as in Belgium, the general rule. The white electric light globes appear numerous, hidden in turn by the buildings, themselves set off by their white windows. A characteristic glimmer illumines the air, charged with steam, and forms like a dome of clearness above the agglomeration. What gives Elberfeld this peculiar appearance at night is the quantity of arc lamps used in the streets for lighting shop fronts. These lamps are placed outside, like reflected gasburners which are used now, specially by jewellers. There is a notable economy for shops to replace this row of gasburners by these electric lamps placed outside. This private lighting contributes largely to the lighting of the public streets, and the promenaders, by the irresistible attraction of this light, direct their way to the points thus abundantly lighted. There is, again, in the streets of Elberfeld, the most complete variety of all kinds of lighting. By the side of a shop lighted with magnificent petroleum lamps, one finds a hairdresser's shop, or a cigar shop,

[JULY 26, 1889.

lighted by incandescent lamps; there, gas with the old shaded burners, or Wenham and Butzke lamps; elsewhere, arc lamps outside or in. There are few applications of electricity to public lighting. The Elberfeld station is communal; it was constructed for the city by the firm of Siemens & Halske. This firm had to work the station two years before handing it over; the guarantee for the cables was fixed at five years. The station is built nearly in the centre of the town, 200 metres from the river, in the Hofkampferstrasse. It will be remarked here, as at Berlin, that the choice of a position for the stations (for direct currents) is regulated especially by the preoccupation of a situation favourable to the distribution of the current, considerations relative to the carriage of the necessary coal and water being considered second. The following are details of this station :-It has a superficies of 400 square metrès for the machinery room, and of 484 for the generators. It has been fitted to supply 10,000 16-candle lamps; it will allow of 14 dynamos of 43,000 watts each, or 602,000 watts altogether. These dynamos will be worked by seven steam engines, of Kuhn's (of Stuttgardt) system, with Knüttel regulation, of 170 horse-power effective, fed by five Cornish boilers with 123 square metrès of heating surface. The line is calculated for 10,300 lamps of 60 watts, of 100 to 120 volts. The system in use is that known as the three-wire; the dynamos work two in series. The greatest length of the cable is 800 mètres on one side, and 970 mètres the other side of the station. This system shows the advantage of a great saving in cables over the two-wire system of Berlin, and, consequently, permits of transport to greater distances. The largest cable (triple) employed at Elberfeld has a section of 3 × 330 square mètres. The three cables are concentric and enclosed in a single armed covering. Let us remark that this system is to be employed at the new stations being constructed at Berlin, and also at Mülhausen. The commutation table in the Elberfeld station is very interesting.

The working of this station was begun on November 15th, 1887, with 2,500 lamps installed. The present number of subscribers is about 100, with 4,300 lamps installed, or their equivalent (nearly 2,300 incandescent lamps and 250 are lamps). Four engines and eight dynamos are at work, of which a fourth is in reserve. The average use of the lamps installed has been 1.75 hour per day from November, 1887, to November, 1888. In winter the average use is three hours. Satisfaction is expressed at Elberfeld with Aron meters. The number of meters of 12 ampères (the smallest) is 50 per cent. ; those of 25 ampères form 30 per cent. of the total of subscribers. The conditions of subscription at Elberfeld differ little from those of Berlin. The price of the ampère hour is the same. The prices of placing the meters are lower. The annual tax of 6 marks per lamp installed is not maintained; but each lamp must burn an average throughout the year of 1 hour per day. If, according to the indication of the meter, it is found that the lamps have not been used this minimum number of hours, a charge is made of 2 pfennigs for each hour wanting. The official results published are very favourable; it will be understood, however, that conclusions, at the end of the first year of working, would be premature. In order that these conclusions should be of value, it is necessary that the working should be more advanced and in its normal course. The results from April, 1888, to April, 1889, will soon be known and published. The confidence in the working on a large scale of the electric light is so great in Germany that several municipalities have not hesitated to follow the example of Elberfeld. Installations at Hamburg, Lubeck, Bremen, Frankfort and Magdeburg are being carried out. It is to be remarked that in Germany few applications have hitherto been made of the system of distribution by transformers. Some accumulators are employed at Vienna; they will also be utilised at Darmstadt and Barmen. The imposing Ferranti installations at Deptford, where engines of 10,000 horse-power will be at work at the end of the year, and at Kensington, will show us much as to the

use of high-tension currents. It will be particularly interesting to see how the cables will behave under a 10,000 volt potential. According to the declarations of M. Ferranti before the Board of Trade, the trial made with a potential of 1,000,000 volts on a certain length of cable was very satisfactory.

The reason why low tension has been generally adopted in the installations hitherto made is the small extent of the line. In most cases, the distribution of electricity has been limited to a single central part of the town in which direct supply, without transformation, was possible without leading to an exaggerated expense for canalisation. The three-wire system allows of the distribution within a radius of a kilomètre. When more considerable extensions are entered upon high tension currents will probably be utilised. Then the experience of this kind of distribution will be more complete; and, without doubt, also, alternate current electro-motors will be found and experimented

on.

But there is a desire not to wait; electricity becomes a general need. The light "de luxe," as the gasfitters call it, in regard to its present price, will in a few years have taken a formidable extension. There is no longer a town, however unimportant, which does not seek the means of installing it. The luxury, moreover, is a very relative matter. Nearly every novelty begins by being an object of luxury, a superfluity for which the need does not exist. This law is verified in small things as in great. When the first Swedish matches arrived in the country, it seemed that they would never succeed in making us abandon those which had till then perfectly satisfied us; to-day they are in every household. When the first tramways were laid down, they were only looked upon as a modification applicable with utility to the long line of omnibuses; at present the towns are crowded with trams, and the receipts are as high for the big lines as for the small. It will be exactly the same with the electric light. Its price, which is higher than that of gas, to-day restricts its use to special cases where its advantages are evident-theatres, public establishments, shops, and workshops. But we are convinced that the greater number of those who now pay for the luxury of lighting by gas will only wait to take to electricity till its price be lower or equal to that of gas. Despite all the improvements in intensive burners the preponderating place of gas in the domain of lighting will be invaded by electricity as soon as it is suitably worked on a large scale. Further, the electrical industry every day makes marked progress, and the reduction in price is only a question of time. Gas is perfectly suitable for uses in which it is a question of producing warmth. But, in producing light, a gas burner only utilises a very small portion of the energy consumed; the remainder is lost in heat. The electric lamp, on the contrary, transforms into light a very notable fraction of this energy. That is what has been already often repeated, and lately again by M. Aimé Witz, in his lecture to the Industrial Society of the North of France. "Let us compare,” he said, "the yield in light of a kilogramme of coal in the two cases. This kilogramme supplies the labour of a horse-hour, and it can consequently feed at least seven 16 candle lamps, producing more than 15 carcels; the same quantity of pit-coal, distilled in a retort, will produce 80 litres of gas, from which will be drawn at most 32 carcels. Nothing can prevail against these figures, despite the utilisation of the sub-products of gas factories." In the same lecture we find the following calculation "Sixteen candles give 22 carcels; a London argand burner, with double crown in steatite, burns 90 litres per carcel; that makes 198 litres per 16This light costs in electricity 6 c. 5; that is, consequently, gas at 33 c. the cubic metre. We conclude that in towns where gas is cheaper than 33 c., electric lighting by incandescence is a luxury."

candle hour.

Since I am speaking, allow me, gentlemen, to examine this conclusion. M. Witz was right in seeking to place himself on practical ground, and, for the same reason, we believe we are doing a useful thing in showing that M. Witz did not go far enough, and that, consequently, he was led into error in his conclusion. We have just

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now at our disposal a very instructive official document, giving particulars of the survey made for the reception of the electric installation at the Monnaie Theatre. The average luminous value of an electric lamp in service is less than its initial intensity. It is, therefore, in the first place incorrect to calculate as M. Witz does, the intensity of a lamp said to be 16 candle by multiplying by 16 the value of a candle. This value of the English candle is not, moreover, that given it by M. Witz, that is to say, 0.135 c.; this is rather the value of the German candle. The English candle is weaker. In the second place, the denominations of lamps of 16, 20, &c., candles are purely commercial; incandescent lamps always exceed, and notably, their nominal value (contrary to what happens in general for arc lamps). In short, there is only one means of getting true figures-direct experiment. It has been given us by the survey at the Monnaie, where experts took at hazard 50 lamps among those in service and having been very variable periods in use. If we take among these the 16-candle lamps, we find the experts tried 25, and that their average luminous intensity was 2-22 carcels. By accident, M. Witz's figures correspond with the result of this experiment. On the other hand, the true luminous value of gas burners has been measured. For iron butterfly burners there were found (by eight experiments) 221 litres of gas per carcel hour; for butterfly burners in steatite (12 experiments) 195 litres per carcel hour. Only the results furnished by the iron butterfly burners need be noted; in a theatre the keeping up of these burners leaves much to be desired. But with regard to other burners of this theatre, where a gasfitter is permanently employed, we must admit. that their maintenance is not different to that of similar trade burners employed everywhere. In the second place, we observe that in private houses and shops, gas is burnt half by butterfly burners and half by others. In cafés and workshops it is rather the butterfly burners which are in a large majority. Let us admit, in the meantime, that the carcel of light, obtained by consumers in their lighting by gas of the present service, is furnished by the average of consumption of the two kinds of burners. It would result then, from the details given above, that in the present service the 195 + 113 or 154 litres of gas carcel of light demands. 2 per hour. M. Witz accepts as the mean price of sale of electricity 6 c. 5 per hour lamp of 16 candles. This average results from the prices of the few following small stations:-Bellegarde (8 c.), Perpignan (6 c.), Nancy (6 c.), Elberfeld (5 c.), Bremen (6 c.), Milan (4 c.), adding thereto 0 c. 5 for renewal of lamps. It is strange that the Berlin price does not figure in this list. It is, however, from installations of this nature that we must rather take the price of electricity, and not from small installations like Bellegarde, Perpignan, Bremen, &c., which do not number 3,000 lamps. At Berlin the price is 5 c., or 5 c. 5 with the lamp, and this price is still further reduced, as we have seen above, as soon as the duration of lighting attains 800 hours. At the Berlin price, which, according to us, can alone be considered as applying to stations of any importance, 5.5 the carcel hours costs, therefore, or 2.5 centimes. 2.2' From what precedes, we conclude that the carcel hour furnished by gas lighting by the apparatus at present in use being 154 litres, the same light, furnished at the Berlin price at 2 c. 5 by the incandescent lamps of the present service, costs as much as if one burnt gas at 2.5 or 16.2 centimes the cubic mètre.

0.154'

As will be seen, we are very far from the figure of 33 c. given by M. Witz, and according to which he is led to say that the electric light is a light of luxury. In order to make a serious comparison, we must absolutely consider the final result at which we arrive in the two kinds of lighting. Our deductions are supported on such results; we will add that the electric and photometric experiments of the Monnaie installations have been specially executed and directed by the same experimenter, Prof. Rousseau, whose competence

94

no one will contest. These are figures taken in reality, and have nothing in comparison with those on which M. Witz has argued. The London argand burner notably, with double crown in steatite, which was taken as a type by the lecturer, is a burner which the public does not employ, and will not employ. A very important remark to make on this subject: whatever the efforts made by the gas industry for so many years past, the public accepts no other burners then the quite simple trade burners which it will neither repair nor renew often. It is principally, remark it well, in order not to have this tiresomeness, that the public prefers gas to petroleum, and willingly pays more dearly; the other motives are but secondary. The infatuation for intense lamps, Wenham and others, will perhaps only last a certain time; at the end of a few years only it will be seen that a long use will have decided. "The sale price of central stations being equivalent to gas at 33 centimes, we will conclude," says M. Witz, "that in towns where gas is cheaper, incandescent lighting is a luxury." But precisely in all the large towns, where gas is cheaper, the sale price of electricity will also be lower than the average thus calculated according to the price of small towns. The price of electricity, like that of gas, varies with the importance of the town considered with the importance of the working. You see the inconsequence of such a general rule. In a preceding paper, we estimated at 120 litres per carcel hour the average consumption of the gas burners in use. The verifications obtained by the experts at the Monnaie Theatre show how moderate this estimate was; and now we will keep to our figure of 120 litres. In adopting this figure, incandescent electric lighting 2.5 would be gas at or 20 c. 8. Let us say, at the 0-120' maximum, 22 c., in order to take into account, so as to forget nothing, how much dearer the electric meter is than the gas meter, at present, at least. Such is for us the estimate of the actual price of electric lighting by incandescence compared to gas lighting.

The work of M. Witz, which has been reproduced con amore by the gas journals, also contains other errors which will come to the notice of all electricians. Thus 1 horse-power feeds now, not 7 16candle lamps, but from 8 to 10, the minimum being 8. Thus, it is not permissible to compare the industrial yield of a kilogramme of engine coal with that of a kilogramme of gas coal without mentioning the difference in price. The gas coal costs at the pit mouth 50 per cent. more than the best engine coal; at the place where it is used there is still a difference of 30 per cent. We will conclude by a few reflections on the subject of what M. Witz, and the public in general, call an element of undeniable inferiority of central stations over gas works. That is, that electricity has not yet reservoirs comparable to gasometers; that, consequently, the energy must be produced in proportion to the needs, and that it is necessary to have a large reserve material. One must guard himself from exaggerating the inconvenience of this necessity for electricity. The situation is not at all the same for the two products: if such a necessity existed for gas, and it were necessary to make gas in proportion to and during the time of consumption, the difficulty would be enormous, one may say, impossible. Storage is a facility for gas, but also an absolute necessity; the expense of gasometers is a forced one, like that of reserve machines for electricity. In a central station, comprising a series of motors, the expense for the reserve is not proportionally so large as that for gasometers at the gas works. These gasometers are important structures, which, without reckoning the ground, absorb 30 per cent. of the capital necessary for the whole works. One must also not imagine that in a gas works there is no apparatus installed to guard against

[JULY 26, 1889.

possible accidents. There is always specially a considerable gasometric reserve; there are extractors in duplicate, ovens, canalisations, &c. Accidents are possible in gas distribution as in that of electricity; but the latter having hitherto only been worked in small installations, in which the expenses to be incurred in order to obtain complete security are regarded as too large, there have often been extinctions. In an important central station, perfectly installed in all respects, the guarantees which the reserve machines present are greater than those resulting from the presence of gasometers in gas works. We have seen the whole lighting of a town interrupted after an explosion in the gas mains; on another occasion, after an escape of gas, a fire has rendered the apparatus in the regulator room unserviceable, &c. Obstructions in pipes and explosions are causes of the danger of extinction much more to be feared in gasworks and much graver in their consequences than are the possible accidents in a good central electrical installation. Marine engines, and those used in the working of mines, are striking examples of the almost absolute safety realised now in mechanical installations. By varied means electricians succeed in considerably decreasing the inconveniences referred to. They instal machines which can increase their power within considerable limits; the working then becomes less economical, but it will be understood that in that there is a calculation of compensation to establish. This disposi tion is much in use in America. Also, there are employed, in some installations, accumulators, the object of which is to supply a part of the current during the critical hours of the evening. The two means can be employed at the same time. We are well aware that the accumulators now known are not yet very practical or economical. But it would not be astonishing to see produced, before many years, in a few months perhaps, a good accumulator. Numberless researches are directed to this object in every country; and we may be certain that they will not cease till it has been found. For our part, we know of several new systems now being experimented upon very seriously, patents for which will not be taken out until they are put in working by strong companies.

But we have no need to discount the future. Present facts and results suffice. They confirm the conclusions to which we have come previously, in which we have insisted on the true value of the luminous apparatus in use. "Taking into account," we said, "these different practical considerations, one must conclude that if electric lighting can be delivered at 5 or 6 centimes per hour lamp of 16 candles, and at 3 or 4 centimes per hour lamp of 10 candles, the difference between the cost of the two lights becomes less, and may even be nil. The prices in different towns show that we are not far from this position." Our gasfitting friends will not fail to recognise the justice of the observations which long practice in the distribution of gas permits us to make. They can but know us as willing to seek to set forth the true position, and, notably, to remove the errors committed even by the best-informed persons, when they do not look at the question from the general data of reality. They will convince themselves that the opposition, formerly justified, is no longer so, at least in large towns, and that it is perhaps to their interest to follow the example already given by several gasworks, which have themselves resolutely undertaken the supply of electricity. We maintain that as soon as a central electricity station can be established in our towns, with prices as above, the favour of the public, now gas consumers, will be promptly acquired. We do not wish to say immedi ately and at one stroke; but at the end of the shortest time compatible with the habitual inertia which every innovation must vanquish. The objection drawn from a certain difference in price compared with gas is not so important as is believed. The public does not calculate like us, basing their deductions on photometric results; it only becomes disquieted within large limits. It sees scarcely any difference between a light of 1 carcel or of 2 carcels. The unit of light is not for it

JULY 26, 1889.]

the carcel, but the lamp or burner. Practically, there are two units or types: the lamp for the office or dining room, and that for the corridor or underground. The number of luminous foyers influences the total expense much more than the variation of supply or individual expense between the varieties of luminous foyers. Thus, the public only considers two things: (1.) Comfort. (2.) The total cost of the lighting of its premises. It is always the first consideration which carries it when the second does not show too notable a difference. Proof of this is superabundantly supplied by gas customers themselves; in order to enjoy the comfort which gas brings, they spend double what it would cost them for lighting with handsome petroleum lamps. Let not any one oppose us here by laboratory experiments; we say that in practice gas lighting costs double that of petroleum, even at the present low price of gas.

For these consumers there only really remains one of the above considerations-comfort. In place of paying double to have gas, they will pay quite as much, and even more, to have electricity, if it offer them any advantage whatever in the way of comfort. We have shown what are the numerous cases in which this advantage exists. When, then, electric lighting is established on a large scale in a sufficiently important centre, we may rest assured that it will be adopted by a large majority of gas consumers. We are convinced as regards Brussels, the price of electricity there being possible to be lower even than that of Berlin, where the coal used for the engines costs 24 francs per ton!

NOTES ON THE DYNAMOS AT THE PARIS EXHIBITION.

II.

THE dynamos of M. Fabius Henrion, of Nancy, which we illustrate in figs. 1 and 2, are well worthy of notice. These machines are of the Schuckert type, with disc armatures, being, indeed, a development of the wellknown Schuckert machine, which at one time was made by M. Henrion. The smaller incandescence lighting machines and those for arc lamps in series are made with two poles, as in fig. 1, while the larger sizes for incandescence lighting have four poles, as in fig. 2, or a greater number depending upon the currents to be carried. The armature core is formed by winding soft iron wire on a gunmetal supporting ring, which is turned slightly hollow on the rim for its reception. To this gunmetal ring are fastened the arms which carry the armature round, these projecting outwards from the ring on each side of the core, to afford lateral support for its several layers of wire. Between the adjacent layers strips of paraffined paper are interposed, these practically dividing the iron of the armature into a number of concentric ribbons, by the edges of which the lines of force enter. After being properly insulated with coverings of tape the core is Gramme wound in the usual way. It will be noticed that in the two-pole machine, fig. 1, the magnets, instead of being placed one directly above the other, lie at an angle of about 45 degrees, this arrangement rendering the brushes and commutator very accessible. When constructed for arc lighting these machines give generally a current of 8 ampères, to suit the normal type of Pilsen lamp, and are built for any difference of potentials up to 1,000 volts. Machines of this pressure support 20 lamps in series taking 50 volts each. They have in their commutators 56 sections.

The two methods of regulation which are employed by M. Henrion for keeping the current constant under a varying number of lamps are very neat. In an installation of incandescence lamps the difference of potentials at the mains has to be kept constant, while the current varies to suit the lamp requirements, but in an installation of arc lamps in series the current has to be kept constant, while the difference of potentials varies with the number of lamps alight. Until recently

95

there were no dynamos supposed to be capable of constant current regulation save the Brush and ThomsonHouston machines, since from the way in which the connections were made between the armature coils and commutators these were little influenced in their working by sparking, which in Gramme connected machines would have proved fatal. But lately there has been introduced quite a host of constant current regulators applied to ordinary Gramme wound machines, the working of which has proved very successful. These are generally in the nature of a mechanical device for varying the angle of the brushes on the commutator, the action of which is governed electrically, and thus becomes automatic. One of M. Henrion's methods consists in the application to his machines of such an arrangement, the second method he employs consisting in varying the resistance of a shunt across his field. coils.

pin

The automatic regulator used for the latter is shown in fig. 3. It consists of two tablets, on the upper of which is fixed a solenoid, A, with a movable iron core suspended by a spring, and on the lower two electromagnets, B and C, the resistance coils, R, and the mechanical gearing below. A, B, and C are in direct circuit with the arc lamps, the current under normal conditions going through all three in series. The spring by which the core of A is suspended can be adjusted for any strength of current within limits. The extremities of the core are provided with contacts so arranged that its movement in one direction has the effect of short-circuiting the coil of the magnet, B, while its movement in the opposite direction shortcircuits the coil of C. Some distance below B and C is fixed on the tablet a stud upon which two ratchet wheels, fastened together but with their teeth cut in opposite directions, are free to move. To these wheels is fixed a radial arm, the outer end of which makes contact with the studs of the resistance coils and by its movement increases or diminishes the resistance, R, shunting the fields. Pivotted on the stud carrying the wheels is an oscillating lever, the lower end of which is slotted while the upper end has fixed in it which carries a double ended pawl capable of engaging the teeth of either ratchet wheel. This pawl in its normal condition lies horizontally and has its ends directly under the electromagnets, B and C. these latter are equally magnetised the pawl does not engage either ratchet; but if one of the magnet coils is short circuited, the end of the pawl under it immediately falls on one of the ratchet wheels, and being carried backwards and forwards by the oscillating lever, the wheels, and with them them the radial arm, are moved round, thus increasing or diminishing the resistance as necessary. The oscillating movement is given to the lever by a pin lying in its slotted end, this pin being screwed into the face of a disc at the end of a short spindle driven from the dynamo or countershaft. When the current is at its normal value and flowing through A, B and C in series, the iron core of A occupies an intermediate position in which no contact is made with B or C. But when from an increase or reduction of the current the core of A ascends or descends, B or C is at once short-circuited, and the pawl dropping on one side the radial arm is moved until the current again attains its normal value.

When

For his method of altering the angle of the brushes on the commutator, M. Henrion employs a modification of the gearing above shown. The regulating solenoid, A, and the magnets, B and C, are carried on a standard fixed on the dynamo frame, and to the ratchet wheels is directly attached the quadrant carrying the brushes. Here no resistance coils are necessary. It will be seen that as the pawl engages one or other of the ratchet wheels the lead of the brushes is increased or diminished. At the Exhibition there is a machine for 15 lamps, in which the automatic regulator is attached directly to the brush quadrant. We were unfortunately unable to see this machine at work, but M. Henrion assures us that he can by this arrangement vary the lamps from 1 to 15 without causing sparking at the brushes.