SEPTEMBER 13, 1889.]

Self-exciting.

Separately excited.

In both cases the speed with the brass studs was somewhat lower than when the iron ones were used. The gain will be perhaps better exhibited by estimating the total number of lines of force passing through the armature in the several cases. The voltage in the table has been corrected in the case of self-excitation, for the loss in the armature itself, due to the current required to excite the field. The voltage given is therefore the total E.M.F. generated in the armature; the loss in the voltmeter being so small as to be negligible. Using the formula found in Thomson's "Dynamo-Electric Machinery," p. 350, third edition, which is, EX 108 in which N is the total number of

N=

n c

lines cut, E the E.M.F. generated, n the speed per second, and C the total number of wires on the armature, counting entirely round the periphery (in this case 768), we have for the two cases of self-excitation 190,000 and 252,000 lines respectively. The apparent gain is therefore 62,000 or 32.6 per cent. In other words, this small machine has its capacity increased 32.6 per cent. by substituting the brass studs for steel and iron. It would be an error, however, to suppose the leakage was actually 62,000 lines; for as the machine is self-exciting and the field magnet was magnetised much below the saturation point, any increase in the magnetic lines passing through the armature increased the E.M.F. generated, which in turn increased the ampère-turns round the field magnet. Thus a part of the 62,000 lines was due to this cumulative effect on the field.

This will be exhibited more clearly if we estimate the number of lines with the field separately excited. Applying the foregoing formula we have, for the iron and brass studs respectively, 164,600 and 184,100 lines. The gain in this case is 19,000 lines, or 11.2 per cent. This, therefore, represents the actual leakage through the steel and iron studs.

Two series of measurements of currents and E.M.F. were taken, first with iron studs and then with brass. The resulting characteristic curves exhibit throughout a difference similar to that estimated above.

At a

In the Edison machine the iron bedplate is always appreciably magnetised when the field magnet is excited. This indicates some leakage through the 23inch space between the pole pieces and the bedplate, which is filled in with zinc. The dynamo was dismounted, and was set on a base made of 2-inch pine plank, doubled and strongly screwed together. Care was taken to have a plane surface and to secure a proper alignment. The machine ran well on its extemporised base. No load was put on, the only current furnished being that necessary to produce its own field. speed of 1,760 revolutions per minute, the total E.M.F. generated with iron and wood base was 154 and 163.62 volts respectively. The total number of conductors. round the armature is in this case 348. Therefore applying the formula there were 1,510,000 and 1,605,000 lines of force cut by the armature, or a gain of 95,000 lines by the removal of the cause of leakage, an increase of 6.25 per cent. It is not, of course, to be imagined that the efficiency of these machines is increased by any such per cent. as indicated by the gains due to removal of magnetic leakage. The capacity of the machines is increased by this amount, and a saving is certainly effected in two ways. One is the saving in material of construction for a machine of any required capacity; the other is the saving in energy required to produce the requisite field. Both of these items are of enough importance to be taken into account in designing a first class dynamo.

287

COMPARATIVE COST OF ELECTRICITY AND GAS.*

THE question as to whether the electric light costs more than gas light is one which has been raised on many occasions by different individuals, and is now being particularly discussed by the gas companies and corporations who propose to obtain powers to supply electrical energy in addition to their present gas business. The solution of the problem is not very difficult to find. On nearly all sides we hear it stated that the cost of the electric light is twice that of gas, but, as a rule, such statements are made without any actual knowledge of the expenditure required in putting up installations, and in their maintenance. The cost of the electric light, generally speaking, depends to a certain extent upon the size of the installation. We have seen many small installations, both in London and in the provinces, where they have been in operation for two or three years, and where, from figures given regarding the initial expenditure and the maintenance, it has been conclusively shown that the cost of electricity has not been in excess of that incurred for gas lighting. Indeed, we have in our mind's view at the moment several installations where the expenditure has been less, and even in cases where the number of lamps has not been more than 110 of 16-candle-power, or their equivalent. In one case a 10-horse-power Stockport gas engine is used to run a small dynamo supplying 95 16-candle-power glow lamps, and six 50-candle-power lights. This is in a large butcher's establishment. Formerly the whitewashing, painting, &c., which were necessary three or four times a year, owing to the gases given off by the combustion of coal-gas with the oxygen of the atmosphere, darkening and spoiling the shop ceilings and walls, were a serious item in the expenditure; but when the electric light had been adopted and had been in operation for two years, the ceilings and walls had not in the least deteriorated. This was due to the fact that the electric light-we are, of course, speaking of glow or incandescent lamps-cannot possibly give off any foul gases, because the light burns in a vacuum, that is to say, because the air in the glow lamps had been pumped out or exhausted in the process of manufacture.

In London, and we believe also in the provinces, the electric lighting companies are not permitted by the Board of Trade to charge a higher rate than Sd. per Board of Trade unit, which, as mentioned in a previous article, is equivalent to 6s. 8d. per 1,000 cubic feet of 16 candle-power gas. In the metropolis, as far as we are aware, the companies are charging almost the eightpenny rate, but in the provinces this figure is not always enforced. In one instance a company issued a circular stating that they would supply current at 43d. per unit (1,000 watt hours). There is, of course, a great difference between 43d. and 8d., but the company in question had in view the object of doing a large business with small profits, and a large total income rather than a small trade at high prices and a smaller aggregate income. The price of gas, as our readers are aware, varies in this country from about 2s. to 6s. 6d., and even 7s. per 1,000. Now, in towns where the higher prices prevail, it will be equally as cheap for the public to have the electric light as gas. It is not only in towns where gas is cheap that the gas companies and corporations should take up the supply of electricity, but especially in those districts where it is dear, and thereby obtain an additional income.

As some particulars regarding the relative cost of gas and the electric light may be interesting, we give below a table calculated on the basis of the Board of Trade unit at 8d. The table shows the cost of gas per 1,000 cubic feet at various prices, and the equivalent rate at which the unit would have to be supplied to be equal to the price of gas :

Gas and Water Review and Journal of Electric Lighting.

288

Gas at per 1,000 cubic feet.

s. d.

Price per unit for the electric light.

d.

23

211

2 0

2 3

2 6

2 9

31

[SEPTEMBER 13, 1889.

the armature parallel to its circumference. The four magnet bars are of soft annealed wrought iron, and are joined together by four cast iron pole shoes; two of the pole shoes on the horizontal line are made in halves and bolted together, enabling the top half of the machine to be lifted off and the armature taken out.

The magnets are carried on a massive cast iron bedplate with four projecting standards, which keep the bottom pole shoe slightly above the floor level.

The armature is of the disc type, but of large sectional area compared with its diameter, and is wound with a single layer of rectangular wire.

In the 15-unit machine shown at Birmingham there are 60 sections of four turns each, the wire being 16 x 14 section.

The spindle is of steel, with thrust collar to take up end play; the bearings are of cast iron, with adjustable keeps, and lined with brass shells fitted with white metal.

cheaply as gas-although, as already stated in these columns, the price will not always be considered, as the public will have the electric light.

THE BIRMINGHAM EXHIBITION.

(Continued from page 240.)

The Lighting of the Building.-The "Tyne" dynamo, manufactured by Messrs. Ernest Scott & Co., of Newcastle, and used by them for lighting one of the bays with 6 3,000-C.P. Tyne arc lamps, is of novel construction.

The machine has been designed by Mr. Mountain, and is now their adopted type for all sizes, from 3 units upwards, and it will be observed that the machine is of the 4-pole four magnets being arranged around

+

This construction has been adopted in preference to the ordinary method of running white metal into cast shells, as it enables new brasses to be fitted in at a moment's notice, it not being necessary to heat the bearing to melt out the metal.

The white metal itself is of special quality, made by Messrs. Ernest Scott & Co., for their marine and other high-speed engines, and is stated to have double the wearing qualities of any other metal in the market.

The commutator is of drawn copper, insulated by mica, and mounted upon a gun-metal sleeve se cured to the spindle by locks, nuts, and a feather.

Owing to the powerful magnetic field of these dynamos, and the small resistance of th Ane armature, the shunt machines are practically self-regulating. Throughout the construction of these,in dynamos the makers have endeavoured to combine t electrical qualities with high mech and, as an evidence of this, it will be

horoughly good anical efficiency, observed that the

SEPTEMBER 13, 1889.]

machine runs absolutely without sparking or wear on the commutator, and perfectly steadily.

The "Tyne" arc lamp used for lighting the bays has also been designed by Mr. Mountain, and feeds by gravity. The upper carbon rod is cut in the form of a rack, and gears into a pinion carried on a spindle running in a sliding block in the inner frame of the lamp. This block is free to move vertically, and on the outside are two brake wheels. Upon the brake wheels there is a rocking lever carrying two friction chains. One end of the lever carries the iron core of the solenoid, and the other end the air dash.

When the current passes through the lamps the core is sucked up, tightening the friction chains upon the pulleys and raising the sliding block and thus striking the arc.

When the lamp is in its feeding position the sliding block rests on two adjustable stops, and as the current weakens in the solenoid the core is slightly lowered, releasing the friction chains and allowing the carbon rod to descend.

In practice it has been found that these lamps work perfectly well in moist or dry atmospheres, and that they will stand any amount of knocking about, and are thus eminently suited for all classes of arc lighting, and especially for factories or mills where they are subject to rough usuage.

The lamp is made in two types, viz., the globe, as shown at the Birmingham Exhibition, and the factory type with square lantern and reflector and an adjustable resistance coil for adjusting the E.M.F. at the terminals of the arc lamps is also shown in the engine room, and is of substantial and simple construction.

THE ELECTRIC TRAM LINE AT BUDA-PESTH.

[FROM A CORRESPONDENT.]

THIS day, September 5th, the second great line of the net of electric tramways belonging to the municipality, and designed by the firm of Siemens and Halske, was formally tested as to its admissibility, both from a technical point of view and from that of public safety.

After the steps to be taken had been agreed upon at the place of meeting, the commission proceeded first to the central station in the Gârtner St. (Ward VII.) Here was examined the central station for producing the electric current, the installation of special machines for working the new line, and the accessory cable conductors. The arrangement of this establishment, at once suitable and elegant, met with universal approbation. Especial notice was taken of the smokeless furnace, which is so perfectly constructed that the

289

members of the municipal building commission and council pronounced it a pattern for similar undertakings in populous urban districts.

After the lapse of about a quarter of an hour the commission proceeded to the end of the Andrassy Road in the Town Wood, where is the terminus of the new electrical line.

The line begins at the Rudolf Quay, in front of the Hungarian Academy of Sciences, turns then with a curve of 27 metres radius into Széchény Street, and passes along it to the Frohner Hotel. So far the line is single, but it divides here and passes along Palatine Street to the new offices of the Department of Agriculture, and then in Báton Street is a double track to the premises of the Minister of Public Worship, formerly the station of the Western Railway. The line then leads along Woll Street, past the German Theatre, crosses the Waitzner Boulevard and the opening of the Grossenfeld Road and goes along Podmanitzky Street, until it crosses the Theresa Ring, still double. Here there is an arrangement of rails which is very interesting from a technical point of view. The lines of the electric tramways here cross each other, the two tracks of the Podmanitzky Street line crossing here and connecting with the double tracks of the Ring-Roads line, thus producing a very complicated net of rails.

After crossing the Theresa Ring the line passes along the outer Podmanitzky Street in a single track provided with the necessary places for meeting and passing. The line turns then with a curve of 35 metres radius, rising at the time 16 per 1,000 into the Arena Road, and leads along it to the opening of the Andrassy Road where it comes to an end, for the present, at the drinking fountain of the artesian well. The line, however, is to be continued from here to the park and up to the bridge of the artesian bath, having its terminus at the southern gate of the Palace of Industry. In the Arena Road there is, on a plot of land purchased for the undertaking, the well-equipped working station of the line, a substantial structure of masonry with iron roof and sheds for the tramcars and a well provided workshop for repairs, with the necessary lines and turntables.

At present there are five electric locomotives tastefully equipped ready for use, to which other cars can be coupled as the traffic may require.

The system of this electric line is that of Siemens and Halske, with underground leads for the current, as in the line formerly constructed in Station Street, and as in that about to be completed along the Great Ring Road.

The line was traversed three times by the Commission, all the details of the installation, the means of intercommunication, and the manner of working, being carefully tested in all their combinations. No objection was found, and the Commission declared unanimously that the concession for commencing regular traffic should be granted.

The speed of travelling in the interior of the town is 13 and in the suburbs 20 kilometres per hour (respectively 8 and 12 miles).

The opening ceremony was attended by W. von Siemens, the son of the celebrated Werner von Siemens, of Berlin.

Electric Lighting Tenders Wanted.-The Municipal Council of Sydney, New South Wales, invite applications for the right to establish a system of electric lighting in the streets, lanes and reserves of that city, under the control of the Council. Such system may include the application of the light for domestic purposes, and the use of electric power generally. Upon a satisfactory system being submitted and approved, the Council will be prepared to enter into an agreement for the lighting of the whole or a section of the city, as may be considered advisable. Further particulars may be obtained at the offices of the Agent-General for New South Wales, 9, Victoria Street, Westminster, London, S.W

с

290

THE GWYNNE-COOPER STEAM DYNAMO.

WE illustrate here a combined steam engine and dynamo, the joint patent of Mr. John Gwynne, of Messrs. J. and H. Gwynne, and Mr. C. F. Cooper, of Messrs. Paterson and Cooper. The construction of this machine is clearly shown by our engraving. The cast iron side frame of the engine is thickened up to form part of the magnet, an exciting coil being placed on the heavy bar of wrought iron standing vertically above the armature, which forms another part. The lower end of this bar constitutes one of the poles, the engine bed plate forming the other. The recess for the armature is bored out when the magnet bar is fixed in position, the two gunmetal side brackets seen in the

[SEPTEMBER 13, 1889.

wire. The magnet core has an area of 55 square inches, and the exciting coil is compound wound, with 132 turns of series wire 220 inch in diameter and 1,710 turns of shunt wire 065 inch diameter. The machine gives a current of 50 ampères at a difference of potentials of 65 volts, the speed being 470 revolutions per minute. There is no sparking visible at the brushes. It will be seen that the steam dynamo takes up very little room, and is therefore valuable for ship lighting or for use in situations where space is a consideration. In the machine shown, the armature is overhung outside the second main bearing, but in the larger sizes the commutator is placed between the second bearing and the armature, while a third outside bearing takes the place which in our illustration is occupied by the commutator.

illustration tying the latter firmly to the bed. The side frame, wrought bar, armature and bedplate thus constitute a complete magnetic circuit magnetised by a single coil.

The engraving has been executed from the photograph of a 50-light steam dynamo just completed. The engine is of the "Invincible" pattern, by J. and H. Gwynne, having a cylinder 5 inches diameter and a stroke of 4 inches. It is fitted with a Pickering governor and provided with arrangements for continuous lubrication. The electrical parts have been made by Paterson and Cooper, the armature being constructed as in their well-known "Phoenix" dynamos. In this machine the armature core has a diameter of 12 inches with an interior opening of 7 inches, and is > inches wide. It is Gramme wound in 36 sections, aving each 12 convolutions of triple 065 inch diam.

INDIAN TELEGRAPHS.

FROM the Gazette of India, dated August 10th, we cull the following information respecting the telegraphic appointments in that country :

TELEGRAPHS.

The 9th August, 1889.

No. 243. Mr. W. H. M. Hare, Assistant Superintendent, Class V., first grade, Indian Telegraph Department, is appointed to officiate as a Superintendent in Class IV., with effect from July 22nd, 1889, and until further orders.

No. 246.-Sir Albert J. Leppoc Cappel, K.C.I.E., Director-General of Telegraphs, is permitted to retire from the service, with effect from the forenoon of July 1st, 1889.

THE monotonous wrangle over execution by electricity still continues. The argument on behalf of the opposers is conducted with ever-increasing acrimony, while Mr. II. P. Brown's advocacy of the advantages of an alternating current for killing purposes is set down to any other motive but that of its effectiveness, and its superiority, on the score of humanity, over other methods of dealing the capital stroke. The discussion is a never ending one; it reminds one of the mechanical toy in which a train runs into a tunnel on one side only to emerge immediately afterwards from another tunnel on the opposite side; this procession of the same train in the toy, or the recapitulation of statements in the discussion, is equally wearisome. American readers Inust be quite as heartily sick of the whole controversy as we are, and it is somewhat surprising that the subject has not been tabooed long ago. Apparently there is not much chance of the matter dropping within a measureable limit of time, at least, not to anyone unacquainted with the various episodes throughout the contest; but to the initiated there comes a ray of hope that the end is drawing near. The argument has shifted considerably; it is now no longer a question as to the desirability of executing by electricity, and the most proper kind of current for doing so; it has degenerated into a combat between the advocates of the intermittent and the continuous current supply, in which Mr. Brown plays the part of an important fortress, whose guns must be silenced before the alternating current party can claim a victory. It is said that when argument fails abuse begins, and it is just here where the beginning of the end may be visible. It is stated that the entire list of experiments instituted by Mr. Brown was contrived for the sole purpose of bolstering up the continuous current companies at the expense of their rivals who supply the alternating current; that the direct current party supplied all the funds and paid their champion handsomely for his support, and that the letters published by the New York Sun conclusively prove that he is simply the paid tool in the Edison and Thomson-Houston interests.

Legitimate methods of attack must be somewhat exhausted when the solicitor of George Westinghouse, jun., descended to such vulgar abuse as to call his opponent "an unmitigated liar," and it would be curious to hear the language used by the rank-and-file; Billingsgate and the Irish biddies would surely be backseated.

It seems to be forgotten that the original contention of Mr. Brown was not only an onslaught against the alternating currents, but, one quite as determined,

against the high potential continuous current, which latter was answerable for the lives of most of the victims from electric shocks. It was to be expected that the Edison Company would see the obvious value to itself in thus enlightening the general public on the dangers attendant on the use of currents of high potential; and the company cannot be blamed for utilising, to the best of its ability, the chance thrown in its way of showing the safety of the low tension current adopted under its own system. The opportunity was too good to be lost, and consequently its laboratory was placed at the disposal of Mr. Brown, and means provided for him to carry out his experiments in a satisfactory manner to himself and to the enhancement of the company's business. In the course of the experiments it became manifest that an alternating current, as the majority of electricians throughout the world believed and do believe, had a more prejudicial effect on the human frame than a continuous one of the same potential; it can scarcely be wondered at, then, that the proprietors of continuous, or so-called continuous, current systems should endeavour to derive some benefit rom the facts made patent during the trials. This will account for such assistance as the Thomson-Houston Company gave in authorising Mr. Brown to challenge the Westinghouse Company to an electrical duel, in procuring him Westinghonse dynamos on favourable terms, and a promise of $1,500 to carry out some tests with those dynamos.

These facts came out in a series of 47 letters, published by the Sun, forming a correspondence with many people, extending from September last year up to July 18th of this year. It is passing strange how these letters, provided they are genuine, came into the possession of the above paper; it cannot have got hold of them with the consent of the owners of the originals; the probability is, therefore, that there has been some serious breach of trust on the part of employés, or, what is more likely, the letters have been stolen from Mr. Brown's office. Any way, the correspondence chiefly brings forward, in a prominent manner, that Mr. Brown had also an eye to business, and that, although he might be actuated in the first instance by philanthropy, he did not intend to allow virtue to be its own reward, not, at all events, when an alternative in the shape of a big advertisement, accompanied by plenty of dollars, was to be had. In one of the letters, he says, the December challenge to Westinghouse cost $275 for a single insertion in the New York Herald, World, the Sun, and the Tribune, and in each case the marks of "Adv." were omitted. The practice of advertisements appearing in the form of articles in American papers is so unusual that we are compelled to give implicit belief to the statement made by the Sun declaring the above accusation to be absolutely false. The correspondence occupies some six columns, and constitutes a batch of light literature such as the ordinary Sunday reader must have thoroughly enjoyed.

The report that Mr. Edison had an understanding with Mr. H. P. Brown that the latter was to work against the alternating current people appears to be unfounded, for, when Mr. Edison was examined before the City Referee, he testified there was no such arrangement; he had given a testimonial just as he would to any other man experienced in electrical matters.

From another source we learn that Mr. Charles F. Heinrichs, who made exhaustive researches on electrocide for the State, has some interesting views on the Westinghouse dynamo; he considers the alleged conspiracy against the Westinghouse Company to be all imagination. The scientific facts are that the Westinghouse high voltage alternating currents are dangerous to life, and the most suitable ones to serve electrocution causing the most instantaneous and painless death. No little surprise was caused by the evidence of the Westinghouse employés, in the Kemmler investigation, to the effect that they had received alternating currents of the full power of their machines, which amounted to many electrical H.P., and were none the worse, with the exception of some pain and slight wounds. Mr. Heinrichs thinks that these witnesses were painfully