288

1863. It is nothing short of infamous even to hint that Jenkin forged the passages in his edition of the reprint.

As if this were not enough, he goes on to bring against the late Professor Fleeming Jenkin another accusation hardly less astounding, namely, that Jenkin "had reasons" for not supplying Mr. Samuel Alfred Varley with duplicate standards, and, while giving him to understand that other standards would be supplied, "had all along never intended" that they should be so supplied. If Mr. Samuel Alfred Varley and the editors of the ELECTRICAL REVIEW think that it is decent or honourable thus doubly to slander the memory of one whose life and labours were as noble as those of the late Professor Jenkin were, that is their affair. The rest is silence.

Silvanas P. Thompson.

[We do not think it necessary to refer to Professor Thompson's elegant epistle beyond calling attention to the letter below; the two together form as good an illustration of dignity and impudence as does the celebrated representation of these two states of being by Sir Edwin Landseer. Furthermore, we would request the Professor to confine himself to Mr. Varley; the REVIEW can take care of itself.EDS. ELEC. REV.]

My attention has been called to the following statement which appeared on page 254 of your number of last week :"I was reluctantly forced to the conclusion that for reasons best known to Fleeming Jenkin, he had all along never intended me to be supplied with a duplicate standard."

The writer, Mr. S. Alfred Varley, clearly did not know Fleeming Jenkin. I did know him, and it is simply impossible that he ever promised to send a duplicate standard intending not to do so. I am perfectly certain that every person who ever knew Fleeming Jenkin must agree with me in this conviction.

Major-General Webber's Paper.

It having been represented to me that my remarks on Major-General Webber's paper on the distribution of electricity, at the Institution of Electrical Engineers, as reported in the technical journals, may give rise to a false impression, I beg to enclose for insertion a letter from the electrician-incharge, at the Bath Electric Light Works, the correctness of which I have not the slightest reason to doubt. According to this, the defective insulation was not due to the mains, but to faults in the lamp-posts, which alters my view of the suitability of the insulation. The defective circuits were arc-light circuits. The tests of the other circuits were quite satisfactory as shown by the accompanying figures. Insulation-resistances of Incandescent Circuits. Circuit No. 1 Over 15 89 megohms.

....

2

15.88

[COPY.]

George Forbes.

Bath Electric Light Works. Dorchester Street, Bath. February 21st, 1891. T. O. Callender, Esq. Dear Sir,-In reply to your inquiry with reference to the visit of Professor Forbes here, I beg to inform you that all the tests made were on circuits with lamps in series, or transformers connected, and that no tests were taken of the mains by themselves.

The two results to which you specially refer, viz., resistances to earth of 40 and 60 ohms, were on the public arc lines supplying 36

[FEBRUARY 27, 1891.

and 45 lamps respectively-and Professor Forbes knew when testing that his figures included lamps and leading-in wires, and did not give, by any means, the actual insulation resistance of the mains.

The low readings in question arose, as a matter of fact, from faults in the lamp-posts. They had just been localised by means of the fault-finding apparatus to which he refers, and on being put right on the following day, the resistances were 124 and 146 megohm. It may be well to point out that Professor Forbes tested all our circuits, eleven in number. I remain, dear Sir, faithfully yours,

(Signed.) MARTIN C. OLSSON, Electrician-in-charge.

Re Cantor Lecture on Monday, 16th inst. Dear Sir, I am requested by the managing director to draw your attention to the enclosed printed matter with reference to data relating to the Barking Road electric installation which is the property of the General Electric Power and Traction Company, Limited. The figures thus given are entirely misleading, and the publication of them is calculated to seriously injure our interests as well as those of the North Metropolitan Tramways Company, and we must request you accordingly to withdraw the Tables 4 and 5, and the statements made by you based thereon at the next Cantor lecture in such a public manner as will be likely to reach all persons before whom the original tables and statements have come.

If the statements have been based upon information obtained from Mr. Frazer, we may call your attention to the fact that he left the company's employ in July last and has since had no opportunity of acquiring any knowledge as to the improvements that have taken place since then, which renders the data published by you still further misleading.

In the event of your failing to comply with our request, we shall, in the interests of our shareholders, be compelled to consult our solicitors on the subject.

Yours faithfully (Signed)

W. G. M. MACKENZIE, Secretary. [COPY.]

31, Parliament Street, S.W., February 21st, 1891. The General Electric Power and Traction Co.,

35, New Broad Street, E.C.

Dear Sir,-In reply to your letter of yesterday, the statements to which you object were based on figures obtained from Mr. Fazer, and were given at the Society of Arts distinctly on his authority and not on mine. After your explanation, which puts a totally new complexion upon the matter, I am, of course, myself desirous to withdraw from my lecture any statement or table, the accuracy of which is questioned, and I shall on Monday withdraw the two tables, 4 and 5, and statements connected with them. At the same time, allow me to point out that in your interest as well as in mine, withdrawal alone would not be so effective as withdrawal combined with the substitution of the correct figures, and I should feel obliged if on Monday you would send me a telegram authorising me to state that when the lectures appear in print the obsolete figures of Mr. Frazer will be replaced by figures corrected up to date and supplied by you. Yours faithfully, (Signed)

GISBERT KAPP.

Kennedy's New Electrical Distribution Scheme.

Referring to your leading article and Mr. Kennedy's description of his method of utilisation of alternating currents, we think that you might with advantage publish a description of Lieutenant F. J. Patten's system of distribution by alternating currents, an illustration and description of which is given in the New York Electrical World of January 25th, 1890. Mr. Kennedy's proposals are on the face of them very interesting, but we think Lieutenant Patten's method has the advantage of simplicity, and certainly accomplishes all the objects proposed by Mr. Kennedy without the additional complication involved in his method. pro Mavor and Coulson, A. W.

Glasgow, February 23rd, 1891.

ENGLISH SUBMARINE CABLES.

WE find in the French Annales Télégraphiques an article on gutta-percha, which tends to prove that all, or nearly all, cables up to the present time, manufactured by English firms, are worth absolutely nothing, because the chemical. composition of the cores does not correspond to the standard. formula that M. Lagarde gives as being that of good gutta. Details are given in another column.

According to his ideas, and here he is not alone, the lower the insulation the better the gutta. He is ready to reject a gutta that gives an insulation resistance of 1,600 megs. per kilometre, while core is being daily manufactured that gives an insulation resistance of 3,500 to 4,000 megs. per nautical mile, or 6,500 to 7,400 megs. per kilometre.

M. Lagarde omits to tell us if he has laid many submarine cables, and how long they have lasted. We will only refer to two points in this article to prove how recklessly the Chemist of Posts and Telegraphs lays down the law, and we hope for the honour of France that the manufacturers do not concur with the ideas of the officials of the Telegraph Administration.

Firstly, we find a table showing analyses which prove that the insulation resistance per kilometre is inversely proportional to the quantity of pure gutta.

At factory A, a diminution of 8 per cent. of pure guttapercha produces an increase of 1,100 megs. in insulation resistance.

At the factory B, a diminution of 3 per cent. of G.P. produces an increase of 600 megs.

But if we compare a G.P. coming from the factory A and a G.P. coming from factory B, having the following compositions:

we find for one 500 megs. for the other 800 megs., being a difference equal to 60 per cent., whilst the gutta-perchas are identically the same, tests being made under exactly the same conditions by the same expert.

One cannot even suppose that there has been something left out of the analysis, since the total of 100 parts shows it to be complete.

We are therefore led to conclude that the relation said to exist between chemical analysis and specific insulation resistance holds good only when one remains within the four walls of the particular factory in which this relation was established; and if, as M. Lagarde desires, and as seems to be the practice already in operation in France, specifications are to establish a normal, chemical composition, to correspond to a given maximum of insulation, factory A would be favoured to the prejudice of factory B, because, for a given composition of its gutta, it produces only half the insulation.

Again we find M. Lagarde demonstrating to us that gutta turns to resins in water as quick and sometimes quicker than in air, so much so, that in two months the composition of gutta has changed 3 per cent. M. Lagarde has evidently had to deal with very peculiar qualities of gutta-percha, for if there is a well recognised fact, it is the absolute unalterability of gutta-percha in water.

M. Lagarde lays down the law regarding the relation of chemical composition to insulation resistance; but we think that if manufacturers were ready to publish their experience of gutta, viewed as a useful material for insulating wires in submarine cables, it would not be difficult for them to show that the application of M. Lagarde's law would often involve the rejection of a useful gutta, while it would not prevent the treatment of bad ones in such a way as to make them fulfil the conditions which M. Lagarde would like to see stipulated in future specifications.

The vast majority of the gutta cores so sweepingly condemned by M. Lagarde have not only served their purpose for long terms of years already, but they also show no signs. of failing; while we believe that one of the cases of failure under the test of age occurred in a core that was manufac

tured by the firm which has probably devoted more attention than any other to the chemistry of guttas.

We do not think that the article is destined to revolutionise our knowledge on gutta, and, in any case, if it does effect a revolution, we shall quickly return from our errors, and be guided by the experience of 40 years; but an article of this nature, coming from an eminent member of the French Administration, will not fail to cause lively sensations of pleasure and disgust in the respective factories, A and B. The chemist is undoubtedly a very useful man in his place, but recognising his inability to distinguish even between gutta and rubber, it would surely have been prudent of M. Lagarde to be less dogmatic.

THE LONDON AND PARIS TELEPHONE LINE.

THE submersion of the cable which completes the telephone line between London and Paris will probably have been effected ere these pages leave the printer's hands, and next week experimental work will be carried out through the circuit prior to the opening of the line for public use. A great deal will probably be made of the fact that telephonic communication has been effected between the two capitals, though the feat, if it can be called such, is not actually one of particular magnitude, for a longer length than the one in question (telegraphically), including 28 miles of cable, has been for some time in operation in South America with success. Great care has, however, been exercised in the case of the London-Paris line to make the conditions for working as favourable as posssible, and the cable and aerial wires have been specially designed for the purpose; the margin allowed within the breakdown point of good speaking is large, the "KR" being a little over 5,000, as compared with 10,000, the limiting value; there is little fear, therefore, but that excellent speech will be attained. As regards the financial value of the line, it is extremely difficult to give a forecast; opinions differ, we believe, considerably on the point. Many express the belief that the opening of the line will be speedily followed by the construction of others of a like nature, rendered necessary for the large traffic which will pass over the wires. Personally we are not sanguine that such will be the case, and we imagine that the enthusiasm on the subject is more marked on the French than on the English side of the Channel. However, the whole experiment will not be a costly or risky one, for should it be found that the traffic is not after all of a heavy nature the wires would of course be available for ordinary telegraphic communication; and we believe that an extra link or two of this kind would not be a mere luxury, for the steady increase in telegraphic work across the Channel must eventually necessitate additional means of communication.

[MARCH 6, 1891.

in the armature of the other motor, illustrating in a simple, but very effective manner the electric transmission of power. The slightest motion of the generating armature produced sufficient current to overcome the inertia of the armature in a distant receiver, which simultaneously rocked to-and-fro, giving the system the appearance of motion between mechanically connected bodies. The E.M.F. generated in a given armature can be calculated by means of Kapp's formula. Without much introduction, and without mentioning the existence of ring armatures, the lecturer went on to describe the various methods of winding drum armatures. Table II. (see p. 315) is intended to show how the wires are laid on in succession, and how the potential increases from wire to wire in the case of an 8-pole dynamo. The letters F and B refer to the front and back of the armature core, and letters D and U denote "down or "up," as the conductors are carried round the ends of the core. In text books it is usual to illustrate the methods of winding by means of diagrams showing only a few conductors, and the present table is intended to convey the idea of the adding up of the E.M.F. produced in the adjacent wires or coils on an armature.

Relation of Speed and Power in Transmission Plants.

In the case of series motors driven by series dynamos, automatic regulation can only be obtained within certain limits, as was shown by the aid of characteristic curves, at the lower portions of which "racing" of the machines would take place after a sudden and considerable reduction of the load. Where constant speed is requisite with greatly varying loads, shunt machines must be employed, which at a constant potential maintain a constant field, and thus effectually prevent racing; this Mr. Kapp demonstrated experimentally. It is, however, necessary that the field magnets be of wrought iron, and that the machines are never worked up to their full load, in order that they may respond readily to sudden changes in the load. For locomotive purposes, on the other hand, it is necessary to have variable speeds, and then it is usual either to insert artificial resistances between the switch and motor, aud thus waste a portion of the energy, or to arrange, as is done in Mr. Reckenzaun's system, that the resistances of the field magnet coils themselves can be varied, and thus have no idle wire, and yet get a variable field. The novel self-regulating device for electric transmission plants, introduced by the Allgemeine Elektricitäts Gesellschaft, and mentioned by Mr Kapp on Monday last week, we described on page 115 of our issue, dated January 23rd. So much time was taken up by experiments that the latter and most important part of the second lecture relating to the best section of conductors, and the cost of plant and working expenses, had to be left over, and the audience had to be contented with a study at home of Tables III. and IV.; the latter gives the cost of existing plants operating in various countries.

Power Transmission.

THE third and final of the Cantor Examples of Electric lectures on the electric transmission of power was delivered on Monday last at the Society of Arts. It was full of interesting facts, and it may be regarded as the most valuable of the series. Mr. Kapp opened his discourse by referring to certain rules laid down by Sir William Thomson, and by Professors Ayrton and Perry for calculating the best size of conductors, and it was shown that neither of these methods was universally applicable. Professors Ayrton and Perry's paper, read at the Institution of Electrical Engineers, in 1888, started with the assumption that the current has a constant value, whilst Sir William Thomson's rule ignores the voltage. Table III. was prepared by the lecturer, and it contains all the functions entering into any system of electric transmission, and Table

IV. gives the cost of transmission plants in actual operation. After paying a well deserved tribute to Mr. Brown, of Oerlikon, for his liberality in supplying full information on the subject, Mr. Kapp described the installation at Schaffhausen, which provides the Spinning Mills Company with electric power, and incidentally an interesting comparison was made between rope transmission, hitherto so much used in Switzerland, and electric transmission. It is satisfactory to note that electricity is rapidly replacing the teledynamic methods, for the following main reasons: the maximum power, which can be transmitted by a single rope, is 330 H.P.; whereas, with electricity there is no such limit; ropes wear out, electric cables scarcely deteriorate; the pulleys over which the rope is carried require attention and involve costly charges; finally climatic influences, wet and dry, interfere with the efficient working of ropes. The generating station at Schaffhausen contains five 350 H.P. turbines, of which only two are used at present. Motion is transmitted from the turbines to the dynamos by means of ropes. The dynamos have six poles and generate 330 ampères at 624 volts. There are four cables of 437 square inch section to transmit the electric current to the mills, 750 yards distant. Great care has been exercised in the insulation on the poles, and provision against damage through lightning has been made, firstly, by connecting the steel wire rope which runs over the the tops of the poles, to earth, and secondly, by the employment of four lightning arresters at each station. The dynamos, which are "over-compounded," run at 300 revolutions per minute. With the full current flowing through the line the loss of potential is 24 volts at the extreme end. In order to start the motors gradually, without resorting to cumbersome resistance coils, Mr. Brown has devised an ingenious method of cross-coupling of wires in the machines, but it would be difficult to describe this without diagrams. The commercial efficiency of the plant is 78 per cent.; the variation of speed with extreme loads, 3 per cent.; its entire cost was £6,800; and the company at Schaffhausen charges £13 12s. per H.P. delivered per annum, which is considerably less than steam power in the district.

Electric Trans

Falls.

THE largest of existing plants will soon mission at Niagara be eclipsed by the projected scheme of converting a 25,000 H.P. waterfall, a minute fraction of one of the Niagara falls, into electric energy and transmitting it to a place of application 20 miles distant. The commission charged with this project invited tenders in all parts of the world, and among 20 competitors, 14 complied with the conditions stipulated. Eight of these competitors tendered for both the generating plant and the transmission plant; four offered to supply generating machinery only, and two tendered for methods of transmission. Among the mixed systems of transmission there were seven electrical, six pneumatic, and two hydraulic. Electrical engineers, said Mr. Kapp, are hardly prepared as yet, to undertake such gigantic work at the present day, but the time was near at hand when there will be no limit to the dimensions of electric transmission plants; it is merely a question of voltage, and that can be solved by means of transformers.

291

greater tension. The placing of several machines in series again presents serious difficulties; therefore, in the event of power being transmitted in large quantities at high tension, alternating current machines and transformers will have to be resorted to. The alternators will be made to give a moderate E.M.F., which can be transformed up. The difficulty of commutators being eliminated, it is only a question of obtaining sufficient insulation in the transformers, and this has been attained by surrounding the entire coils with an insulating oil. Mr. Kapp has tested such a transformer with potentials of from 2,500 to 17,000 volts continuously for several days. Mr. Brown has gone as far as 36,000 volts without breaking down the insulation. At the receiving end the current will be transformed into low tension for working the motors.

Alternating Current

Motors.

2

FOR several years past, from the days of

Prof. Ferrari's investigations, which were followed by those of Tesla, Zipernowsky, and a host of imitators, we have periodically heard of the question of alternating current motors being solved. More than once have we questioned the solution of this difficult problem, and certain enthusiastic inventors had the free use of our pages for the ventilation of their pet theories, yet we are not aware of the existence of any commercially successful motor, one which gives a good efficiency with a reasonable speed at variable loads, and which is entirely self-starting. If those gentlemen, who then contradicted our assertions, can now show us any radical improvements, we shall be glad to record them. Mr. Kapp spoke of several types of small alternating current motors with two and three wires, but he has not pointed out any successful applications. We were particularly struck with Mr. Kapp's ingenious model for illustrating the theory of rotation by alternating currents. This model consisted of two cranks capable of revolving simultaneously two connecting rods and a disc movable on its centre. The centres of the cranks and the centre of the upper junction of the connecting rods formed a triangle. The pin through the eyes of the connecting rods represented a phantom magnet influencing the motion of the disc. By varying the relative angle between the cranks, the pin (phantom magnet) described straight lines, circles, or ellipses, dragging with it the disc which revolved with more or less regularity according as there was any slip, such slip indicating loss of energy. We had to imagine that the crank angles corresponded to the position of the wire coils on the armature relatively to each other.

Electric Machine Tools.

66

Electric

AMONG practical examples on electric transmission to short distances, Mr. Kapp pointed out several useful tools in use at Messrs. Denny Brother's shipyard, Dumbarton, and he showed in operation a tube cutting machine and a drilling machine, worked by continuous currents obtainable from the Society of Arts installation. The drilling machine is provided with its own holding on magnets so that it can be swung over the side of a ship, or a boiler, and stick to it as long as required without any clamping or fixing. The convenience of such a machine is very great, a considerable saving in time and labour resulting from its use. motors have been applied with perfect success to boring tackles for stern tubes, furnace flues and a variety of engineering purposes with decided economy. Some of the electric mining machines recently described at the Institution of Civil Engineers were also exhibited at the Society of Arts, and we have no doubt that the audience went away fully convinced of the enormous capabilities of electric motors for industrial purposes. Mr. Kapp wisely emphasized the fact that whilst electricity will not rival steam, it is nevertheless, an excellent medium for the utilisation of waterpower at a distance, for the propulsion of tramcars, for underground railways, and for numerous tools and appliances in everyday life.

COMMUNICATIONS FROM AUSTRIA

HUNGARY.

[FROM OUR OWN CORRESPONDENT.]

THE shares of the General Electricity Company, recently constituted in Vienna, are now introduced into the market by the Anglo-Austrian Bank, and the public is invited to subscription in a prospectus giving some interesting data on the previous working of the electric establishment in the Neubadgasse, Vienna, which the company in question has taken over from the firm of Siemens and Halske.

The operations of this establishment were commenced in September, 1889, with lighting up the German People's Theatre, with a capacity of 2,195 glow-lamps at 16 normal candles each. In October, 1889, further installations were added, and the number of lamps rose to 2,700, in November to 3,850, and in December to 4,700. The monthly returns during 1890 are as follows:-January 6,070, February 6,450, March 7,080, April 7,640, May 7,800, June 8,040, July 8,220, August 8,540, September 9,400, October 10,500, November 11,470, and December 12,580. The present number is about 13,300. To meet the constantly-growing demand, a fourth steam engine, two boilers, and a system of accumulators have been procured.

According to the conspectus, on the working receipts and outlay for the year 1890, submitted by Messrs. Siemens and Halske, on an average capital of 1,440,000 florins.

The expenditure does not include the depreciation of buildings and machinery, and the net profit is accordingly so much smaller than the surplus shown.

The shares of the nominal value are offered at 225, and on February 23rd they were being dealt in on the Vienna Stock Exchange at 231 florins.

The erection of electrical works at Budapest, which is eagerly demanded by the public, is now being diligently considered by the metropolitan magistracy. The municipality has accepted the last proposals of the gas company prolonging the gas agreement to the year 1910, in return for which the company renounces its right of priority as against other methods of lighting. The city has now consequently the right to grant concessions for the erection of electrical works, and a resolution has already been concluded by the municipal representatives which empowers, or, in fact, instructs the magistracy, to take without delay steps for the prompt introduction of the electric light in Budapest. Applications for concessions were handed in some time ago, among others one from the International Electricity Company of Vienna, which undertakes to erect alternating current works outside of the inhabited districts capable of supplying all the wards of Budapest and the suburbs. How urgently the want of the electric light is felt is proved by the circumstance that a memorial has been addressed to the authorities by a number of influential citizens praying that the application of the International Electrical Company of Vienna be at once examined on its merits, and quickly decided on, so that it may be possible to supply the city with electric light next winter. Messrs. Ganz & Co. have joined in this application, and the intention is subsequently to convert the works into an independent Hungarian undertaking.

The electric lighting of the Royal Hungarian Palace at Ofen has been finally agreed on, and the firm Ganz & Co. are entrusted with its execution. Operations are to begin in the month of March, immediately after the departure of the Court, which is at present staying here. The installation

[MARCH 6, 1891.

will be connected with the works to be erected in Budapest, and if the latter is not ready and in action by next winter, the Royal Palace will be provisionally supplied with light by a cable from the works of Ganz & Co.

As we learn, the Popp Compressed Air Company is again aiming at the erection of electrical works in Budapest. Victor Popp has addressed a letter to the authorities, with the request that his scheme for supplying the community with compressed air and electric energy may be taken into consideration.

From the recent report on the activity of the electric department of the firm Ganz & Co. for the year 1890, we gather the following facts :-

This department has during the year just expired carried out 136 electric lighting installations, with a total of 183 arc lights and 60,500 glow lamps, from 29 central stations on their system of alternating current transformers. Of these central stations there are in Hungary, 2; Austria, 4; Italy, 6; France, 5; Spain, 3; Russia, 2; Switzerland, 2; Sweden, 1; Brazil, 3; Australia, 1. The firm has also carried out several electric installations in India. It has also arranged the electric lighting of the Imperial Russian domains at Zarskoje Selc, and the Palaces of the Grand Princes Alexis and Michael.

It must also be mentioned that the Hungarian Minister of Commerce has rejected the petition for the concession of an electric railway between Vienna and Budapest.

SOME EXPERIMENTS ON GUTTA-PERCHA.

THE Annales Télégraphiques for January-February, 1891, contains an article written by M. Lagarde, an important functionary of the French Telegraph Department, on certain experiments he carried out with the view of determining the influence exercised upon gutta-percha as an electrical insulator by the respective constituents of that material.

The gutta-perchas experimented upon were such as were met with by the author when testing cables, but although numerous samples were tested, only a few gave, results which could be considered as fairly conclusive.

The elements of gutta-percha are given as

with about per cent. of mineral substances.

Some stress is laid upon the fibrous structure, M. Lagarde stating that the better qualities are the most fibrous, and that this characteristic affords skilled observers a valuable method of determining the quality of a specimen.

The methods adopted by M. Lagarde for separating the various elements were as follows:

To evaporate the water the gutta was heated to 110° C. in a current of carbonic acid gas, the quantity of water being ascertained by the difference of weight.

The resins were separated from the percha by treatment in pure alcohol at boiling temperature.

The following table gives the results of three series of tests taken on gutta-percha coming from three different works; in each of the series the percha came from the same manufactory, and was used as the core for cables similar to one another, and a comparison is thus obtained between the two experiments in each series: