OCTOBER 11, 1889.]

masterly address of Mr. Norwood to the proprietors of the London and St. Katharine Docks Company, we firmly believe that a feeling would be produced in their minds which had not previously existed there, and the evils of strikes would be forcibly brought home to them. They now think only of themselves and the present; the disastrous results of their illadvised action to many other sections of the community, and what the future has in store for them, form no part of their calculations. No one can dispute the absolute right of the labourer to decline work on terms which to him seem unsatisfactory, but compulsion should not be exercised upon others who think differently. It may not be inappropriate to introduce here the opinion of a daily contemporary, with whose remarks every well regulated mind will agree:-" A wider question still is whether the public, under the influence of its amiable sympathy with the Dockers, has been wise to play into the hands of the agitators, and to afford able and unscrupulous demagogues like Mr. Burns so instructive an object lesson. Was it prudent to show these gentlemen that almost anything can be obtained by skilfully playing at once upon the fears and the good nature of the well-to-do classes? Is it likely to tend to the security of industry or to the prosperity of the country, for employers and capitalists to know that they may be at any moment at the mercy of a few professional wirepullers, who are able to declare that if their demands are not conceded they will cause the greatest inconvenience to the whole community? The lesson, at any rate, has been taught and learned; and it is far from improbable that the forced surrender of the Dock Companies will be followed by a long series of disastrous industrial struggles, which, in the end, will damage no class so much as that of the labourers themselves."

Such scenes as we have recently witnessed in and around London would not have been tolerated for a day in St. Petersburgh, Berlin, or Vienna; but England is fortunately, so we have been taught to think, a free country, and the pretensions of labour can be carried to an extreme. Trade disputes should be settled between the parties fighting for their rights, and no one would desire to see Government interfere with either side; but employers are too often heavily handicapped by hostile public opinion, formed in ignorance of the merits of the case, and against which they have to contend. Is it too much to hope that legislation can, within a reasonable time, be brought to bear upon these trade disputes, and, at least, put down intimidation with a firm hand; and that all disagreements shall be submitted to arbitration, work in the meantime to go on unchecked while settlements are pending?

THE recent gale has of course produced the usual results as regards the telegraphic system of this country, that is to say, in many cases a complete cessation of communication has taken place. Who is to blame for this? Not the Post Office, for the department is prepared at any time to lay down a system of underground circuits provided the order is given, and the necessary funds are furnished for the purpose. It is for the

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public to stir in the matter through their representatives in Parliament, and the sooner it is done the better. Surely the Chambers of Commerce are sufficiently strong to press the matter forward. The inconvenience produced by the breakdown must have been very great to the commercial world, and has caused a great deal of grumbling, but grumbling without action is, it is needless to say, useless, and we are only surprised that such an important matter has not received the attention it deserves. For an expenditure of £6,000,000 we believe all the main trunk wires could be placed below ground, and, although the sum may be a large one, the nation can well afford to expend it, and it ought to do so.

WE hear that a syndicate for the promotion of a fast-speed telegraph system is at present in London exhibiting the apparatus; it is claimed that 500 words per minute could be obtained through an Atlantic cable. The apparatus includes a dynamo, a steam engine, and an induction coil giving a continuous two inch spark. How any telegraph inventor, who has common sense, could suppose that such a potential would be permitted or could be used on a cable is surprising. The idea that such a high speed as that named could be obtained through a cable is perfectly childish; we are quite certain that no proper experiment could have been made to prove that the apparatus could work, as there is no artifical cable that would carry such a high potential without "sparking across" taking place. Some few years ago an American fast speed apparatus, which worked at 1,000 words a minute, was tried in this country; this speed was obtained through an ordinary resistance (the usual test of those who know nothing about practical telegraphy), but when the apparatus was connected to an aerial line, 400 miles long, the result was-30 words a minute; the promotors, after this experiment, scuttled back across the water, and subsequently orders came across for several complete sets of Wheatstone fast speed instruments to be shipped to the States.

AT a meeting of the Executive Council of the Edinburgh International Electrical Exhibition of 1890, on Friday last, it was intimated that a committee had been formed for the purpose of interesting the citizens of London in the Exhibition. The Lord Mayor Elect, Sir Henry Isaacs, has agreed to act as president of the London committee and as one of the vice-presidents of the Exhibition. Sir George H. Grubb is to be executive chairman of the London committee, for which offices have been procured at 3, Victoria Street, S.W. Satisfactory progress was intimated with regard to the guarantee fund, which is now close upon the sum fixed by the executive as the minimum, and no difficulty is anticipated in securing a great deal more than that amount. The Lord Provost, magistrates and Town Council of Glasgow have agreed to receive a deputation from the executive committee, the object being to enlist the co-operation and support of the Corporation of Glasgow in arousing the interest of the people in the west of Scotland in the Exhibition.

THE half-yearly meeting of the shareholders in the Commercial Gas Company was held on the 4th October at the Cannon Street Hotel. Mr. George Livesey expressed his conviction that no electric light could touch gas, even for the purpose of lighting the streets; and Sir Robert Rawlinson endorsed that opinion. What funny reading this will be 10 years hence! Poor benighted Livesey!

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NOTES ON THE DYNAMOS AT THE PARIS EXHIBITION.

VIII.

THE Desroziers machine exhibited by the Maison Breguet, and illustrated in fig. 1, has been recently brought into prominence on the Continent. It is of the disc type, the armature consisting of a number of flat coils laid on each side of a disc frame of German silver, which is clamped firmly between two half hubs keyed to the driving spindle, and has its rim stiffened by two rings of gun metal. The coils are first laid on cardboard discs, so that on each disc all the radial wires are on one side, and all the circumferential wires on the other. These cardboard discs, with the coils thus laid on, are fixed one on each side of the German silver frame and clamped to it, the coils being next the German silver, and the cardboard outside. When the coils are firmly clamped in position, the cardboard parts

(OCTOBER 11, 1889

resistance of the armature in machines of the Desroziers class is somewhat greater than in those of ordinary type. The magnets are placed on each side of the armature, the poles being alternately N and S in a circle, and the N of one circle facing the s of the other. In the 14,400 watts machine exhibited there are six magnets on each side, the poles having extension pieces which face each other and leave an opening of from inch to inch for the armature. This machine runs at 200 revolutions per minute, and the current is collected by two sets of three brushes, placed 60° apart on a Gramme commutator having brass segments, the armature coils being therefore cross connected. In fig. 2 we show the directly driven combination of engine and Desroziers dynamo which is supplied for ship lighting. Several other forms of machine are exhibited, but for the present the Desroziers seems to be the type most pushed by the firm.

The Société l'Eclairage Electrique, of Paris, exhibit several dynamos of M. Rechniewski's design, one of

covering the radial wires are cut out and taken off, thus leaving all the radial wires of the coils exposed, while by the clamping of the circumferential parts, the coils are securely fastened to the German silver disc. The armature thus built is very thin and light, and the makers assert that it is at the same time sufficiently strong and rigid. We are unable to give particulars of the exact method of securing the coils to the disc of German silver, for beyond the general statement that the coils are clamped on, Messrs. Breguet keep the manufacturing details a secret. In reply to a question as to whether Foucault currents were generated in the disc, we were informed that they had been eliminated by making the metal very thin, and giving it a particular shape. Our readers may guess from this that there are openings in the disc of such shape and size that the electromotive forces induced in the parts remaining are in opposite directions, which thus prevent the flow of local currents. It is claimed that a larger density of current can be employed in the conductors of the armature, since there is very good ventilation and no heating from the presence of an iron core; at the same time, it should be mentioned that the

which is shown in fig. 3. The armature core is built up of discs of soft iron 024 inch thick separated by varnished paper. These discs have Pacinotti teeth on their exterior, between which when they are laid together, the coils are wound Siemens fashion; they are carried upon a central bush of gun metal keyed to the shaft, this bush having twisted arms inside the central opening in the core, by which a current of air is caused to circulate through the interior of the armature. The field magnet is of the single horseshoe upright pattern, but differs from other machines in being built up of thin plates of wrought iron separated by paper, a construction adopted to prevent the armature projections causing heating in the magnet. The magnet is fixed on a cast iron bed plate, on which are also supported the brackets which carry the armature. The type shown in the figure is made in sizes up to 25,000 watts. Above this the machines are constructed with multipolar fields and Gramme armatures. As these present no specially novel feature other than that the magnets are built up as described, we need not describe them farther.

Amongst the odds and ends we noticed a directly

OCTOBER 11, 1889.)

attached combination of a Brotherhood engine and a Victoria dynamo with overhung armature and outside commutator. Messrs. Escher, Wyss & Co., of Zurich, exhibit a two-pole drum-wound dynamo of the Lahmeyer type, coupled direct to a jet wheel. Messrs. Buffaud & Robatel, of Lyons, show a centrifugal sugar machine, with an electro-motor for driving it, attached direct to the vertical spindle. Messrs. Aveling and Porter show a single cylinder portable and traction engine, having a Victoria dynamo mounted above the boiler on a wrought iron saddle, the machine being driven by a cog-wheel on the crank shaft, the wheel having teeth of red fibre, gearing into a gun metal pinion on the dynamo.

A comparison of Continental and American dynamos with those of English design has doubtless been made by our readers as these articles have been perused. As regards the first, one is struck with the number of multipolar machines of small size, engineers on the Continent looking with more favour on this type than we do. Electrically, multipolar and bipolar machines present no difference, and the decision as to which

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shall be adopted is mostly a manufacturer's question, inasmuch as when other things are equal, the decision lies generally in favour of the least costly to make. To the case of large dynamos these remarks do not apply as beyond a certain size a multipolar machine is in many respects preferable. Some neat arrangements of brush holder gear will not have failed to attract attention, with other little details which add to the look and finish of machines. The extensive use of cast iron for field magnets will doubtless have been observed.

Though the designs are many and varied, it cannot be said that in general workmanship and finish there is much difference on the whole between machines of English and foreign make. It is a mistake to judge modern machines of Continental manufacture by the flimsy ill-constructed Grammes which made their appearance here 10 years ago. Since then the foreigner has walked up, and we have in him a keen competitor, and one, moreover, who has the advantage

show will be a thing of the past, its influence on our industry will not fail to be widely felt if our manufacturers have learned thoroughly the lesson it had to teach. W. B. E.

Lecture. An interesting and instructive lecture with, experiments on "electricity and animal magnetism," was delivered by Mr. J. Jerritt, A.I.E.E., of Plymouth, in the Corn Exchange, Chard, on Friday, October 3rd, in aid of the funds of the Taunton Hospital. The hall was filled with an appreciative audience, from six to seven hundred people being present. The telephones exhibited were kindly lent by Mr. Lewis, general manager of the Western Counties and South Wales Telephone Company, Bristol. Some splendid specimens of submarine, electric lighting, and torpedo cables, manufactured by Henley's Telegraph Works, London, were also exhibited.

ELECTRIC LIGHTING AT PORTSMOUTH.

AT length practical steps have been taken with a view to the general introduction of the electric light into the Borough of Portsmouth, which has hitherto, through a variety of reasons, been almost neglected by serious promoters of the new illuminant. The Portsmouth and South Hants Electric Supply Company which was recently registered with a capital of £50,000 in 9,900 ordinary shares of £5 each, and 100 founders' shares of £5, is, however, starting under apparently favourable auspices. The list of directors comprise several prominent townsmen, including Col. Charles Mumby (chairman of the Alverstoke Local Board), chairman; Colonel C. Lanyon Owen, J.P. (director of the Borough of Portsmouth Waterworks Company; Mr. Alexander Ross, C.C. (Ross and Homan), Mr. A. W. White, Mr. W. H. Handley, with Mr. Robert Hammond, managing director of the House-to-House Electric Supply Company.

The company, which will not start operations until the necessary Parliamentary power or the consent of the local authorities has been obtained, has been formed for the purpose of establishing a central station or central stations in the Borough of Portsmouth and at Gosport, at which electricity will be generated on a large and economical scale, and then distributed by means of "mains" or "conductors" placed either underground or overhead as the local authority of each district may determine.

The prospectus which has just been issued says:"The necessary statutory notices have already been given to the local authorities of Portsmouth and Gosport respectively, of the intention of the company to apply to the Board of Trade for provisional orders under the provisions of the Electric Lighting Acts, 1882 to 1888, authorising the supply of electricity within the Borough of Portsmouth and in Gosport, and the directors have also applied for the consent of each of such local authorities to a Board of Trade licence to enable the company to commence operations forthwith. It is fully anticipated that in Portsmouth and its neighbourhood there will be a wide and rapidly increasing demand for the electric light, and with even a moderate average consumption it is confidently believed that the undertaking will secure a revenue which, after providing for all expenses of production and administration (as also for depreciation of plant, mains, and buildings), will return a substantial dividend to the shareholders. The company's first central station will be erected at Portsmouth on a plan which will permit of the regular and economical expansion of the plant required from time to time to meet the growing demand for the light; as the increase of capital for such purpose will be relatively smaller and the cost of production for the greater output will be proportionally less, it is anticipated that the dividends of the company will grow steadily with the extension of its business. The proposed station will be of similar construction to the central station erected at Kensington by the House-to-House Electric Light Supply Company, Limited, whose engineers were enabled to profit by the practical experience they had previously gained at Eastbourne and Brighton. The Kensington station has elicited the marked approval of many eminent authori. ties, including Mr. W. H. Preece, F.R.S., chief electrician to the Post Office, and the directors are of opinion that it combines all the advantages to be derived from the most advanced scientific discovery and the selection of the best elements of the various systems of supplying electricity. The company will, however, be as free as the gas companies are to acquire and use any improved apparatus or method that may hereafter be discovered. A contract dated September 27th, 1889, has been entered into between the company of the one part and the House-to-House Electric Light Supply Company Limited, of the other part, under which that

Contracts to erect at Portsmouth a central buildings and all incidental works, machipliances, and to lay down the necessary

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[ОСТОВЕР 11. 1589

mains or conductors' estimated for the first requirements of the company (the whole being a duplicate, except as to officers, of the House-to-House Company's station at Kensington) for the sum of £25,950, payable, at the option of the directors, either in cash or as to one-half in cash and as to the other half in ordinary shares of the Portsmouth Company, issued as fully paid. No promotion money has been paid nor will be paid by the company, and, after providing for the preliminary expenses attending the formation and registration of the company, the whole of the capital will be available for the purposes of the undertaking."

INDUCTION AND OTHER THINGS.

(Continued from page 377.)

A LARGE share of the space in Dr. Fleming's work has been allotted to descriptions of the work of Joseph Henry and Faraday. It is difficult to say whether this is a good plan or not; we think not. There is nothing in the work of Faraday or Henry that is not now incorporated into modern books, except what has been superseded. If Dr. Fleming's book is to be taken as an encyclopædia article, it should have the historical portions picked out and put together at the beginning, where they could be skipped at once. It is supposed to be the proper thing for every electrician to read Faraday's and Cavendish's researches, and now that Dr. Fleming has said so much about Henry, his works I will have to be included too. We have read none of them, and do not mean to. If an electrician wishes to become a good original experimenter, he can, of course, gain a great deal from the example of these men; but if he wants knowledge of facts it is not the best way of obtaining it, and the order of discovery is seldom the best order for learning. This is not said through any want of respect for the giants of the past, and that sort of thing; but people are apt to waste a great deal of valuable time through a sort of hero worship. If a man wants to study, say, Ethics, he is told to read the works of a lot of ancient writers. A large number of young men spend a great deal of time in learning a dead language or two on purpose to drink in the wisdom of the ancients quite pure, but generally stop after using a great deal of good time, before they have begun to taste. Now whatever we may privately think, it might be treason to say that any modern philosophers have as great minds as the old Greeks; but we will say that though a writer of a modern textbook may have no ability at all in comparison with, say, Aristotle, Plato, or Socrates, he probably knows much more than the three of these somewhat prolix and mystifying writers put together. Though this veneration for the past may have great influence in Theology, Ethics, Law, Metaphysics, and in fact all the departments of knowledge of a foggy kind, it should be studiously kept out of Science. No chemist would think of reading up old chemistry books. It is the business of writers of text books to extract all that is worth keeping from old books and papers.

Some time ago Dr. Fleming divided electrical engi neers into two classes; those who could not get beyond Ohm's law, and those who could think of alternating currents. We would go further than this, and would sub-divide the last class into those who try to deal with alternating currents as they really are, and those who assume the simple sine law. The latter should be apprehended under 1 and 2 Vict. cap. 38, or whatever it is, and should be accused of making their data fit their calculations; they should then be convicted of pure mathematics, and locked up with vagrants and tramps and other useless members of society. Finally they should be condemned to the last penalty of breaking the shunt circuit of a big dynamo through their bodies..

OCTOBER 11, 1889.]

A great deal of Dr. Fleming's book is useless to practical engineers, because it depends on unwarrantable assumptions. He points out that the variation of permeability and the magnetic hysteresis in a transformer core will alter the character of the secondary curve, even if the primary is a curve of sines. A very small extension of these ideas will show that there is nothing in a dynamo to make it give a curve of sines. Even if it gives an approximately sinoidal curve at no load, it would not at full load. The departure may be small or great, but no one knows to what errors such assumptions may lead. As we said in a recent review of a book by Mr. Blakesley, this sort of treatment may be useful to get rough results, but that is all that can be said for it. It is usual to have recourse to Fourier's theorem at this stage of the argument; and Dr. Fleming, of course, points out its exceedingly great value and convenience, and then makes no use of it whatever. We do not here deny the value of Fourier's theorem in other branches of physics, we merely say it is no use in alternating current work. Given a periodic function, there is no difficulty in splitting it up; but if you have the curve you do not want it split up. If you have not got the curve, Fourier's theorem will not help you to get it from a dynamometer reading. This part of the book, like a great many other parts, may have a special interest for the mathematical student. Dr. Fleming is a remarkably clear writer. No exact degree of mathematical knowledge on the reader's part is assumed; and some parts require a knowledge that would make other parts very elementary. Probably the best rule is that followed by Dr. Fleming, of explaining everything as clearly as possible, using advanced mathematics only where simple are ineffectual. In one or two places he refers to mathematical text-books in which the particular processes adopted by him are to be found. This is an admirable plan, and might be very much extended. Many people find mathematical books very hard reading, and much prefer to get their mathematics combined with physical meanings by reading science with purely matbematical books as commentaries. While on the subject of making sine curves with cylinders cut obliquely, Dr. Fleming might have added Clifford's method of splitting up a given curve into a Fourier's series. Written more clearly, it might be interesting to many.

The term "impedance," as defined by Dr. Fleming, has no meaning in practical engineering, because it assumes harmonic current variation. A choking coil, as explained by Dr. Fleming, modifies the current curve, even if the electromotive force curve is sinoidal. As Dr. Fleming also mentions, L may be given three meanings when there is iron in the coil. The result of this is that to talk of the impedance of a choking coil conveys no meaning. Even if "effective resistance" had been adopted we should have had a loose and unscientific term thrust upon us, as the effective or apparent resistance depends on what is done with the coil. In old days people used to talk of the apparent resistance of a charging secondary battery, or of a motor; but they soon got clearer ideas, and understood that they were dealing with a resistance and a back electromotive force acting simultaneously. In alternating current work we are passing through the same stage. Very soon electricians will think of alternating circuits as having resistance and giving a back electromotive force, instead of confusing the things together. At present Dr. Fleming and a few others talk of "ohmic resistance to distinguish resistance from the relation between the back electromotive force and the current. The expression "ohmic resistance is absurd, else, as a common sense American remarked, work is the product of the poundic mass by the footic length.

The discussion raised by Mr. Sumpner as to the three definitions of the coefficient of self-induction of a circuit which magnetises ircn are interesting. It is questionable whether the term coefficient can be rightly used here at all, as it would merely mean a division by the current in use at the particular instant and in the particular case under discussion. But, leaving out the

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question of the coefficient, how are we to define the self-induction of an electro-magnet with a given number of ampère turns current in its coils? The third way is to consider the energy stored up; but we do not know whether we are to measure the energy that was absorbed in raising the current to that value, or that would be got out of the electric circuit on reducing the current to zero. There is a difference in the case of an electro-magnet. The second method proposed is to measure the whole induction through the circuit. This also depends partly on the past history of the iron. Neither of these definitions is of scientific importance, as no one wants to make calculations about such things, and they are obviously of no practical value. According to the first definition the self-induction is measured by the back electromotive force as the current increases. This is the idea most people have of self-induction, and in practical work it is the only one of any use. In practice, however, people never want to measure self-induction. There is a sort of idea afloat that when the benighted practical man is better educated he will measure the coefficient of self-induction of transformers, dynamo armatures, and mains; but he could not obtain any useful information by such an attempt.

Dr. Fleming uses the secohm as the unit of selfinduction. In some ways we are sorry this name was given up, as Profs. Ayrton and Perry had done so much in connection with the measurement of self-induction that their name might have been kept. Like voltampère and volt-coulomb, it was a compound word and thus did not really fit the system of units well. The name now adopted is the "quad." This is not the name of any electrician, and it represents a length which is not a round number of metres, and it suggests that self-induction and length are the same thing, a matter on which we will have more to say presently. Before any unit of work was in use, and while people used the watt as a unit of energy a contraction of voltcoulomb was proposed in this journal. The vomb was to be the unit of energy, and instead of Greek affixes being used, we were to have the vomboon and vombling. Instead of this the joule was put into circulation, and there is no settled way of pronouncing it yet. The coefficient of self-induction should certainly have been called after some one; and why should Poggendorff be omitted? We frequently use the whole name when we wish to express ourselves strongly, or use what a young friend calls bad grammar; but we ought to have the practical unit of self-induction called the pogg. The multiple and sub-multiple would be, following old English practice, the poggoon and the pogglet.

The main subject, according to the title of Dr. Fleming's book, is transformers; but the practical and descriptive part will be in the second volume, which we hope may be soon published. We do not follow all of the statements as regards the efficiency of transformers, and fear that some are inaccurate. The loss in a converter may be divided into the loss in the copper, which can be got accurately by multiplying the resistance of each coil by the square of the effective current in it, and the loss in the iron core. The magnetising current, that is the primary current when there is no secondary current, is practically a quarter of a period behind the primary electromotive force, so the power spent in the copper by it may be taken as independent of the load on the transformer. As the loss in the core and the loss in the copper, due to the magnetising current, are constant, and as the rest of the loss in the copper varies as the square of the current, it is obvious that a given transformer gives its highest efficiency when the loss in the iron, together with the loss in the copper due to the magnetising current, is equal to the rest of the loss in the copper. In an ordinary closed circuit transformer the product of the square of the effective magnetising current and the resistance of the primary is inappreciable; so the highest efficiency is when the loss in copper is equal to the loss of iron. Similarly, in a given dynamo, the highest efficiency is when the loss in the armature and series coil is equal to the constant losses in the machine. The problem of finding the