such a hurry to put its hands on this service, on the ve of the elections, that it has not taken time to have valuation made of the matériel of the General Telehone Company, still less of paying the price. Not eing able to instal rapidly in its own premises the matériel which it purchased by virtue of the contract we have already mentioned, the Government has thought it to take possession of the premises to which the subcribers' lines lead. The General Telephone Company, which was in possession of the premises in question, efused to deliver them up; it only yielded to force. All passed off, however, in a very simple manner. 0 o'clock 12 engineers or sub-engineers, designated by M. Cael, directing engineer of the district of Paris, each accompanied by a police commissary, presented hemselves at the 12 Parisian telephonic offices. In each of these offices they were received by a manager or high official of the General Telephone Company, assisted by a sheriff's officer.

At

The Government hoped, by proceeding on a Sunday to these various violations of domicile, to avoid the egal reports of the Ministerial officers; but thanks to an ordinance of the President of the Tribunal of Comnerce, the sheriff's officers required were authorised so work yesterday (Sunday). These officers limited hemselves, however, to verifying the facts; they could not draw up their reports till to-day.

In presenting himself before the delegates of the Telephone Company, the Police Commissary read the Ministerial warrant of August 30th, consecrating the seizing, and ordering the taking possession of the premises belonging to the Telephone Company. After this reading the Police Commissary informed the representatives of the company that he had received orders to place the engineer of the Administration of Posts and Telegraphs in office, and to warn the office employés that it was this new functionary they had henceforth to obey. It was M. Clément who arrived at the Avenue de l'Opéra agency. This gentleman, and the engineer who accompanied him, were received by M. Lair, chairman of the General Telephone Company, and by M. Berthon, assisted by a sheriff's officer.

"Do you give way before the Ministerial warrant I have read to you?" asked M. Clément of M. Lair.

"Not at all," answered the chairman of directors of the Telephone Company; "we shall only yield to force."

M. Clément hereupon informed M. Lair that the Ministerial warrant empowered him to use force. "In that case," said M. Lair, "I give way; but you will recognise in your report that I have only yielded to force; you will also tack on to this report the written protest which I hand you in the name of the company." The text of this protest is as follows:

1. The company declares that it only yields to the injunctions made as constrained and forced, and under the most express reserve of its rights, means, and actions, as much on account of present facts as of all anterior facts on the subject of which protests have been made previously.

2. It protests against the present and effective seizure by the State of its working matériel, before comformably to the principles of common law and the stipulations in the agreement, the price of acquisition to which the company is entitled has been fixed and previously paid, and even before an agreement or even a definitive decision has been come to regulating the method of assessment and payment of the said price.

3. It demands an official certificate by which the Administration of Posts and Telegraphs has taken possession of the premises which the company occupies, in the absence of any consent or stipulation as to their cession to the profit of the State.

A very amusing incident marked the seizure of the telephone office in the Avenue de l'Opéra. The artist of an illustrated journal was sketching the scene in the office, when M. Clément went up to him, took his paper from him, and forbade him to sketch the scene. The seizure of the departmental offices was gone through with the same formalities and the same protests. No regrettable incident occurred.

The General Telephone Company looking after, before everything, the interests of its subscribers, had taken the necessary measures, so that the public service should not be interrupted. The Direction of Posts and Telegraphs promises large reductions in the price of the telephonic service, this is all right; but what will be wanting especially, in the period on which we are entering, is the discretion of the employes who have become functionaries. The secrecy of telephonic conversations is henceforth lost; we beg our friends not to forget it.

NOTES.

Bradford Electric Lighting Scheme.-The arrangements for the supply of electric light in Bradford are now practically complete, and it would be possible, we are informed, to lay on the current at once were it considered urgently necessary. It was stated that the engines had been thoroughly tested, and proved to be efficient for their work, and all the apparatus, with the exception of some internal fittings at the generating station in Bolton Road, was in a satisfactory condition. It will be necessary, however, to engage a staff of employés, and, inasmuch as the demand for the new lighting medium is not likely to be very great until the evenings lengthen, it was thought advisable to postpone the inauguration of the installation until about the middle of next month.

Electric Lighting at Bournemouth.-Last week the Brush Electrical Engineering Company, Limited, gave a brilliant display of the electric light in the fine square at Bournemouth, with the view of showing how effective this mode of illumination is for the exterior of hotels and public institutions. The company have established a plant and central station in the Gas Works Road, and provided on the present occasion five arc lamps of 2,000 C.P. each. Arrangements have now been perfected at Bournemouth, and the company propose to make an effort to introduce the light into Bournemouth on a sound and permanent basis. Newlyn's Royal Exeter Hotel and Highcliff Hotel will shortly be lighted by the company.

Electric Light in the House of Commons.-The London correspondent of the Manchester Evening Mail says: An opportunity will soon be afforded to contractors to light the Houses of Parliament by electricity. Up to the present time the authorities of the building themselves have had control of the small electric installation which exists, and has been completely successful in the hands of Mr. Prim, the resident engineer; but the Treasury seems to be unwilling to sanction the large expenditure necessary to light the whole of the palace. They therefore propose to call in the aid of some outside company, which will supply electricity at a fixed price per Board of Trade unit. No definite arrangements have as yet been made in this respect, and there is not likely, as far as can be seen at present, to be much competition for the contract.

Gas v. the Electric Light.-A good deal of stir has been occasioned at Bournemouth by the proposal to purchase the local gas works on behalf of the town. A town's meeting was held last week to consider the subject, when Dr. Clegg, who was one of the speakers, observed that the chief grounds of the opposition seemed to be the fear of the electric light diminishing the profit of gas. He had for some considerable time past studied the subject of electricity in all its branches, and had consulted some of the most eminent engineers, who concluded that the electric light must always be regarded as a light of luxury. He strongly supported the proposal. A resolution was eventually passed, by a large majority, in favour of purchasing the gasworks, but a poll was demanded.

268

The Lighting of Dublin.-On Monday, at the monthly meeting of the Municipal Council, Mr. Robinson, C.E., moved the adoption of the report recommending the borrowing of £50,000 to carry the electric lighting scheme into effect. After considerable discussion the motion was adopted by 38 votes to 3.

Telegraph and Telephone in Uruguay.-A Manchester paper says:-The telegraph communication of the country is ample for present needs, and places Uruguay, through the capital, with all the countries of the world. In Monte Video there are two telephonic companies in active operation, and, though there are only 150,000 inhabitants, the average of the daily communications number 6,000. The telephonic subscribers in the city are 2,226, the proportion being 159 subscribers to every 10,000 inhabitants; whereas in Berlin it is only 48; in Paris, 21; and in Buenos Ayres, 65. Monte Video has more than double the number of telephones that Madrid has with 398,000 inhabitants, more than three times the number that Lyons possesses with 402,000 inhabitants, and almost six times as many as Marseilles.

Electric Lighting in Stockholm.-The electric light is steadily gaining ground. The greater part of the Royal Palace is partly lighted. Messrs. Leith and Rosen have fitted up the new market halles with 353 glow and 14 arc lamps, the former of 10-16, and the latter of 800 candle-power each. They are worked by two compound Schuckert dynamos. The plant is guaranteed for two years, and the lamps for 180 hours; the total cost for the installation is £1,800. There is every possibility of a central station being soon established, and the gas board have urged upon the municipality the necessity for this step. This was suggested as far back as 1886, but not carried out on the grounds that any work at that period would soon become obsolete.

The Tabor Steam Engine Indicator.-[Abel Heywood and Son, Manchester, and Simpkin and Marshall, London, 1889.] This little work emanates from the firm of John Musgrave and Sons, Limited, of the Globe Iron Works, Bolton. It is bound up conveniently with a pocket to contain loose diagrams. Besides setting forth the description of, and the advantages pertaining to, the Tabor indicator, with instructions for its management, a chapter devoted to calorimeter testing is accompanied with a diagram and full particulars of a simple form of apparatus for making these tests; 34 useful tables are also appended. The firm have in addition endeavoured to supply a want by the production of a revolution counter which they are willing to supply for the small sum of 4s. 6d.

Electricity on Ships.-During the past month several large ships have been lighted by electricity. Among these may be mentioned the Inman Liner City of Paris, a large screw steamer, built by Messrs. Scott & Co., Greenock, for the Mala Real Portuguesa and many others. It is also intended to fit the electric light plant on three Admiralty cruisers which are being built by the London and Glasgow Shipbuilding and Engineering Company, Limited. Several Clyde shipbuilders are introducing electrical departments in their yards, and will thereby be enabled to undertake contracts for ship lighting.

The Swedish Government and Electricity.-The Government some time ago despatched Lieut. L. A. Aufelt to the Paris Exhibition, in order to study the most recent development of electrical science, particularly as regards lighting, motive power, and submarine mines. He has now proceeded to Germany for the same object.

Count Edison,-Modern Light and Heat (Boston) says Mr. Edison has been made an Italian Count, which honour carries with it the title of Countess for Mrs. Edison.

[SEPTEMBER 6, 1889.

Water Power.-At a meeting of the Norwich Town Council last week the question was asked whether a fall of water could not be utilised for the supply of electricity. It is to be hoped the Council will not neglect this opportunity, if practicable, of utilising 80 advantageous a power.

Bottone on the Electrician's Slide Rule.-We re produce the following letter of S. Bottone to the editor of the English Mechanic, which has reference to Dr. Fleming's slide rule, which we noticed in a leaderette three weeks ago :-I sent you, sir, for publication in the English Mechanic (see p. 472, Vol. XLVII.) a description and illustration of an electrician's slide rule, designed by John Innes, F.C.S., Llanelly, by the aid of which all questions connected with volts, horsepower, and watts on the one hand, and incandescent candle-power, ampères, metal deposited per hour, & on the other, could be immediately read off. Your illustration of this rule was so good as to enable anyone to construct such a rule had he been so inclined. I have just received from the Edison and Swan Electric Light Company a circular dated August, 1889, in which a slide rule, differing in no essential respects from the above, is described and figured, and attributed to Dr. J. A. Fleming. As even the mode of using the slide is given in words which are almost the ipsissima verla used by Mr. John Innes, I am surprised that neither the Swan-Edison Company, nor yet Dr. Fleming, should have acknowledged the source from which the idea of this slide rule was originally derived. While on this subject I may point out that the Woodhouse and Rawson Company are selling (see Electrical Plant, p.4, No. 26), and Messrs. King, Mendham and Company have actually patented, a "watch" form of pocket galvanometer that I have been making and selling for the last four years; the only difference is that my instrument indicates, besides volts and ampères, the direction of current and the N. and S. poles, all these being marked on the dial.

The Swiss-German Rhine Canal Company, Birsfelden (Basle).-A correspondent writes:-"The Finance Committee of the above-named company has again published the prospectus (on which I recently sent you a report), see ELECTRICAL REVIEW, August 30th, in which the public is invited to subscribe for shares in the undertaking. But this new edition of the prospectus shows, by small modifications scarcely noticed at the first glance, a sense of the peculiar circumstances of which I have informed you. In the first place, the list of places where subscriptions may be paid is reduced from 25 firms (19 German and 6 Swiss) to 16, since besides the firms mentioned in my former communica tion, which have publicly denied their connection with the undertaking, six further firms (three German and three Swiss) have been omitted in the list. Further, the statement that considerable sums have been deposited with the Commercial Bank of Basle as a guarantee, has been omitted in the modified prospectus. On the other hand, the firm Thomson-Houston figures in the revised prospectus with the name Housten. As regards the ominous guarantee deposit, the projectors publish in Swiss newspapers a very peculiar explanation. The bank, Kidder, Peabody & Co., of Boston-so they tell us-has handed over to Baring Bros., of London, a guarantee deposit of 50,000 dollars, in order to transfer it to a Swiss bank in the interest of the company. This is the substance of the somewhat confused explanation. In opposition to the statement of the three banks which (as explained in my former letter) had been introduced in the prospectus against their will, it is now asserted by the promoters that the three firms had offered to receive subscriptions, and had stipulated for the exclu sive agency in extensive districts. Messrs. Bell & Co., of Kriens, who have also been named in the prospectus of the above society-as furnishers of the turbines for the proposed plant are now protesting in the Allegemeine Schweitzer Zeitung against their firm being named in combination with the said enterprise."

SEPTEMBER 6, 1889.]

A New Dynamo.-A new dynamo is used for the lighting of the Geelong Times office, Melbourne. It is the invention of Mr. Alcock, of the firm of Messrs. A. W. Alcock and Co. of that city, and he intends applying for a patent. We have not yet particulars to hand.

Profit in Motor Work.-The following appears in a recent edition of the New York Electrical World:-The question, "What profit is derived from selling current for operating electric motors?" was recently put to the superintendent of a well-known electric light and power station furnishing current to about 125 H.P. in small motors. His answer was, 38 per cent. net profit on the original investment. Part of his daily expense account for operating the motors only is made up as follows: Coal, $9; water, $1.20; waste and oil, 10 cents; sundries, $3; labour, two men, $4. It is evident that the profit lies largely in the fact that the motors are numerous and small. The same quantity of current supplied to, say, four large motors of 30 H.P. each, would not yield any such return. But even then there would be a much better margin than is suspected by those who have not yet looked into motor problems, or noted how remarkably the varying call for current practically doubles the capacity of the plant for motive power purposes.

Belfast Telegraphists. In the House of Commons on Tuesday, in answer to Mr. Sexton, Sir H. Maxwell said: During the past 15 months no resignations have occurred in the first class of telegraphists at Belfast. Five resignations occurred in the second class. The Postmaster-General received some time ago a memorial from the telegraphists asking him to create a number of first class appointments in order to give them promotion. This memorial he carefully considered, and came to the conclusion that there were no duties to be performed that would justify additional superior appointments at that time, and he caused a reply in this sense to be sent to the memorialists. The question will shortly come again under his consideration, when he will see if there is any change in the circumstances. Mr. Sexton asked the Postmaster-General whether a vacancy in the Belfast Telegraph Office in the first class had been filled by the appointment of a gentleman who had for years held, and still holds, the position of telegraphic instructor in the Midland division of Ireland; whether this official had been absent from the Belfast office some eight years; and whether, during this period, he was connected with the Surveyor's Office in Dublin, and under the immediate control of the authorities there; and if so, whether it was in accordance with usage to appoint to a first class post in the Belfast office an official who continued to perform a specific duty in another section; and whether, in view of the stagnation of promotion existing in Belfast, this appointment would be made redundant. Sir H. Maxwell I have to say in reply to the hon. member that the facts, so far as they are stated in his question, are substantially correct. It should, however, be added that the inspecting telegraphist referred to is a member of the Belfast staff, and was the senior officer on his class qualified for promotion. The question of making an additional first class appointment, which would in effect give a promotion, is under the consideration of the Postmaster-General.

Books Received.- "The Alternate Current Transformer in Theory and Practice," by Dr. J. A. Fleming, M.A. Electrician, London.

"A B C of Electricity," by Wm. H. Meadowcroft, endorsed by T. A. Edison. John Heywood, Manchester and London.

"University College, Bristol, Calendar for the Session 1889-90," Arrowsmith, Bristol.

John A. Roebling, Sons & Co., Trenton, N.J.: List of bare and insulated wires. This latter is a neat little booklet, in which the various wires are admirably set forth, and will probably be of great assistance to the profession.

269

An Effect of the Copper Syndicate.-The report of the Barmen Chamber of Commerce affords an illustration of the widespread character of the evil done to trade by the notorious French copper "ring." The manufacture of brass eyelets is an industry of some importance at Barmen. The great advance in prices which the manufacturers were compelled to make to cover the additional cost of the raw material drove away a large proportion of the trade to Paris, where the makers of eyelets were favoured by the syndicate. This loss of trade, which has been keenly felt, is not likely to be soon recovered.-Industries.

The Circular of the Institution of Electrical Engineers. In our correspondence columns we publish further letters on this subject-one from Mr. Webb, secretary of the Institution, explaining how the mistake arose.

Destruction by Lightning.-Early on Wednesday morning four farms and premises, situated at Rayne, Sampford, Waltham, and Dunmow, were burned to the ground with all the live stock on them. A house of Mrs. Walford, at Seal Chart, about two miles from Sevenoaks, was struck by lightning, and the dwelling completely gutted. The lightning entered the servants' bedroom, which was soon ablaze, and the inmates had a narrow escape. Several sheep at Sutton Vallence were killed by the lightning, and a bullock was killed near Maidstone. Messrs. Evans's silk-printing mills at Crayford were set on fire by lightning, and over £10,000 damage was done.

University College, Liverpool.-A prospectus has been sent to us of the day classes in Arts and Science, and of the evening lectures for the approaching session. It is announced that the Professor of Experimental Physics, Dr. Oliver Lodge, intends delivering a course of lectures on the Functions of the Ether, or Recent Progress in Electricity, in which he will treat of the subjects which are exciting so much attention at the present time, and the unusually interesting discoveries which are being rapidly made, the hope being expressed that contemporaneous discovery may be introduced as the lectures proceed.

The Electric Railway on Ryde Pier.-This railway has turned ont a decided success, and it has been found that one line of rails is totally inadequate for the fast increasing traffic. It is the company's intention to lay down a second line to meet this want, and also to effect other extensive improvements on the pier.

Important Sales.-Messrs. Wheatley Kirk and Co. announce for sale, on the 24th, some first-class engines, machine tools, and other effects, at the yard adjoining St. George's Church, St. George's Circus, Borough Road. Further details will be found in an advertisement. The contents of Mr. Oppermann's electrical works, at Amhurst Road, Hackney, are also to be dis; posed of in the same way on September 18th. We understand that the electrical bell and signal business of Messrs. Jensen and Co. has been disposed of by the same firm in one lot as a going concern.

Machine Driving by Electricity. The expectation which electrical engineers entertain that a great movement is about to take place in the direction of an extensive use of electro-motors, has induced the United Electrical Engineering Company to prepare for publication a descriptive illustrated pamphlet for the information of prospective users. Being addressed to those who desire to cheapen and simplify manufacturing, or other processes in which power is employed, it deals concisely with the main principles involved, and refers to some of the numerous useful purposes to which the electro-motor is applied. Prominence is given to the special types of apparatus supplied by the company; but a considerable amount of general information is given also, rendering the publication well worth perusal by everyone interested in the subject.

Hyde Park Electric Works, Glasgow.-New premises are being built at this address for Messrs. Anderson, Campbell & Munro. The works are being fitted up specially for the business, and it is intended by the firm to manufacture their own machines, &c., arc lighting and transmission of power being specially attended to.

The Year Book of Commerce.-This volume of 292 pages, which is compiled under the authority of the London Chamber of Commerce, and published by Cassell & Co., is a development of the statistical section which for the last six years has formed part of the annual report presented to the Chamber. The council considered that these statistics, thus amplified and made more general, would prove worthy of a special and separate publication. The year book will no doubt supply a convenient handbook of statistics for commercial purposes, especially as the information given is made up to dates far in advance of that available in any other single publication.

Electricity and Railways.-The following letter has been sent to the Newcastle Daily Journal :-" There is a proposition I should like to place before the meteorological section of the approaching meeting of the British Association. It opens out a problem which I have never seen mooted at any time, yet I conceive it to be of considerable importance, and well worth discussion by savants who have studied the subject of electricity. What I wish to submit for consideration is, 'In what manner will the electricity in both earth and air be effected by the long lines of iron railways (first-rate conductors) which run north and south, also ramify in all directions over our island.' I cannot for a moment suppose that this wide spread network of iron cannot to a very great and appreciable degree influence the distribution of electricity, either equalise it throughout or cause a dangerous accumulation of electric fluid at some point where the atmosphere is in an abnormally excited state, causing a flow of electricity to this already overcharged centre, having a deleterious effect on the climate. 1 do not presume to give an opinion, but merely throw out the suggestion, hoping that some one more competent to deal with the subject may take it up." This idea is by no means a new one, the subject has been referred to more than once, and many years ago. We remember having seen it stated that the introduction of the iron road across the arid prairies of America has greatly modified their climatic conditions.

[SEPTEMBER 6, 1889.

Okonite. With reference to a remark occurring in our leading article last week, the English represen tatives of the Okonite Company point out that the okonite insulation has stood the test of 20° F. below and 250° F. above zero, repeated many times on the same wire without deterioration.

OFFICIAL RETURNS OF ELECTRICAL

COMPANIES.

British Electric Propulsion and Traction Company, Limited (formerly the International Engineering Company, Limited).-An agreement of 16th ult., filed on the 26th, cites that by an agreement of 15th ult. the company agreed to purchase for £1,884, in fully paid shares, certain property mentioned therein. This present agreement confirms the previous document. The registered office of the company is situate at 50, Gresham Street, E.C.

African Direct Telegraph Company, Limited.-The annual return of this company, made up to July 31st. was filed on the 1st ult. The nominal capital is £300,000 in £10 shares. 23,600 shares are taken up, and the full amount has been called and paid thereon.

Hermite British Electro-Bleaching Company, Limited. The annual return of this company, made up to July 8th, was filed on July 9th. The nominal capital is £50,000, divided into 1,500 A shares of £30 each, and 1,000 B shares of £5 each. 1,000 A shares and 1,000 B shares are allotted, the former being considered fully paid, and the full amount has been paid upon the latter.

J. G. Statter and Company, Limited (electricians).At an extraordinary meeting of the members of this company, held at the Alliance Works, West Drayton, on the 29th June, the following resolutions were passed, and at a meeting held at the same place, on the 27th July, they were confirmed, and were duly regis tered 10th ult., viz. : 1. "That the capital of the company be increased by the creation of 1,000 new shares of £10 each, to be issued on such terms and conditions as the directors may determine." 2. "That the directors be empowered to add to their number, and to their remuneration, to provide for the proposed new director." The nominal capital is now £30,000 in £10 shares.

Kay Brothers, Limited (manufacturers of electrical, chemical, surgical, and scientific apparatus).-The annual return of this company, made up to the 23rd May, was filed 1st June. The nominal capital is £100,000, divided into 9,990 ordinary shares of £10 each, and 100 founders' shares of £1 each. The shares taken up are 7,120 ordinary and 100 founders. Upon the former £71,300 is considered as paid. Registered office, St. Peter's Gate, Stockport, Cheshire.

TRAFFIC RECEIPTS.

The Cuba Submarine Telegraph Company, Limited. The estimated traffic recents for the month of August were £2,700 as compared with 2,860 in the correspo ing month of last year. The receipts for the month of May, estimated al £3,500, realised £3,513.

The Direct Spanish Telegraph Company, Limited. The estimated receipts fo the month of August were £1,624, against £1,643 in the corresponding period f last year.

The Eastern Extension, Australasia and China Telegraph Company, Limited. The receipts for the month of August, 1889, amounted to £39,469, as against £* in the corresponding month of 1888.

The Eastern Telegraph Company, Limited. The receipts for the month of August 1889, amounted to £32,012, against £43,703 for the corresponding month of last

year.

The Great Northern Telegraph Company, Limited. The receipts in August, 1999 £24.000; January 1st to August 31st, 1889, £178,200; corresponding months, 158, £179,200; and of 1887, £174,120.

The Western and Brazilian Telegraph Company, Limited. The traffic receipts for the week ending 30th August, 1889, after deducting the fifth of the gro receipts payable to the London Platino-Brazilian Telegraph Company. Limited, were £3,622.

The West Coast of America Telegraph Company, Limited. The gross earnings for the month of August were £4,850.

The West India and Panama Telegraph Company, Limited. The estimated receipts for the half-month ended the 31st August are £2,118, as compared with £2.520 in the corresponding period of 1888. The May receipts, estimated at £6.212, realised £6,203,

SEPTEMBER 6, 1889.]

DYNAMO ROOM ACCESSORIES FOR INTENSITY, POTENTIAL, AND RESISTANCE

MEASUREMENTS."

By C. C. HASKINS.

THE investigator who expects to find a steam plant running without a water and a steam gauge at the present day will reckon without his host, and in very many instances he will find also a tell-tale pressure gauge in the office of the manager, who can turn at any moment, without moving from his desk, and see as well as if he took a run over to the engine room, what pressure the boiler is carrying. It was not so in the days of Boulton and Watt, but the fact that those worthy representatives of the past were without such modern appliances has not kept these from becoming honoured occupants of the engine room of to-day. Progress is near akin to that mother of invention of whom we so often hear, and progress just now calls for more and better appliances for the improvements of our methods of producing and the handling of that boundless and wonderful energy which we call electricity. We have advanced far enough to see that economy in production is essential, and we are now learning that having once developed that energy, the old and homely adage of Franklin, "Waste not, want not," is as applicable to electric economy as to matters of Inerchandising or the cultivation of the soil.

While the inventor is striving, and with reasonable success, too, to lessen the fuel expense, and the wear and tear is being looked after by the constructor, we may ask, Is the operator keeping his end of the burden level by a proper attention to the means within his reach for aiding in the general economy? That the inventor has assiduously laboured at his part of the task is abundantly

8, Solenoid; F, centre of motion; G, water inlet; V, valve; W, overflow; L, L, line wire. FIG. 1.

shown by the records. There are meters and meters. Ingenious meters, and almost judicious meters. No sooner was it seen that a necessity had arisen for something by which to measure currents, than men of inventive ability and men without, nearly tumbled over each other in their haste to reach the front, and present their various claims. A look at a few of these may not be uninteresting. I have not endeavoured to classify the following, nor do I claim to have gathered all there are in existence. To many of these there are several claimants, and I bave quite generally adopted the rule of mentioning no names, a safe method, perhaps, of keeping out of the muddle which sometimes arises from a trifle of jealousy, and leaving the ownership to be decided by others. My object is to cite the apparatus, not the inventor. Gravier, in 1880, suggested that with a given carbon, the current consumed would bear a direct ratio to the amount of light given. He supported his statement by mathematical calculations and comparative tests by other methods. This was ampère measuring by photometry. In the same year Marcel Deprez and Siemens and Halske brought out nearly parallel inventions. In the former, a long coil is placed parallel to, and between the legs of a horizontal horseshoe magnet, extending from the neutral point to the poles. This coil is so adjusted as to revolve, like a shaft at right angles to its length, being delicately supported at either end.

FIG. 2.

An index

attached to the shaft is made to act as a scale beam, and a sliding weight restores it to zero. This form of galvanometric weighing differed principally from Siemens and Halke's invention in that the latter was a vertical arrangement of coil and magnet. Becquerel and Joule had also accomplished much the same result before them. Hopkinson's voltmeter had two parallel wires, through one of which the current was passed. To one of these an index was attached, the other being part of a graduated arc. dilatation of the wires by normal heat moving both index and

The

Paper read before the National Electric Light Association, Niagara Falls, 1889.

271

scale in the same direction kept the indicator at zero, so that when a current traversed the second wire there was no error due to normal temperature to be corrected. Heat in this case was the measure of pressure. Siemens and Halske, among other inventions, exhibited one of a still different form. In this, there is a combination of solenoids and clockwork, with a registering disc.

A very radical departure was made by an English inventor, who is well known in electric lighting. In the system which he patented, a lever at one extremity terminated in a solenoid core, while at the other extremity of the lever was a plunger valve. When the current passed through the coils of the solenoid, the core was sucked in, the valve was opened, and water flowed out more or less rapidly in proportion to the size of the opening, which at last, of course, was governed by the suck of the solenoid, a sort of temperance ampère-meter. An automatic syphon emptied the reservoir and then it filled. The quantity of water was assumed to be directly proportioned to the flow of current. See fig. 1. In Blythe's ampère-meter, a vertical solenoid has an adjustable core suspended from a spiral spring. A vernier gives the direct reading of from one-tenth of one ampère to 100 ampères.

The Deprez-Carpentier ampère meter came to the front about this time in the succession. It contains two permanent magnets, bent half way round the inner circumference of a circular box. When nearly at the quarter of each side, the ends are bent inward, parallel with the diameter, and extend parallel with it until they nearly touch. Now we have two magnets, each not wholly unlike the capital letter C, with the open portions facing each other in the middle of the box. In the space left by the magnets, where the four poles so nearly join, is an electro-magnetic coil, which carries the needle and is actuated by the current traversing it. This was a bold step in advance. Kapp modified the Deprez-Carpentier instrument by making the magnets electromagnetic, instead of permanent. The scale was graduated experimentally, and the instrument was formed for an ammeter or voltmeter, according to the size of wire used. Here was quite a radical departure. Uppenborn developed a novel idea in the use of an eccentrically shaped armature lying on a simple electromagnet core, and a pointer fixed to the same axis as the armature. The pointer stands at one end of the curved scale when at zero. As the current increases, the eccentric face of the rolling armature gives to the pointer a movement along the scale, and a direct reading may be had. This graduation is arbitrary-done by a sort of cut and try method, or thumb rule. The improved voltmeter of this form has two coils instead of one, the greater to extend its sphere of usefulness. A switch gives choice of the coils. There are forms in which the needle is loaded with small magnets, and the poles of electro-magnets are so placed as to double the magnetic action of these on the balanced needle. The molecular structure of glass is so affected by the magnetism as to change the direction of a beam of light transmitted throught it, and this property has been taken advantage of to measure currents of electricity by the deflection of a ray of light. In one of that form of voltmeter which measures current by the expansion of a wire through the heat generated by the passage of a current, some improvement has been made. In this a wire of platinum silver is enclosed in a brass tube held in tension by springs or weights. Formerly the absolute tension of the wire did not give exact results if the wire was exposed to changes of atmospheric temperature. Even when not in use the zero of the instrument is changeable. In the more recent instrument the brass tube surrounding the wire is made to have the same coefficient of dilatation as the wire itself, so that by compensation the zero remains very nearly absolute. The outer air has no longer any power to change and falsify the record of the instrument. Another form of voltmeter in which the dilatation of a wire is utilised to measure current pressure is a modification of the last. There were unforseen difficulties in the way of accuracy. The increased length of the wire was assumed to be solely due to heat expansion, but investigation showed that with that expansion there must be considered the change in stress consequent upon the elongation, and the accompanying increased sag. A remedy very similar to the former remedy was applied, and the work is now sufficiently correct for all practical purposes.

A French invention is dependent for its results upon the action of solenoid attraction upon a movable core, the depth of this plunge being compensated by a weight which slides on a steel yard arm attached to the pointer-a method of weighing the current. Deprez, according to Niaudet, conceived the idea of valuing current by weighing it by the aid of a solenoid coil. The scale of proportions was arrived at by actual experiment. A certain known current balanced a given weight. A second current would balance a greater or less weight, according to its quantity, and thus he was enabled to say " with a magnet of such and such proportions I find that a current which weighs blank grammes is a current of 10 ampères."

A well-known inventor has endeavoured to utilise the heat generated by a current to turn a horizontal wheel, against the diagonal paddles of which the rising air impinges. In another form there are two upright solenoids and two cores. These cores are fixed to, and are a part of, a rectangular frame which moves on two centres at the middle of the top and bottom bars of the frame. At two diagonally opposite corners the cores are placed, and the winding of the coils is such that when one core is sucked up into one coil, the other is drawn downward into the other coil. This see-saw motion is communicated to the pointer from its being fastened to the frame at the upper centre of motion. A counterweight tends to hold the pointer at zero when in a state of rest See fig. 2.