NOVEMBER 22, 1889.]

The motor is series wound, the resistance of the armature being 0065, and that of the field 0.061 ohms ; total, 0·126 ohms. The weight of the motor without pulley is 8 cwts. 3 qrs. 5 lbs. It is designed to work with a current of 150 volts pressure, and a speed of motor spindle of 250 revolutions per minute. According to the terms of the competition, the weight was not to exceed 950 lbs., the speed of the motor spindle was not to exceed 250 revolutions per minute, the pressure was not to be less than 100 or more than 500 volts, and a commercial efficiency of 80 per cent. should be aimed at. The prize motor, although falling short of this standard of perfection, has been considered by the Judges to come sufficiently near it to merit the award. The judges were Mr. W. H. Preece, F.R.S., Prof. G. Forbes, M.A., F.R.S.E., and Prof. Grylls Adams, M.A., F.R.S. Mr. F. V. Andersen is an old contributor to our pages, and we congratulate him and his colleague on their achievement.

A Policeman's Life, &c.-Sergeant McDonald, of that urbane and polite force, the New York police, was called to remove an obstruction in the roadway, caused by a derelict wire, and after the usual manner of his kind, went for this wire with his drawn club; the wire, however, hit him one on the head, which shocked him into insensibility. The police were of no further use; the obstruction remained until the skilled linesmen came on the spot. It must have been a new experience to the gallant sergeant, who will no doubt recollect in future that even a (wire) worm will turn.

Funny Folks at Gravesend.--The question of lighting the borough of Gravesend with electricity, and in connection with which it was resolved at a previous meeting of the Town Council to give consent to all the companies applying for provisional orders, has been reopened, it having been ascertained that the giving of consent to the whole would deter any of the companies from moving under these conditions. The consequence has been the moving of resolutions favouring the municipal company with provisions that they commence operations within 12 or 15 months or forfeit £500 to the Corporation. These resolutions have been opposed by several prominent members, including Alderman Edmonds, the Deputy-Mayor, whose particular objection appeared to be that the capital was £25,000 in £10 shares and the directors qualification being £25, whilst other councillors advocated the formation of a local company. Some discussion also ensued in committee as to the power of shareholders in the gas company taking part in discussions on lighting questions, but this was overruled as not pertinent, the question not being one of gas versus electric light. After other "edging discussion had been introduced it was resolved, in direct opposition to the previous decision of the Town Council, that no consent should be given to any of the companies, this decision being upheld by eight votes to seven.

587

The Otto Gas Engine.-The Secretary of the late Birmingham Exhibition informs us that a special gold medal was awarded by the jurors to Messrs. J. Wright and Co. (who exhibited for Messrs. Crossley Bros.), of Birmingham, for Otto gas engines, but by some oversight their name was omitted from the list sent to us and, we believe, to other papers.

Telegraph Communication with China.-The Times says:-It is reported from China that the telegraphic convention between the Great Northern and the Eastern Extension Companies, and the Chinese Government, which was negociated two years ago at Chefoo, has at last been signed by Li Hung Chang and M. Coumany, the Russian Minister at Pekin, on behalf of the two companies. Under it the Chinese telegraph system will be connected with the Siberian lines at Kiachta. In all messages to Europe the Chinese Administration will be allowed to charge 5 f. a word to Kiachta, the Russian line charging 3 f. for the rest of the way. It is also reported that the Chinese lines are to receive a subsidy from the two cable companies of about £30,000 a year. The convention is to last for 14 years, and its practical effect is that telegrams from China will remain at $2 a word. The convention has not yet been made officially known, but these are the terms as published in China, and they have caused much dissatisfaction in the foreign mercantile communities.

Personal.—Mr. J. F. Moulton, Q.C., has been elected a Bencher of the Honourable Society of the Middle Temple, in succession to the late Judge M'Intyre, Q.C.

Electricity and the Mormons.-The Western Electrician says street lighting by electricity will soon be introduced into Salt Lake City. It appears that the electric light wires are strung on the same poles as the telephone wires, and in many instances within a few inches of them. Commenting on this fact, a local electrician predicts that there will be by no means mild remonstrances from the telephone company when the electric lights are started up.

The National Telephone Company, Limited. The annual supper of the employes of the National Telephone Company, Limited, took place last Friday night at Glasgow. The chairman, Mr. D. Sinclair, ín the course of a short address, mentioned that it was 12 years since the company started in Glasgow in a very small way: They had now 3,134 subscribers, and during last year alone had put in 548 new wires. In Glasgow the wires now extended to a total length of 3,440 miles, the increase during last year being 1,000 miles, and the exchanges in the city numbered 30. The company throughout Great Britain had altogether 26,632 subscribers, using 32,040 miles of wire, and making an average of 230,688 calls per day. In Glasgow the average number of calls per day was 30,341, or 9.86 calls for each subscriber. Several toasts followed, and a number of songs were given by gentlemen present.

Enterprise.-On Saturday night Mr. W. J. Corse, Devonport, lighted up his business premises with electric light, the installation having been completed by himself.

Alleged Theft of Electric Bells at Darlington.The Northern Echo says: George Todd (about 18) was remanded on Monday on a charge of stealing electric bells from Mr. Cox-Walker, of Darlington, with whom he was apprenticed. It was stated that prisoner had been making bells and selling them to people in the town, and that when it became known to his employer he absconded and paid his passage at Stockton on a steamer for London.

588

The Cable at Rye Station, America.-The shore end of this cable, owned by the Direct United States Company, is laid among the stumps of a submerged forest. Last spring the tides had worn and worked all the sand and gravel away, leaving the cable bare. Usually cables are buried in trenches three or four feet deep, but in this case the cable lies fully in view as it runs up to the cable station. The cable is the ordinary single conductor shore end. The iron sheathing is entirely intact, and bears no sign of decay. The cable goes from Rye Beach to Halifax, N.S., and is there connected to the cable from Halifax to Ballinskelligs Bay, on the coast of Ireland, a distance of 2,400 miles. The stumps among which the cable lies are very large, measuring 8 feet or 10 feet in circumference. They are mostly of cedar, and are of a rare quality not known, it is said, to exist in forests of the present age. The forest extends out a considerable distance.

Manchester. It would appear that the prevailing opinion relative to the electric lighting scheme of the Corporation, is that the area chosen is far too small for a successful issue, especially as the area embraced is almost entirely an early closing portion of the city, and there are probably few places which would require the light after 7 p.m. Strangely enough, the Town Hall is just without the boundary. The lighting is to be carried on under the constant current low-pressure system, and it is understood that Mr. Shoolbred has been consulted on the system to be adopted.

An Electric Lighting Age.-If all the schemes for electric lighting which are officially scheduled are carried out many of the leading towns in England will soon enjoy the most recent method of illumination.

Dundee.-The Town Council will apply for a provisional order.

Provisional Orders.-The number of applications to the Board of Trade has now reached 430, and power to apply will remain open until the 30th inst.

Action Against the Taunton Electric Light Company. An action has been brought by a lady, Miss Harrison, against the above company for an alleged trespass by the defendants' wires being attached to the chimney of her house. After a great deal of evidence had been given decision was reserved until next month's court.

Messrs. Immisch's Mining Plant.-A successful experiment was carried out at Normanton on Wednesday of Messrs. Immisch's pumping and hauling plant. There were a good many visitors from all parts of the country.

The London Electric Supply Corporation.-When is the lighting of London from Deptford to commence ? The delay must have the effect of making the shareholders anxious, and we notice that the quotations for shares of the company are steadily lacking, £5 shares being now quoted, 4 to 43.

[NOVEMBER 22, 1889.

The Chattanooga Accident.-Electric Power of New York, referring to the recent electric tramcar acciden says "It cannot be expected that the rapid growt of electric railways throughout the country can contine without a certain percentage of accidents, possibly involving the loss of life or limbs. That which occurred on September 20th at Chattanooga, however, conveys & warning which it will be well to heed. It appears to have been caused by the attempt to drive a heavily. laden car up a steep grade, the rails being moist with dew. The force of gravity was in excess of the tractive effort, and of course under the circumstances any ordi nary braking system was useless. The conductor wa placed in the position of deciding at once which of two things the passengers should do-stay on the er or jump off. The latter alternative was chosen, and of those who followed his advice two were, perhaps, fataly injured, and a dozen or more less seriously. Relieved of its excessive burden the car was brought under control and stopped; but the newspaper report states that the car which followed was reversed upon the 'motorneer's' discovery of the danger of a collision, and we may therefore place to the credit of the electric car that it may be instantaneously reversed, thus introducing an element of safety in street railway practice that should at least counterbalance any liability to ace dent. It is well to understand, however, that there is a safety limit in the climbing of grades by a self-propelled motor, that for the general welfare of the public as well as for business reasons should not be exceeded We must admit that we have feared the possibility of an accident of this nature, and it now appears necessary that on roads where heavy grades are to be encountered. suitable track brakes should be provided for use in an emergency of the character in question.

A Proposed Central London Railway.-At last there seems a possibility that the congested state of certain mos important thoroughfares will be relieved. The scheme appears to be well backed up by influential City gentlemen. The preliminary powers have been applied for, and shortly we may hear that work has been commenced The engineers to the undertaking are Messrs. Fowler, Baker and Greathead, whose recent operations hav attracted considerable attention. Briefly, it is proposed to construct two iron-lined tunnels, about 11 feet in diameter, deep below all sewers and pipes, and well below the gravel upon which the houses are built, se that the tunnels being in the solid clay, there will be no trouble from water, and no settlements can possibly arise, as the tunnels will be driven under the protection of a steel shield, such as was successfully used by Mr. Greathead recently in driving the tunnel under the Thames, close to, and below the level of the foundations of London Bridge. No shafts will be made in the streets at any point, but all the clay excavated will be brought to the surface by shafts on the company's private property alone. We should imagine the work along Holborn, Newgate Street and Cheapside should be comparatively easy, as there still exists all along the proposed route the Pneumatic Despatch Company's iron tube, which is about 4 feet 6 inches in diameter.

A Correction.—Mr. Lewis, the general manager of the Western Counties and South Wales Telephone Company, Limited, sends us the following:-" In your issus of the 15th inst. there is a paragraph under the head of Telephonic Communication in the West.' in which you state that this company is rapidly extending its operations, and have reduced their charges by one-third in a the towns connected with their trunk lines. We have in a few solitary cases in South Wales reduced our toll charges from 1s. and 9d. to an all-round rate of 63., bat your paragraph, as it stands, is very misleading.

Edinburgh Town Council.-The members of this body appear to be arriving at a state which, in rela tion to the electric lighting of the city, may be described as foggy.

NOVEMBER 22, 1889.]

Insulation.-A correspondent writes :-"A whole lot of subscribers are very anxious to know how the new patent insulating material used on the machines and mains at Deptford stands the 10,000 volts ?"

Electrical Register.-One of the latest American inventions, and one that has not yet been made public, is the "electrical register." It is intended to be used for a variety of purposes. A series of buttons along the inside of a horse-car, within easy reach for the conductor, connect with the register at the end of the car. By pressing one of these buttons the fare is registered, and the announcing bell rings simultaneously. In the system used at present the conductor pulls the leather strap, which rings the bell, and the fare is registered by the return action of the belt. It is said that in the present method the gong can be rung without registering the fare by skilful manipulation. Again, in unloading a ship, switches can be so arranged that each parcel of similar size, as in tea cargoes, registers as it passes the electrical connection.

589

Progress of Electric Traction in the States.-F. J. Sprague, of the Sprague Company, was recently in Chattanooga, Tenn. He said to a reporter: "I expect to see all cars in Chattanooga run by electricity in less than a year. Electricity, as applied to street railways, is making more rapid progress than any electric enterprise has ever done. Improvements and apparatus are being brought out very rapidly, and in the very near future the electric motor will be the most perfect piece of apparatus for the development of power ever created, and capable of more continuous and arduous duty. I was in Nashville a few days ago, and they intend to put up two lines. The South Nashville and the Nashville and Edgefield. They start with twenty cars, and are going to put in a station capacity for sixty, which show that they mean business. We have seventy-five or eighty roads in the country, and good prospects for an increase. Several roads have already increased double." -Western Electrician.

First Tunnel Lighted by Electricity.-Washington claims the honour of the first large railway tunnel to be lighted by electricity, this is the Stampede Pass tunnel on the Northern Pacific Railroad, which is 9,540 feet long, and is fitted up with a 600-light Edison municipal plant, using water-power, fed from melting snows from the mountain peak, for driving the dynamo.

The Use of Gas.-There is a Thomson-Houston exhibit at the Mechanics' Fair that shows well the saving when gas is used as a fuel instead of an illuminant. An Otto silent gas engine is used. During the evening's run at the fair, the gas engine working the ThomsonHouston electric plant consumes 300 cubic feet of gas, and furnishes 53 16-C.P. incandescent lights, while 53 16-C.P. gas lights, with 5-foot burners, would require 618 feet for the same length of time. This is a saving of over 50 per cent., and would, in a short time, pay for the first outlay of an electric plant, and the consumer would have the benefit of a brighter and more attractive light.-Pacific Lumberman.

OFFICIAL RETURNS OF ELECTRICAL

COMPANIES.

Montevideo Telephone Company, Limited. The annual return of this company, made up to the 31st ult., was filed on the 9th inst. The nominal capital is £220,000, divided into 29,000 preference and 15,000 ordinary shares of £5 each. The shares taken up are 27,000 preference and the whole of the ordinary, and the full amount has been called upon both classes of shares. The calls paid amount to £210,000. Registered office, 25, Abchurch Lane.

Devon and Cornwall Electricity Supply Company, Limited. The statutory return of this company, made up to the 8th inst., was filed on the following day. The nominal capital is £100,000 in £5 shares. Only nine shares are at present taken up, and upon these no call has been made. The office of the company has not yet been registered, as required under the Companies Acts.

Scottish Automatic Supply Company, Limited (automatic, mechanical, and electric machines). The statutory return of this company is made up to the 1st July. The nominal capital is £12,500 in £1 shares. 8,507 shares are taken up, and of these 8,500 are considered as fully paid. Upon the remaining seven shares no call has been made. Registered office, 17, Devonshire Chambers, Bishopsgate.

Municipal Electric Light and Power Company, Limited. The statutory return of this company, made up to the 2nd inst., was filed on the 9th inst. The nominal capital is £25,000, divided into 2,490 ordinary shares of £10 each, and 100 founders' shares of £1 each. The shares taken up are 37 ordinary and 30 founders' shares. Upon 30 ordinary and 30 founders' shares the full amount has been called, and upon 7

590

shares no call has been made; the calls paid amount to £120, and unpaid to £60. Registered office, 33, Old Broad Street.

Elmore's Foreign and Colonial Patent Copper Depositing Company, Limited.-The statutory return of this company, made up to the 18th October, was filed 23rd ult. The nominal capital is £120,000, divided into 15,000 priority shares, and 9,000 founders' shares of £5 each; the whole of the former and 3,000 of the latter are taken up, and the full amount has been called thereon; 6,000 founders' shares are also allotted as fully paid. The calls paid amount to £88,282, and unpaid to £1,718. Registered office, 20, Bucklersbury.

An agreement of 21st August (filed on the 5th inst.), between Woodhouse and Rawson, Limited (the vendors) and the company, provides for the allotment to the vendor of 6,000 fully paid shares in satisfaction of the obligation imposed on the company by an agreement of 4th June, under which the company acquires certain patent rights, &c., for £110,000, payable £80,000 in cash, and £30,000 by the issue of 6,000 fully paid founders' shares.

Fireless Motor Syndicate, Limited (mechanical and electrical engineers).-The statutory return of this company, made up to the 24th ult., was filed on the 30th ult. The nominal capital is £25,000 in £10 shares. 1,250 shares are taken up and are fully paid. Registered office, Crow Buildings, 18, Booth Street, Mosley Street, Manchester.

Electrical Porification Association, Limited.-The annual return of this company, made up to the 11th inst., was filed on the 14th inst. The nominal capital is £15,000, in £1 shares; 14,105 shares have been taken. up, 5,000 being considered paid up. Upon 5,505 shares the full amount has been called, and upon 3,600 shares 4s. per share has been called. The calls paid amount to £6,005, and unpaid to £220. Registered office, 8, St. Martin's Place, Charing Cross.

Westminster Electric Supply Corporation, Limited. -At an extraordinary general meeting of this company, held at 2, Victoria Mansions, on the 11th ult., it was resolved that the capital be increased to £300,000. The resolution was confirmed on the 30th ult., and was duly filed on the 14th inst.

LEGAL.

The Queen v. Redman.-This was an appeal from the decision of a Divisional Court, consisting of Mr. Baron Huddleston and Mr. Justice Mathew. The London Electric Supply Company had erected at Deptford very large buildings, the eastern wall of which adjoined the premises of the General Steam Navigation Company. The buildings were completed in March, 1888, and in November, 1888, the General Steam Navigation Company discovered by digging that the wall had not proper footing as required by section 12 of the Metropolitan Building Act, 1855. Mr. Redman, the district surveyor for North-East Deptford, having refused to put in force the provisions of the Act, and to compel the London Electric Supply Company to comply with it, the General Steam Navigation Company obtained a mandamus to Mr. Redman to compel him to enforce the Act. From this Mr. Redman appealed. The Master of the Rolls said that the Court would not give judgment for a fortnight, and meanwhile the parties would do well to come to some arangement. It was impossible for them to say which way the Court would decide, and they would do well to take this course. Justice Lindley thought it ought to be easy to come to some arrangement. Lord Justice Lopes entirely agreed in the suggestion.

Lord

[NOVEMBER 22, 1889.

The Secretary having read the notice convening the meeting, The Chairman said: Gentlemen, it will be within your recol tion that when we met in July last you passed a resolution upproving an agreement which we had then entered into with the Brush Company. I then told you I thought it highly probabl that certain arrangements would have to be made which woul render necessary an alteration in the terms of that agreement and I fully prepared the shareholders for the possibility of calling another meeting to make a statement as to the new arrangements so entered into. I may mention also that at that moment the Brush Company were in a condition of transition, acquiring est only powers to increase their capital, and powers to extend ther operations by amalgamation with a manufacturing company, but to actually change themselves into a new company, and, therefore, we were advised by our solicitor, Mr. Ince, that for that reass alone, if for no other, it would be advisable to make a change in the arrangement. You will observe (as you have been already informed in the circular) that by the present arrangement we do not propose to hand over to the Brush Company the whole of the assets of this undertaking, but we agree to sell, and indeed have sold, subject to your approval, the patent rights and goodwill f the business in India and the Cape, Australia, and Australaca generally, and also the shares which this company holds in the Melbourne Company. We retain the whole of the other neta, comprising the plant in England, India, and Australia, book debta and various matters, including the balance of a call in course of payment. Under this arrangement, therefore, the Brush Company, under the name of the Brush Electrical Engineering Company give us for the patent rights and the other assets I have mentioned £30,000 in their shares. These shares will be divided par passu among the shareholders of this company. I may mention that the shares of the Brush Company are at a premium of 53. to 103. per share, so you will, I trust, be placed almost immediately in possession of assets which can be immediately realised and sold, if you desire to sell. It is evidence of the approval of the general body of shareholders in the Brush Company of the proposed amalgamation, and the general prospecta, that the shares have risen to a premium since these arrangements were entered into. Consequently, the directors feel certain that you will have a proper value, realisable at any moment, and. therefore, having a great advantage over the shares which you have unfortunately held in this company for some years part, and which have not been saleable for some time, except at a large discount. We take it upon ourselves to realise the remaining assets. It is a condition of the agreement that we shall within a few months liquidate this company. We have made an arrange ment with our purchasers that they themselves will provide the expenses of the liquidation, including the stamp duties on the transfers, &c., so that there will be no reduction on that account from the £30,000 in shares which you are to have. In addition to that we shall do the best we can when we go into liquidation, and the proceeds of the other assets we shall divide among the shareholders pro rata according to their holdings, so that we hope in addition to the shares which we shall hand over to you, to return you something in cash. There are one or two other points in the agreement. There is an option to the purchasing company to take over the assets which we do not assign to them now at the sum of £15,000. If they do not exercise that option, we are at liberty to realise these, and in that case we shall do the best we If we sell the plant, we shall offer it to them on the 1st February next at the same price as we should be willing to accept for the same from another party.

can.

A resolution confirming the agreement between the companies was then carried unanimously.

A vote of thanks to the chairman terminated the proceedings.

Berlin Electrical Works.

Year July 1st, 1888, to June 30th, 1889.

THE annual general meeting of this company was held on October 26th last. It appeared that a nett profit of 383,609 marks had been realised. After paying over 5 per cent. of this sum, = 18,963 marks to the reserve fund, as the German law demands a dividend of 8 per cent. on the three million marks share capital was declared, making 240,000 marks. A further sum of 15,000 marks was paid, according to agreement, to the municipal authorities To the sinking fund were handed over 45,000 marks and 25,000 to the repairs fund. The original capital of three millions (marks) has been increased, but no dividend will be paid on this sum until the next season.

CITY NOTES, REPORTS, MEETINGS, &c.

The Australasian Electric Light, Power and Storage Company, Limited.

We have been furnished with the following report of proceedings at an extraordinary general meeting, held at the offices of the company, 39, Coleman Street, E.C., on Tuesday, 12th November, 188 Mr. B. H. Van Tromp in the chair.

TRAFFIC RECEIPTS.

The Brazilian Submarine Telegraph Company, L'mite l. The receipts for the week ending November 15th, 1889, amounted to £3,201. The Western and Brazilian Telegraph Company. Limited. The traffic receipt for the week ending November 15th, 1889, after deducting the fith of the gre receipts payable to the London Platino-Brazilian Telegraph Company. Limited, were £3,714.

West India and Panama Telegraph Company, Limited. The estimated traffic reipu for the half month enoed the 15th November, are €1,841 as compared with £2.319 in the corresponding period of 1888, The July receipts estimated as £5,209 realised £5,225.

PROCEEDINGS OF SOCIETIES.

The Institution of Electrical Engineers.
(Continued from page 564.)

"HE selection of a suitable mechanical dynamometer was not easy. "he following conditions were laid down as essential :

1. It must be susceptible of a fair degree of accuracy, and show stantly any variation in the load.

2. It should be of such a form that errors are not likely to arise om the difficulty (owing to the thickness of the belt) of ccurately determining the virtual radius of the pulley; and no -ower should be absorbed between the point at which the pressure s measured and the dynamo spindle.

3. Any springs contained must be so placed that centrifugal orce will not introduce uncertain effects on the indications of the nstrument.

4. It must be portable, and easily fitted up.

The first condition simply requires that whatever the principle nvolved it shall be faithfully executed, and that the moment of nertia and number of moving parts shall be as small as possible. The second condition requires that the power shall be transmitted o the spindle of the dynamo at some fixed distance from its axis of rotation, and that it is the pressure at this point which is shown on the indicating mechanism."

The simplest way of fulfilling the above conditions seemed to be to give the dynamometer the form of a pulley to be directly applied to the spindle of the machine tested. It is important that the displacement of any of the parts of the mechanism shall be very small, even though the indicator passes from zero to its maximum reading.

་

A pulley was accordingly constructed, the principle of which is as follows:-The energy supplied to the machine is transmitted through a fixed point at a distance intermediate between the axis of the spindle and rim of the pulley. By means of levers and pistons the pressure is transmitted to a fluid filling the chamber. u which the piston moves, and by it through a glass tube which lies in the axis of rotation to a spring chamber, the capacity of which varies with the pressure on the enclosed fluid. The presure on the point through which the energy is transmitted is shown by the displacement of the fluid in the glass tube.

The pulley (see diagram above) was made so that the rim, R, could turn freely on the nave, N. Two radial chambers, c, were carefully bored in the nave at the opposite ends of a diameter, and pistons were accurately fitted in them, so that though water

tight they could move freely. Two bent levers, L, were hinged at the nave, each being so shaped that when one arm pressed on the centre of the piston, the line passing through this point of contact and the centre of the hinge, was at right angles to the radius drawn through the point of contact. At the same time the other arms of the levers stood in a direction such that the surface of the lever remote from the piston coincided with the radius passing through the centre of the hinge. These arms were of such length that they just cleared the inner surface of the pulley rim. The connection between the rim and nave was made by means of two blocks of iron, B, riveted to the inner surface of the rim in such a position that they would come in contact with the projecting arms of the levers. The point of pressure was rendered definite by the use of knife edges, and any shock was relieved by the interposition of a suitable spring. Two smail holes were drilled parallel to the eye of the pulley opening into the cylinders. The indicating apparatus was fixed so that it would coincide with the axis of rotation when the pulley was in use. It consisted of a glass tube, with a carefully fitted ebonite piston which served as a marker. This piston was made about 10 diameters long, and had several small grooves turned in it. The glass tube was mounted with a metallic chamber at each end, one being bolted to the pulley nave, the other closed with a circular corrugated steel spring similar to those used in some steam pressure gauges. The metallic chambers were mechanically connected by an iron tube in which three longitudinal slots were cut to enable the glass tube to be seen. The angular width of each slot was 60°. The scale was fastened on the inner side of the bars of the iron tube; consequently each time a slot turned towards the eye the glass tube and ebonite piston were seen projected on the scale that was fastened to the opposite bar. When in rapid motion the scale appeared as if drawn round the glass tube, and the end of the black ebonite piston formed a well-defined line from which to read. Every tenth division was marked in red, and the fifties were shown by a bright line on the outer surface of the iron tube.

In the pulley used the diameter of the bore in the glass tube was about th of that of either piston. Hence, if both pistons were in use, the motion of the ebonite piston would be about 1,250 times as great as that of either of the main pistons. The length of the scale was about 6.5 inches, so that a motion of the main pistons of th of an inch would cause the indicator to travel over the whole length of the scale. The pulley was arranged so that one or both pistons could be used. By this means the range of the instrument was doubled. Using one piston and running at 900 revolutions per minute, the maximum reading corresponded to about 30 horse-power, and with both pistons to about double that value.

It will be seen that a dynamometer of this form may be constructed to fulfil fairly well the conditions laid down as essential. The sensitiveness is determined by the stiffness of the steel spring and length of glass tube used. In practice a very great degree of sensitiveness is not required, as the variations in the power absorbed were found to exceed two, or at times even three per cent. of the total, whereas one-half per cent. could have been easily read. The ammeter showed fluctuations in the current at least equal in relative magnitude to those shown by this mechanical dynamometer.

To calibrate the dynamometer pulley it was keyed on a fixed horizontal spindle. A long balanced arm was bolted to the rim, and at a distance from the centre of the spindle (measured

10

radius of feet. The reading showed at once the tangential pull at this radius, and, multiplying by ten, the number of footpounds absorbed per revolution of the armature.

It should be noted here that the levers in the pulley were counterbalanced for the centrifugal force of the pistons and fluid below them. The correctness of the balancing was tested by mounting the pulley on a spindle and rotating it rapidly in both directions, first of all having removed the rim. If the balancing were correct a small deflection should be produced, its direction depending on the direction of rotation, and the two deflections should be equal at the same speed of rotation. No error was detected, owing to the unequal distribution of the fluid pressure on the circular spring caused by centrifugal force. This fact is not surprising, when it is remembered that the effective diameter of the spring was only 1.25 inches, and that the fluid (glycerine) used was light.

The dynamometer pulley was placed on the machine which it was desired to test, in the daytime, and fresh glycerine put in. One of the bolts holding the field magnet core was taken out, and a similar one, but with a hole bored in it to receive the thermometer, put in its place.

The electro-dynamometers were always carefully adjusted for position after all machines were in full work, so that no disturbing effect would be introduced by the action of the current in leads which ran near the testing table. Each reading noted gave the mean position of the indicator for about 15 or 20 seconds in all measurements, whether electrical or mechanical