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DECEMBER 20, 1889.]

ELECTRICAL REVIEW.

olding-piece carries a bare hard-drawn copper wire, along which he current flows, returning by the rails. Where feeders are used, hey run along one side of the street, and connections are made at ntervals with the central wire. The way the conductor is carried ound corners is on a par with the rest of the work. Posts are set t the further corners of the street, and from each of these two, hree, or four steel wires are run at an angle with each other, neeting corresponding wires run from posts on the inner side of he curve. In this way the wire is made to take the form of part f a rough polygon, while the horizontal and vertical movements f the fishing-rod connector on the car are sufficiently ample to eep the contact-wheel on the wire when the car is going round a

orner.

This method of erection does not look very nice, certainly, but t appears to answer the purpose well. Such work could, I think, e more solidly carried out here for about £70 a mile. In a few laces standards with projecting arms placed in the centre of the treet have been used for carrying the overhead conductor. If eatly constructed, there is no reason why these should be unightly, and they can be used for the further purpose of lighting he streets.

A great point about these electrical tramcars is the way in which their speed can be varied. They can be run at three or our miles an hour in crowded streets and while turning corners ; r in broad roads in suburbs, where there is not much carriage raffic, the pace can be increased to 16 miles an hour. The ars are stopped very quickly and reversed, and will, of course, un either way on the same track.

The companies claim a reduction of 50 per cent. in the cost of working over the employment of horses, putting aside all the extra facilities which the electrically propelled car gives. A very noticeable point about all electrically propelled cars is the quiet and gradual manner in which they start and come to rest, and he evenness of their motion while running. In these points they greatly surpass both cables and horses. I took the opportunity of alking with a good many members of the general public in the rain and hotels about the working of these cars. There is no loubt that the outside public thoroughly appreciate them and inderstand their value. At present electrical tramway work is he most "live" branch of the electrical industry in the States, and everyone connected with it was full of buoyancy and hope at ts future prospects. It is really sad to think that, after all the kill and care which has been lavished on electrical tramway work here, it should be dragging along in such a half-hearted and pottering fashion.

While in America, through the kindness of Mr. Lockwood, I had an opportunity of going over the telephone exchange system of New York with him, and of seeing the Courtland Street Exchange, which contains more than 3,500 subscribers, and is capable of extension to double that number. I also visited the Western Electric Company's factories, both in Chicago and New York, where all the telephonic apparatus for use in the States is made. Although a description of the present state of this industry would properly come under the heading of my paper, seeing that the paper has already extended to such length, and that, owing to circumstances, telephony is a matter of comparatively limited interest here, however important in itself, I will not say more about it, but will conclude with a few general remarks.

CONCLUSION.

In the early portion of this paper I endeavoured to convey an idea of the roughness and crudeness of American outside construction work. After reading over the proofs of the paper, I do not think I have overdrawn the picture; rather it is underdrawn, if anything. At the same time, I do not wish it in any way to be understood that American engineers are necessarily rough and untidy in their ideas and incapable of different work. Besides their electrical plant, the numbers of beautiful tools, crowned by the latest pattern of the phonograph, which come over here from America, point to an entirely different conclusion. In accuracy of workmanship and careful finish, when they consider it suits their purpose, the Americans are our equals, if not our superiors: the difference lies in the fact that our ideas often differ from theirs as to where this accuracy and careful finish should come in. English engineering would hardly dare to appear before its fellowcitizens as the responsible owner and designer of such a terrible eyesore as American outside work is; but the American engineer appears to look at it from a different point of view. It is not his business to think of his fellow-citizens. Each of his fellowcitizens, he considers, is quite competent and capable of taking care of himself. It is the business of the electrical engineer to forward and extend the applications of electricity. If in doing this he does anything disagreeable to his fellow-citizens, it is for them to protest when it becomes intolerable to them, not for him to think of it beforehand.

And I would like you to try and think for yourselves, and really feel the enormous facilities which American engineers have in the past enjoyed, and still enjoy, in extending their business, by simply being allowed to erect open wires everywhere through the streets. Even where wires are now being put underground, they are largely put underground in order to carry on existing work and to extend it, not merely to take advantage later of what may chance to turn up on the route.

Besides this, we have all had it drilled into us by this time that it does not matter how perfect, how desirable, how useful a thing is likely to be, before it can come into general use the public have got to be educated up to it, to see it, and feel its desirability and utility, and its practicability-to understand it each man for him

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self. Now, the American system of overhead wires and cheap line construction, bad as it may be in itself, has from the very first brought electricity home to everybody-right to their very doors -not so much as a luxury, but as a practical desirable factor of everyday life, an attraction to public resorts, and a good advertisement for business. Consequently electricity is in America no more a wonder, but a fact of everyday life to an extent that it is not yet here.

Looking at their plant, looking at their apparatus, and looking at the facilities which Americans have enjoyed for extended practical experiments on a large scale, it does not appear to me that their actual achievements, simply from an engineering and scientific point of view, have been greater than ours have, in spite of the apathy on the part of the public and investors with which we have had to contend. Still, the fact remains that they have done more business than we have, even considering the difference in population.

Of what work we have done so far, Englishmen may feel justly proud, and with better times I trust we may still be able in friendly rivalry to show that we are competitors worthy of America's best mettle.

AUTHORISED ABSTRACT OF DISCUSSION.

The PRESIDENT, in inviting discussion, remarked that a paper of such interest could not be adequately dealt with in the time then at their disposal, and announced that the discussion would be continued at the next meeting on December 12th. In the meantime printed copies of the paper can be had on application to the secretary.

Prof. FORBES admired the realistic description of electrical work in the United States given in the paper, and fully endorsed the author's account of American electrical engineering, particularly as regards the rough-and-ready way in which the work is usually carried out. Although this class of work may be necessary for the rapid extension of electric lighting (as well as of railways) in America, where great distances have to be covered, yet he thought the more solid construction adopted by English engineers would prove better in the long run. For some time past he had frequently heard of great advances made on the other side of the Atlantic, and expected to have heard something definite about them from Mr. Addenbrooke, but, with the exception of electric tramways, little change seems to have been made since his visit two years ago. At that time, however, most tramways were worked by accumulators. Information about motors and meters would have been very acceptable, particularly for alternating current work. Speaking of American factories, Prof. Forbes said that great attention was paid to testing, and as a result the efficiency of converters had been considerably increased. As regards distribution, he was glad to hear of the frequent use of feeders, and hoped they would be more generally adopted in England. In conclusion, he asked what kind of cable was used for underground work.

Mr. H. C. DONOVAN considered that the apparent disregard of insulation was to be attributed to the dryness of the climate, and expected to have seen this brought out in the paper.

Mr: W. P. GRANVILLE said the usual method of specifying insulation resistance of cables (viz., in megohms per mile) was unsatisfactory, and that the diameter of the conductor should be taken into account, for if this is not done the same material used on conductors of different sizes would give quite different insulation resistances. He also thought that the insulation tests of lead-covered cable should be made before sheathing, and whilst the cable is immersed in water. In his opinion the whole subject required reconsideration.

Prof. S. P. THOMPSON had hoped to hear that in the five years since he visited the States improved methods of wiring, &c., would have been adopted, but no great change seemed to have taken place, excepting in the use of alternating currents. On his visit he obtained an insulator even more crude than the one described by Mr. Addenbrooke. This he promised to exhibit at the next meeting. After making enquiries as to the kind of motor used in the constant current arc circuits, Dr. Thompson expressed his opinion that the alleged greater steadiness of American arc lights was not due to any superiority in the design or workmanship of the lamps, but to the greater personal pride and confidence which the attendants have in the particular system with which they are connected.

Mr. SWINBURNE pointed out the great difference which exists in the management of English and American factories, and thought the system adopted in the latter, where the perfecting of designs and the experimental work are kept quite distinct from the wholesale manufacturing part of the business, was most likely to lead to success. So far, however, he believed machines of English design better than American, for the weight efficiency of the former is generally higher. Referring to Mr. Granville's contention, he said that instead of insulation resistances being given in megohms per mile, they should be expressed in megchi miles for each size of conductor.

The PRESIDENT, whilst deprecating imperfect work in general, thought it advisable that English electricians should acquire whatever good could be got from the "rough and ready" method adopted in America, and considered that progress might be retarded by waiting too long to attain perfection. He was anxious to know how constant currents were used for motors, and also whether the overhead wires used for tramways interfered with the ordinary street traffic.

Replying to Prof. FORBES's question as to recent advances, Mr.

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ELECTRICAL REVIEW.

ADDENBROOKE said he had not concerned himself with them, for his object was to see the systems and apparatus in common use. As to motors, he made no enquiries respecting their peculiarities, but as regards meters he was informed that numbers of the Westinghouse type were in constant use. He agreed with Prof. Forbes about the way in which testing is appreciated, and with Prof. Thompson as regards the interest which the men take in their work; the latter fact Mr. Addenbrooke attributed to better wages and greater chances of promotion. Speaking of the insulation of cables, he thought the absolute thickness of insulating material should be stated. In reply to the president's question relating to tramway wires, Mr. Addenbrooke pointed out that they were placed 8 or 9 feet above the tops of the cars, contact being made by a fishing-rod" connection. In some cases these wires are carried by brackets projecting from poles fixed along the middle of the roadway, the poles being also utilised for supporting arc lamps and for general lighting circuits.

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December 12th, 1889.

After the adoption of the report of the Council, and the passing of the usual votes of thanks, the discussion on Mr. Addenbrooke's paper, "Electrical Engineering in America," was renewed.

Mr. LANT CARPENTER, who paid a hurried visit to America during August and September, said he quite concurred in Mr. Addenbrooke's remarks about the temporary character of the work, particularly in the Western towns. In many places on the Pacific slope, he found that water-power was extensively used, both for arc lighting and for tramway work; one town in Washington, he observed, had laid down electric tramways before making the common roads. Incandescent lamps are comparatively rarely seen in the far West, and from enquiries he learned that where they had been tried, the stations were so badly managed that the life of the lamps averaged between 200 or 300 hours. Passing on to Canada, he said that Quebec, Montreal, and Ottawa were all lighted electrically by water-power, and, in the latter city, he was informed that many alternate current motors of the Tesla type were in constant use. Another fact that struck him was the large numbers of long-distance telephone wires in use in the States. He also noticed that many of the wires were now being put underground.

Mr. G. S. RAM said he could not agree with Mr. Addenbrooke on the glaring character of arc lamps fixed on poles, and added that the tower system had been almost abandoned in New York in favour of poles. He greatly preferred the blaze of light in that city to the comparative darkness of London. As regards the character of overhead work, he thought the account given in the paper was not overdrawn, and, in support of this, he exhibited a photograph of a building in Broadway, New York, in which hundreds of wires were unintentionally included. On careful examination of the photograph, the insulation on some of the wires was seen to be hanging in shreds.

Mr. SPAGNOLETTI thought the necessities for insulation were so different in England and America, that the systems could not be compared on the same basis. To show the great variation of insulation resistances in this country, he said that on the South Wales Branch of the Great Western Railway, the insulation resistance of the telegraph lines varies from several megohms to a few thousand ohms, according to the weather. He also mentioned the difficulties experienced by Mr. Edison when experimenting in London and at Ealing with his automatic chemical telegraph; the maximum rate he could attain here was 500 words per minute, whereas in America he could get 2,000.

Mr. PREECE, speaking of insulation requirements in the two countries, said that, in his opinion, the differences arose from the facts that the prevailing winds here are warmed and moistened by passing over the Gulf Stream, whilst in America the shores being washed by polar current, the winds are cold and dry. Referring to his own visits to America, the speaker said he always benefitted considerably by being associated with the "go-aheadedness" of American engineers, and he believed that on visiting this country American engineers derived similar advantages.

Mr. CROMPTON said the paper would bear a good deal of study, and there were some points upon which he desired further information. For example, the method of preventing vibration mentioned on slip 6 of the paper, would, if effective, be of great importance, for one would have expected such an arrangement to increase rather than diminish vibration. Judging from the remarks about regulating resistances, he would infer that in this respect America was behind European practice, for on this side of the water such resistances had been done away with. The fact of alternate current machines not being usually run in parallel (as attested by Mr. Addenbroke) tended to confirm his (Mr. Crompton's) statements made in his paper on "Central Station Lighting," read in April, 1888. As regards the boiler described on slip 10, he thought such a design would not be tolerated in this country, for the upper parts of the tubes were liable to get overheated and collapse. Speaking of tramway work, Mr. Crompton said American engineers had been greatly favoured by being allowed to erect overhead wires anywhere and anyhow, but he was afraid such facilities would never be granted in England. Mr. A. RECKENZAUN deprecated the wholesale condemnation of posts made by Mr. Addenbroke, and said that many were not unsightly, while some were ornamental. He considered the paper chiefly a criticism of the bad work done in America, and the good work was barely mentioned. For example, little is said of installations in ich secondary batteries are employed, although there

[DECEMBER 20, 1

are many in constant operation; and electric railway described.

Mr. F. RECKENZAUN concurred in his brother's remarks a the unfair criticism contained in the paper, and thought the 1 ferences of opinion arose from the totally different ideas u way in which electrical engineering should be carried out ha American methods, he said, great skill and ingenuity warte in combining economy with simplicity and efficiency. Athug the arc lamps are not ornamental, yet they are simple and ener and cheap construction admits of their being universally He agreed in general with Mr. Lant Carpenter's remar incandescent lighting, but was inclined to believe its hard was due to the people wanting the biggest and best light o able at the price.

Mr. ADDENBROOKE, in reply to the Messrs. Reckenzaun, mi, had specially mentioned in his paper that the Thomson-Ho Company were putting up work much better than the average a as to posts, he was glad to say the tramway companies were a considerable improvements. The arrangement of flooring re to by Mr. Crompton was not intended to diminish vibratin to prevent such vibration being transmitted to the brick As regards the boiler criticised by the same speaker, be Y Addenbrooke) could only say that those in charge of t informed him that it was intended to have more of them. It not his intention to criticise all American electrical esse ing in a hostile spirit, for he thought there was little d2. ence in the capacity of English and American engineers L necessities, however, of the two countries were entirely difere and each had to adapt himself to his own surroundings motors used on the arc circuits were, as far as he could leg: simply series ones, provided with switches for cutting out par the magnet coils. In concluding, Mr. Addenbrooke said he the opportunity of conversing with many of the American eng neers who visited this country in the summer, and all were gr pleased with the kind and courteous manner in which they a received..

.After the thanks of the meeting had been given to the su for his paper, Dr. S. P. THOMPSON directed attention to wo American blue glass insulators, which he had brought for inspe tion, and remarked that in a recent American work on elez lighting, which was now being circulated in this country, the insulators are recommended as suitable for almost any purpose

Mr. ADDENBROOKE also exhibited a piece of the cable used ! underground work in New York; the chief point of interest be the hardness of the insulating material employed.

Physical Society, December 6th, 1889.

Prof. REINOLD, President, in the chair.

Mr. J. W. Swan was elected a member of the Society. The following communications were read: "On the Electri tion of a Steam Jet," by SHElford BidwelL, F.R.S. The auth showed that the opacity of steam issuing from a nozzle is grea increased by bringing electrified points near it, and that colour is changed to orange-brown. Electrified balls and des when placed in the steam, produce similar effects, and when the are connected with an influence machine at work, the decoles tion of the jet rapidly responds to each spark. On examining ku absorption spectrum of the unelectrified jet, little or no select absorption was detected; but on electrification the violet dis peared, the blue and green were diminished, and the orange & red remained unchanged. From these results the author o cludes that electrification causes an increase in the size of t water particles in the steam, from something small compared w the wave length of light, to about th of an inch in diamete Allied phenomena with water jets have been observed by L Rayleigh, who found that a straggling water jet is rendered s more coherent by bringing a rubbed stick of sealing-wax nes? These observations are of considerable meteorological interve for the steam jet phenomena go far towards explaining the of the intense darkness of thunderclouds, and of the larid yelllight with which that darkness is frequently tempered.

After making his experiments, the author learnt that sims observation had recently been made by the late Robt. Helm who viewed the steam jets by reflected light against a dark bar ground. On electrification, the jets became much better defas and presented diffraction colours. Luminous flames also prodt w similar effects, and Mr. Bidwell has found that glowing t paper is equally efficient. Helmholtz conjectures that the sud condensation may be due to molecular tremors or shock imparts by the electrification, upsetting the unstable equilibrium of supersaturated vapour, just as a supersaturated saline soluti suddenly crystallised when disturbed. Another hypothesis sugg that condensation is caused by the introduction of solid s into the jet hy the exciting cause, thus providing nucle which the vapour may condense.

On reading Helholtz's paper the author tried the effect of o flames on water jets, and found that when luminous they influe the jet considerably, whereas non-luminous flames had no appr ciable effect. He also found that lnminous flames are pasize, electrified, and demonstrated this before the meeting.

Prof. Rücker thought the surface tension of the films surround ing the water jets would be modified by the presence of an el-fied body, and that the smoke from the touch-paper used in 2 of the experiments on steam jets would introduce solid pars. and facilitate condensation.

ELECTRICAL REVIEW.

Mr. RICHARDSON enquired whether a red-hot iron had any fect. Dr. FISON said he had made experiments on the electrification flame, and found that potentials varying from + 2 volts to 14 volts could be obtained in the region within and surroundg a Bunsen flame.

Prof. S. P. THOMPSON Commented on the contrast between Mr. idwell's experiments and those of Dr. Lodge on the dissipation fogs by electricity, and also asked whether the colour of the jet epended on the length of spark produced by the machine. Prof. FORBES thought a crucial test between the two hypotheses Helinholtz could be obtained by trying the experiment in a ermless globe.

The PRESIDENT said he had recently noticed that gas flames ere electrified.

Mr. BIDWELL, in reply, said he ought to have mentioned that he effect of flames on jets may be due to dirt, for if soap or milk e added to the water in the steam generator, no effect is prouced by electrification or flame. As to change of colour with park length, little (if any) variation is caused thereby. He ad not tried whether a red-hot iron produced any effect on steam jet.

"On the Behaviour of Steel under Mechanical Stress." By Ir. C. H. CARUS-WILSON.

This is an enquiry into the properties of steel, as illustrated by he stress-strain curves given in automatic diagrams from testing machines, and by magnetic changes which take place during esting.

After pointing out that the permanent elongation of a bar under ongitudinal stress consists of a sliding combined with an increase f volume, the author showed that the "yield" is caused by the mit of elastic resistance (p) parallel to one particular direction a the bar (generally at 45° to the axis), being less than along any ther direction. When this lower limit is reached, sliding takes lace in this direction until the hardening of the bar caused hereby, raises the limit of elastic resistance in the direction eferred to, to that of the rest of the bar, after which the stress must be increased to produce further permanent set.

From considerations based on the stress-strain curves of the ame material when hardened to different degrees by heating nd immersion, &c., it was concluded that the increase of (p) luring "yield" is the same for all the specimens, and that the "yield" is a measure of the "hardness."

The question of discontinuity of the curves about the "yield point" was next discussed, and evidence to the contrary given by pecimens which show conclusively that the yield does not take place simultaneously at all parts of the bar, but travels along the par as a strain wave. In these specimens the load had been removed before the wave had traversed the whole length; and che line between the strained and unstrained portions is easily recognised. As additional evidence of continuity, the close analogy between the stress-strain curves of steel of various degrees of hardness, and the isothermals of condensible gases at different temperatures when near their point of liquefaction, was pointed out; the apparent discontinuity in the latter probably being due to the change from gas to liquid taking place piece-meal throughout the substance (see Prof. J. Thomson, Proc. Roy. Socy. 71, No. 130).

In seeking for an explanation of the hardening of steel by permanent strain the author was led to believe this due to the displacement of the atoms within the molecules of the substance. To test this hypothesis experiments on magnetisation by stretching a bar in a magnetic field were made; these show that the magnetisation increases with the stress up to the "yield point," and is wholly permanent when approaching that point. On comparing his results with Joule's experiments on the elongation of loaded wires produced by magnetisation, the author infers that there are two kinds of elongation; firstly, that produced by relative motion of the molecules; and secondly, an elongation resulting from a straining of the molecules themselves. To this latter straining the hardening by permanent strain is attributed, and this view seems compatible with the results of Osmond's researches on the hardening of steel.

Mr. F. C. Hawe's paper was postponed.

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16249.

"An improved 'bar' or 'bridge' electric light switch." A. P. LUNDBERG. Dated November 9. 8d. Consists of an improved method of applying the throw-off springs, the springs being applied in such a manner as to cause the two ends of the contact bar or bridge to be pulled or pressed down on to the contact or pole pins, by the pressure of the two springs, each acting at equal distances from the centre of the bar or bridge, so as to remain equal pressure on both sides of the centre of the bridge, and thereby securing a good rubbing contact while the bridge is in motion, and a firm decided contact when the bar or bridge is in the "on" position. 1 claim.

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17964. Improvements in electric generators and motors." SIEMENS BROS. & Co. (Communicated from abroad by A. M. Taylor, of India.) Dated December 8. 6d. The inventor provides two iron rings preferably made up of iron wire or of laminated iron, each wound like a Pacinotti or Gramme ring, with an equal even number of coils of insulating conducting wire, such, for instance, as 16 coils. The one ring is so much smaller than the other that, with its coils, it can freely revolve within the outer ring. On the axis of the inner ring is fixed a commutator, having on its periphery a number of insulatsd plates suited to the number of coils, to which plates the ends of the coil wires are connected in such manner that the plates are alternately + and The commutator also has on it a + and a insulated ring, the one connected to all the + plates, and the other to all the plates. On the plates of the commutator bear a pair of brushes insulated from each other, placed side by side, and of such length, or in such position, that while one of them is in contact with a plate, the other is in contact with the next plate in order. There are also two brushes, one bearing on the + ring, and one on the ring. When the machine is used as a motor, the two conductors by which alternating currents are led to and from it are provided with double switches, by which they can be connected to the two ring brushes for starting the machine, or, after the machine is started, to the two plate brushes, which brushes are permanently connected to the two terminals of the coils of the outer ring, these coils being connected in series. When the inner ring is driven by mechanical power, alternating currents are produced by it. 1 claim.

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17568. Improved means in connection with multiple electric circuits for measuring current passing in either of them as desired." L. PARIS & SCOTT, Limited, and R. LAURENCE. Dated December 1. 8d. The object of the invention is to provide in connection with multiple electric circuits, or two or more conductors diverging from one common junction, means whereby the current passing in either circuit or conductor can be ascertained independently of that flowing in the other conductor or conductors without having to interrupt the working of the circuits for the purpose, and with the employment of but one measuring instrument. For this purpose there is provided in connection with the several circuits or conductors, and the one measuring instrument, a switch of a character which will allow the current of either of the circuits or conductors as desired to be passed through the instrument and measured. 2 claims.

17590. "Improvements in apparatus and devices for carrying and separating the plates of secondary batteries." H. P. HOLT. Dated December 3. 8d. The plates are suspended by means of a lug cast or formed upon one of the upper corners of each plate, from a rectangular frame resting on an elastic cushion upon the upper part of the cell. The under side or edge of the frame is formed to an inverted camber, so as to distribute the weight uniformly over the top of the cell. 5 claims.

17694. "Improvements in voltaic batteries." H. I. HARRIS and J. GARFORD. Dated December 4. 11d. The object of the invention is to effect further improvements in the voltaic batteries described in specifications 7th July, 1885, No. 8,228, and 30th March, 1887, No. 4,744. .

18233. Improvements relating to duplex electric telegraphs." H. A. TAYLOR. Dated December 13. 8d. Consists in the employment of a compensation circuit comprising one or more electromagnets wound with one or more wires as described. 6 claims.

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18659. "An improvement in electric motors worked by alternating currents." SIEMENS BROS. & Co. (Communicated from abroad by A. M. Taylor, of India.) Dated December 20. 8d. Claim: For starting an electric motor worked by alternating currents, connecting the commutator brushes to the field magnet coils and to a pair of terminals, connecting the alternate plates of the commutator to two rings furnished with brushes connected to another pair of terminals, and providing a double switch whereby the main leads can be connected to either pair of the terminals, substantially as described.

18856. "Improvements in printing telegraphs." G. V. SHEFFIELD and M. LowENSTEIN. Dated December 24. 8d. The invention comprises a transmitter formed of two rollers adapted to carry forward a perforated strip of paper representing the message, a series of spring actuated fingers, insulated from each other and held in contact with one of the rollers or the paper strip passing between them, so that when the paper passes through the rollers each finger is made to drop on to the roller, wherever an opening in the paper strip occurs in the path of the said finger. This roller is connected with one pole of the battery, the remaining pole of the battery being connected with the ground wire, and each finger is connected with one of the line wires, there being as many line wires as there are characters in the code. The invention further comprises a receiver consisting of a series of steam cylinders arranged in a circle, and connected with printing levers ; an electro-magnetic device connected with each cylinder and with one of the line wires, and a series of whistles connected with the steam cylinders, and adapted to be operated by the exhaust.

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In your last issue, in "Notes," the following passage occurs: "In 1872, Mr. Ayrton had not gone out to Japan, much less returned." Now it was Prof. Ayrton himself who suggested that, at the time referred to, he had not returned from Japan, and therefore I feel no complaint can be fairly made against me on this point. I would also remark I never intended to imply, nor did I wish it to be thought I considered I was indebted to Prof. Ayrton for the suppression in the Society's journal of the speech made by me during the discussion on Mr. Preece's paper on "Lightning and Lightning Conductors; " rightly or wrongly, I attributed its suppression either directly or indirectly to the Postal Telegraph Department.

The facts can be stated in a very few words. A paper was read at the Society of Telegraph Engineers, in which my lightning bridges were condemned by Mr. Preece for conforming to a regulation which the then chief engineer of the Postal Telegraphs attached importance to, and insisted upon; in other words, the views of the chief engineer were opposed through the medium of my lightning bridges; the published letter of Mr. Culley, which I quoted, leaves no doubt on this point. Naturally I objected to being made a scapegoat of, and I spoke at some length; the whole of what I said was, however, suppressed in the published proceedings.

Some day I may write the history of the introduction by me of undemagnetisable instruments These instruments of mine have proved to be an advance of great value. Their introduction was nevertheless bitterly opposed by those who afterwards, as officers of the Postal Telegraph Department, had to adopt them simply on their merits.

On the strength of the Government monopoly which made the Postal Department all-powerful, telegraphically, this Department took credit to themselves in a Postmaster-General's report for the introduction of my instruments, which they described, truly enough, as the greatest improvement which had been made in the Wheatstone needle telegraphs since their introduction; and a few years afterwards, at the late Loan Collection of Scientific Apparatus, the Postal Telegraph

[DECEMBER 20, 1889.

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I am glad to find one statement in which I a thoroughly agree with Mr. Leonard Joseph. Steam not a force. Steam is associated with force and energy but is not itself force or energy. "Steam is matter force is not." We know that steam is matter, beca it is ponderable; its weight is the same as that of u water converted into it.

But, supposing steam to be imponderable, should then, have any evidence of its materiality, or of analogy to matter, excepting the property of pote ability? Or would it be possible to consider it a mode of force or of energy?

The question can be readily answered. Apart f the phenomena of momentum and vis viva, depend upon its mass, the fact that it is not only indestructi but absolutely inconvertible into heat or work, wo be sufficient to reveal its analogy to matter.

Now, if there be any thing-such as is commen termed electricity, or quantity of electricity-cor sponding to the values Q

E

=

R

in electrostatics (R bein

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electro-dynamics (R being here a conductive resis ance), this entity is analogous to matter, in much as it is not only indestructible, but abs lutely inconvertible into work or heat. And, if ther be any thing corresponding to these values (a por that is fairly open to question) it is certain that the entity may, like steam, be associated with vary quantities of force or energy. Thus, as 1 have elsewhere, "the same quantity of electricity, passin through conductors of the same resistance (but not the same time), may, in one case, scorch and rend: tree with the terrific violence of the lightning flash, may fuse a bar of iron, and in another case be hardi capable of raising the temperature of a gramme d water by a fraction of a degree." But, in both cases when the energy (Q E) has been partly or wholly e pended, the value, Q, remains the same.

In the words of Clerk Maxwell :-" While admittin electricity to the rank of a physical quantity, we m not too hastily assume that it is, or is not, a substance. or that it is, or is not, a form of energy, or that it b longs to any known category of physical quantitie All that we have hitherto proved is that it cannot b created or annihilated, so that if the total quantity electricity within a closed surface is increased a diminished, the increase or diminution must ha passed in or out through the closed surface. This > true of matter. It is not true of heat, for he may be increased or diminished within a closed surfs without passing in or out through the surface. . . There is, however, another reason which warrants in asserting that electricity, as a physical quantity synonymous with the total electrification of a body, not, like heat, a form of energy. . . . The quantite 'electricity' and 'potential,' when multiplied together produce the quantity energy.' It is impossible, there fore, that electricity and energy should be quantities c the same category; for electricity is only one of the factors of energy, the other factor being 'potential."

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If Mr. Leonard Joseph can give the calor equivalent of electricity, or can give any instance u the conversion of electricity into heat or work, then shall be ready to admit that his contention as to the nature of electricity is correct. But I must warn hiz that all such instances-even when brought forwa by a learned professor-have hitherto been proved be fallacious, and that the idea of electricity being "force" or "mode of energy" has been relinquishe in science.

Desmond G. FitzGerald

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HE LIGHTING OF RAILWAY TRAINS.

'HE success attending the trials of the electric light, o which we referred in a previous article, would ppear to fairly dispose of any question of doubt as to ts practical application for this purpose. It is undertood that these trials were undertaken, in the first nstance, with the object of ascertaining whether this orm of light could be applied in such a manner as to neet, to the utmost, the exigencies of railway working. To this intent the trains were to be capable of being proken up, or made up, at any point of the journey; portions were to be sent certain distances dependent entirely upon the current stored up within the vehicles so despatched; carriages were to be "slipped" on the way, and the whole train was to be capable of being urned about in any direction. In fact, the officials were to deal with it precisely as they would with any other train not so fitted with electrical apparatus, except that the stock was to be kept together, so far as t could be, in order that the electrical continuity hroughout the train might not be disturbed-not that his has always been secured. On the best regulated ines mishaps will arise, and so, with these experinents, cases have occurred more than once when this continuity has, by the interposition of an unfitted wehicle, been broken. Yet the lighting has gone on. Of course, the vehicles thus separated from the dynamo have missed their charge on the journey; but it does not appear to have done much harm, for, with prompt regularity, the trains may have been noticed arriving and leaving St. Pancras at their appointed times.

Now, when we come to consider that here we have two trains specially fitted, required to run long tripsLondon, Manchester, and Liverpool-to and from, daily, without spare vans or dynamos, subject to really unavoidable interference occasionally, and yet continuing to respond satisfactorily to that demanded of it, we are forced to the conclusion that the obstacles which stood forth when its application to general railway requirements were first considered, and which we

may assume have for so long deterred others from boldly facing them, have been overcome, and that electricity has found in railway train lighting a field of utility of no mean extent. The practicability of its application is established.

Happy in the success achieved, it, however, behoves us to pursue our way with unwonted wariness. We have little fear of the verdict of the public in their choice of the form of light which would be most agreeable to their taste; still, the voice of the public, recognised as it often is, is not always strong enough to control the purse-strings. In compressed oil gas the electric light will find a powerful opponent. In gas we have an old-established friend which needs no experiments to prove its adaptability. It has been in use on our Metropolitan, and to some extent on other lines, the Midland included, for some time. As an illuminant opposed to the old oil lamps it has gained praise, and been received by many with satisfaction. Doubtless, with strict attention to the pressure and a somewhat more liberal supply of burners, it may be made as good a reading light as can be required. But when this has been done and the highest brilliancy required has been attained, have we achieved all that is desired? Would gas, even then, hold the field against the electric light? We believe it will not. We believe the electric light is destined to be the light of the future in this as in many other ways. We are by no means bigoted in this assumption. Our reasons are obvious.

Railway companies will naturally not be oblivious. to the views of their patrons, still they will consider the question of cost, and that very carefully. Gas, as we say, has passed its experimental stage. What it will do; what it will cost is before us. Electricity is, in this case certainly, in its infancy. What it can do we know, but what it will cost is not so clear-with electricity everything is new. Its cost, whatever it is, is at its maximum; with it, not as with gas, progress means reduced cost. Each extension of its application will show us some way of reducing charges-some way of simplification. With trains fitted with the

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