JULY 5, 1889.]

position of the glare from a white cloud upon the normal image of the flash. To test this, sparks from a Wimshurst machine were photographed, and before development the plates were exposed to diffused gaslight for a short time. The bright sparks yielded normal images with reversed margins, and the faint ones were completely reversed. Other experiments showed the reversal to spread inwards as the time of exposure to gaslight increased. Finally, reversal was effected by placing a white screen behind the spark to represent a white cloud, the only illumination being that of the spark itself.

In the discussion which followed, Mr. W. N. SHAW exhibited a photograph taken during the same storm, which is particularly rich in dark flashes branching outwards from an intensely bright

one.

In some places the bright line has dark edges, and in one part a thin bright line runs along the middle of an otherwise dark portion of the flash. In answer to Mr. Inwards, Mr. Shaw said the plate was exposed about half a minute, and the former thought that under those conditions the appearance of the plate did not contradict Mr. Clayden's hypothesis.

Speaking of the same photograph, Prof. PERRY considered that Mr. Clayden's observations would explain the result, for a bright flash required more exposure to diffused light to reverse it than a faint one did.

Prof. RAMSAY reminded the meeting that Prof. Stokes's "oxides of nitrogen" explanation was still a possible one, and Mr. C. V. BURTON asked whether they may be due to faint sparks cutting off light from brightly illuminated clouds, just as a gas flame absorbs light from a brighter source.

In reply, Mr. CLAYDEN thought the "oxides of nitrogen" hypothesis improbable, and said his experiments did not enable him to answer Mr. Burton's question. As regards Mr. Shaw's plate, he believed the diffused light from the clouds would be sufficient to reverse the fainter tributary flashes, although it was insufficient to reverse the primary one. From data obtained when the ribbon flash was taken, he had made some calculations which gave the height of the clouds about 1,000 yards, and the ribbon flash 1,300 yards long and 100 yards wide.

"Researches on the Electrical Resistance of Bismuth," by Dr. ED. VON AUBEL. The paper, which is in French, was taken as read. A translation will appear in the Proceedings of the Society.

Expansion with Rise of Temperature of Wires under Pulling Stress," by J. T. BOTTOMLEY, M.A., F.R.S. The investigation was to determine whether the coefficient of expansion of wires depends on the stress to which they are subjected, and was undertaken in connection with the secular experiments on the elasticity and ductility of wires now being conducted at Glasgow University.

Two wires, about 17 feet long, of the same material were suspended side by side within a tube through which steam could be passed to change the temperature. One wire was loaded to half and the other to one-tenth its breaking weight, and in the preliminary experiments the elongations were read by a Quincké microscope cathetometer. About 150 heatings and coolings, extending over three months, were necessary to bring the heavilyloaded wire to its permanent state, so that consecutive expansions and contractions were equal. When this stage was arrived at, hooks of peculiar shape were attached to the lower ends of the wire. These hooks form a relative geometrical guide, and their horizontal parts mutually support a small table which carries a plane mirror. If the wires expand or contract unequally, the mirror becomes tilted, and the relative displacement is observed by means of a telescope and scale fixed nearly vertically over the mirror.

From experiments on copper wires, the coefficient of relative expansion was found to be 0.32 x 10-6 per degree centigrade, or about th of the ordinary linear expansion of the material. The heavily-loaded wire expanded most. The results for platinoid give 0 27 × 10-6 as the relative coefficient under the conditions named above; this is about th of the ordinary linear expansion, which from separate experiments was found to be 154 × 10-6.

Mr. H. TOMLINSON thought the probationary period for copper might be considerably shortened by repeatedly putting on and taking off the load, and by subjecting the wire to torsional oscillation. With iron wires this would not be the case, for they behave in a most peculiar manner, and require long periods of rest after each oscillation. From experiments he had conducted during the last two years he found that the permeability of iron could be enormously reduced by repeated heatings and coolings whilst undergoing magnetic cycles of small range.

Mr. GREGORY said the paper threw considerable light on some experiments on the sag of stretched wires upon which he was engaged. He also suggested heating the wires by electric cur

rents.

27

Dated

6893. Improvements in electro-magnetic and magneto-electric generators." E. Cox WALKER. Dated May 9. 8d. The inventor employs an armature and permanent or other magnets of ordinary or any suitable construction, but he dispenses with the toothed or frictional multiplying gear usually employed to transmit a rotary motion to the armature, and in lieu thereof he makes use of a rapid pitch screw, such as is employed in an ordinary Archimedian drill, which may engage in the hollow spindle of the armature, causing the latter to rotate rapidly when pushed in or pulled out. 4 claims.

6985. "Improved switch for electrical tramcars." M. IMMISCH. Dated May 10. 11d. Claim:-The improved switch for electromotors, consisting in a spindle mounted eccentrically to a disc and carrying an arm with a projection capable of engaging with projections on the disc, so that the latter is actuated thereby for only a portion of the travel of the switch arm, such arm serving to introduce resistances successively before the circuit is broken, and to take out such resistances after the circuit is again completed, the contacts for establishing and breaking the circuit being carried by the disc actuated by such arm, all substantially as and for the purposes specified.

7523. "Means and apparatus for electric lighting.” E. J. HOUGHTON. Dated May 22. 8d. Claim:-Combining a dynamo with a lamp circuit and with accumulators in such manner that the accumulators are arranged in two portions, either in parallel or in partial parallel, and that a resistance is interposed between the dynamo and the lamp circuit, whereby, while the current from the dynamo is made to charge the two sets of accumulators alternately by a switch, a small portion only of such current passes through the resistance to the lamp circuit, together with the current from the charged set of accumulators, substantially as and for the purposes set forth.

8765. "Improvements in holders for incandescent electric lamps." W. ROWBOTHAM and W. Fox. Dated June 15. 8d. The inventors form the holders for capped lamps of a tube of sufficient internal diameter to admit the cap of the lamp, closed at the lower end with a disc of insulating material fitted to the inside of the tube after the manner of a piston, and pressed toward the mouth of the tube by a spiral spring fitting close in the tube, the spring bearing at one end against the base of the tube, and at the other end against the bottom face of the insulating disc. The insulating disc is pierced in the centre to allow the leading wires to pass through, and carries two screw studs to receive the ends of the wires, said studs being in such a position as to bear against the plates on the base of the lamp when the lamp is in the holder. In each of the opposite sides of the tube is cut a straight slot, extending from a short distance from the top to near the bottom, and a second slot is cut in an oblique direction from the top to meet the first slot a little distance from its end, so that on the trunnion pins on the lamp caps being passed into the second slot and the lamp pressed downward, the slot causes the lamp to make a slight movement sideways; and on the pressure being removed the trunnion pins fall into the ends of the first slots, locking the lamp in position. A guide pin is inserted into each side of the insulating disc, projecting into the first slots, to prevent rotation of the insulating disc. claims.

8809. Improvements in electric switches." (Communicated from abroad by S. Bergmann, of America.) Dated June 15. 8d. Consists in a novel switch for electrical purposes,

28

in which is employed a rotary part or wheel made of incombustible material, much, for instance, a parcelain. This rotary part or wheel is provided with alterase metallic and non-metallic surfaces. The improvement als costs in the combination with a switch wheel of a se pere of insulating material, an upright sheil secured a te have pece, a rotary part or wheel of incominsthie naterai monte com said shell, a shaft supported by the shell, and a ammentar between the shaft and the switch wheel. The dams me 21 in number.

1905 Improvements in electric batteries." H. LAHOUSSE & da mut 1 Cuma Died June 18. 8d. Claims:-1. A two iamd atter where a solution of bisulphate of mercury and oncentrated nter weid in suitable proportion in water, as set orch, is employed at an a zinc in a porous vessel, and in which gramier refera cim is employed in combination with the ordiiary rions. Jeng mmersed in nitric acid with the object of ncreasing the song merface, and at the same time facilitating the employment of a pitch or other like seal, substantially as described suit ilustrated in the drawings. 2. The combinations and arrangements of parts and materials constituting the improvements in Heetere bacteries as described.

*. * Improvements in magneto-electric bells." E. CoxWKER and A. A CAMPBELL-SWINTON. Dated June 21st. 8d. The inventors employ a suitable horseshoe electro-magnet with an armature pivotted in front of its poles in such a manner that the saui armature as vibrate in front of the said poles under the influence of the attraction of the same with facility, the said armature having attached to it a striker or hammer to strike the gong or gongs employed. 4 claims.

9406. A method and apparatus for transforming alternating into continuous currents of electricity for charging electrical accumulators." R. F. YORKE. Dated June 28. 6d. An electrical motor espable of being worked by alternating currents of electricity is fixed so as to drive an ordinary continuous current dynamo. When the alternating motor is working a continuous current will then be produced by the dynamo, and this current may be employed either for charging accumulators alone or for charging accumulators and lighting electric lamps at the same time. 2 claims.

9487. Improvements in electrical instruments operated by electro-magnetic attraction." F. L. RAWSON and W. WHITE. Dated June 29. 8d. The inventors wind a coil of wire upon a tube and mount this between pivots whose axis is at about the middle of the coil and in a direction at right angles to the magnetic axis of the coil, so that the whole coil is free to rotate on the pivots in a plane parallel to its magnetic axis. The free ends of the coil or connection pieces attached to them are carried out at one end of the coil and arranged to dip into two mercury cups forming the terminals of the instrument, and thus the coil is included in and completes the electrical circuit in which the instrument is placed. A movable core formed of a soft iron ball is placed nside the tube; when the instrument is in its working position with the coil ends in the mercury cups, this iron ball rests against a soft iron screw placed at the end of the tube next the mercury cups, and to keep it normally in this position, the axis of the coil and tube is inclined downwards somewhat towards this end. When the current passing through the coil exceeds a determined amount, the iron ball is drawn up into the coil by the attraction exerted upon it by the current in the coil, which overcomes the effect of gravity and the magnetic attraction of the iron stop screw; the lower end of the tube and coil is thus relieved of the weight of the iron ball, and the system being suitably balanced, this end rises, lifting the coil and connections out of the mercury cups, and so breaking the circuit. The coil system turns sufficiently on its pivots as the circuit is broken to leave the axis of the tube inclined in the opposite direction to what it was before, so that there is no tendency for the iron core to return to its former position. 4 claims.

9825. "Improvements relating to switches for electrical purposes." W. MACKIE. Dated July 6. Claim:-A loose

8d.

driving crank, having "back lash" or lost time between the driving pin of the handle and the crank pin itself, and making the crank pin pull or push on or off the connecting pieces of an electric switch in connection with a spring, substantially as described.

9854. "Improvements in and connected with secondary batteries or electrical accumulators." L. BRISTOL. Dated July 6. The inventor intimately mixes and incorporates with the red equivalent active material employed to form the plates a proportion of animal hair, preferably human, or feathers feathers, or thin shearings or shavings of horn, or bre, or asbestos fibre, or any other suitable fibrous to proper and suitable dimensions. 4 claims. An improvement in electric current and tension meters." LIVO-DOBROWOLSKY, and the Company " ALLGEMEINE ATSGESELLSCHAFT," both of Berlin. Dated July 7. 8d. electric current and tension meters, and the improve's in the combination, with a solenoid, of an axle being rforming an angle with the axis of the solenoid and e or more bunches or pencils of thin wires of soft iron er, the said axle having connected to it a weight or a sch normally maintains the axle in such position that a sing though the solenoid and magnetising the wires

hes will cause the axle to turn, while with Fgle of rotation the resistance presented by pring increases, either in the same or in quantity or tension of the current thus

[JULY 5, 1889.

measured by the latter is indicated by the pointer on a graduated arc. 1 claim.

10107. Improvements in casing used for electrical conductors." C. S. SNELL. Dated July 11. 8d. The inventor forms the casing of paper or its equivalent composition such as millboard, strawboard, pasteboard or papier-maché and moulds, sets, rolls or otherwise forms it into convenient shape for one or more electrical conductors. This paper, or its equivalent, he treats either in the pulp stage or after its final shape has been given with waterproofing or fireproofing solutions or both, or he may intermix with or form the pulp partially from asbestos with alum and borax, this paper being very incombustible. The waterproofing solution may consist of a solution of oxide of copper in ammonia which partially dissolves the cellulose of the paper and converts it into an impermeable varnish or simple coating with soap and then with sulphate of copper or alum or any other well known composition or medium may be used. The claims are 5 in number.

17267. Improvements relating to electric apparatus for propelling tramway cars and other vehicles, and to means for transmitting electric currents to such apparatus." H. H. LAKE. (Communicated from abroad by J. Klames, of America.) Dated November 27. 8d. Relates to electrical mechanism for propelling street cars and other conveyances, and the object thereof is to provide simple means whereby contact may be preserved between the main conductor or cable and the arm or arms taking the current therefrom to the motor. Another object of the said invention is to provide means whereby the rocking movement of the car, as well as the rise and fall of the frame by variations in the weight carried, may be automatically compensated. A further object of the invention is to provide a simple insulating bearing for the contact arms, which shall avoid the necessity of lubrication and give complete insulation. A still further object of the said invention is to provide a conduit for the purpose of transmitting elec trical energy to a motor by which a public conveyance is propelled. The claims are 9 in number.

CORRESPONDENCE.

A Severe Test.

My attention has been called to a short editorial in your issue of May 24th, 1889, giving an account of how I had succeeded in forestalling Mr. Sprague in treating the armature of a motor to a 24-hour salt water bath, taking it out and then running it on an overload, without first drying it.

The facts as to the experiment are correct, but the parties thereto are rather mixed. I am an officer of the Sprague Company, and it was only as such that I described in the Electrical World, May 11th, the experiments which Mr. Sprague directed and at which I assisted. I merely write this that you may know that it was Mr. Sprague, after all, who carried out his own promise.

S. D. Greene,

Chief Engineer, Sprague Electric Railway and Motor Company.

New York, June 18th, 1889.

Spinning Crystal.

..Si

As quartz threads are likely to play a considerable part in the future of our galvanometers, &c., it may possibly be of interest to the readers of your interesting journal that a full account of spinning crystal may be found in the Magazine of Science for April, 1842, p. 39. The article is an account of the experiments of M. Gaudin; a few extracts from the letter are as follows::"M. Gaudin has succeded in drawing out crystal into threads, several feet in length, with the greatest ease." "It resembles steel in elasticity and tenacity." liceous compounds act nearly in the same way as rock crystals." "The emerald threads well, and its threads, which scratch rock crystal, are more tenacious than crystal threads." He uses the oxyhydrogen blowpipe for welding the crystal; he found that threads of quartz appeared irridescent and floated on the air. "Threads of pure quartz were always cylindrical and transparent; "he also drew out quartz into sticks for burnishers."

ELECTRIC TRACTION PROBLEMS.

MANY of our readers will recollect the very complete tests made by Mr. A. Reckenzaun at Philadelphia in the year 1887, and published in our issues of July 6th and 13th last year. These were probably the first

systematic tests carried out with electric cars in the United States, and the articles contained a summary of some 13,000 observations made on storage battery cars of his construction during the ordinary daily services. in the streets of a busy city, where all the varying conditions of tramway traction come into play. Mr. Reckenzaun has shown in his "Notes" that the current at starting, and on steep inclines, rose to as much as 80 ampères, and that even on moderately level parts the variations, owing to frequent stoppages, slowing down and speeding up, were very marked. As an example, he cited the distance of 10 blocks of houses from Broad Street to Fourth Street, Philadelphia, traversing which showed the following mean current densities, viz. 31-25, 21.05, 42.64, 8.26, 26.59, 0, 16:53, 41.66, 0, and 20-62 ampères respectively. The average, during an entire trip over 3 miles, was 36 ampères with an E.M.F. of 157 volts, the approximate load of car and 40 passengers being 7 tons. The roads were in the usual dirty condition, weather dry, and the speed. of the electric car had to be regulated to the horse traffic on the same line. Careful measurements were also taken of the energy used in charging the batteries at the station, and the densities of the electrolyte in the cells were ascertained before starting and after returning from a given number of trips.

:

The value of such exhaustive tests cannot be overestimated, for they give us a clear idea of the amount of energy required; they tell us the maximum power to be provided for, and are the means of bringing about improvements which cannot be arrived at by mere guesswork and rule of thumb blundering.

Following Mr. Reckenzaun's initiative, Dr. Louis Bell, of Purdue University, recently made similar tests with the electric cars at Lafayette, Indiana, on a road supplied

with overhead conductors of the Sprague type. We reprint elsewhere Dr. Bell's interesting article, taken from the Electrical World of New York, in which the author states that he did not concern himself with theoretical motor tests and curves, but to actual tests of power and efficiency, and to the evidence of the ammeter and the indicator diagrams at the power station. "The man who contemplates putting his money into an electric road does not particularly care about the characteristic of the motor used, but he does want to know how much power must be developed on his cars, how much coal he must burn, what efficiency he may expect from the system, what are the weak points, and how they may be strengthened." The programme which Dr. Bell set to himself was carried out in a thoroughly practical manner, and we do not in the least doubt the accuracy of his figures, which are exceedingly instructive, and upon which we now offer a few comments and suggestions. The Lafayette Street Railway is 3.6 miles long, single track. At the time of the tests it had been in operation for about eight months. It has a grade of 7.34 per cent. for 100 feet, and one of 6.6 per cent. fully 800 feet long. There are about a dozen curves. Six cars are in continuous use; each of these seats 20 persons, and weighs complete 5,200 lbs. There are two Edison dynamos, each of the normal capacity of 30,000 watts, or rather more in case of need. The first car leaves the end of the road at 6.20 a.m., and the last car gets in at 10.20 p.m. Each car makes from 35 to 40 miles per day.

The mean indicated horse-power throughout the day was 39.05; the highest figure reached during the tests was 793 I.H.P. The mean electrical H.P. was estimated at 14.58, and the greatest output by the dynamos was 90 ampères at 410 volts, giving 49.46 electrical H.P. But it is observed that occasionally 75 electrical H.P. may be demanded. The ammeter readings frequently fell to zero for a few seconds at a time. Thus the current on the line varied from 0 to 90 ampères, and the E.M.F. from 405 to 480 volts. The coal burnt during the day was 4,500 lbs. of slack, which is at the rate of 7.3 lbs.

B

Fig. 1 gives the variations of the H.P. and efficiency throughout the day, and fig. 2 the variation of current as given by the five-minute readings between the hours of 10 and noon. Dr. Bell adds that "even this does not represent the real amount, for as a matter of fact, the current is never even approximately constant for more than a few seconds at a time, and varies from nil to 60 or 70 ampères, in a way that nothing but a continuous record can show. As a result of this, the mean output is, on a system of this size, less than 25 per cent. of the maximum, which may be called for, and must be furnished at any moment. As the system becomes larger, the ratio of mean to maximum output increases, until for a large system it may amount to one-half."

The figures given by Dr. Bell teach us two important lessons. At Lafayette the maximum work done is 240 car miles a day, with an average expenditure of 650 H.P. hours. This gives 2-6 H.P. hours per car mile, and is in excess of the energy expended on storage battery cars, although they weigh more, and occasion a loss of nearly 40 per cent. in conversion. The higher average efficiency of traction with storage batteries may be accounted for by the fact that the plant at the charging station is always running at its full power, whereas the fluctuations in the supply through conductors are very great, as will be readily seen by diagram fig. 2. Furthermore, the engine has to be as large, if not larger, with the overhead system, as with the accumulator system, to produce the same useful effect.

The second inference we draw from Dr. Bell's figures is, that in a system with conductors, where the average output is only 25 per cent. of the maximum, it would be wise to use a much smaller engine, in conjunction with a set of accumulators at the supply station, for steadying the work upon the prime mover and the dynamo, and thus have practically a constant load upon the central station plant. This has been advantageously introduced in electric lighting stations where the fluctuations are insignificant, in comparison with those in an electric tramway system with overhead or other conductors. The addition of storage batteries on a line like the one at Layfayette would, without doubt, be found more economical and safer in the long run than a direct supply under such unfavourable conditions. Dr. Bell's article is full of interesting points, and some of his suggestions are worthy of a careful study on the part of those engaged on electric traction problems. He, however, lays all the stress of his arguments upon the employment of special steam engines to remedy the difficulty, and he recommends working the engine on the average at its most economical point of cut-off, while retaining the power of responding to sudden, though brief, demands for several times the

[JULY 12, 1889.

fly-wheel, will not meet the demand, and the ideal method of steadying the work is, as we have said, by means of good accumulators.

ONCE more attention has been drawn in Parliament to the question of overhead wires, and once more the question has practically been shelved, although for the future electric light wires will be under restrictions. There seems to be a general impression that nothing will be done in the matter until some "great catastrophe," akin to the bursting of the Johnstown dam, takes place, though of the nature of the catastrophe, and why it should take place, there exists but the vaguest notion in the minds of those who form the idea. In spite of the prophesies of the most dire results, the erection of telephone and electric light wires goes on apace, and has gone on for some years, without serious results arising therefrom. Accidents, of course, have happened, and may happen, if careless work is done, and therefore a proper system of inspection of overhead wires is desirable; but that a wholesale disaster is likely to take place time has proved it, we think, to be improbable. From an æsthetic point of view, the removal out of sight of the network is much to be wished, and in many districts underground could be substituted for open work, though at a very heavy expense; but, unfortunately, it is not in such districts that the advisability of the substitution arises; it is where the wires are most crowded together that the disfigurement and danger are greatest, and it is here where it is least possible to adopt underground work, for in such districts the space under the pavement and roadways is already fairly choked with pipes of all kinds. To put down fresh pipes for telephone wires would be exceedingly difficult, but to utilise further the existing pipes belonging to the Postal Department, or to enlarge the same, would probably be practicable; such an arrangement, however, could only be carried out by the Government acquiring the telephone system, an arrangement which many consider very advisable, and one which will probably be considered when the time of expiry of the patents draws close.

WE notified a short time ago that the Edison Company had made a reduction in the prices of incandescent lamps, but it now appears that what on the face of the circular looked like a boon to the trade, is not so. The altered price carries with it a greatly reduced discount, so that in reality traders have now to pay more for lamps than they did previous to the issue of the new terms. Surely this shuffling with figures is neither dignified nor fair on the part of the company, and it is calculated to handicap the trade still more? What we require now that electric lighting prospects look somewhat more rosy is a real reduction of prices all round, or, at least, wherever possible, and not an advance under the guise of a benefit. This kind of thing is eminently suited to an enterprising draper who sells off somebody's bankrupt stock at an enormous sacrifice; but we had looked for a truer regard for its own interests in dealing comprehensively with the subject than the Edison Company appears to possess.

THE gas engine recently introduced by the Campbell Gas Engine Company, of Halifax, is said to have been tried very successfully for electric lighting, and three engines of this make are to be employed in connection with the lighting of the Electrical and Industrial Exhibition at Birmingham. Being simple in construction, the Campbell gas engine is cheap, suitable for hard and constant

JULY 12, 1889.]

work, and requires little attention. There are no slides with their many objectionable features, such as constant wear and tear from friction, necessitating delicate adjustment and continual overhauling. As there is an ignition at every revolution, the engine when working at full power can be run steadier than can those having an impulse only every two or three revolutions. This feature of igniting the combustible mixture two or three times oftener than in the ordinary gas engine, while only using the same quantity of gas, enables the motor to be put into less space, and the weight per horse-power is considerably reduced, the latter consideration being of some importance where the engine has to be placed on an upper floor. When the work is of an intermittent nature the governor automatically regulates the exact quantity of gas needed to perform the actual work done. We shall be glad to have particulars of its performance at the approaching exhibition.

THE "Borough Engineer" as if his duties were not already enough to, at times, drive him very near the verge of distraction, will now have to add another to his innumerable accomplishments. Mr. Silcock, whose remarks on electric lighting we print on another page, has come to the conclusion that everyone of his confreres must eventually add electrical engineering to their professional duties. Perhaps it would be easier to turn those who have already acquired an extensive knowledge of the subject into borough engineers; but these matters will settle themselves in the ordinary course of events. We feel inclined to agree with the President of the Congress of the Association of Municipal and Sanitary Engineers and Surveyors, who remarked that it was questionable whether electric lighting should ever be added on to the work of the town official. One thing is quite certain, and that is that in the present stage of electric lighting his time would be so fully occupied with his new duties that many others would go to the wall. The lapse of time and further improvements might, however, bring with them less necessity for devoting the bulk of the day to solving problems in electrical distribution.

A WRITER in Fair Play attempts to teach his readers the dynamo principle. He says, "if we take a piece of wire in our hands and move it past the end of a magnet we shall find that in the act of so moving it we have set up a current of electricity in the wire." He furthermore states that instead of a short length of straight wire we can have a great length rolled into a coil. Now, half truths are not sufficient when one is engaged in trying to instruct the uninitiated; and it is absolutely fallacious to state that a current is generated in a short length of straight wire when moved in front of the magnet pole. One can see perfectly well what the writer is driving at, but he has not mastered his subject sufficiently well to instruct others.

WE are enabled to state that satisfactory progress is being made with the preliminary arrangements in connection with the Electrical Engineering and Mechanical Inventions Exhibition, which is to be held in Edinburgh next year, to commemorate the opening of the Forth Bridge. An influential general committee of over 200 members has already been formed. The Marquis of Lothian, Secretary of State for Scotland, has been approached with the view of obtaining his lordship's services as president. In Glasgow an important committee is in course of formation, and it is intended also to give other large cities an opportunity

31

of contributing to the success of the exhibition. Support has been promised from America, and some of the exhibits in the Paris Exhibition are to be transferred to Edinburgh. Altogether, the prospects of the exhibition are most encouraging.

IN the description of Carl Hering's wire coupling, which we give on another page, the statement, on the authority of the Electrical World, is there published that joints as ordinarily made offer 50 per cent. of the total line resistance. So far as this country is concerned we scarcely need say that such joints as are here indicated would not be tolerated, and we can hardly think that our contemporary correctly represents American practice. Nevertheless the remark affords an opportunity of suggesting that very valuable information might be obtained, particularly by electric lighting companies, as to the real difference that jointDoubtless ing makes in the conductor resistance. quite a number of methods are employed in connecting together copper leads, and if the resistances of several conductors of different diameters, but of the same length, which should be considerable, were taken, and the wires afterwards cut up into, say, a dozen separate lengths, and then jointed, it could readily be ascertained by a second test what difference had been made in the resistance, and the comparative value of various kinds of joints could also be determined. If such an enormous variation as that stated by our contemporary comes into the question it should be taken into consideration when selecting the size of lead to carry any given current, but we doubt whether the matter of jointing, as affecting the resistance of the conductor, is ever taken into account at all.

IT appears, judging from M. Bovet's lecture on the electric light at the Paris Exhibition, that the syndicate which was formed to carry out the necessary arrangements will have no cause to regret the financial results of its enterprise. There is money and to spare for carrying out any number of enterprises in this country, but the difficulty is to get adherents to any scheme which does not at the first blush look particularly rosy; perhaps the success of the French Syndicate may do something towards loosening the purse strings of some of our financiers who have hitherto held aloof from participating in any new venture.

It is evident that there is still need of a great improvement in incandescent lamps. Mr. Silcock, whose practical paper on p. 32, is well worth perusing, calculates that if consumers can be supplied with electrical energy at a cost equivalent to gas at 3s. 9d. per 1,000 cubic feet, it is necessary to allow another 9d. for breakages, which brings the cost up to gas at 4s. 6d. He reckons the average life of a lamp to be 1,000 hours; to prolong this to twice or three times that period means considerable reduction in the cost of electric lighting.

OUR esteemed contemporary the Electrician seems to have discovered a bogey by which timid manufacturers may be frightened. In the Edison patent for laminated armatures they see a possible means of Messrs. Mather and Platt, the present owners, claiming royalties from other makers, but up to the time of going to press we do not find that any intimation has been made to manufacturers of such an intention on the part of the eminent Salford firm. We have far too high an opinion of Messrs. Mather and Platt to imagine for one moment that they contemplate the policy at which our contemporary hints.