construction, and are really rocking switches, and come into action at the moment when the half batteries are just in or out of charge. Their function is to introduce into the charging circuit a carbon resistance, o, between the time that one half battery goes out and the other enters, the position of being "under charge."

The groups of four cups on the outsides of these relays are half positive and half negative, and the relative positions of the arms incline in the same direction. To pull them into those positions and maintain them there, each arm is actuated from below by two electro-magnets placed in a local circuit, to which I will refer further on.

used to collect the hydrogen gas formed by one plate in one of the cells under charge. This cell is called a master cell. When no current traverses the coil of the solenoid, the valve is open, and no gas is retained in the holder.

At this point the duty of the holder, F, may be described. When the half battery is approaching full charge, gas is given off, and the valve alluded to being kept closed by the charging current, gas is retained by the holder, and commences to fill it.

The gas given off is collected first in au ebonite gas chamber and acid trap, marked H. The trap prevents any gas from this particular plate going anywhere else than into the gas chamber.

When the right half battery, s1, is in charge, the right relay, C1, is in contact on its right (as it presents itself on the diagram). The positive and negative cups are respectively in connection with corresponding cups on the outside of the right-hand transposing switch, A1. The intermediate terminals are severally connected with the poles of four sets, each of 54 cells, so that these 216 cells are in circuit in series.

On the way to the right-hand charging circuit relay, the positive conductor has formed the coils of a charging solenoid, marked E. Its function is as follows: When the current is passing, the solenoid closes a valve in connection with a little gasholder, F,

From the chamber the gas passes into a bubbling bottle, a, with oil in it, which is intended to extract the moisture, and thence to the little holder. The size of the holder is calculated so as to contain just sufficient gas as will be given off by one plate after the proper state of milkiness of the cells has been attained. The moment it fills, a contact is made with the arm of a switch which is underneath it. This switch closes the local circuit, to which I have already alluded, as actuating the pulling-down magnets of the charging circuits, C1, C2.

To return to A, the right-hand transposing switch. Let it be remembered that its right-hand contacts are dipped in their cups

and the left-hand contacts are elevated out of them, and the charging current can go nowhere else but through the half battery.

Meantime, discharging into the lamp system is going on from the left-hand half battery, and while this is going on the righthand contacts of the rocking arm of the left transposing switch are dipped.

These contacts are so arranged and connected with the poles of the four sets of cells that they are in position to discharge in parallel. It is evident that when the positions of the rocking arms of the two transposing switches, ▲, and A, are reversed, the left half battery will be "in charge " and the right half battery discharging; and, again, that if the inner ends of the two rocking arms are dipped and they stand with opposing angles, then both half batteries are discharging, and charging has ceased.

Let us return to what takes place at the moment the arms of the switches rock into a fresh position. Underneath each of these arms, as in the case of those belonging to the charging circuit relays, C, Co, are placed two electromagnets to pull them down. These electromagnets are also placed in the local circuit mentioned twice before. This operation of rocking over, so to speak, is sufficiently slow between the break and make in the mercury cups as to allow an interval of disconnection of less than half-aminute.

During this interval the charging current does not cease, but for the time, as has been already described, is relayed through the resistance, o, by the operation of the charging circuit relay, c1, the rocking arm of which, instead of moving slowly like that of the transposing switch, moves instantaneously.

The operation is effected in the following order and manner: As has been stated, the gasholder closes the local circuit in the pullmagnets under the elevated end of the rocking arm of the righthand transposing switch, which commences to move slowly over, aided by a balance weight rolling in a groove on its upper side.

As the charging contacts leave the mercury other contacts under the arm break the current in the pull-down magnet of the outer end of the rocking arm of the charging relay, which being weighted, falls the other way, and effects simultaneously the introduction of resistance, o.

The rocking arm of a A, continues moving slowly over. It first makes the contacts, which bring the right half battery into the position of discharge in parallel, and finally makes other contacts, which, acting on the local circuit through a small rocking switch, starts the rocking arm of the transposing switch, A. Its first action is to cut the left half battery out of the lamp system, and when it completes its journey to throw the left half battery in series into the charging circuit. At the same moment, by a separate contact, it closes the local circuit which actuates the pull-down-magnet of the charging circuit relay, c2, the effect of which is simultaneously to transfer the charging current from the resistance, o, to his next duty.

When the left half battery is charged, the next and final stage is carried out by the gasholder acting as before on the local circuit, the work of which is confined to inciting the rocking arm of the left-hand transposing switch to rock over, so that the second half battery goes to the assistance of its fellow.

A tell-tale wire back to the generating station from the transposing switch actuates a relay at the generating station the moment that the left-hand contacts lift out of the mercury. The current so transmitted actuates a relay which cuts off steam at the generating station.

On each side of the diagram are shown four resistance cells of the same type as those for accumulating, marked B, &c. The duty required from them is as follows:

1. To supply counter E.M.F. with which to regulate the pressure in the lamp system.

2. To give the required energy to actuate what has several times been referred to as the local circuit, of which there are actually two -one for each side of the apparatus.

This bring us to the consideration of what occurs in discharging from the batteries. In a system requiring a pressure of 100 volts, varying 14 per cent. above and below, that from 54 cells is excessive, even allowing for the fall between the station and the ends of the feeders. At the same time it is necessary to have ample reserve to meet occasions of heavy discharge. To keep the pressure constant at the ends of the feeders, there must be tell-tale wires from those points to the E.M.F. governor, м, fixed on the governing board.

This apparatus is a fine wire coil in parallel with the feeders, and its function, when the E.M.F. is above or below the normal limit, to move a solenoid up and down. A lever bar connected with this completes a local circuit in a relay marked J, which, in its turn, actuates the two double-acting solenoids, D, and D2, which operates simultaneously on sliding contacts in connection with resistance switches B, B, B, B and B B B2 B. These solenoids act as rheostats on the discharging circuit, by putting in or taking out the counter E.M.F. cells one at a time, and even two at a time.

The E.M.F. governor, m, is also in series, with a temperature compensator, marked L. This little apparatus keeps constant the resistance of the fine wire coil of x, by altering the length of a carbon filament, which is in circuit with the coil of M. This alteration of length, which minutely varies the resistance, is caused by the expansion and contraction of alcohol in a bent glass tube which presses on a column of mercury, into which one end of the filament is inserted.

As the bulk of the alcohol alters through temperature, the Pressed up or down, and less or more of the filament is

mer

[ОСТОВЕР 4, 1889.

short-circuited. In order to maintain an equal discharge from each half battery, a current balance, marked x, is used.

This apparatus is made of two coils of large section copper, wound spirally apparently, but really cut out of a piece of copper tube. The whole current from each half battery passes through one of these.

Should one half battery be giving current at such a rate as to run some 10 per cent. below the other, the coil acts solenoidically and completes the circuit in D, or D, whichever may be affected, and thereby, through the intervention, as before, of one of the resistance switches, B, cuts out one of the counter E.M.F. cells The reduction of counter E.M.F. to the half battery which has been under discharging at once brings the two half batteries up to the same line.

The diagram shows at two places the connection to which the feeding mains of each kind are led. At r is placed an ammeter to measure the total discharge into the feeding mains, which can be cut in or out. At the other pole is shown a set of safety fuses; these are also used on the other pole. Of course there are many minor very important and interesting features of this beautiful invention of Mr. F. King's to which I have no space to allude.

The small relay, marked N on the drawing, has not been described, and I think it desirable to call your attention to it, not with the object of including it in the description, but in case any question may be asked about it. It completes the local circuit and causes switch A, to be brought into position of charge. It is actuated by a current from the generating station when the engineer is ready to start charging.

It is claimed for the system which has been under description That the cost of the generating and storage plant does not exceed that of any other system. In support of this, I have a calculation before me, made by the Electric Power Storage Company for a generating and storing plant for 30,000 30-watt lamps at £45,000, or at the rate of 303. per lamp. On the same lines, the actual cost in Chelsea for a 9,000 lamp plant has been 40s. per lamp. Under the best conditions, the generating plant itself need not exceed in indicated capacity of one-half of the maximum capacity of the system, assuming that the proportion of energy for which the consumers will pay is at least 70 per cent. of the energy produced at the terminals of the charging dynamos. The economy in space thus acquired is equivalent to the demand for space for storage.

It is also claimed that the cost of the mains is less than in any other system. And, again, it is claimed that the working cost must necessarily be considerably below that of any other system on account of the working of the motive plant always at its full power. To this particular feature of the system I wish to draw marked attention, together with the economical advantages in working, arising out of the complete stoppage of the machinery in motion each day for periods varying according to the time of

year.

SPECIFICATION OF THE GENERAL CONDITIONS TO BE COMPLIED WITH IN WIRING HOUSES FOR THE ELECTRIC LIGHT. Compiled for the use of the Customers of the Chelsea Electricity Supply Company. Limited.

The contract under this specification includes all conductors commencing at the point where the supply company's work ends, and all electrical fittings which do not actually form part of the lamp fittings. It includes no lamp fittings unless otherwise specified.

1. Except where otherwise specified, the whole of the work to be carried out in accordance with the rules of the Society of Telegraph Engineers and Electricians, and the company in whose office the building is insured.

2. In every room or closet throughout the house one light will be separately controlled by a switch at the door, placed so as to be of easy access to the hand immediately the door is opened. In dressing and bed rooms this light will be suspended over the dressing table, the length of the lead to permit of the lamp fitting being about 7 feet above the door. In other rooms the light to be so controlled will be selected as being the one most likely to be in

common use.

3. No lamp lead is to be less in cross section than the equivalent to a No. 18 S.W.G., and in the case of floor connections less than No. 16 S.W.G.

4. All mains and sub-mains where not carried between floor and ceiling, will be placed in approved wood casing. Where carried between floor and ceiling, they will be laid between the joists or in notches cut in the same, not less than 6 inches apart, and in no case will any pair of leads be carried between the same joists or through the same holes in partitions, &c. They will be painted throughout with asbestos paint: positive red, negative black.

5. Wherever between floor and ceiling branches leave the main, they will be laid with sufficient slack, so that the branches shall not approach nearer to the main on the opposite pole than 6 inches, the necessary cleats being attached to, and holes bored in the joists to secure that end.

6. When the lamp leads serve lamps in rooms with wainscoting or ornamental walls, where casing is not suitable, they will be led separately and by different routes to the point where the lamps are fixed, following the lines of the moulding or ornament; in such case they will be uncovered and fixed with saddles, and in no case, except where casing is used, may lamp leads approach nearer than 2 inches of each other.

7. Where there are wall hangings or tapestry the lamp leads

OCTOBER 4, 1889.]

1 be carried behind the same, if not in casing, as prescribed for ween floor and ceiling.

5. In the case of plain walls lamp leads will be laid in casing m the floor upwards, or the ceiling downwards, which will be into channels cut in the walls. Should it be desirable not to turb the decoration or paper, they will be laid on the face of wall, and secured by saddles. In such case the colour of the ering of the conductor should harmonise as much as possible h the colour of the walls.

. A wooden wall block will be fixed at every point where a lamp, Il plug, switch, or cut-out are specified to be fixed under the tract; except where panelling or stone ornament already sts, when special means of attachment must be arranged for. 10. Distribution boards will be supplied and fixed if required, I will carry the following fittings besides the necessary termis. To each circuit and sub-circuit will be furnished a switch I double pole cut-out.

1. When a distribution board is not required, a cut-out will be ed at, or as near as possible to, the junction with each principal anch with the main.

2. Cut-outs will not be fixed at any other point in the system n those referred to in 10 and 11 except at each lamp.

3. Wall plugs, unless otherwise specified, will be fixed 2 feet 6 hes from the floor, and where there is a dado, they will be fixed ve the top rail.

4. Floor plugs will make connection through a plate of insuing material laid flush with the floor, and the sockets will not less than 3 inches apart, and must be open at the base, so that at may fall through into a cavity beneath.

5. Unless otherwise specified, the ends of the leads to serve aps, of which the fittings are destined to be attached to the lls, will be left, so that the future fittings can be fixed anywhere tween 4 feet 6 inches and 7 feet above the floor.

6. Samples of all electrical fittings of every kind, and a drawof the distributing boards will be submitted, and be subject approval before being fixed.

17. Any deductions from, and additions to, the contract will be de only under instructions in writing from the superintending gineer, and no day work will be undertaken without his instrucns; and no claim for such day work will be admitted unless a ily time-sheet for the same is handed to, or sent to, him on the lowing day.

(To this follow pages on which to draw up the number, nature, d position of the lamps, the descriptions of the route of each cuit, and a form of agreement to be entered into by the tractor.)

ECIFICATION FOR THE SUPPLY AND LAYING Down Underground OF ELECTRICAL MAINS FOR THE CHELSEA ELECTRICITY SUPPLY COMPANY, LIMITED.

The contracting company is the Callender's Bitumen Telegraph d Waterproof Company, Limited.

1) Route.-The routes to be followed to be as nearly as possible ose shown in the plans attached, but where necessary, by reason unforeseen obstructions, they may be changed, subject to the proval of the Chelsea Company.

(2) Excavation.-The trenches to be made in the foot or roadys, as the case may be, on the route described. The depth der the footpaths shall be as little as is consistent with safety. hen under the roadways the depth of the trench shall be 2 feet der, or such other depth below the surface level of the roadway the nature of the paving or macadam may require. When cessary, to avoid existing obstacles, pipes, &c., this depth may be reased or diminished, subject to the conditions of safety. (3) The existing paving of all kinds to be removed, and on comtion of work replaced. The execution of the whole of this rtion of the contract to be subject to the satisfaction of the rveyor of Chelsea parish, and to be carried out in terms any orders or rules he may lawfully make, and to conform conditions laid down in clauses 13 to 19 inclusive, and in clause of the Chelsea Electric Lighting Order Confirmation Act of 36, 50 Vic., cap. xviii.

(4) Open Trenches.-The work to be so carried out that no one etion of greater length than 100 feet shall remain open for hours.

(5) Notices. All the notices which are laid down in the abovemed Act as obligatory in connection with the works shall be ven by the Chelsea Company, who shall relieve the contracting mpany of any responsibility in consequence of any neglect on e part of the Chelsea Company to comply with the requirement, t at the same time the contractors shall be required to give e Chelsea Company ample notice over and above the time notices prescribed by the said Act to enable the Chelsea Comny to fulfil its conditions; and, in case of the contracting comny's defaulting to do so, the said company shall not be relieved om loss or responsibility arising out of any such failure on their (6) Plans. The plans and drawings made in duplicate, as preribed by the said Act, shall be prepared by the contracting comny and delivered to the Chelsea Company.

.rt.

(7) Deposit.-Any deposit which the Vestry may require as a arantee for the proper reinstating of the footpaths and roadays shall be made by the contracting company, and all arrangeents connected with the same shall be made directly between the estry and the said company.

(8) Negotiations with Vestry.-Although the Chelsea Company all give all the legal notices required by the Act, or otherwise,

389

the negotiations with the Vestry, their surveyor, or contractors, as to the actual mode and time of doing the work shall be carried on by the contracting company, advice of same being given to the Chelsea Company.

(9) Cable Cases. In the trenches, as described, cable cases shall be placed and jointed together into continuous lengths. The cases shall be of the Callender-Webber type, of the sizes and with the number of ways as specified in the schedule.

(10) Cable Cases. The cases shall be made of the best bitumen concrete, of the same quality as those laid in 1887 at the Borough Road works of the Anglo-American Brush Electric Light Corporation, Limited. The thickness of material between the individual ways and between the ways and the outside of the case shall be at least half-an-inch. The inside of the ways shall be made truly circular in section and equal in area throughout, smooth and free from projections or roughness of any kind.

(11) The cases shall be made in lengths of 6 feet each, the ends trued to fit each other, and they shall be jointed together by means of saddle-pieces and bitumen cement, and with the assistance of suitable mandrills for each separate "way," so that the ways shall be equal throughout and watertight, and the inside of the ways at the joints in every respect of the same section, within at least th of an inch, as smooth and free from roughness as elsewhere. Tight joints shall also be made between the E.M.F. draw and service boxes and the lengths of casing which join them.

(12) No bends shall be allowed of a shorter radius than ** ; they shall all be such as will allow the cables to be drawn in or out with ease, and the line of casing shall be laid out to avoid all unnecessary divergencies from the straight or level. No curved length of casing will be used in which the circular section of the ways has been altered in form by the process of bending.

(13) Drawing-in cords to be provided by the contracting company, and left in the ways as and when the cases are laid. When cables are drawn in, these cords to be used for drawing in the necessary drawing wires, which will be recoverable by or be returned to the contracting company, remaining their property in the interim.

Drawboxes.-(14) Draw boxes to be provided at all points as

follows:

(a) All change in direction of line of 90° or thereabouts, or where changes of direction prevent the use of curves.

(b) At all points of junction between one main and another. (c) Sudden alterations in level.

(d) All straight lengths, in which boxes do not occur for the above reasons once in every 100 yards.

(15) The drawboxes must be securely joined to the main casing. The covers of the boxes to be of cast iron, resembling the Post Office specification of weight and thickness, and to be of the designs, dimensions, and patterns agreed on between the management of the two companies.

(16) If during the progress of the work it is found expedient to place additional boxes, this shall be done by the contracting company on orders being given by the Chelsea Company.

-, or

(17) E.M.F. Boxes.-The distributing or E.M.F. boxes to be placed at the points shown on the attached drawing and marked elsewhere, if required. They will be constructed of brickwork in cement, or laid in bitumen, and with floors and covers of best York landing. They will be constructed on the general design shown on the attached drawing, modified to suit the particular conditions of each case. The copper junction pieces to which the mains are jointed will be of special design, suitable to each position, and the joints with the same, and their insulation shall be made in all respects as mechanically and electrically secure as the joints in the rest of the system, described elsewhere.

(18) Service Boxes.-Service boxes to be of cast iron, and to be provided and fixed in number at least one for every two houses, as shown in schedule No. These to be of the design, dimensions, and pattern agreed on between the two companies. Wherever possible only one line of distributing cables to be interrupted and pass through these service boxes. Service boxes and house connections to be fixed either at the same time as the casing is laid, or subsequently as found most convenient.

(19) The cables used to be made as follows: Conductor.-The strand to be of copper wire of high conductivity, guaranteed not less than 98 per cent. that of pure copper. Each wire to be tinned separately and to be of the size shown in schedule.

(20) Dielectric.-To consist of a solid sheath of bitite (vulcanised bitumen) put on under pressure to a diameter of not less than the dimensions named in schedule No.

(21) Tapes.-The cable to be taped over the dielectric three times with prepared tape and compounded between each. Braid to be of hemp yarn closely plaited and served with liquid bitumen compound, then with an asphalte compound, and finally passed through blacklead to facilitate drawing into the way. The cables to be coiled on large drums, having a boss of not less than 3 feet in diameter, and not to be subjected during manufacture or afterwards to any undue strain by bending or otherwise.

(22) Joints in Cables.-The joints between the sections of the cables, each to each, to be made by a long soldered joint in the conductor. The seven central wires to be run together solid, and each of the outer wires to be individually jointed to the corresponding wire in the other cable. The wires to be short and long alternately on each cable to form a strong marriage joint. The whole to be then bound with fine copper wire and soldered over all.

(23) This conductor to be lapped with tape, and then covered in not less than three thicknesses with sheet bitite, made specially

390

for this purpose. The whole to be well welded together, and to be finally protected by strong prepared tape and compound.

(24) Each joint when finished to be tested for insulation and conductivity. In each draw and distribution box a maximum of 2 feet and a minimum of 1 foot slack to be left on each cable for the purpose of allowing the sections of cable to be drawn backwards or forwards a few inches from time to time to prevent adhesion to the insides of the cases, and to secure their freedom and the possibility of at any time withdrawing the cables for the purpose of maintenance.

(25) Service Joints.-The joints of service leads to the mains for house supplies to be T-joints, and made as described above, except that the service wire will be jointed on the main by passing through the centre of the main, and lapping three times round the strand, the whole to be then firmly soldered and insulated as before described.

(26) In the service boxes care to be taken that the joint is as near as possible in the middle of the space, so as to allow the cable being safely moved when drawn periodically backwards and forwards to prevent adhesion. The service leads to have sufficient slack in the box to allow of this being moved without strain to the mains.

(27) House Connections.-House connections to be provided from each service box to within the boundary wall of the premises, and such connections to consist either of a two-way Callender-Webber case or of a cast iron pipe carrying two cables each of the size required to supply the current to be agreed on with the customers. A price to be paid for all such connections as shown in schedule No. This to include breaking through and making good the house or area walls.

(28) During the execution of the work the Chelsea Company to have free access for purpose of supervision to all parts of the work, and their representative to have the right to reject any labour and material which he considers in the interest of the work should not be employed, and upon receiving written notice to that effect from him the representatives of the contracting company will cease to use the same.

(29) Every separate length of cable shall be tested for its insulation resistance after having been drawn in to the casing and placed in situ before being jointed to the next length. The result of each such test must give infinity with a Wheatstone bridge, Post Office patterns, both between the conductors and between each conductor and earth; the current used to have an E.M.F. not exceeding 100 volts.

(30) The next test will be of the same lengths when jointed together from end to end from a station to a feeding box. From this test the same result will be required.

(31) Similar resistance results will be required from the distributing mains before the house service branches are joined in as from the charging and feeding mains.

DISCUSSION.

Prof. FORBES said: We have a good deal of matter to discuss in a short time, and I think many will agree with me that the paper which Major-General Webber has given is one of the most important papers that we have had on the subject of distribution of electricity. It is not a hypothetical paper in any way, it deals with what has actually been done by his company, and it is the first large scale application of storage batteries on this side of the water. Everyone must see, from the description that has been given in the paper, that every part of the scheme has been thought out with a care which is by no means common in central stations which have been devised on new plans. In every part of this scheme, whether it be in the arrangement of the batteries or in the motors, an enormous amount of thought has been bestowed, consequently this is one of the most interesting central stations that has been erected, and the working of which will attract a great deal of attention in the immediate future, financially and otherwise. There are some details which I should like to speak about, though not with the intention of criticism, but rather to draw attention to points which seem to be of special interest in the system which has been described by General Webber. The system of the distribution is very thorough indeed. There is only one or two points about which I do not quite understand. He has his feeders and charging mains distributing conductors all arranged in what seems to be an admirable manner, and, moreover, he has done what is a very desirable thing to do in the varying of potential, and that on a direct system of supply is a most important thing to induce counter electromotive force cells, such as he is introducing, when dynamos are being used, in order to adjust the pressure in the different feeders. One of the most interesting things is the system of conduits, that is, having a separate channel for each conductor. When we consider, however, it becomes a little difficult to see what the exact object of the conduit is, because if they were not waterproof, and did not act as air insulators, they can only be used as a protection for the cables, and the material being friable, steam rollers or pickaxes will be apt to break them; however, if the only advantage is the facility of drawing in and out cables it is a very great advantage indeed. As to the bare copper wire, we are indebted to General Webber for giving us results of actual experience. It has been very difficult to get actual experience. The fact that he was obliged to give it up makes one think that it was not so good as one thought. General Webber has not dealt with financial results in this paper. We shall look forward to financial results, for this is really the point which is of most interest. Everyone will agree that the storage battery system is better than any other which has

[ОСТОВЕР 4, 1889.

been proposed, if the cost of maintenance and durability v sufficiently reduced. With regard to Mr. King's system of e teries, I have taken great interest in these, and seen not only va was done at Colchester, but at Millwall. Mr. Swinburne drawn attention to the fact that very bad transformers are bey made, and also to the fact that since many of the modern tra formers have very largely lost through hysteresis, it would much better to have open circuit transformers, to prevent hysteresis from being injurious. At the same time, Mr. Swint z is mistaken as to the figures being so very incorrect as to ency; the transformers were not in the most efficient cond and those that I have examined myself have been higher tem those which he has given here.

Prof. EWING: In connection with the meter which has described, I should like to ask General Webber whether be found in practice that there is any serious error in the resta of this meter on account of effects of retentiveness in the in which controls the indicator. When a strong current has be sent through the meter one may expect that subsequent readie: will be unduly large as compared with those readings L follow a weak current, on account of the iron core retaini portion of its previous magnetisation. In regard to Mr. Sz burne's paper, I do not think it easy to pronounce any opr. z without having an opportunity of thinking out the matter a fully than one can do while hearing this paper read. The *: of the matter of his contention seems to lie in this: that in t magnetic circuit of a transformer you may, on the one hand, ba a circuit consisting wholly of iron, a substance of great perus bility, but, at the same time, open to objection on account its dissipating energy through hysteresis, or, on the other han you may have a magnetic circuit in which a part of the circ is formed through air, a substance having the drawback of b comparatively very impermeable, but having, on the other han. the advantage that in magnetic cycles there is no dissipatz through hysteresis. Mr. Swinburne's hedgehog form has a posite circuit, consisting partly of wire and partly of air, spreading of the ends facilitating the connection between the w It seems to me that a better result might perhaps be achieved by simply reducing the quantity of iron, and working with a high induction, for one must bear in mind that the dissipation of a through hysteresis becomes much less in proportion to the 2 duction when the induction is high, that is to say, iron become so to speak, more nearly elastic as regards cyclic changes of netisation the higher we go in the induction.

Prof. S. P. THOMPSON: It is quite true if you get the magn elasticity through magnetisation, you also do much work on t iron in toto, the iron would get very hot unless it had adequa surface. The real point of Mr. Swinburne's paper seems to be t he introduces into the magnetic circuit of the transformer certain portion of air. Perhaps it is better explained analogy. At one time it was thought better to regulate a alternating current systems by the introduction of read ance; now it has been found better to regulate the alternati current system by the introduction of reaction coils. If we we now to regulate the action of the transformer by acting on the an part, we could do it by increasing magnetic resistance, the by putting in air-gaps or by thinning the iron. In one ar thinning the iron leaves us in the presence of iron which de pates energy by reason of its imperfect magnetic elasticity; in other case introducing the air leaves us in the presence of a stance of which the magnetic elasticity is perfect. It has residual magnetisation; the rapid reversal of its magnetic engenders no heat and wastes no energy. Its action may there be likened rather to that of the choking coil than to that of ohmic resistance in an electric circuit. I am not sure the: should agree with Mr. Swinburne's way of constructing this o what is the real gain of spreading out the ends of the wires a hedgehog form, as he calls it? really, if the core is long. cannot seriously diminish the resistance by spreading out in the way, and it adds to the difficulty of construction, and I am that it does notadd to the risks of the system. Mr. Swinter does not say how long his cores are; of course, the question b far the resistance is effected depends on the length of th core. The meter described by General Webber is a interesting addition to those interesting instruments, we are all very anxious to know whether it is going t be the practical electric meter of the future. The subject electric meters is one in which a great deal remains to be d There is no one meter which shows itself superior to others, s we cannot point to one and say that is the right one to put your house for your electric consumption. The difficulty of properties of iron is got over by the most ingenious way of th so-called integrating piece. I should like to ask how the pr effect of that cam is found out: is it ascertaiaed once for certain piece of iron, or has every meter to be subsequently terü and the complicated cam cut for each.

Mr. POWELL was rather surprised to hear Mr. Hedges say the precautions were necessary to secure immunity from dangers individuals.

Mr. PREECE: There is an immense amount of interest felt in success or the failure of this system of distribution of electrat by accumulators in Chelsea, probably because the first att: == made at Colchester some years ago was a failure, but secus..! because there is a most remarkable and strange want of confi-in accumulators. Now, I find by experience this: that those have no confidence in accumulators are those who never used the " while those who have used accumulators have very great confid=== in them. I, as you know, have been a staunch advocate of a

CTOBER 4, 1889.]

ators from their very earliest introduction in this country, my house for nearly six years was lighted by accumulators, and ch are used very largely in the Post Office for telegraph purposes , we have 300 circuits which have been working for the last years; we are now introducing them for telephones. My own ression is that it is only a question of time to find the 30,000 that we have in use in the Post Office in London replaced by at 1,000 perhaps accumulators. Hence experience of accuators is very much in their favour, and why it is that people ersist in decrying them I cannot make out. It may be due to thing, they have been ill-used. People get batteries and fancy I will do a great deal, and they put in a great deal more ent than they ought to receive; when accumulators are treated y and properly, when they are not overcharged, and when are called upon quietly and gently, the life of a battery is ly at the present moment unknown. I am quite prepared to that their life is equal to a renewal of 15 per cent., and with ing years we shall be able to maintain our batteries with proy 10 per cent., we may even come to 7 per cent. for renewals. shall watch those experiments in Chelsea with interest, and forward to have a report before this section from General ober of the progress made at Westminster. There is one mous advantage which General Webber has over those elecans who have been carrying out the system of distribution, he has experience of underground wires and they have not. I not know one thing where experience is wanted so much n the knowledge of laying down wires underground and ntaining them." There was a terrible heresy committed his room by Mr. Hedges, who spoke of the relative condis of underground wires and overground wires, he spoke as igh an underground wire gave no insulation whatever, and that insulation of an underground system was far inferior to that n overground system; the reverse is the case; underground ems not only give a very much higher insulation, but you rely upon the uniformity of the insulation of underground, e the insulation overground is very variable and troublesome. re was one other thing that Mr. Hedges referred to, and that ie statement that the London Electric Supply are going to use as with one conductor put to earth; that is not true; there is stem, and a very delicate system, used at the present moment Il our principal towns, and that is the system of Telephone hange, and if the outside conductor of such a main as that Josed be laid down, and if the outside conductor were put to h, it would entirely upset the whole telephone system in don. We cannot allow that, and the Government has been ged to step in and say that the outside conductor shall not be to earth, you must provide something else; and the result is, main which the London Electric Supply Company are going y down has the outside conductor very carefully insulated. It concentric cable, a solid wire in the centre which is insulated; ide this is a cylinder of copper, also insulated and covered I wire, and I hope it will answer the purpose. With respect [r. Swinburne's paper, I have very few remarks to make; these the kind of papers we want, and when we find men deliberately o work with the experience and mathematical knowledge of Swinburne, we can only hail such papers with great pleasure. re is one point he has not touched upon; he alluded to the that these transformers may cause an immense amount of te when the instruments are laying idle. At the present aent they are devising switches by which the transhers shall be switched off during the day and switched only when wanted at night. One word as regards the gers. When I spoke the other day, I referred solely langers to persons, and to-day we have heard more of gers from fire. It is a great mistake to imagine that in an tric lighting system you are entirely free from risks of fire. It ften said have electric light, you will be absolutely safe. re is no fear of your house being burnt down. It is a mistake. re is not the slightest doubt, there is as much danger in rd to fire by introducing the electric light as there is from oducing gas. In the electric light the chief danger arises a the use of imperfect material, and especially from the employit of inexperienced men; also from the want of just those very rivances which Mr. Hedges has brought before us. If good erial is used, if experienced men are employed, and if all the aratus of safety, such as we have heard to-day, are admitted, a electric lighting is absolutely safe, but not unless you do ething of this sort of thing. As regards danger to persons, t is quite a different thing. I alluded the other day to a nge remark made by Mr. Stevenson, one of the reasons he uced against the use of the distribution of power by means of tricity was, that if a man touched a wire he would be killed, tis-in unscientific language-absolute rot (laughter and lause); the difficulty with electric currents is not to prevent a 1 from killing himself, but to know how to kill him. The State of York recently passed an Act making execution by electricity he future; they have not rescinded that Act, yet they will be iged to do so, because they cannot find an electric current to men with certainty. I remember on one occasion making some eriments with enormous induction coils with a spark about iches long to kill a rabbic, and we could not; they volunteered ry me, but I was not quite ready to offer my body at the present ment, but there are many of us who have taken immense cks. Colonel Armstrong, at Chatham, took shocks that were posed to kill individuals, but he was very well after it, and ked all the better after it. I can say this, speaking from exience, that there is absolutely, with ordinary precautions, no iger to persons and no danger to life. Newspaper correspon

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dents are very fond of getting up some sensational paragraphs. There was a case in Brighton where a brewer's man was stated to be killed by the electric lighting currents. The man was certainly dead, he was found resting against the wire, there was a mark on the back of his neck, but the fact was the electric light current was put off two hours before the man was supposed to be killed, so it is doubtful whether the man in Brighton was killed by the currents generated by the central electric lighting station there.

Mr. WEBBER: I thank Prof. Forbes for the friendly way he has spoken of my system. As regards the E.M.F. cells, I beg to remind him that the E.M.F. cell is considerably above the standard of distribution of pressure required in the mains, and that they are destined, as it were, to keep down the excessive pressure at the commencement of the discharge.

Mr. KILLINGWORTH HEDGES said, in reply to Mr. Powell, that the question of fire risks is practically settled, and danger is minimised. I think Mr. Preece can hardly have meant the insulation of underground system is perfect. I happen to have the discussion on the paper read in 1888 on the distribution of electricity. I have also the remarks of Captain Cardew, who is the Board of Trade inspecter referred to by Mr. Preece, and he says the question has given anxious consideration to Government, and in all underground systems there is the danger of leakage.

Mr. SWINBURNE: Prof. Forbes pointed out that the Gaulard and Gibbs transformers gave very high efficiency. I think it is about 88 per cent., and that is rather a confirmation of my paper. They were not the best designed, being rather long. It was also mentioned that open circuits were more efficient. There was a loss owing to the free magnetisation. I do not know whether I am quite accurate in saying that, but that was my impression of the reason given before. Prof. Ewing says that the iron ought to be reduced. In the paper I have taken several inductions, and high induction induced rather low efficiency. I do not quite follow Prof. Ewing's figures, for the loss of c.c. were taken as one cause, and what he calls graded cycles. Prof. Thompson does not quite follow the advantages of the spreading out of the ends. I do not like to use the term " magnetic resistance;" hedgehogging makes the magnetic resistance of the air enormously smaller.

REPORT OF THE COMMITTEE ON CERTAIN MOLECULAR PHENOMENA CONNECTED WITH THE MAGNETISATION OF IRON.

(Read by Prof. BARRETT on September 13th, 1889.) Ar the meeting of the British Association at Bradford in 1873, a paper was read by the Secretary of this Committee, and subsequently published in the Philosophical Magazine for December, 1873, On certain remarkable molecular changes occuring in iron wire at a low red heat." In this paper the phenomenon known as the recalescence of iron was first published, it having been discovered by the author early in September, 1873. At the suggestion of the late Prof. Balfour Stewart, a small committee was appointed, of which Prof. Barrett was appointed secretary, to investigate and report on recalescence and other molecular phenomena attending magnetisation. This committee had some meetings, and a good deal of unpublished experimental work was done by the secretary, but no quite satisfactory explanation of the main point, the phenomenon of recalescence, was arrived at. The lamented death of the two principal members of the committee, Prof. Clerk Maxwell and Prof. Balfour Stewart, left the matter in abeyance, and the committee lapsed before a report was presented. Recently, however, the committee has been reappointed, and now consists of Prof. Fitzgerald as chairman, Mr. Trouton, Mr. Newall, and Prof. Barrett as secretary. Owing to various causes it is not proposed on the present occasion to do more than present a formal interim report reserving to next year the full report of the committee.

So much work has of late been done on the general subject of the molecular phenomena attending magnetisation that it would now be beyond the scope of the committee adequately to report on the whole matter. We propose, therefore, in the first instance, to confine our report to those phenomena accompanying the socalled critical temperature of iron-that point in, or near, which the magnetic state is lost in heating and regained on cooling. Here, at a dull red heat, a series of profound and remarkable changes occur in iron and steel, to which attention was first called by the paper read by Prof. Barrett in Bradford in 1873. The principal points in that paper were as follows:

"1. Mr. Gore, in 1869, had discovered that a momentary elongation of iron occurred in cooling after heating a wire of that metal to a white heat. In 1873 the author found a similar but reverse action took place in heating the wire. 2. This anomalous deportment was found, both in heating and cooling, to coincide with, on the one hand the loss, and on the other with the resumption of the magnetic state of iron or steel. 3. At the critical temperature the wire, having cooled down to a dull red heat, suddenly flashed into a bright glow; likewise during the heating of the wire the temperature remains stationary for a short time when the critical temperature is reached; a rise in the specific heat of wire and steel therefore occurs at the critical temperature. 4. A curious crepitation occurs at the critical temperature, similar to that heard in the magnetisation of iron, or in the production of the scales of oxide on the wire. 5. Prof. Tait's remarkable thermo-electric change in iron occurs at this same temperature. 6. Hard iron wire and steel wire exhibit recalescence, but certain specimens of good soft