Chapter MIX: And Genest's Microphone Telephone (1)

We illustrate in the annexed engraving the microphone-telephone constructed by Messrs. Mix & Genest, of Berlin, which, after extended trials, has been adopted in preference to others by the imperial postal department of Germany. There are now more than 5,000 of these instruments in use, and we need scarcely mention that the invention has been patented in many countries.

In some microphones a rattling noise is frequently occasioned, which borne along with the sound of the human voice causes an audible disturbance in the telephone. The chief cause of these disturbances may be ascribed to the fact that the carbon rollers in their journals, rest loose in the flutings of the beam, which is fastened to the sound plate. Owing to the shocks given to the entire apparatus, and independent of the oscillations of the sound plate, they are set in motion and roll to and fro in their bearings.

In microphones in which the sound plates are arranged vertically (as shown in Fig. 2), these disturbances assume such a character that there is no possibility of understanding the speaker, for in this case the horizontally directed oscillations of the sound plate, _m_, cause themselves a backward and forward motion on the part of the carbon rollers without increasing or decreasing at the same time the lying-on pressure of the roller journals, and by doing so bring the places of contact one on the other, and thus occasion a conducting resistance of greater or less force. This circumstance serves as an explanation of the reason why the sound plates in Ader's microphones are not arranged vertically, although this way of arranging them offers many advantages over a horizontal or slightly inclined arrangement of the sound plates. Speaking is more convenient in the vertical arrangement, and moreover the plates can be fitted on to instruments better in this way.

All the drawbacks just enumerated and found in Ader's microphones are avoided in the apparatus made by Messrs. Mix & Genest. A sort of braking contrivance operates on the carbon rollers in such a way as to prevent their journals from lying on the lower points in the flutings of the beams. Thus, for instance, if in a microphone with a horizontal sound plate, as illustrated in Fig. 3, the carbon rollers are pressed upward by outward force, it is evident that only a very trifling rolling and disturbing motion can occur, and only small pieces of carbon can be knocked off, which would act injuriously as a secondary contact. The same may be said of the journals of microphones with vertical sound plates, as represented in Fig. 2, when the carbon rollers are pressed in the direction of the arrow, _p_, that is to say, against the sound plate. In this case the journals, _a_, are fixed in the flutings of the beams, _b_, in a direction given them by the power and gravity operating on them, which is clearly represented in the accompanying design, Fig. 2.

In all such cases the regulating contrivance applied to brake the carbon rollers in their motion has the result that only the oscillations transmitted from the sound plate on to the contacts come in operation, whereas disturbing mechanical shocks resulting from any outward influences occasion very insignificant vibrations, which are not perceptible in the telephone. The separate contacts thus form a firm system with the sound plate, so that the former are influenced in their motions and effects solely and alone by the shocks and oscillations which operate direct on these sound plates. The roller motion of the carbon is thus removed, and the distinctness of the words spoken is greatly augmented.

The above Figs. 1 and 2 show the microphone in side view and in cross section.

A metal ring, R (see Fig. 1), is fastened by means of the four screws, _r_{1}_ _r_{2}_ _r_{3}_ _r_{4}_, on a wooden mouthpiece. In a recess of the above ring is the diaphragm, M, which is provided on its outer edge with an India rubber band and is held in position by the two clamps, _a_ and _a_{1}_. The diaphragm is cut out of finely fibered firwood and is well lacquered to preserve it against dampness. On it there are two carbon beams, _b_, and in the perforations of the latter are the journals of the carbon rollers, _k_. The alterations in contact take place in the touching points. The cross piece, _f_, that runs straight across the carbon rollers serves as a braking contrivance, which is regulated as may be necessary by the large projecting screws.

Fig. 3 shows the apparatus in cross section. T is the mouth piece, R the metal ring, M the diaphragm, _f_ the breaking cross piece. On the latter is a metal block fastened by means of two screws. On this metal block is a soft elastic strip (d) of felt or similar material. The letters _s_ and _s_ indicate the regulating screws for the braking contrivance.

The excellent qualities of other microphones, in particular their extreme sensibility for the very least impressions, are undeniable; but it is just this sensibility that is the cause of the complaints made by the public. In practical use this overgreat sensibility proves to be a fault.

In the apparatus constructed by Messrs. Mix and Genest the well-known deficiencies of other systems are avoided. The effect of the sound and the distinctness of the human voice are clearer and far more intelligible. One simple regulation of the microphone suffices for the installation, for there is no danger of its getting out of order. Owing to its peculiar construction, this new microphone is very firm and solid, and for this very reason offers another advantage, namely, the possibility of transmitting sound over very long distances. In the competitive trials instituted by order of the imperial postal department, apparatus of various systems and constructions were subjected to tests, and the apparatus we are speaking of showed the favorable results just mentioned. This microphone has overcome in particular the difficulties connected with the using of combined lines above and below ground, and with the aid of it the excellent telephonic communication is carried on in Berlin, in which city the telephone net is most extensive and complicated. At the same time this microphone transmits the sound over long distances (up to 200 kilom. even) in the most satisfactory manner. Another peculiar advantage of this construction is that it exercises a very small inductive effect on cables and free lines, and consequently the simultaneous speaking on parallel lines causes but little disturbance.

After repeated trials made by the German imperial postal department with the microphones constructed by Messrs. Mix and Genest, these apparatus have been introduced in the place of the telephones and Bell-Blake microphones hitherto used in the telephone service. At present we understand there are about 8,000 of these apparatus in use.

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ELECTROLYSIS AND REFINING OF SUGAR.

Mr. G. Fahrig, of Eccles, Lancashire, has invented a new process of refining sugar through electrolysis. The brown sugar is decolorized by means of ozone produced by electric currents of high tension from a dynamo. The electrodes consist of metal grills covered with platinum or some other inoxidizable metal, and are placed in a vat with the intervention of perforated earthenware plates. After being ground and dried in hot air, the crude sugar is placed between the plate and the grills, and the discharges passing between the electrodes produce ozone, which separates the sugar from the coloring matter. To purify the sugar still further, Mr. Fahrig dries it and places it in another vat, with carbon or platinum conducting plates separated by a porous partition. The sugar is placed on one side of this partition, and water circulates on the other side.

The current from a dynamo of feeble tension is sent through the vat between the plates. The water carries along the impurities separated by the current, and the sugar is further whitened and refined.

The accompanying figure shows a series of four vats arranged one above another, in order to permit the water to circulate. Here _i_ and _h_ represent the plates connected with the poles of the dynamo through the conductors, _f_ and _g_; _m_ represents the porous partition; L, the spaces filled with sugar; and _l_, the compartments in which the water circulates.--_La Lumiere Electrique._

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[THE ELECTRICIAN.]

A CURRENT METER.

We give a description of a meter we made in June, 1883. You will find a cross section of the meter and also a printed dial we had made at the time. We called it an ampere register, but no doubt we would give it a better name to-day. The meter consisted of a glass tube, _c_, both ends of which were fitted into two bent pieces of piping, D and F, as shown. Through these bent tubes, D and F, passed the wires, a and _b_, which were connected to the binding posts, A and B. The part of the wire where it passed into the tubes was well insulated. At the ends, _a'_ and _b'_, was connected the coil, R, which consisted simply of a few turns of copper wire whose diameter was less than the leading wires, _a_ and _b_. To the tube, D, was attached a square tube, E, which had a little opening at the top so as to permit a small undershot wheel, I, to revolve freely. This undershot wheel was well pivoted and constructed very light. To the axis of this wheel was connected another system of wheels with indicators, as shown, J. Now the tubes, E and F, were connected to a reservoir, G. This reservoir consisted of a square tank, in the inside of which were soldered in an alternating manner square sheets of copper as shown in the drawing, _g_ _g'_ _g''_ _g'''_ ... These sheets acted as diffusers. These plates or sheets presented a very large surface. On the outside of the tank, G, were also diffusers, _h_ _h'_ ... arranged all round and presenting an appearance as if two books were open so as to form a square with their covers, the leaves being the diffusers. The diffusers on the outside were at right angles to those inside.

The action of the meter was thus: When a current passes through the coil, R, it heats the liquid at the place, thus causing a circulation, the warm liquid ascending while the cold liquid descends as shown by the arrows. This circulation causes the undershot wheel to revolve, and its revolutions are registered by the clockwork. The stronger the current, the more the heat, and thus the more rapid the circulation. The warm liquid once in the tank, which is of a reasonable size, will impart its heat to all the diffusers. The surface of the glass tube, etc., is very small in comparison to the surface of the tank. It will be seen that the function of this apparatus is independent of the outward temperature, for the motion of the liquid is due only to that heat which is generated by the current. When the current does not pass, it is evident that the liquid, at whatever temperature it may be, does not circulate, as all parts are of the same temperature; but the moment the current passes, a difference is produced, which causes a circulation in proportion to the current. We may mention that we tried various liquids, and give preference to pure olive oil. It will also be seen that this meter is good for alternating currents. In conclusion, we may remark that the tests we made gave satisfaction, and we wanted to publish them, but that Mr. Jehl was called away to fit up the Edison exhibit in the Vienna exhibition for the Societe Electrique Edison of Paris. After the exhibition we began our work upon our disk machine, and had almost forgotten our meter. The whole apparatus is mounted on a base, K.

JEHL AND RUPP. Brünn, Sept. 26, 1887.

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STORAGE BATTERIES FOR ELECTRIC LOCOMOTION.[1]

[Footnote 1: From a paper read before the National Electric Light
Association, New York, August, 1887.]

By A. RECKENZAUN.

The idea of employing secondary batteries for propelling vehicles is almost contemporaneous with the discovery of this method of storing energy. To Mr. Plante, more than to any other investigator, much of our knowledge in this branch of electrical science is due. He was the first to take advantage of the action of secondary currents in voltaic batteries. Plante is a scientist of the first grade, and he is a wonderfully exact experimenter. He examined the whole question of polarization of electrodes, using all kinds of metal as electrodes and many different liquids as electrolytes, and during his endless researches he found that the greatest useful effect was produced when dilute sulphuric acid was electrolyzed between electrodes of metallic lead.

A set of Plante's original cells was exhibited for the first time in March, 1860, before the Paris Academy of Sciences. Scientists admired and praised it, but the general public knew nothing of this great discovery thus brought to notice. Indeed, at that period little commercial value could be attached to such apparatus, since the accumulator had to be charged by means of primary batteries, and it was then well known that electrical energy, when produced by chemical means in voltaic cells, was far too expensive for any purpose outside the physical laboratory or the telegraph office.

It was twenty years after this exhibition at the Academy of Sciences in Paris that public attention was drawn to the importance of storage batteries, and that Mr. Faure conceived the idea of constructing plates consisting of lead and oxides of lead. At that time the advantages accruing through a system of electrical storage could be fully appreciated, since electrical energy was already being produced by mechanical means through the medium of dynamo-electric machines.

It was the dynamo machine which created the demand for the storage battery, and the latter was introduced anew to the public at large and to the capitalist with great pomp and enthusiasm. One of Faure's accumulators was sent to Sir William Thomson, and this eminent scientist in the course of experiments ascertained that a single cell, weighing 165 lb., can store two million foot-pounds of energy, or one horse power for one hour, and that the loss of energy in charging did not exceed 15 per cent. These results appeared highly encouraging. There we had a method of storing that could give out the greater part of the energy put in. The immense development which the electric transmission of energy was even at that early day expected to undergo pointed to the fact that a convenient method of receiving large quantities of transmitted energy, and of holding it in readiness until wanted, must be of the highest importance. Numerous applications of the Faure battery were at once suggested, and the public jumped to the conclusion that a thing for which so many uses could be instantly found must necessarily be a profitable investment, and plenty of money was provided forthwith, not with the idea of commencing careful experiments and developing the then crude invention, which would have been the correct thing, but for manufacturing tons of accumulators in their first and immature form.

I need not describe the disappointments which followed the first unfulfilled hopes, nor repeat the criticism that was heaped upon the heads of the early promoters. Those early hopes were untimely and unreasonable. A thousand difficulties had to be overcome--scientific difficulties and manufacturing difficulties. This invention, like most others, had to go through steady historical developments and evolution, and follow the recognized laws of nature, which are against abnormal and instantaneous maturity. The period of maturity has also been retarded by injudicious treatment, but the ultimate success was inevitable. Great advances have been made within the last few years, and I propose now to offer a few facts and figures relating to the present state of the subject with reference to the application of storage batteries to locomotive purposes. It is not within the province of this paper to discuss all the different inventions of secondary batteries nor to offer any suggestions with regard to priority, therefore I will confine myself to general statements. I am aware of the good work that was done in the United States by Kirchhoff twenty-six years ago, and of the more recent work of Mr. Brush, of Cleveland, Mr. Julien and others, but I am more particularly acquainted with the recent achievements of the Electrical Accumulator Company, who own the rights of the Electrical Power Storage Company, of London. I have used the batteries of the latter company for propelling electric boats and electric street cars. The first of the boats was the Electricity, which was launched in September, 1882, and which attained a speed of seven miles an hour for six consecutive hours. Since then a dozen electric boats of various sizes have been fitted up and worked successfully by means of storage batteries and motors of my design. The most important of these were the launch Volta and another similar craft, which is used by the Italian government for torpedo work in the harbor of Spezia. On the measured mile trial trips the Italian launch gave an average speed of 8.43 miles an hour with and against the tide. The hull of this vessel was built by Messrs. Yarrow & Co., and the motors were manufactured by Messrs. Stephens, Smith & Co., of London. The Volta, which was entirely fitted by the latter firm, is 37 feet long and 7 feet beam. She draws 2'6" of water when carrying 40 persons, for whom there is ample sitting accommodation. There are 64 cells in this boat. These are placed as ballast under the floor, and actuate a pair of motors and a screw coupled direct to the armature shaft running at 700 revolutions a minute. We crossed the English Channel with this boat in September of last year, leaving Dover at 10:40 in the morning, arriving at Calais at 2:30 P.M.; stayed about an hour in the French harbor for luncheon and floated into Dover docks the same evening, at 6:30, with full speed. The actual distance traversed without entirely discharging the cells was 54 miles. The current remained constant at 28 amperes until 5 P.M., and it only dropped to 25 amperes at the completion of the double voyage between England and France. Several electric launches are now being constructed in London, and one in New York by the Electrical Accumulator Company.

M. Trouve exhibited a small boat and a tricycle, both worked by Plante accumulators, at Paris, in 1881.

The first locomotive actuated by storage batteries was used at a bleaching works in France in 1882. During the same year I designed an electric street car for the storage company, and this was tried on the lines of the West Metropolitan Tramways in March, 1883. It had accommodation for 46 passengers. This car had many defects, and I reconstructed it entirely, and ran it afterward in its improved form on the South London Tramways, and also on a private track at Millwall, where it is now in good condition, and I have a similar car in Berlin. M. Phillippart exhibited a car in Paris and M. Julien made successful experiments in Brussels, Antwerp, and Hamburg. Mr. Elieson is running storage battery locomotives in London. Mr. Julien has also been experimenting with a car in New York, and I believe one is in course of construction for a line in the city of Boston. Messrs. W. Wharton, Jr. & Co. have a storage battery car running at Philadelphia on Spruce and Pine streets, and this energetic firm is now fitting up another car with two trucks, each carrying an independent motor, similar to my European cars.

I have mentioned all these facts in order to show that there is a considerable amount of activity displayed in the matter of storage batteries for street cars, and that continued and substantial progress is being made in each successive case. The prejudices against the application of secondary batteries are being rapidly dispelled, and there are indications everywhere that this method of propulsion will soon take a recognized place among the great transit facilities in the United States. I feel convinced that this country will also in this respect be far ahead of Europe before another year has passed over our heads.

There are several popular and I may say serious objections to the employment of storage batteries for propelling street cars. These objections I will now enumerate, and endeavor to show how far they are true, and in what measure they interfere with the economical side of the question.

First objection: The loss of energy, which amounts in practice to 20 and sometimes 30 per cent. Now, every method of storing or transmitting energy involves some waste, but in saying this we need not condemn the system, for after all the term efficiency is only a relative one. For instance, a 10 horse power steam engine consumes three times as much fuel per horse power hour as a 1,000 horse power engine does, yet this small engine must be, and is regarded as, one of the most economical labor-saving appliances known to us. Considered as a heat engine, the efficiency of the most economical steam motor is but ten per cent.--90 per cent of the available units of heat contained in coal being lost during its transformation into mechanical energy. Thus, if we find that the storage battery does not return more than 70 per cent, of the work expended in charging it, we ought not to condemn it on that account until we have ascertained whether this low efficiency renders the system unfit for any or all commercial purposes. It is needless to go into figures in order to show that, when compared with animal power, this objection drops into insignificance.

The second, more formidable, objection relates to the weight of storage batteries--and this involves two disadvantages, viz., waste of power in propelling the accumulator along with the car, and increased pressure upon the street rails, which are only fitted to carry a maximum of 5 tons distributed over 4 points, so that each wheel of an ordinary car produces a pressure of 1¼ tons upon a point of the rail immediately under it.

The last mentioned objection is easily overcome by distributing the weight of the car with its electrical apparatus over 8 wheels or 2 small trucks, whereby the pressure per unit of section on the rails is reduced to a minimum. With regard to the weight of the storage batteries, relatively to the amount of energy the same are capable of holding and transmitting, I beg to offer a few practical figures. Theoretically, the energy manifested in the separation of one pound of lead from its oxide is equivalent to 360,000 foot pounds, but these chemical equivalents, though interesting in themselves, gives us no tangible idea of the actual capacity of a battery.

Repeated experiments have shown me that the capacity of a secondary battery cell varies with the rate at which it is charged and discharged. For instance, a cell such as we use on street cars gave a useful capacity of 137.3 ampere hours when discharged at the average rate of 45.76 amperes, and this same cell yielded 156.38 ampere hours when worked at the rate of 22.34 amperes. At the commencement of the discharge the E.M.F of the battery was 2.1 volts, and this was allowed to drop to 1.87 volts when the experiment was concluded. The entire active material contained in the plates of one cell weighed 11.5 lb., therefore the energy given off per pound of active substance at the above high rate of discharge was 62.225 foot pounds, and when discharging at the lower rate of 22.34 amperes the available useful energy was 72.313 foot pounds, or nearly 2.2 electrical horse power per pound of active matter. But this active substance has to be supported, and the strength or weight of the support has to be made sufficiently great to give the plate a definite strength and durability. The support of the plates inclusive of the terminals above referred to weighs more than the active material, which consists of peroxide of lead and spongy lead; so that the plates of one cell weigh actually 26.5 pounds. Add to this the weight of the receptacle and acid, and you get a total of about 41 pounds per cell when in working order. Seventy of these cells will propel an ordinary street car for four hours and a half, while consuming the stored energy at the rate of 30 amperes, or over 5.6 electrical horse power. The whole set of seventy cells weighs 2,870 lb., which is barely one-fifth of the entire weight of the car when it carries forty adult passengers. Therefore the energy wasted in propelling the accumulator along with a ear does not amount to more than 20 per cent. of the total power, and this we can easily afford to lose so long as animal power is our only competitor. From numerous and exhaustive tests with accumulators on cars in this country and abroad, I have come to the conclusion that the motive power for hauling a full-sized street car for fifteen hours a day does not exceed $1.75, and this includes fuel, water, oil, attendance, and repairs to engine, boiler, and dynamo. We have thus an immense margin left between the cost of electric traction and horse traction, and the last objection, that relating to the depreciation of the battery plates, can be most liberally met, and yet leave ample profits over the old method of propulsion by means of animals.

The advantages of storage battery street cars for city traffic are self-evident, so that I need not trouble you with further details in this respect, but I would beg those who take an interest in the progress of the electric locomotive to give this subject all the consideration it deserves, and I would assure them that the system which I have advocated in this brief but very incomplete sketch is worthy of an extended trial, and ready for the purposes set forth. There is no reason why those connected with electric lighting interests in the various cities and towns should not give the matter their special attention, as they are the best informed on electrical engineering and already have a local control of the supply of current needed for charging.

In the car which we use in Philadelphia there are actually 80 cells, because there are considerable gradients to go over. Each cell weighs 40 pounds and the average horse power of each battery is six. Sometimes we only use two horse power and sometimes, going up grades of 5 per cent., we use as much as 12 horse power, but the average rate is 6 electrical horse power. With reference to the weight of passengers on the cars, we have never carried more than 50 passengers on that car, because it is impossible to put more than 50 men into it. There are seats for 24, and the rest have to stand on the platforms or in the aisle.

The changing of the batteries takes three minutes with proper appliances. One set of cells is drawn out by means of a small winch and a freshly charged set is put in. It takes the same time to charge the battery as it does to discharge it in the working of the cars, so one reserve set would be sufficient to keep the car continually moving.

The loss of energy from standing about is probably nothing. If a battery were to stand charged for three months in a dry case, the loss of energy might be in three months 10 per cent. I purposely had a set of cells standing for two years charged and never used them. After two years there was still a small amount of energy left. So as regards the loss of energy in a battery standing idle, it is practically nothing, because no one would think of charging a battery and letting it stand for three months or a year.

I have had them stand three or four months and I could hardly appreciate the loss going on, provided always that the cells are standing on a dry floor. If the exterior of the box be moist, or if it stands on a moist floor, there will naturally be a surface leakage going on: but where there is no surface leakage the mere local action between the oxides and metallic lead will not discharge the battery for a very considerable time.

I have made experiments in London with a loaded car pulled by two horses. I put a dynamometer between the attachment of the horse and the car, so as to ascertain exactly the amount of pull, measured in pounds multiplied by the distance traversed in a minute. You will be surprised to know that two horses, when doing their easiest work, drawing a loaded car on a perfectly level road, exert from two to three horse power. I have mentioned a car in Philadelphia where we use between two and twelve horse power. A horse is capable of exerting eight horse power for a few minutes, and when a car is being driven up grades, such as I see in Boston, for instance, pulling a load of passengers up these grades, the horses must be exerting from 12 to 16 horse power, mechanical horse power. That is the reason that street car horses cannot run more than three or four hours out of the twenty-four. If they were to run longer, they would be dead in a few weeks. If they run two hours a day, they will last three or four years.

The life of the cells must be expressed upon the principle of ampere hours or the amount of energy given off by them. Street car service requires that the cells work their hardest for fifteen or sixteen hours a day. The life of the cells has to be divided; first, into the life of the box which contains the plates. This box, if appropriately constructed of the best materials, will last many years, because there is no actual wear on it. The life of the negative plates will be very considerable, because no chemical action is going on in the negative plate. The negative plate consists almost entirely of spongy lead, and the hydrogen is mechanically occluded in that spongy lead. Therefore the depreciation of the battery is almost entirely due to the oxidation of the positive plates. If we were to make a lead battery of plates ¼ inch thick, it would last many years; but for street car work that would be far too heavy. Therefore we make the positive plates a little more than one-eighth of an inch thick. I find that the plates get sufficiently brittle to almost fall to pieces after the car has run fifteen hours a day for six months. The plates then have to be renewed. But this renewal does not mean the throwing away of the plates. The weight is the same as before, because no consumption of material takes place. We take out peroxide of lead instead of red lead. That peroxide, if converted, produces 70 per cent. of metallic lead, so that there is a loss of 30 per cent. in value. Then comes the question of the manufacture of these positive plates, which, I believe, at the present day are rather expensive. But I believe the time will come when battery plates will be manufactured like shoe nails, and the process of renewing the positive plates will be a very cheap one.

I ascertained in Europe that the motive power costs 2 cents per car mile; that is, the steam power and attendance for charging the batteries. We have to allow twice as much for the depreciation of a battery at the present high rate at which we have to pay for the battery--$12 for each cell. But I believe that as soon as the storage battery industry is sufficiently extended, the total cost for propelling these cars will not be more than six cents a mile, or about one half the cost of the cheapest horse traction.

I have made some very careful observations on the cable tramway in Philadelphia, which is quite an extensive system. I have never been able to ascertain the exact amount of waste in pulling the cable itself; but I have it on the authority of certain technical papers that there is a waste of about eighty per cent. I do not intend to depreciate cable or any other tramways, but there is a difficulty about introducing cable tramways. It is necessary to dig up the streets and interfere with the roadways. I have been told that the cable arrangements in Philadelphia cost $100,000 a mile, and that the cable road in San Francisco cost more than that. One of the directors of the cable company in Philadelphia told me that if he had seen the battery system before the introduction of the cable, he would probably have made up his mind in favor of the former. The wear and tear in the case of the storage system is also considerable. There is a waste of energy in the dynamo; secondly, in the accumulator charged by that dynamo; thirdly, in the motor which is driven by the accumulator; and fourthly, in the gearing that reduces the speed of the motor to the speed required by the car axles. It would be difficult to make a motor run at the rate of eighty revolutions per minute, which is the number of revolutions of the street car axle when running at the rate of ten miles an hour. Take all these wastes, and you find in practice that you do not utilize more than 40 per cent. of the energy given by the steam engine. But this is quite sufficient to make this system much cheaper than horse traction.

It is well known that we can discharge the storage battery _ad libitum_ at the rate of 2 amperes or 200 amperes. I can get out of a storage battery almost any horse power I like for a short space of time. I have not the least objection to the direct system. But when you come to run twenty or thirty or fifty cars on one line, you will require very large conductors or dangerously high electromotive force. The overhead system is applicable to its own particular purposes. Where there are only five or ten, or even twenty, cars running on one line, and that line runs through a suburb or a part of a city where there are not many houses, that system is to be preferred. The objection to the overhead system is not so much the want of beauty, but the want of practicability. You have to put your posts very high indeed, so as to let great wagon loads of hay and all sorts of things pass underneath. Most of the trouble comes in winter, and when it is snowing hard a great many difficulties arise. As regards the loss, suppose that the resistance of the overhead lines is one ohm. To draw one car it will take an average of 20 amperes, and the only loss will be 20 multiplied by 20, that is, 400 watts through line resistance. But if there are ten cars on that line, you get 40,000 watts loss of energy, unless you increase the conductor in proportion to the number of cars. If you do that, you get an enormous conductor, and have a sort of elevated railroad instead of a telegraph wire, as most people imagine an overhead conductor to be.

The current required to run a street car is about thirty amperes, and an electromotive force of about 180 volts. If cars are run in connection with an incandescent light station, we can arrange our apparatus so that we can use an E.M.F. say of 110 volts, and then we can put in a smaller number of cells with a larger capacity that will give a corresponding horse power. We can charge such larger cells with 50 or 60 amperes instead of thirty.

In regard to arc lighting machinery, the arc lighting dynamo should not be used to charge the accumulators. They can be used, but they require such constant attention as to make them impracticable. We can only use shunt-wound dynamos conveniently for that purpose.

In regard to using two motors on a car, there are several advantages in it. I use two motors on all my cars in Europe, and always have done so from the beginning. One of the advantages is that in case of an accident to one motor the other will bring the car home; secondly, with two motors we can vary the speed without changing the E.M.F. of the battery. If I want very much power, I put two motors in parallel, getting four times the power that I do with one machine, and an intermediate power of two motors.

There is another advantage of having two motors, and that is that we can use two driving axles instead of one, and we can go up grades with almost double the facility that way, because the adhesion would be double. These are the main advantages arising from the use of two or more motors.

Mr. Mailloux asked if I would give my experience in regard to the mechanical transmission between the motor and the car axle. I have used almost everything that was known at the time, but in order to give you a full and detailed account of the various modes of transmission which I have used I should have to give you figures to bear out certain experiments. I should only be able to do that in a lecture of at least five hours' duration, so I hope that you will kindly excuse me on that point.

With regard to the durability of plates, I have taken into consideration fifteen hours a day. In regard to the application of electrical brakes, I will say that that was one of the first ideas that entered my head when I began to use electric motors, and other people had that idea long before me. I have used an electric brake, using the motor itself as a brake--that is, as the car runs down a grade by momentum, it generates a current, but this current cannot be used for recharging a battery. It is utter nonsense to talk about that unless we have a steady grade four or five miles long. The advantages are very small indeed, and the complications which would be introduced by employing automatic cut-outs, governors, and so on, would counterbalance anything that might be gained. As regards going up an incline, of course stopping and starting again has to be done often, and anybody who at any time works cars by electricity, whether they have storage batteries or not, has to allow for sufficient motive power to overcome all the difficulties that any line might present.

One of the great mistakes which some of the pioneers in this direction made was that they did not put sufficient power upon the cars. You always ought to put on the cars power capable of exerting perhaps 20 to 40 per cent. more than is necessary in the ordinary street service, so that in case of the road being snowed up, or in the case of any other accident which is liable to occur, you ought to have plenty of power to get out of the scrape.

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BRISTOL CATHEDRAL.

An Augustinian monastery, founded by Robert Fitzhardinge in 1142, had its church, of Norman architecture, to which additions were made in the early English period. When Edmund Knowle was abbot, from 1306 to 1332, the Norman choir was replaced by that which now exists. His successor, Abbot Snow, built the chapels on the south side of the choir. Abbot Newland, between 1481 and 1515, enriched the transepts with a groined roof and with ornamental work of the decorated Gothic style, and erected the central tower. Abbot Elliott, who followed Newland, removed the Norman nave and aisles, intending to rebuild them; but this was prevented by his death in 1526 and by the dissolution of the monastery a few years afterward; he completed, however, the vaulting of the south transept. The church remained with a nave, and otherwise incomplete, until the modern restorations; after which, in 1877, it was reopened with a special service. Messrs. Pope & Bindon, of Bristol, were the architects employed. The exterior, of which we give an illustration, viewed from St. Augustine's Green, or Upper College Green, is not very imposing; from the Lower Green there is a good view of the central tower and the transept. The height of the tower is but 127 ft. It is of perpendicular Gothic architecture, but the piers supporting it are Norman. The interior presents many features of interest. The clustered triple shafts of the piers in the choir, with their capitals of graceful foliage, the lofty pointed arches between them, and the groined vaulting, have much beauty. The chancel is decorated with tracery of a peculiar pattern.

The Abbey of St. Augustine at Bristol was surrendered to King Henry VIII. in 1538, and became, in 1542, the cathedral of the new Episcopal see then created. The first Bishop of Bristol, Paul Bush, was deprived of his see by Queen Mary, being a married clergyman and refusing to part with his wife. Bishop Fletcher, in Queen Elizabeth's time, afterward Bishop of Worcester and of London, was twice married, at which this queen likewise expressed her displeasure. He was father of Fletcher, the dramatic poet; and he is said to have been one of the first English smokers of tobacco. Among noted Bishops of Bristol were Bishop Lake, afterward of Chichester, and Bishop Trelawny (Sir Jonathan Trelawny, Bart., of Cornwall), two of the "seven bishops"; imprisoned for disobeying an illegal order of James II. "And shall Trelawny die? Then twenty thousand Cornishmen will know the reason why." But the most eminent was Bishop Joseph Butler, the author of "The Analogy of Natural and Revealed Religion" and of the "Sermons on Human Nature." He was born at Wantage, in Berkshire, and was educated as a Nonconformist. He was Bishop of Bristol from 1738 to 1750, when he was translated to Durham. In 1836, the see of Bristol was joined with that of Gloucester; and the Right Rev. Drs. J.H. Monk, O. Baring, W. Thomson (now Archbishop of York), and C.J. Ellicott have been Bishops of Gloucester and Bristol.--_Illustrated London News._

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WAVES.

In the first days of August, two startling announcements reached us from the United States. They were as follows:

(1.) "The commander of the Cunarder Umbria reports that at 3 o'clock on July 27, about 1,500 miles from Sandy Hook, the vessel was struck by a tidal wave 50 ft. high, which swept the decks, carried away a portion of the bridge and the forward hatch, and flooded the cabins and steerage."

(2.) "The captain of the Wilson line steamer Martello reports that at half-past 8 on the evening of July 25, when in lat. 49° 3' N., long. 31° W., an enormous wave struck the vessel, completely submerging the decks."

In view of these reports, and inasmuch as questions were asked on the subject in Parliament, though it is quite possible that, as regards the "tidal" character of the waves, there may be something of newspaper _gobemoucherie_ in the announcements, we offer a few remarks on _waves_ in general, which may be useful to some of our readers.

_Tidal phenomena_ present themselves under two aspects: as alternate elevations and depressions of the sea and as recurrent inflows and outflows of streams. Careful writers, however, use the word _tide_ in strict reference to the _changes of elevation_ in the water, while they distinguish the recurrent streams as _tidal currents_. Hence, also, _rise_ and _fall_ appertain to the tide, while _flood_ and _ebb_ refer to the tidal current.

The _cause of the tides_ is the combined action of the sun and moon. The relative effects of these two bodies on the oceanic waters are directly as their mass and inversely as the square of their distance; but the moon, though small in comparison with the sun, is so much nearer to the earth that she exerts the greater influence in the production of the great _tide wave_. Thus the mean force of the moon, as compared with that of the sun, is as 2¼ to 1.

The attractive force of the moon is most strongly felt by those parts of the ocean over which she is vertical, and they are, consequently, drawn toward her. In the same manner, the influence of the luminary being less powerfully exerted on the waters furthest from her than on the earth itself, they must remain behind. By these means, at the two opposite sides of the earth, in the direction of the straight line between the centers of the earth and moon, the waters are simultaneously raised above their mean level; and the moon, in her progressive westerly motion, as she comes to each meridian in succession, causes two uprisings of the water--two high tides--the one when she passes the meridian above, the other when she crosses it below; and this is done, not by drawing after her the water first raised, but by raising continually that under her at the time; this is the _tide wave_. In a similar manner (from causes already referred to) the sun produces two tides of much smaller dimensions, and the joint effect of the action of the two luminaries is this, that instead of four separate tides resulting from their separate influence, the _sun merely alters the form of the wave raised by the moon_; or, in other words, the greater of the two waves (which is due to the moon) is modified in its height by the smaller (sun's) wave. When the summit of the two happens to coincide, the summit of the combined wave will be at the highest. When the hollow of the smaller wave coincides with the summit of the larger, the summit of the combined wave will be at the lowest.

It is necessary to have a clear and distinct conception of the difference between the _motion_ of a _wave_ and that of a _current_. In the current there is a transfer of water; in the wave the transfer is no more than would be brought about by a particle of water impinging on another where that particle has a motion perpendicular to the surface, and a rising and falling results. The onward movement of the wave itself is always perceptible enough. That the water is not moving with the same velocity is also evident from watching the progress of any light body floating on its surface. This fact may be practically illustrated in the case of a ship at sea, sailing before the wind in the same direction as the waves are moving. When the crest of a wave is near the stern, drop a piece of wood on it. Almost instantly the wave will be seen shooting ahead of the vessel, while the wood is scarcely removed from the position where it fell on the water. The wave has moved onward, preserving its identity as a wave, the water of which it is formed being constantly changed; and thus the motion of the wave is one thing, that of the water in which the waves are formed is quite another thing.

Again, waves are formed by a force acting horizontally; but in the case of the tide wave, that force acts uniformly from the surface to the lowest depths of the ocean, and the breadth of the wave is that curved surface which, commencing at low water, passes over the summit of the tide down to the next low water--this is a wave of the first order. In waves of the second order, the force raising them acts only on the surface, and there the effect is greatest (as in the wind waves)--where one assists in giving to the water oscillating motion which maintains the next, and gradually puts the whole surface in commotion; but at a short distance down that effect entirely disappears.

If the earth presented a uniform globe, with a belt of sea of great and uniform depth encircling it round the equator, the tide wave would be perfectly regular and uniform. Its velocity, where the water was deep and free to follow the two luminaries, would be 1,000 miles an hour, and the height of tide inconsiderable. But even the Atlantic is not broad enough for the formation of a powerful tide wave. The continents, the variation in the direction of the coast line, the different depths of the ocean, the narrowness of channels, all interfere to modify it. At first it is affected with only a slight current motion toward the west--a motion which only acquires strength when the wave is heaped up, as it were, by obstacles to its progress, as happens to it over the shallow parts of the sea, on the coasts, in gulfs, and in the mouths of rivers. Thus the first wave advancing meets in its course with resistance on the two sides of a narrow channel, it is forced to rise by the pressure of the following waves, whose motion is not at all retarded, or certainly less so than that of the first wave. Thus an actual current of water is produced in straits and narrow channels; and it is always important to distinguish between the tide wave, as bringing high water, and the tidal stream--between the rise and fall of the tide and the flow and ebb.

In the open ocean, and at a distance from the land, the tide wave is imperceptible, and the rise and fall of the water is small. Among the islands of the Pacific four to six feet is the usual spring rise. But the range is considerably affected by local causes, as by the shoaling of the water and the narrowing of the channel, or by the channel opening to the free entrance of the tide wave. In such cases the range of tide is 40 to 50 feet or more, and the tidal stream is one of great velocity. It may under such circumstances even present the peculiar phenomenon called the _bore_--a wave that comes rolling in with the first of flood, and, with a foaming crest, rushes onward, threatening destruction to shipping, and sweeping away all impediments lying in its course.

It is certain that in the open ocean the _great tide wave_ could not be recognized as a wave, since it is merely a temporary alteration of the sea level.

_Waves_ which have their origin in the action of the wind striking the surface of the water commence as a series of small and slow undulations or wavelets--a mere ripple. As the strength, and consequently the pressure, of the wind increases, waves are formed; and a numerical relation exists between the length of a wave, its velocity of progress, and the depth of the water in which it travels.

The _height_ of a wave is measured from trough to crest; and though waves as seen from the deck of a small vessel appear to be "enormous" and "overwhelming," their height, in an ordinary gale, in deep water, does not exceed 15 to 20 feet. In a very heavy gale of some days' continuance they will, of course, be much higher.

Scoresby has observed them 30 ft. high in the North Atlantic; and Ross measured waves of 22 ft. in the South Atlantic. Wilkes records 32 ft. in the Pacific. But the highest waves have been reported off the Cape of Good Hope and Cape Horn, where they have been observed, on rare occasions, from 30 to 40 ft high; and 36 ft. has been given as the admeasurement in the Bay of Biscay, under very exceptional circumstances. In the voyage round the world the Venus and Bonite record a maximum of 27 ft., while the Novara found the maximum to be 35 ft. But waves of 12 to 14 ft. in shallow seas are often more trying than those of larger dimensions in deeper water. It is generally assumed that a distance from crest to crest of 150 to 350 ft. in the storm wave gives a velocity (in the change of form) of from 17 to 28 miles per hour. But what is required in the computation of the velocity is the period of passage between two crests. Thus a distance of 500 to 600 ft. between two crests, and a period of 10 to 11 seconds, indicates a velocity of 34 miles per hour.

The following table, by Sir G.B. Airy (late Astronomer Royal), shows the velocities with which waves of given lengths travel in water of certain depth: