-----+----+-----+------+---+-----+------+-----------+-------------+------+------------| L | | | | | | | || o | | Train | | | | Consumption | || c | | alone. | | | | Including | |Date.| o | | | | | | Lighting up.| |1883.| m | |----+-----| | | | | Cost || o |Train|Num-| | Dis-| Car | | | of |Atmospheric| t | |ber |Gross|tance|miles.| Fuel. |-------+-----| fuel |temperature| i | | of |load.| run.| | | | Per | per | and| v | |Loa-| | | | | Total |train| train| weather.| e | |ded | | | | | |mile.| mile.|| . | |cars| | | | | | | |-----+----+-----+----+-----+-----+------+-----------+-------+-----+------+------------| | | No.| Tons|Miles| | | | |Pence.|-----+----+-----+----+-----+-----+------+-----------+-------+-----+------+------------| 8 |32-23| 25 | 400 | 388 | 9,700|Anthracite.| 31799 |81.90|11.957|-17° to -18°| |32-23| | | | | | lb. | lb. | | Reau.,Feb.| | | | | | | | | | | equiv. to8 | |24-21| | | | | | | | |-6° to -8½°| 14 |24-21| 25 | 400 | 388 | 9,700|Bituminous |37557.5|96.53|14.093| Fah.| | | | | | | Coal. | lb. | lb. | || 7 |26-29| 25 | 400 | 194 | 4,830|Petroleum | 9462 |48.77| 5.487| Strong| | | | | | refuse. | lb. | lb. | | side wind.-----+----+-----+----+-----+-----+------+-----------+-------+-----+------+------------| 24 |32-23| 25 | 400 | 194 | 4,850|Anthracite.|12639.5|65.15| 9.512|-5° to -9°March| | | | | | | | lb. | lb. | | Reau.,6 | 21 |24-21| 25 | 400 | 194 | 4,850|Wood, in | 1071.8| 5.52| 8.5 | equiv. to| | | | | | | billets. | c. ft.|c. ft| | 21° to 12°| | | | | | | | | Fah.| 23 |26-27| 25 | 400 | 194 | 4,850|Petroleum | 7228 |37.28| 4.188| Light| | | | | | refuse. | lb. | lb. | | side wind.-----+----+-----+----+-----+-----+------+-----------+-------+-----+------+-----------
Prices of fuel:Petroleum refuse, 21s. per ton; Anthracite and bituminous coal, 27s. 3d. per ton;Wood, in billets, 42s. per cubic sajene = 343 cubic feet;equivalent to 1.47d. per cubic foot.Dimensions of locomotives:Cylinders, 18 ⅛ in. diam. and 24 in. stroke; Wheels, 4 feet 3 in. diam.;Total heating surface, 1,248 sq. feet: Total adhesion weight, 36 tons;Boiler pressure, 8 to 9 atm.
The preceding table shows the results of comparative trials made in winter with different sorts of fuel, under exactly similar conditions as to type of engine, profile of line, and load of train. Two sets of comparative trials were made, both of them in winter. The three engines used were some of those built by Schneider. In comparison with anthracite, the economy in favor of petroleum refuse was 41 per cent. in weight, and 55 per cent. in cost. With bituminous coal there was a difference of 49 per cent. in favor of petroleum as to weight and 61 per cent. as to cost. As compared with wood petroleum was 50 per cent. cheaper. At a speed of fourteen miles an hour up an incline of 1 in 125 the steam pressure was easily kept up at 9 to 9½ atm. with a No. 9 injector feeding the boiler all the time.
Up to the present time the author has altered seventy-two locomotives to burn petroleum; and from his own personal observations made on the foot plate with considerable frost he is satisfied that no other fuel can compare with petroleum either for locomotives or for other purposes. In illustration of its safety in case of accident, a photograph was exhibited of an accident that occurred on the author's line on 30th December, 1883, when a locomotive fired with petroleum ran down the side of an embankment, taking the train after it; no explosion or conflagration of any kind took place under such trying circumstances, thus affording some proof of the safety of the petroleum refuse in this mode of firing. Although it is scarcely possible that petroleum firing will ever be of use for locomotives on the ordinary railways of coal-bearing England, yet the author is convinced chat, even in such a country, its employment would be an enormous boon on underground lines.
[2]
Abstract of paper read before the Institution of Mechanical Engineers.
KILN FOR BURNING CHARCOAL.
KILN FOR BURNING CHARCOAL.
In answer to the inquiry of a correspondent about charcoal making, we offer two illustrations that show a method of manufacture differing from that usually adopted, which is that of burning on the bare ground, and covering with soil or sods to exclude the air. These kilns are made of brick, one course being sufficient, bands of iron or timber framework being added to strengthen the brickwork with greater economy. The usual style is conical, and the size is 24 feet in diameter, with an equal height, holding about 40 cords of wood. The difference in price is 1⅛ d. per bushel in favor of these kilns as compared with the usual mounds, the burner being furnished with the use of the kilns, and the timber standing, the kiln burning costing 2⅛ d., and the other 3¼ d. The kilns must be lined to about halfway up with fire-brick, the cost of which will vary with the locality, but will be about £200, and as 40 to 50 bushels of coal have been made per cord the extra yield on good charcoal and the lessening of the cost of making soon covers any extra outlay on the cost of the kilns. The wall of the kiln is carried up nearly straight for 6 feet, when it is drawn in, so as to become bluntly conical. Upon the top a plate of iron is fastened in the manner of the keystone of an arch, and bands of iron are passed round the kiln and drawn tight with screw bolts and nuts to strengthen it. Double doors of sheet-iron are made at the bottom and near the tops, by which it is either filled or emptied, and a few air-holes (B), which may be stopped with loose bricks, left in the bottom. The second figure shows a kiln of another shape made to burn 3,000 bushels of charcoal, or about 80 cords of wood. The shape is a parallelogram, having an arched roof, and it is strengthened by a framework of timber 10 inches square. As the pressure of the gas is sometimes very great, the walls must be built a brick and a half thick to prevent their bursting. The usual size is 16 feet wide and high, and 40 feet in length, outside measure. The time occupied in filling, burning, and emptying a small cone is about three weeks, and four weeks is required for the larger ones.—The Gardeners' Chronicle.
KILN FOR BURNING CHARCOAL.
KILN FOR BURNING CHARCOAL.
Our illustration is a view of the entrance facade to Tiddington House, Oxfordshire, the residence of the Rev. Joshua Bennett. The house is an old building of the Georgian period, and though originally plain and unpretentious, its bold coved cornices under the eaves, its rubbed and shaped arches, moulded strings, and thick sash bars, made it of considerable interest to the admirers of the "Queen Anne" school of architecture, and led to the adoption of that style in the alterations and additions made last year, of which the work shown in our illustration formed a small part. Between the "entrance facade" and the wall of the house there is a space of some twenty feet in length, which is inclosed by a substantially built conservatory-like erection of Queen Anne design, forming an outer hall.
ENTRANCE TIDDINGTON HOUSE OXON.—Morris & Stallwood—Architects.
ENTRANCE TIDDINGTON HOUSE OXON.—Morris & Stallwood—Architects.
The works were executed by Messrs. Holly & Butler, of Nettlebed. The brick carving was beautifully done by the late Mr. Finlay; and the architects were Messrs. Morris & Stallwood, of Reading.—The Architect.
Since Poggendorff in 1842 thought of substituting in the Bunsen battery a solution of bichromate of potash and sulphuric acid for nitric acid, and of thus making a single liquid pile of it, in suppressing the porous vessel, his idea has been taken up a considerable number of times. Some rediscovered it simply, while others, who were better posted in regard to the work of their predecessors, took Poggendorff's pile as he conceived it, and, considering the future that was in store for it, thought only of modifying it in order to render it better. Among these, Mr. Grenet was one of the first to present the bichromate of potash pile under a truly practical form. As long ago as 1856, in fact, he gave it the form that is still in use, and that is known as the bottle pile. Thus constructed, this pile, as is well known, presents a feeble internal resistance, and a greater electro-motive power than the Bunsen element. Unfortunately, its energy rapidly decreases, and the alteration of the liquid, as well as the large deposit of oxide of chromium that occurs on the positive electrode, prevents its being employed in experiments of quite long duration. Mr. Grenet, it is true, obviated these two defects by first renewing the liquid slowly and continuously, and causing a current of air to bubble up in the pile so as to detach the oxide of chromium in measure as the deposit formed. Thus improved, the bichromate pile was employed on a large scale in the lighting of the Comptoir d'Escompte. In an extensive application like this latter, the use of compressed air for renewing the liquid can be easily adapted to the bichromate pile, as the number of elements is great enough to allow of the putting in of all the piping necessary; but when it is only desired to use this pile for laboratory purposes, and when there is need of but a small number of elements, it is impossible to adopt Mr. Grenet's elements in the form required by an electric lighting installation. It becomes absolutely necessary, then, to come back to a simpler form, and attempt at the same time to obviate the defects which are inherent to its very principle. In accordance with this idea, it will be well to point out the arrangement adopted by Mr. Courtot for his bichromate of potash piles—an arrangement that is very simple, but, sufficiently well worked out to render the use of it convenient in a laboratory.
Fig. 1.—COURTOT'S ARRANGEMENT OF THE BICHROMATE PILE.
Fig. 1.—COURTOT'S ARRANGEMENT OF THE BICHROMATE PILE.
Fig. 1 gives the most elementary form. It consists of an earthen vessel into which dip four carbon plates connected with each other by a copper ring which carries one of the terminals. In the center there is a cylindrical porous vessel that contains a very dilute and feebly acidulated solution of bichromate of potash into which dips a prism of zinc, which may be lifted by means of a rod when the pile ceases to operate. It is true that the presence of the porous vessel in the bichromate of potash element increases the internal resistance, but, as an offset, although it decreases the discharge, it secures constancy and quite a long duration for it.
Fig. 2.—COURTOT'S ARRANGEMENT OF THE BICHROMATE PILE.
Fig. 2.—COURTOT'S ARRANGEMENT OF THE BICHROMATE PILE.
The elements thus constituted may be grouped, to the number of six, in a frame analogous to that shown in the engraving, and, sum total, form a small sized battery adapted to the current experiments of the laboratory, and capable of supplying two small four volt lamps for ten or twelve hours. We have had occasion to make use of these elements for the graduation of galvanometers, and, after ascertaining the constancy of the discharge, have found that the internal resistance of each couple is nearly 0.175 ohm, with an electro-motive force of two volts. As may be seen, these elements should, in general, all be mounted for tension, as they are in the figure, inasmuch as the mobility of the zincs permits, according to circumstances, of employing a variable number of them without changing anything. Moreover, with zincs amalgamated in a special manner, the attack is imperceptible, and the work in open circuit need scarcely to be taken into consideration.
Yet, despite the qualities inherent to the arrangement that we have just described, that defect common to all bichromate of potash piles—the deposit of oxide of chromium upon the carbon—is not here avoided. It occurs quite slowly, to be sure, but it does occur, and, from this point of view, the arrangement shown in Fig. 2 is preferable. The elements here are composed of prismatic porcelain vessels containing, as before, the solution and porous vessel.
Fig. 3.—COURTOT'S ARRANGEMENT OF THE BICHROMATE PILE.
Fig. 3.—COURTOT'S ARRANGEMENT OF THE BICHROMATE PILE.
The whole is covered with a sheet of ebonite connected with the zinc and the two carbon plates in such a way that when the pile is not in operation the whole can be lifted from the liquid. Under such circumstances the deposit of oxide is notably diminished, and the duration of the discharge is consequently greatly increased.
Fig. 3 shows the details of a windlass that permits of lifting, according to circumstances, all the elements of the same trough or only a part of them. To effect this, the drum around which the chain winds that carries the carbons is mounted upon a sleeve fixed upon the axle. This latter is actuated by a winch; and a ratchet wheel, R, joined to a click which is actuated by a spiral spring, prevents the ebonite plates from falling back when it is desired to place the bolt under the button, B, of the spring.
When it is desired to put an element out of the circuit, it is only necessary to act with the finger upon the extremity of the lever, D. Under the action of the latter, the piece,s, which carries a groove for the passage of the screws that fix it to the upper cross-piece, takes on a longitudinal motion and consequently gears with the drum through the toothed sleeve, E. When an experiment is finished the zinc may thus be lifted from the liquid, and the deposit of oxide be prevented from forming upon the carbon. As may be seen, the arrangements which we have just described exhibit nothing that is particularly original. The windlasses used for removing the elements from a pile when the circuit is open have been employed for a long time; the bichromate pile is itself old, and, as we said in the beginning, it has been modified in its details a number of times. In spite of this, we have thought it well to point out the mode of construction adopted by Mr. Courtot, since, owing to the simplicity of the arrangements, it renders convenient and easily manageable a pile of very great constancy that may be utilized for supplying incandescent lamps, as well as for the most varied experiments of the laboratory.—La Lumiere Electrique.
There has been much said in recent times about the distribution of electricity by means of induction coils, and the use of this process has given rise to several systems that differ but little from one another in principle.
The following are a few details in regard to a system due to a Dutch engineer:
In the month of December, 1881, a patent relating to the distribution of electricity was taken out in Germany and other countries by Mr. B. Haitzema Enuma, whose system is based upon a series of successive inductions. The primary current developed by a dynamo-electric machine gives rise to secondary, tertiary, etc., currents. The principal line runs through the streets parallel with their axes, and, when the arrangement of the places is adapted thereto, it is closed upon the generator itself. In those frequent cases where it is necessary to cause the line to return over a path that it has already traversed, it is more advantageous to effect the return through the earth or to utilize the street water mains or gas pipes as conductors. This return arrangement may likewise be applied to the lines of secondary, tertiary, etc., order, as may easily be seen.
The induction is effected by the aid of bobbins whose interior consists of a bundle of soft iron. The wire of the inducting current is wound directly around this core. The wire of the induced current is superposed upon the first and presents a large number of spirals. It is useless to say that these wires must be perfectly insulated from each other, as well as from the soft iron core. We shall call primary bobbins those which are interposed in the principal line, and secondary bobbins those in which the inducting current is a secondary one, and so on.
It will be at once seen that this arrangement permits of continuing the distribution of electricity to the interior of buildings by the simple adjunction of one or several bobbins. Each electric apparatus, whether it be a lamp or other mechanism, is furnished with a special current. If the number of these apparatus be increased, it is only necessary to increase the number of bobbins in the same ratio, on condition, be it understood, that the intensity of the currents remain sufficient to secure a proper working of the apparatus in question. When such intensity diminishes to too great a degree, the bobbin must be replaced by a stronger one.
DISTRIBUTION OF ELECTRICITY BY INDUCTION.
DISTRIBUTION OF ELECTRICITY BY INDUCTION.
It results from what precedes that each apparatus must be put in in such a way as to permit, of the opening and closing of the corresponding circuit. This arrangement, moreover, has no need of being dependent upon the apparatus, and may just as well be transferred to any part of this same circuit. As regards lighting, it is preferable to employ alternating current dynamo machines; yet there is nothing to prevent the use of continuous current ones, provided that there is an arrangement that permits of constantly opening and closing this same circuit. That portion of the line which is placed under ground is insulated in the ordinary way at the places where it is necessary. As for the underground circuit and the induction coils connected therewith, these are protected against all external influence, and are at the same time insulated very economically by covering them with a coat of very fine silicious sand mixed with asphalt.
It is only necessary to inspect the annexed figure to get an accurate idea of this system of distribution. C represents the building in which the generator of electricity, D, is placed; B, the public street, and Q the house of a subscriber. The principal line, E, starts from the terminals,a, b, of the machine, passes through the primary bobbins, G, and is closed through the earth at F. It will be seen that the primary current communicates throughdandcwith the internal winding of the bobbins, G, while the secondary currents, H, are connected througheandfwith the external winding. The same arrangement is repeated for the tertiary currents, M, and the quaternary ones,o, p. In the annexed example all the lines that run parallel with the axis of the streets are closed through the earth, while those that have a direction perpendicular thereto enter the houses of subscribers and form a closed circuit. In the interior of these houses the wires, as well as the induction coils, are insulated and applied to the walls. At Q is represented the arrangement that would have to be adopted in the case of a structure consisting of a vestibule,r, and two rooms,s, lighted by two electric lamps, R. In the portion of the figure situated to the left it is easy to see the process employed for insulating the line. A commencement is made by digging a ditch in the street and paving the bottom of it with bricks. Upon these latter there is laid a mixture of sand and asphalt, and then the wires and bobbins are put in, and the whole is finally covered with a new insulating layer.
It is a simple statement that we make here, and it is therefore not for us to discuss the advantages and disadvantages of the system. If we are to believe Mr. Enuma, the advantages are very numerous, to wit: (1) The cables have no need of being of large size; (2) the intensity is the same through the entire extent of the primary circuit, secondary one, etc.; (3) the resistance is invariable in all portions of the line; (4) the apparatus are independent of each other, and consequently there may be a disturbance in one or several of them without the others suffering therefrom; (5) either a strong or weak luminous intensity may be produced, since, that depends only upon the size of the coil employed; (6) there is no style of lamp that may not be used, since each lamp is mounted upon a special circuit; (7) any number of lamps may be lighted or extinguished without the others being influenced thereby; (8) when a fire or other accident happens in a house, it in no wise interferes with the service in the rest of the line; (9) the system could, were it required, be connected with any other kind of existing line; and (10) the cost of installation is infinitely less than that of a system of gas pipes embracing the same extent of ground.—La Lumiere Electrique.
Italy, with her volcanic nature, has very naturally made a specialty of movements of the ground, or seismic perturbations. So the larger part of the apparatus designed for such study are due to Italians. Several of these instruments have already been, described in this journal, and on the present occasion we shall make known a few others that will serve to give an idea of the methods employed.
For the observation of the vertical and horizontal motions of the ground, different apparatus are required. The following is a description of those constructed for each of such purposes by the Brassart Brothers.
FIG. 1.—APPARATUS FOR THE STUDY OF HORIZONTAL SEISMIC MOVEMENTS.
FIG. 1.—APPARATUS FOR THE STUDY OF HORIZONTAL SEISMIC MOVEMENTS.
Apparatus for Studying Horizontal Movements.—A lever, (Fig. 1), movable about a horizontal axis, carries a corrugated funnel,i, at one of its extremities. At the other extremity it is provided with a counterpoise which permits of its being exactly balanced, while not interfering with its sensitiveness.
FIGS. 2 AND 3.—DETAILS OF THE APPARATUS.
FIGS. 2 AND 3.—DETAILS OF THE APPARATUS.
The opening of the funnel passes freely around a column,v(Fig. 2), upon which is placed in equilibrium a rod that terminates in a weight, P. The corrugations of the funnel carry letters indicating the four cardinal points, and the funnel itself is capable of revolving in such a way that the marked indications shall always correspond to the real position of the cardinal points. When a horizontal shock occurs, the weight, P, falls in a direction opposite thereto, and into one of the corrugations, where it rests, so that the direction of the shock is indicated. But, in falling, it causes the lever, F, to tilt, and this brings about an electric contact between the screw,h, and the column,n, which sends a current into the electro, E, so that the armature of the latter is attracted. In its position of rest this armature holds a series of parts, S, A, L, which have the effect of stopping the pendulum of a clock placed upon the same apparatus. At the moment, then, that the armature is attracted the pendulum is set free and the clockwork is started. As the current, at the same time, sets a bell ringing, the observer comes and arranges the apparatus again to await a new shock. Knowing the hour at which the hand of the clock was stopped, he sees how long it has been in motion again and deduces therefrom the precise moment of the shock.
The small rod,f, which is seen at the extremity of F, is for the purpose of allowing electricity to be dispensed with, if need be. In this case the screw,h, is so regulated that F descends farther, and thatfmay depress the armature of the magnet just as the current would have done.
FIG. 4.—APPARATUS FOR THE STUDY OF VERTICAL MOVEMENTS.
FIG. 4.—APPARATUS FOR THE STUDY OF VERTICAL MOVEMENTS.
Apparatus for the Study of Vertical Movements.—In this apparatus (Fig. 4), the contact is formed between a mercury cup, T, and a weight, D. The cup is capable of being raised and lowered by means of a screw, so that the two parts approach each other very closely without touching. At the moment of a vertical shock a contact occurs between the mercury and weight, and there results a current which, acting upon the electro, E, frees the pendulum of the clock as in the preceding apparatus. In this case, in order that the contact may be continuous and that the bell may be rung, the piece, A, upon falling, sets up a permanent contact with the part,a(Fig. 3).
FIG. 5.—BRASSART'S SEISMIC CLOCK.
FIG. 5.—BRASSART'S SEISMIC CLOCK.
Brassart's Seismic Clock.—This apparatus is designed for being put in connection at a distance with an indicator like the ones just described. It is a simple clock to which a few special devices have been added. Seismic clocks may be classed in two categories, according as they are stopped by the effect of a shock or are set running at the very instant one occurs. The Messrs. Brassart have always given preference to those of the second category, because there is no need of watching them during a seismic calm, and because they are much more easily constructed. It is to this class, then, that their seismic clock belongs. It is capable of being used for domestic purposes in place of any other clock, and of becoming a seismoscopic clock as soon as it is put in electric communication with the seismic telltales.
To the cross-piece that holds the axle of the drums the inventors have added (Fig. 5) a support formed of a strip of brass, S, with whose extremity is jointed (at the lower part) a double lever, A. This latter is held in a horizontal position by a small counterpoise,i, so that the finger at the opposite extremity shall prevent the pendulum, P, from swinging. To keep the latter in a position of rest a bent lever,n n', is jointed to the upper part of the support, S. The longer arm,n', of this lever is bent forward at right angles, so that it may come into contact with and repel the small rod of the pendulum as soon as the lever has been lifted by means of a small cord which is connected with the larger arm,n, and runs up to a small hook, from whence it descends and makes its exit under the clock-case.
In order to stop the clock, then, it is only necessary to pull on this cord slightly, when, by moving the pendulum to the left, it will thrust it against the inclined plane of the finger of the lever arm, A. It is clear that the extremity of the pendulum, upon striking against the finger, will depress it slightly and go beyond the projection against which it remains fixed owing to the counterpoise,i. The fever,n n', is brought back to its position of rest by means of a small counterpoise at the extremity of the arm,n. When the lever, A, is depressed, the pendulum escapes and sets the clock running. This depression is effected by means of an electro-magnet, E, whose armature, which is connected with the rod,t, t, lifts the arm,i, of the lever, and depresses A. The wires of the two bobbins of the electro-magnet end in two clamps, 1 and 2. The second of these latter is insulated from the clock-case. Both communicate with the extremities of the circuit in which is interposed the seismic telltale that brings about a closing of the current. Having noted the position of the hands on the dial when the clock was running, one can deduce therefrom the moment at which the shock occurred that set the clock in motion.
In addition to the parts that we have described, there are other accessory ones, R Rr, and a third clamp, 3, which constitute a sort of rheotome that is designed to keep the circuit closed after the momentary closing that is produced by the telltale has occurred. This little mechanism is indispensable when the disturbed telltale has also to act upon an electric bell. This rheotome, which is very simple, is constructed as follows: A small brass rod, R, which is screwed to the support, S, carries at its left extremity a brass axis, X, which is insulated from the rod, R, by means of an ivory piece. Toward the center of this small rod, the bent lever,r, carries a small arm that is bent forward, and against which abuts the axis of the pendulum, thus causing it to be thrust toward the left when the pendulum is arrested by the projection of the finger, A. As soon as the pendulum is set free, the lever,r, redescends and places itself against the axis, X. This latter communicates with clamp 3, which is insulated, while the rod, R, communicates with clamp 1. The external communications are so arranged that the circuit in which the bell is interposed remains definitely closed when the lever,r, is in contact with the rod, X.
FIG. 6.—ROSSI'S TREMITOSCOPE.
FIG. 6.—ROSSI'S TREMITOSCOPE.
Rossi's Tremitoscope.—This instrument (Fig. 6) unites, upon the same stone base, three different arrangements for showing evidences of trepidations of the earth. On one side we find (protected by a glass tube) a weight suspended over a mercury cup by a spring, and designed to show vertical motions. The two other parts of the apparatus are designed for registering horizontal motions. The first is a pendulum which causes a contact with four distinct springs, and whose movements are watched with a spy-glass. The second is a steel spring which carries at its upper part a heavy ball that vibrates at the least shock. This ball is provided with a point which is movable within a second ball, so that its motion produces a contact. All these different contacts are signaled or registered electrically.
FIG. 7.—SCATENI'S SEISMOGRAPH.
FIG. 7.—SCATENI'S SEISMOGRAPH.
Scateni's Registering Seismograph.—This apparatus, which is shown in Figs. 7 and 8, consists of two parts—of a transmitter and of a registering device.
FIG. 8.—REGISTERING APPARATUS.
FIG. 8.—REGISTERING APPARATUS.
The transmitter consists of a glass vessel supported upon a steel point and provided beneath with a platinum circle connected with a pile. All around this circle are four strips of platinum, against one of which abuts the circle at every movement of the glass. Each strip of platinum communicates, through a special wire, with one of the electro-magnets of the registering device (Fig. 8). This latter consists of an ordinary clock that carries three concentric dials—one for minutes, one for hours, and one for seconds. In a direction with the radii of these dials there are four superposed levers, each of which is actuated by one of the electros. On another hand, each dial is divided into four zones that correspond to the four cardinal points. When a shock coming from the north, for example, produces a contact, the corresponding electro is affected, and its lever falls and marks upon each of the dials a point in its north zone. We thus obtain the exact hour of the shock, as well as its direction. As may be seen, the apparatus, as regards principle, is one of the simplest of its kind.—La Lumiere Electrique.
FIG. 1.—ARNOULD & TAMINE'S ACCUMULATOR.
FIG. 1.—ARNOULD & TAMINE'S ACCUMULATOR.
In Messrs. Arnould and Tamine's accumulators, shown in Fig. 1, the formation is effected directly by the current, as in the Planté pile, but the plates are formed of wires connected horizontally at their extremities by soldering. These plates are held apart either by setting them into paraffined wooden grooves at the ends of the trough or by interposing between them pieces of paraffined wood.
FIG. 2.—BARRIER & TOURVIELLE'S ELECTRODOCK.
FIG. 2.—BARRIER & TOURVIELLE'S ELECTRODOCK.
In Messrs. Barrier and Tourville'sElectrodock(Fig. 2) the plates are formed of concentric leaden tubes fixed into a wooden cover. These tubes are threaded internally and externally, and the grooves thus produced are filled with a peculiar cement composed of litharge, powdered charcoal, and permanganate of potash, triturated together, sifted, and then mixed with glucose or sugar sirup so as to make a paste of them. This mixture forms a cement that is very adhesive after, as well as before, the electrolytic action.
FIG. 3.—KORNBLUH'S ACCUMULATOR.
FIG. 3.—KORNBLUH'S ACCUMULATOR.
In Kornbluh's accumulators the plates consist of ribbed leaden gratings between which is compressed red lead prepared in a peculiar manner, and constituting, 48 hours after formation, a compact mass with the lead. The tangs of the plates are widened so as to touch one another while leaving a proper distance between the plates themselves, and are hollowed out for the reception of a rod provided at its extremities with a winged nut and jam nut for passing them up close to one another. The plates, properly so called, are held apart by rubber bauds. The glass vessels are placed in osier baskets.—La Lumiere Electrique.
The three models of a secondary battery that I recently made known to the readers of this journal have been the object of continuous experiment. Conformably to the provisions of theory, the zinc accumulator has shown itself practically superior to the two others, and I have therefore chosen this type for getting up an industrial model, which is shown in the annexed cut. The accumulator contains four Planté positives, having a wide surface, and three negatives constructed of smooth sheets of lead covered with zinc by the electrolysis of the acidulated solution of zinc sulphate in which the couple is immersed. Accidental contact with the interior of the pile is prevented by glass tubes fixed to the negatives by means of leaden bands. The seven electrodes are carried by as many distinct crosspieces of paraffined wood, which rest upon the edges of the trough and hold the plates at a certain distance from the bottom. These various crosspieces, which touch one another, take the place of a cover. Each plate is provided with a terminal. The four positive terminals are all on the same side, and the three negatives are on the opposite side. Two brass rods ending in a wire-clamp connect the respective terminals of the same name. The trough consists of two oblong wooden receptacles, one within the other, and having a play of several millimeters. This space is lined with a tight, elastic, insulating cement having tar for a base.
REYNIER'S ZINC ACCUMULATOR. (One-fifth actual size.)
REYNIER'S ZINC ACCUMULATOR. (One-fifth actual size.)
The careful insulation of the trough and all parts of the apparatus, and the purity of the metal and its amalgamation, reduce the local attack of the zinc to almost nothing. So the coefficient of restitution is now comparable with that of accumulators of the Planté type.
The following are the principal numerical data of the new zinc accumulator.
The total electric work stored up is 130,000 kilogrammeters, or 7,600 kilogrammeters per kilogramme of accumulator. Theory indicates that a zinc accumulator might store up as much as 15,600 kilogrammeters per kilogramme. If the present model gives half less, it is because I have purposely exaggerated the solidity of the trough and the mass of the electrodes.
It should be remarked that this capacity of 7,600 kilogrammeters per kilogramme is much greater than that of any other accumulator constructed in France. The new model possesses, then, despite the size of the positives and the box, a relative lightness that will permit it to take a place upon electric locomotives as well as in fixed installations.
Independently of their use as accumulators, secondary zinc batteries may be utilized as regulating voltameters in lighting by incandescence, for deadening piston strokes, attenuating the irregularities in speed, and covering accidental stoppages.—E. Reynier, in La Nature.
Lately we have all felt, I doubt not, a considerable amount of interest in the various phenomena attending this summer's unusually heavy thunderstorms, accompanied, as they have been, by vivid lightning discharges of a more or less hurtful nature. The list of disasters published inKnowledge, No. 143, might be very materially augmented were we to record such damage as has been wrought since that list was compiled.
There is not, I suppose, in the mind of any intelligent man at the present day a doubt as to the electrical origin of a lightning flash. The questions to be considered are rather whence comes the electricity, and in what way is the thunderstorm brought about. In attempting to answer these questions, sight must not be lost of the fact that the very nature of electricity is in itself almost sufficient to baffle any effort put forth to ascertain from lightning, as such, its whence and its whither.
It is possible, however, with the aid of our knowledge of static electricity, to arrive at hypotheses of a more than chimerical nature. In the first place, that our sphere is a more or less electrified body is generally admitted. More than this, it is demonstrated that the different parts of the earth's surface and its enveloping atmosphere are variously charged. As a consequence of these varying charges, there is a constant series of currents flowing through the various parts of the earth, which show themselves in such telegraph wires as may lie in the direction followed by the currents. Such currents are known as earth currents, and present phenomena of a highly interesting nature. But, apart from these electrical manifestations, there is generally a difference of electrical condition between the various parts of the earth's surface and those portions of the atmosphere adjacent to or above them. Inasmuch as air is one of the very best insulators, this difference of condition (or potential) in any particular region is in most cases incapable of being neutralized or equilibrated by an electric flow. Consequently the air remains more or less continually charged. With these points admitted as facts, the question arises, Whence this electricity? There have been very many and various opinions expressed as to the cause of terrestrial electricity, but far the greater portion of such theories lack fundamental probability, and indicate causes which cannot be regarded as sufficiently extensive or operative to produce such tremendous effects as are occasionally witnessed. I take it that we may safely regard the evolution of electricity as one of the ways in which force exhibits itself, that, in other words, when work is performed electricity may result. When two bodies are rubbed together, electricity is produced, so also is it when two connected metals are immersed in water and one of them is dissolved, or when one of the junctions of two metals is raised to a higher temperature than the other junction. I will go further than this, so far, in fact, as to maintain that there is a reasonable ground for supposing that every movement, whether it be of the mass or among the constituent particles, is attended by a change of electrical distribution; and if this is true, it may easily be conceived that inasmuch as motion is the rule of the universe, there must be a constant series of electrical changes. Now, these changes do not all operate in one direction, nor are they all of similar character, whence it is that not only are there earth currents of feeble electro-motive force, but that this E.M.F. is constantly varying, and that, furthermore, electricity of high E.M.F. is to be met with in various parts of the atmosphere.
With earth currents we have here very little to do. The rotation of the earth is in itself sufficient to generate small currents, and the fact that they vary in strength at regular periods of the day and of the year enforces the suggestion that the sun exerts considerable electrical influence on the earth. Letting it be granted, however, that the earth is variously charged, how comes it that the air is also charged, and with electricity of greater tension than that of the earth itself? It was pointed out by Sir W. Grove that if the extremities of a piece of platinum wire be placed in a candle flame, one at the bottom and the other near the top, an electric current will flow through the wire, indicating the presence of electricity. If an electrified body be heated, the electricity escapes more rapidly as the temperature rises. If a vessel of water be electrified, and the water then converted into steam, the electric charge will be rapidly dissipated. If a vessel containing water be electrified, and the water allowed to escape drop by drop, electricity will escape with each drop, and the vessel will soon be discharged.
We regard it as an established fact that the earth has always a greater or less charge; whence it is safe to assume that in the process of evaporation which is going on all over the surface of the globe, more particularly in equatorial regions, every particle of water, as it rises into the air, carries with it its portion, however minute that portion may be, of the earth's electric charge. This small charge distributes itself over the surface of the aqueous particle, and the vapor rises higher and higher until it reaches that point above which the air is too rare to support it. It then flows away laterally, and as it approaches colder regions gets denser, sinking lower and nearer to the earth's surface. The aqueous particles becoming reduced in size, the extent of their surfaces is proportionately reduced. It follows that as the particles and their surfaces are reduced, the charge is confined to a smaller surface, and attains, therefore, a greater "surface density," or in simpler language, a greater amount of electricity per unit of surface.
Electricity, as above set forth, is in what is known as the "static" condition (to distinguish it from electricity which is being transferred in the form of a current), when it has the property of "repelling itself" to the utmost limits of any conductor upon which it may be confined. This will account for the charge finding its way to the surface of the water particles, and will furthermore account for the greater density of the charge as the particle gets smaller and has the extent of its surface rapidly diminished. It may be mentioned that the surface of a sphere varies as the cube of its radius.
Returning to the discussion of the state of affairs existing when the particles have reached their highest position in the atmosphere, we may imagine that they set themselves off on journeys toward either the north or the south pole. As they pass from the hotter to the colder regions, a number of particles coalesce; these again combine with others on the road until the vapor becomes visible as cloud. The increased density implies increased weight, and the cloud particles, as they sail poleward, descend toward the surface of the earth. Assuming that a spherical form is maintained throughout, the condensation of a number of particles implies a considerable reduction of surface. Thus, the contents of two spheres vary as the cubes of their radii, or eight (the cube of 2) drops on combining will form a drop twice the radius of one of the original drops. We may safely conceive hundreds and thousands of such combinations to take place until a cloud mass is formed, in which the constituent parts are more or less in contact, and, therefore, behave electrically as a single conductor of irregular surface, upon which is accumulated all the electricity that was previously distributed over the surfaces of the millions of particles that now compose it.
The tendency of an electric charge upon the surface of a conductor is to take upon itself a position in which it may approach nearest to an equal and opposite charge; or, if possible, to attain neutrality. If, then, a cloud has a charge, and there is no other cloud above or near it, the chargeinduceson the adjacent earth surface electricity of the opposite kind. Thus, assuming the cloud to be charged with positive electricity, the subjacent earth will be in the negative state. The two electricities[3]exert a strong tendency to combine or to produce neutrality, whence there is a species of stress applied to the intervening air. Possibly the cloud will be drawn bodily toward the earth more or less rapidly, according as the charge is great or small. Or, on the other hand, the cloud may roll on for leagues, carrying its influence with it, so that the various portions of the earth underneath become successively charged and discharged as the cloud progresses on its journey.
Should the cloud be near the earth, or should it be very highly charged, the tension of the two electricities may be so great as to overcome the resistance of the intervening air; and if this resistance should prove too weak, what happens? How does the discharge show itself? It takes place in the form of a lightning flash, and passing from the one surface to the other—or, maybe, simultaneously from both—produces neutrality more or less complete.
There has recently been a little discussion in these pages on the subject of lightning, some having stated that they discerned the discharge to take place upward—that is, from the earth toward the cloud. I will not venture so far as to say whether or not the direction of the discharge is discernible; possibly the flash may sometimes be long enough to enable one to tell; but I have never so seen it, and have always looked upon the eye as a deceitful member—very. "The lightning flash itself never lasts more than 1/100000 of a second." It is, however, just as likely that a discharge may travel upward as downward. What controls the discharge? Does the quality of the charge?—that is to say, is the positive or the negative more prone to break disruptively through the insulating medium? Investigations with Geissler's and other tubes containing highly rarefied gases have made it tolerably clear that there is a greater "tearing away" influence at the negative than at the positive pole, and if two equal balls, containing one a positive and the other a negative charge, be equally heated, the negative is more readily dissipated than the positive. But, so far as we at present know, this question enters into the discussion scarcely, if at all. Our knowledge seems rather to point to the substances upon which the charges are collected. The self-repellent nature of electricity compels it to manifest itself at the more prominent parts of the surface, the level being forsaken for the point. The tension of the charge, or its tendency to fly off, is proportionately increased. And if at a given moment the tension attains a certain intensity, the discharge follows, emanating from the surface which offers the greatest facilities for escape. The earth is generally flatter than the cloud, whence, in all probability, the discharge more frequently originates with the cloud.
Should a lightning flash strike the earth and produce direct neutrality, it is possible that no damage will result, although this again is not always certain, because when the cloud charge acts inductively on the earth it produces the opposite (say negative) charge on the nearer parts, the similar (or positive) state is also produced at some place more or less distant. Sometimes this "freed" positive (which, by the way, accumulates gradually and physiologically imperceptibly) is collected at some portion of the earth's surface. When the negative is neutralized by the discharge, the freed positive is no longer confined to a particular region, but tends to dissipate itself, and a shock may be felt more or less severely by any person within the region. Or, again, a similar shock may be experienced by a person standing within the negative zone on the neutralization of the charge.
I may take the opportunity here to mention a highly interesting and instructive incident observed on local telegraph circuits during a thunderstorm. The storm may be taking place at some distance from the point of observation. The electrified cloud induces the opposite charge beneath it, the similar charge being repelled. It is noticeable that the needle of a galvanometer, starting from the middle position, goes gradually over to one side, eventually indicating a considerable deflection. Suddenly, owing apparently to a lightning discharge some distance away, the force which caused the deflection is withdrawn, and the needle rebounds with great violence to the opposite side. In a short time, the cloud becoming again charged on its under surface, and recommencing its inductive effect upon the adjacent earth, the needle starts again, and goes through the same series of movements, a violent counterthrow following every flash of lightning.
If we can so far control our imagination, we may conceive the earth to be one large insulated conductor, susceptible to every influence around it. If then the earth, as a mass of matter, behaves as above indicated, there is no plausible reason for declining to regard any other large conducting mass in a similar light, and as a body capable of being subjected more or less completely to the various impulses affecting the earth. In other words, a large mass of conducting material, partially or perfectly insulated, is, during a thunderstorm, in considerable danger. With this portion of the subject I shall, however, deal more fully when discussing the merits of lightning protectors.
Lightning discharges do not take place between cloud and earth only, but also, and perhaps more frequently, between too oppositely charged clouds. We then get atmospheric lightning, the flash often extending for miles. This form of lightning is harmless, and in all probability what we see is only a reflection of the discharge. The oft-told tale of the lightning flying in at the window, across the room, and out of the door, or up the chimney, is all moonshine, and before dealing with lightning protectors I intend to expose some of the fallacies concerning lightning. Were the discharge to pass through a house, it would infallibly leave more decided traces and do more damage than simply scaring a superstitious old lady now and again. Many people are often and unnecessarily frightened during a thunderstorm, but it may be safely predicted that a person under a roof is infinitely safer than one who is standing alone on level ground, and making himself a prominence inviting a discharge. Rain almost invariably accompanies the discharge, and the roof and sides of the house being wet, they form a more or less perfect channel of escape should a flash strike the building.—Knowledge.