the spring boss, B B the bosses for screwing the covers into, C the metal over the enlarged recess for the journal end. Dimensions for these parts can be taken from the drawings of the parts. The sketches call for little remark, being almost self-explanatory. The keep will be fitted by filing into the axlebox, and the two bored together at right angles with the guiding edge. Note the rounding of for the locomotive springs, but their attachments are modified here. Fig. 90 shows them in end elevation and in cross section. Fig. 92 gives an external longitudinal view, Fig. 93 a longitudinal section, ECONOMICAL ELECTRIC LIGHTING BY MEANS OF BATTERIES. S a source of electricity for permanent "As electric lighting, the voltaic battery, is, in our opinion, practically useless." Such is the dictum of a well-known authority on electric lighting. And another equally high authority has said, "It is impossible, commercially, to supply the electric light by means of any form of galvanic battery or primary battery at present known to us." Perhaps the latter is a safer statement to make than the former. If we had been content with the generalisations which have been made in the past, very little progress would ever have been effected in any direction. It is certain, however, that the primary voltaic battery has proved for a long while a kind of ignis fatuus to inventors, for the possibility of generating electricity, without the aid of a motor and dynamo, which shall be in every way suitable for all household purposes, has been a very attractive problem. There have been many circumstances to favour the solution of this problem. The highest inventive talents have been employed upon it, for it has been quite as seductive to the qualified electrician as to the mere faddist, while the perfection of the incandescent light has provided a "burner" in every way suitable to small instalments. The question seems to resolve itself into one of economy, rather than of possibility. For a good many years cells have been used to a considerable extent whenever a very strong light was required, as, for instance, in lecture experiments, magic-lantern exhibitions, microscopical examinations, photography, &c., for which purposes small voltaic arc lights are very suitable when cost is not a matter of great importance. To such purposes the use of batteries in the production of electric light is now almost entirely restricted. Quite apart from the question of expense, which forbids the use of batteries in ordinary household lighting instalments, a disadvantage has been experienced in the fact that the manipulation of a large number of elements-40 of moderate strength being about the least number required to produce a stable arc-light-presents serious difficulties and drawbacks; moreover, the vapours which are generally given off are highly injurious. In short, the ordinary voltaic battery is, at its best, considered to be a very troublesome source of electricity for lighting. Let us inquire into the question of costliness. Most of the electric lighting in the world is done by the aid of dynamos. The object in using a dynamo instead of a battery is simply this: that, instead of having to use a very expensive fuel, such as zinc, in order to obtain the requisite energy, experience has shown that this energy can be obtained by burning a very much cheaper fuel-namely, coal. It may be said that a considerable amount of the energy obtained by the consumption of coal in a steam-engine is lostfirstly, in the transformation of heat into mechanical work; and secondly, in transformi g mechanical work into electrical energy. That is true; but even with all this leakage, the difference between the cost of using coal in working a dynamo, and in using zinc in a battery, is so great, that the electricity produced on the large scale in the first case is many times less costly than in the second. Independently of the initial cost of the plant, the price of a single arc light produced by one of the common forms of battery might range in a few hours from ten to twenty shillings. Hence it would be quite hopeless to think of employing electricity for general lighting purposes when obtained in such a manner as this. Again, it is not every battery that is suitable. Theoretically, provided that we have at our Perchloride of iron cell. Calland's cell. Spiral cell. Meidenger's modified Daniell cell, &c. A small battery is really required which will supply a strong current; which will not vary; in which there shall be no waste, and with which there should be practically no trouble, and only reasonable expense. The desideratum has yet to be found, unless the new Perreur-Lloyd cell should prove, when further developed, to satisfy all these requirements. Of the attempts which have been made in recent years to adapt the voltaic battery to household lighting, it will be necessary only to refer to two or three. that in open circuit there is no waste or action of any kind, and that in closed circuit zinc oxide and metallic copper are found, both being recoverable. Fergusson has considerably improved this battery, and in the installations which have been set up in London and elsewhere, there is no doubt that a considerable reduction in cost has been effected, because the by-products fetch a certain price, which, of course, must be placed against the working expenditure. Finally, we have to notice the battery invented about five years ago by Upward. A glazed earthenware cell divided into porous compartments contains carbon plates packed with broken carbon, and there are other similar porous compartments placed alternately with them, and containing zinc blocks. The chambers are filled with water, and the carbon compartments sealed up. The admission of chlorine gas into these cells generates the current: this gas is stored for use, and admitted whenever a light is required. And now we turn to the latest novelty in cells for electric-light producing. The Perreur-Lloyd cell, to which we have already alluded, possesses some new features, although in one of its ideas it follows the Lalande cell; that is to say, it endeavours to cheapen electricity by making the by-product saleable. The Perreur-Lloyd battery was first intended to combine the production of metallic salts on a commercial scale with the utilisation of the electric current yielded by the chemical decomposition, and quite recently a special form has been devised, which is stated to be especially adapted to household purposes. The original form of apparatus may be thus described:Tommasi, in 1879, proposed a modification of The generator, as it is called, consists of a the Bunsen cell; but his modification really pre-trough, a (vide Figures), of some material which sented no very novel feature, in spite of the will resist acids and be unaffected by heat. It high-sounding name of "perpetual" which was comprises an upper part which is designed to given to it. The company which was formed to contain the elements, and a lower part which work it managed to raise a capital of 2,000,000fr., acts as a reservoir to receive the concentrated but we have not heard of any single application liquids. For in this arrangement the heat due to of their system of lighting. internal resistance is utilised, so that it causes evaporation and concentration of the liquids whereby the salts formed as by-products crystallise out. The upper part is divided into compartments by glass plates b; each compartment serves as a cell for a distinct element. The same may almost be said of Baudet's socalled "impolarisable battery," of which very great things were anticipated when it was first placed before the public. Then there was the Lalande battery (? Bennett's), which was first brought out, we believe, in 1884. Each cell in this battery consists of an iron tray containing a depolarising layer of copper oxide: above this is a plate of zinc supported on the corners of the ry. The exciting liquid is caustic soda. The ntages claimed for this variety of cell are The elements are formed as follows:-Porous plates are arranged to form cells, or flat porous vessels, c, are employed; these cells communicate with each other. If plates are used, they are placed in vertical grooves formed in the walls of the trough and cemented tight, the communica tion being made by means of special channels. When flat porous cells are employed, such as e (vide Figs. 7 and 8), they communicate laterally by means of small tubes c'. When large porous vessels are employed, these are placed upon edges formed in the trough, and an arrangement of siphons is adopted. The porous plates or cells, as the case may be, rest upon a bottom-plate, d which serves to partly divide the upper from the lower part of the trough; this lower part is always spoken of as the reservoir. In each cell is placed a carbon, C, the thickness of which increases gradually from bottom to top, and there is a plate, F, of metal, e.g., zinc, which forms the soluble electrode, and is arranged between two porous cells, as shown. The reservoir communicates directly with that part of the trough which contains the soluble electrodes. Before going any further it will be necessary to state that Fig. 1 is an elevation, partly in longitudinal section of the electro-chemical generator. Fig. 2 is the corresponding section, a portion being shown without its covering plate of glass or slate. Fig. 3 is a vertical transverse section on the line 1-2. Figs. 4, 5, and 6 are detail views. Figs. 7 and 8, illustrate forms of porous vessels employed. In each of the compartments formed by the plate b are placed a number of cells, the+and - elements being coupled up for quantity, as it is not advantageous to multiply the number of elements in tension; the elements are thus arranged to give a large current. The generators are covered with plates, f, made of glass or slate, through which project the carbons C and the contacts of the soluble electrodes F. The plates f are inclined to facilitate the draught of a chimney, e, placed at the upper part of the generator, and, further, to facilitate the running off into the gutter h of the watervapour, which condenses and then absorbs the nitrous fumes which are given off while the battery is at work. R is a reservoir containing the depolarising solution; R another containing the exciting solution; these are placed above the generator. Taps enable the respective cells to be charged with the depolarising solution-e.g., nitric acid, and to place into communication the trough with the reservoir R', which may contain sulphates, chlorides, &c., of iron, copper, zinc, &c. When the circuit is completed, the sulphates or chlorides are formed within the generator, and nitrous fumes are evolved which are regenerated in condensing towers which act upon the same principle as the Gay-Lussac towers used in the manufacture of sulphuric acid. When the solution in these towers is at 20° strength, it is re-employed after having been concentrated. From the foregoing description it will be understood that the cycle of operations by which metallic salts are manufactured, and electricity generated without other expense than that of the acid and base employed, comprises : 1. Attack of a soluble electrode by exciting fluid, e.g., sulphuric acid, hydrochloric acid, &c. 2. Oxidation of the hydrogen evolved by the depolarising fluid (nitric acid), with which the former vessel containing the carbon is charged. 3. Oxidation in the presence of air of the nitrous products evolved and regeneration of the nitric acid by contact with water which trickles through the condensing towers. 4. Crystallisation of the salts formed in the reservoir of the trough, the solution being brought to the desired degree of concentration by the heat evolved in the generator, and due to the internal resistance. 5. Recharging the generator with the acidulated water on the one hand, and the regenerated nitric acid on the other, this acid being concentrated or strengthened by means of a suitable proportion of sulphuric acid. The generator thus arranged and worked seems to produce the electric current economically for the following reasons: saleable or are to be used in the manufacture of other substances, as, for instance, in the production of permanganates from manganese. The soluble electrode may be either solid or formed of clippings and waste pieces of metal enclosed in asbestos bags, or perforated porcelain It enables the salts formed by the combination vessels, arranged round a central electrode. In of the acids and metallic bases within the Fig. 4 the use of these is illustrated; here apparatus to be collected at a minimum cost, perforated porcelain vessel is placed between two these salts crystallising as soon as they leave the flat porous vessels, and it will be obvious that the generator. The total value of the acids and the clippings of waste metal heaped up between the bases employed being considerably less than the central electrode x, and the perforated walls value of the salts produced by their combinationk, k of the vessel will be attacked before the in the generator, and the cost of the concentration and crystallisation of the solution being almost nil, the sale of these products cover the cost of buying the original materials, as well as the cost of labour, etc. Hence the electric current is practically produced as a by-product. Farther, the depolariser employed in the generator is really the oxygen of the air. The nitric acid is decomposed into nitric acid and oxygen. The oxygen combines with the hydrogen disengaged on the carbon and forms water. The nitric acid forms, in contact with the air, hypo-nitric acid, which is drawn into the condensing towers, through which water trickles, and the hypo-nitric acid is reconverted into nitric acid, which can be used over again. In case the heat arising from the internal resistance is not sufficient, the solution can have its temperature raised by blowing in steam: this condenses in the trough. These generators are particularly suited to the manufacture of the simple or double sulphates and chlorides of iron, manganese, zinc, copper, nickel, tin, &c., whether the products are directly central electrode, because they are nearer to the In Fig. 5 the reservoir 6 is situated below the In Fig. 6 is shown a form wherein ten soluble electrodes are employed to one insoluble one, which increases the local action, the number of contacts or connections, and the space occupied by each generator, and renders the heating of the generator more difficult. Between the generator and the accumulators (for these, of course, are necessary with batteries), which may be arranged to be charged thereby day and night, or between the generator and the place where the electricity is to be utilised, there may be placed electrolytic troughs for refining copper obtained from old brass, &c., or other sources. This refining operation, depending on the decomposition of the sulphate of copper which is reformed continuously within the troughs, will consume very little power, and will entail a small cost, as the same workmen who perform the manipulation necessary for maintaining the generators in action, can also, without inconvenience, attend to the refining operation. This refining renders possible the recovery of the precious metals contained in some kinds of commercial copper, whilst at the same time admitting of the production of an electrolytic copper of considerable value. It will be seen from this description that the Perreur-Lloyd generator constitutes a distinct advance; being economical per se, it permits of the easy recovery of by-products, which are ordinarily lost-a circumstance which must keep expenses down, if it does not, as the inventors claim, reduce the cost of the electricity to nil. Within the past four months the firm of Perreur-Lloyd, et Fils have produced a further development of their idea in the shape of a generator, which is said to be eminently adapted for domestic-lighting purposes. A sketch is given of this in Fig. 9. In principle, it is very much the same as the generator which we have described; it differs, in fact, only in detail. The porous cells contain copper plates, and outside these cells are plates of zinc. Sulphate of copper is stored in jars, situated above the elements, in quantity sufficient to last any length of time as desired. The zinc plates are calculated to last two months. Sulphate of zinc is the substance which crystallises out in this case, and there is an arrangement by means of which the reservoir in which it accumulates can be readily cleaned out. The jars communicate with the porous cells by means of caoutchoue tubes. The circulation insures the distribution of their contents. The accumulators are placed above the jars, and can be charged successively by series of 3, 6, &c., according to the size of the installation. By a simple commutator arrangement, these accumulators are always kept at high tension, and the light never fails. The apparatus shown in the figure is designed to feed a lighting installation of 25 lamps of 10c. p. each. The reservoirs are contained in the movable drawers at the base; above them come the cells, &c.; then the jars of copper sulphate; finally, the accumulators and the necessary apparatus for measuring and directing the current, &c. Our readers will have noticed this ingenious combination of primary with secondary batteries, or accumulators. This precaution has been learned by experience, for the primary battery alone gives currents which, when large enough for lighting, is of a variable nature, and without the accumulator the lamps would be alternately too bright or too dull. We must now leave it with | bell in the order in which it should be struck, so THE "WESTMINSTER" CHIMES. HESE are introduced by Messrs. King, Works, Bristol, for the first time, for call bells, for announcing meals, and for giving other preconcerted signals in a house, mansion, or hotel. The four single-stroke electric points of the curve and square to the chord- that when once fixed the bells are easily rung. A WRINKLE IN SAWING. circular saw can be put, that there seems to This wrinkle is only applicable when the "stuff" is to be sawn to a circle smaller than that of the saw, and the width of the piece regulates the sphere of its usefulness, so the narrower the piece the more room for its applica tion, which is as follows:-We will suppose bells, tuned for the Westminster chimes, many and various are the uses to which a that one desires to concave a piece for any pedestal, or inclosed in a case with perforated the wrinkle I am about to describe is compara-manner shown at Fig. 1 of the sketches. The are fitted either on a board, or on a central be no limit to its capacity; but having heard that purpose. It is done by setting and clamp. ing a straight-edge on the saw-table in the wider the stock the more obtuse will be the angle at which the straight-edge shall be set. For instance, if a 12in. saw is in use, and one wishes to concave a piece 10in. wide, it would require more than a 10in. cutting surface to be exposed above the saw-table, and to obtain this it would be necessary to raise the saw up as far as it would go, and then set the straight-edge at nearly a right angle to it. To attempt to saw it under these circumstances would, of course, be dangerous, and I only cite it as an extreme case, though as every dif ferent width and circle calls for a variation of angle of the straight-edge, it would be difficult to say where danger ceases and safety begins. The only way, however, I can suggest to approximate this is to use care and exact judgment, and this practice alone can teach. Though this wrinkle cannot be used to advantage on all occasions, still its usefulness must be apparent to all mechanics, and it would be wise if they would pigeon-hole it in their memories until some exigency called for its application, when the own reward. knowing how to apply it will (virtue like) be its Suppose the mechanic wishes to fit a piece of any length, as shown in Fig. 1, he commences by laying the job out as shown in Fig. 3, which will explain that if he cut from the piece the arc efd, he will obtain the desired concave, and this can be done with the circular saw. To proceed he must first set the saw so that it projects above the table at a distance equal to ef at its highest part. A straight-edge of sufficient length is now arranged, as shown at Fig. 1. In this figure the saw is denoted by the heavy, black line, the straight edge is clamped in front of the saw, and the angle is found by having the straight edge touch the saw in the front at G, and in the back being distant from it the length of the chord C D of the arc, Fig 3, at right angles to the straight-edge. Everything is now ready; the angle found, the straight-edge fastened, and the saw projecting above the table height of e, p, Fig. 3, in., in., or lin., as the case may be. Here an important point must be noted, and that is "never to attempt to saw the stuff with the saw up the full distance or depth of the concave; but it must be lowered down and fed up gradually about fin. to the cut." This means that the whole cut can't be made at once, but will require to be passed over the saw several times, according to the depth of the concave. The foregoing illustrates a case where the piece is concaved to a sharp edge or arris at Fig. 2; but should a number of "staves" or "laggings" to go round a convex surface be needed, like Fig. 4, it will be necessary to proceed in a slightly different manner. The job is laid out, as at Fig. 5, to get the length of the chord CD, the depth ef, and the straight-edge set to the proper angle, found in the manner before described. Having found the direction of the straightedge, mark its position on the table with a pencil or scratcher. The dotted lines a c and b d, Fig. 5, designate the shape to which the edges of the stave will be planed. After it is concaved, in order to make close joints, measure the length of JC, and set the straight-edge back that distance from the pencil mark and parallel to the mark. Now clamp down the straight-edge, and proceed to saw, as before described. Better results can be obtained if the saw be set a little more on the side next the front. By following the above directions excellent work can be done, and as it saves time and labour, it is an economical and easily-adapted wrinkle. pressure would move the table, and its load I SEND herewith several sketches, which show spherical work may be turned on an ordinary horizontal boring mill. The operation which I show is a pair of Corliss engine, governor halls, mounted upon sharper centres, which are borrowed for the occasion. The cutter revolves in one position, describing a circle, and the ball is slowly turned by worm-gear. After being roughed out and finished as near as possible on these centres, they may be put in the lathe for polishing, after which operation they should be chucked in the steady rest, and drilled for stem; then they are cut off, leaving a ball practically round, and balanced. Anyone possessing a horizontal boring mill can with very small expense equip the same for doing a large variety of milling. With a pair of good sharper |