IMPROVED HAY-ROPE MACHINE.

Hay-ropes are used for many purposes, their principal use being in the foundry for core-making; but they also find a large application for packing ironmongery and furniture. The inventor is James Pollard, of the Atlas Foundry, Burnley.

THE ANGLESEA BRIDGE, CORK.

The river Lee flows through the city of Cork in two branches, which diverge just above the city, and are reunited at the Custom House, the central portion of the city being situated upon an island between the two arms of the river, both of which are navigable for a short distance above the Custom House, and are lined with quays on each side for the accommodation of the shipping of the port.

The Anglesea bridge crosses the south arm of the river about a quarter of a mile above its junction with the northern branch, and forms the chief line of communication from the northern and central portions of the city to the railway termini and deep-water quays on the southern side of the river.

PORTABLE RAILWAYS.

[Footnote: Paper read before the Institution of Mechanical Engineers.]

By M. DECAUVILLE, Aîne, of Petit-Bourg (Seine and Oise), France.

Narrow gauge railways have been known for a very long time in Great Britain. The most familiar lines of this description are in Wales, and it is enough to instance the Festiniog Railway (2 feet gauge), which has been used for the carriage of passengers and goods for nearly half a century. The prosperous condition of this railway, which has been so successfully improved by Mr. James Spooner and his son, Mr. Charles Spooner, affords sufficient proof that narrow gauge railways are not only of great utility, but may be also very remunerative.

In Wales the first narrow gauge railway dates from 1832. It was constructed merely for the carriage of slates from Festiniog to Port-Madoc, and some years later another was built from the slate quarries at Penrhyn to the port of Bangor. As the tract of country traversed by the railways became richer by degrees, the idea was conceived of substituting locomotives for horses, and of adapting the line to the carriage of goods of all sorts, and finally of passengers also.

But these railways, although very economical, are at the same time very complicated in construction. Their arrangements are based upon the same principles as railways of the ordinary gauge, and are not by any means capable of being adapted to agriculture, to public works, or to any other purpose where the tracks are constantly liable to removal. These permanent narrow gauge lines, the laying of which demands the service of engineers, and the maintenance of which entails considerable expense, suggested to M. Decauville, Aîne, farmer and distiller at Petit-Bourg, near Paris, the idea of forming a system of railways composed entirely of metal, and capable of being readily laid. Cultivating one of the largest farms in the neighborhood of Paris, he contemplated at first nothing further than a farm railroad; and he contrived an extremely portable plant, adapted for clearing the land of beetroot, for spreading manure, and for the other needs of his farm.

From the beginning in his first railroads, the use of timber materials was rigidly rejected by him; and all parts, whether the straight or curved rails, crossings, turntables, etc., were formed of a single piece, and did not require any special workman to lay them down. By degrees he developed his system, and erected special workshops for the construction of his portable plant; making use of his farm, and some quarries of which he is possessed in the neighborhood, as experimental areas. At the present time this system of portable railways serves all the purposes of agriculture, of commerce, of manufactures, and even those of war.

Within so limited a space it would be impossible to give a detailed description of the rails and fastenings used in all these different modes of application. The object of this paper is rather to direct the attention of mechanical engineers to the various uses to which narrow gauge portable railways may be put, to the important saving of labor which is effected by their adoption, and to the ease with which they are worked.

The success of the Decauville railway has been so rapid and so great that many inventors have entered the same field, but they have almost all formed the idea of constructing the portable track with detachable sleepers. There are thus, at present, two systems of portable tracks: those in which the sleepers are capable of being detached, and those in which they are not so capable.

The portable track of the Decauville system is not capable of so coming apart. The steel rails and sleepers are riveted together, and form only one piece. The chief advantage of these railways is their great firmness; besides this, since the line has only to be laid on the surface just as it stands, there are not those costs of maintenance which become unavoidable with lines of which the sleepers are fixed by means of bolts, clamps, or other adjuncts, only too liable to be lost. Moreover, tracks which are not capable of separation are lighter and therefore more portable than those in which the sleepers are detachable.

With regard to sleepers, a distinction must be drawn between those which project beyond the rails and those which do not so project. M. Decauville has adopted the latter system, because it offers sufficient strength, while the lines are lighter and less cumbersome. Where at first he used flat iron sleepers, he now fits his lines with dished steel sleepers, in accordance with Figs. 1 and 2.

Fig. 1. Fig. 2.

Fig. 1. Fig. 2.

This sleeper presents very great stiffness, at the same time preserving its lightness; and the feature which specially distinguishes this railway from others of the same class is not only its extreme strength, but above all its solidity, which results from its bearing equally upon the ground by means of the rail base and of the sleepers.

In special cases, M. Decauville provides also railroads with projecting sleepers, whether of flat steel beaten out and rounded, or of channel iron; but the sleeper and the rail are always inseparable, so as not to lessen the strength, and also to facilitate the laying of the line. If the ground is too soft, the railway is supported by bowl sleepers of dished steel, Figs. 3 and 4, especially at the curves; but the necessity for using these is but seldom experienced. The sleepers are riveted cold. The rivets are of soft steel, and the pressure with which this riveting is effected is so intense that the sleepers cannot be separated from the rails, even after cutting off both heads of the rivets, unless by heavy blows of the hammer, the rivets being driven so thoroughly into the holes made in the rails and sleepers that they fill them up completely.

The jointing of the rails is excessively simple. The rail to the right hand is furnished with two fish-plates; that to the left with a small steel plate riveted underneath the rail and projecting 1¼ in. beyond it. It is only necessary to lay the lengths end to end with one another, making the rail which is furnished with the small plate lie between the two fish-plates, and the junction can at once be effected by fish-bolts. A single fish-bolt, passing through the holes in the fish-plates, and through an oval hole in the rail end, is sufficient for the purpose.

With this description of railway it does not matter whether the curves are to the right or to the left. The pair of rails are curved to a suitable radius, and can only need turning end for end to form a curve in the direction required. The rails weigh 9 lb., 14 lb., 19 lb., and 24 lb. per running yard, and are very similar to the rails used on the main railways of France, except that their base has a proportionally greater width. As to the strength of the rail, it is much greater in proportion to the load than would at first sight be thought; all narrow-gauge railways being formed on the principle of distributing the load over a large number of axles, and so reducing the amount on each wheel. For instance, the 9 lb. rail used for the portable railway easily bears a weight of half a ton for each pair of wheels.

The distance between the rails differs according to the purpose for which they are intended. The most usual gauges are 16in., 20 in., and 24in. The line of 16 in. gauge, with 9 lb. rails, although extremely light, is used very successfully in farming, and in the interior of workshops.

Fig. 3. Fig. 4. Fig. 5.

Fig. 3. Fig. 4. Fig. 5.

A length of 16 ft. 5 in. of 9 lb. steel rail, to 16 in. gauge, with sleepers, etc., scarcely weighs more than 1 cwt., and may therefore be readily carried by a man placing himself in the middle and taking a rail in each hand.

Those members of the Institution who recently visited the new port of Antwerp will recollect having seen there the portable railway which Messrs. Couvreux and Hersetit had in use; and as it was these works at the port of Antwerp that gave rise to the idea of this paper, it will be well to begin with a description of this style of contractor's plant.

The earth in such works may be shifted by hand, horsepower, or locomotive. For small works the railway of 16 in. gauge, with the 9 lb. rails, is commonly used, and the trucks carry double equilibrium tipping-boxes, containing 9 to 11 cubic feet. These wagons, having tipping-boxes without any mechanical appliances, are very serviceable; since the box, having neither door nor hinge, is not liable to need repairs.

This box keeps perfectly in equilibrium upon the most broken up roads. To tip it up to the right or the left, it must simply be pushed from the opposite side, and the contents are at once emptied clean out. In order that the bodies of the wagons may not touch at the top, when several are coupled together, each end of the wagon is furnished with a buffer, composed of a flat iron bar cranked, and furnished with a hanging hook.

Plant of this description is now being used in an important English undertaking at the port of Newhaven, where it is employed not only on the earthworks, but also for transporting the concrete manufactured with Mr. Carey's special concrete machine.

These little wagons, of from 9 to 11 cubic feet capacity, run along with the greatest ease, and a lad could propel one of them with its load for 300 yards at a cost of 3d. per cube yard. In earthworks the saving over the wheel-barrow is 80 per cent., for the cost of wagons propelled by hand comes to 0.1d. per cube yard, carried 10 yards, and to go this distance with a barrow costs ½d. A horse draws without difficulty, walking by the side of the line, a train of from eight to ten trucks on the level, or five on an incline of 7 per cent. (1 in 14).

One mile of this railway, 16 in. gauge and 9 lb. steel rail, with sixteen wagons, each having a double equilibrium tipping box containing 11 cubic feet, and all accessories, represents a weight of 20 tons--a very light weight, if it is considered that all the materials are entirely of metal. Its net cost price per mile is 450l., the wagons included.

Large contracts for earthwork with horse haulage are carried on to the greatest advantage with the railway of 20 in. gauge and 14 lb. rails. The length of 16 ft. 5 in. of this railway weighs 170 lb., and so can easily be carried by two men, one placing himself at each end. The wagons most in use for these works are those with double equilibrium tipping boxes, holding 18 cubic feet. These are at present employed in one of the greatest undertakings of the age, namely, the cutting of the Panama Canal, where there are used upward of 2,700 such wagons, and more than 35 miles of track.

A mile of these rails of 20 in. gauge with 14 lb. rails, together with sixteen wagons of 18 cubic feet capacity, with appurtenances, costs about 6601., and represents a total weight of 33 tons.

This description of material is used for all contracts exceeding 20,000 cubic yards.

A very curious and interesting use of the narrow-gauge line, and the wagons with double equilibrium tipping-box, was made by the Societe des Chemins de Fer Sous-Marins on the proposed tunnel between France and England. The line used is that of 16 in. gauge, with 9 lb. rails.

The first level of the tunnel, which was constructed by means of a special machine by Colonel Beaumont, had only a diameter of 2.13 m. (7 ft.); the tipping boxes have therefore a breadth of only 2 ft., and contain 7¼ cubic feet. The boxes are perfectly balanced, and are most easily emptied. The wagons run on two lines, the one being for the loaded trains, and the other for the empty trains.

The engineers and inspectors, in the discharge of their duties, make use of the Liliputian carriages. The feet of the travelers go between the wheels, and are nearly on a level with the rails; nevertheless, they are tolerably comfortable. They are certainly the smallest carriages for passengers that have ever been built; and the builder even prophesies that these will be the first to enter into England through the Channel Tunnel.

One of the most important uses to which a narrow gauge line can be put is that of a military railway. The Dutch, Russian, and French Governments have tried it for the transporting of provisions, of war material, and of the wounded in their recent campaigns. In Sumatra, in Turkestan, and in Tunis these military railroads have excited much interest, and have so fully established their value that this paper may confine itself to a short description.

The campaign of the Russians against the Turcomans presented two great difficulties; these were the questions of crossing districts in which water was extremely scarce or failed entirely, and of victualing the expeditionary forces. This latter object was completely effected by means of 67 miles of railway, 20 in. gauge, 14 lb. steel rails, with 500 carriages for food, water, and passengers. The rails were laid simply on the sand, so that small locomotives could not be used, and were obliged to be replaced by Kirghiz horses, which drew with ease from 1,800 lb. to 2,200 lb. weight for 25 miles per day.

In the Tunisian war this railroad of 20 in. gauge, 14 lb. rail, was replaced by that of two ft. gauge, with 14 lb. and 19 lb. rails. There were quite as great difficulties as in the Turcoman campaign, and the country to be crossed was entirely unknown. The observations made before the war spoke of a flat and sandy country. In reality a more uneven country could not be imagined; alternating slopes of about 1 in 10 continually succeeded each other; and before reaching Kairouan 7½ miles of swamp had to be crossed. Nevertheless the horses harnessed to the railway carriages did on an average twelve to seventeen times the work of those working ordinary carriages. In that campaign also, on account of the steep ascents, the use of locomotives had to be given up. The track served not only for the conveying of victuals, war material, and cannon, but also of the wounded; and a large number of the survivors of this campaign owe their lives to this railway, which supplied the means of their speedy removal without great suffering from the temporary hospitals, and of carrying the wounded to places where more care could be bestowed upon them.

The carriages which did duty in this campaign are wagons with a platform entirely of metal, resting upon eight wheels. The platform is 13 ft. 1 in. in length, and 3 ft. 11 in. in width. The total length with buffers is 14 ft. 9 in. This carriage may be at will turned into a goods wagon or a passenger carriage for sixteen persons, with seats back to back, or an ambulance wagon for eight wounded persons.

For the transport of cannon the French military engineers have adopted small trucks. A complete equipage, capable of carrying guns weighing from 3 to 9 tons, is composed of trucks with two or three axles, each being fitted with a pivot support, by means of which it is made possible to turn the trucks, with the heaviest pieces of ordnance, on turntables, and to push them forward without going off the rails at the curves.

The trucks which have been adopted for the service of the new forts in Paris are drawn by six men, three of whom are stationed at each end of the gun, and these are capable of moving with the greatest ease guns weighing 9 tons.

The narrow-gauge railway was tested during the war in Tunis more than in any preceding campaign, and the military authorities decided, after peace had been restored in that country, to continue maintaining the narrow-gauge railways permanently; this is a satisfactory proof of their having rendered good service. The line from Sousse to Kairouan is still open to regular traffic. In January, 1883, an express was established, which leaves Sousse every morning and arrives at Kairouan--a distance of forty miles--in five hours, by means of regularly organized relays. The number of carriages and trucks for the transport of passengers and goods is 118.

The success thus attained by the narrow-gauge line goes far to prove how unfounded is the judgment pronounced by those who hold that light railways will never suffice for continuous traffic. These opinions are based on certain cases in the colonies, where it was thought fit to adopt a light rail weighing about 18 lb. to 27 lb. per yard, and keeping the old normal gauge. It is nevertheless evident that it is impossible to construct cheap railways on the normal gauge system, as the maintenance of such would-be light railways is in proportion far more costly than that of standard railways.

The narrow gauge is entirely in its right place in countries where, as notably in the case of the colonies, the traffic is not sufficiently extensive to warrant the capitalization of the expenses of construction of a normal gauge railway.

Quite recently the Eastern Railway Company of the province of Buenos Ayres have adopted the narrow gauge for connecting two of their stations, the gauge being 24 in. and the weight of the rails 19 lb. per yard. This company have constructed altogether six miles of narrow-gauge road, with a rolling stock of thirty passenger carriages and goods trucks and two engines, at a net cost price of 7,500l., the engines included. This line works as regularly as the main line with which it is connected. The composite carriages in use leave nothing to be desired with regard to their appearance and the comforts they offer. Third-class carriages, covered and open, and covered goods wagons, are also employed.

All these carriages are constructed according to the model of those of the Festiniog Railway. The engines weigh 4 tons, and run at 12½ miles per hour for express trains with a live load of 16 tons; while for goods trains carrying 35 tons the rate is 7½ miles an hour.

Another purpose for which the narrow-gauge road is of the highest importance in colonial commerce is the transport of sugar cane. There are two systems in use for the service of sugar plantations:

1. Traction by horses, mules, or oxen.

2. Traction by steam-engine.

In the former case, the narrow gauge, 20 in. with 14 lb. rails, is used, with platform trucks and iron baskets 3 ft. 3 in. long.

The use of these wagons is particularly advantageous for clearing away the sugar cane from the fields, because, as the crop to be carried off is followed by another harvest, it is important to prevent the destructive action of the wheels of heavily laden wagons. The baskets may be made to contain as much as 1,300 lb. of cane for animal traction, and 2,000 lb. for steam traction. In those colonies where the cane is not cut up into pieces, long platform wagons are used entirely made of metal, and on eight wheels. When the traction is effected by horses or mules, a chain 14½ ft. long is used, and the animals are driven alongside the road. Oxen are harnessed to a yoke, longer by 20 in. to 24 in. than the ordinary yoke, and they are driven along on each side of the road.

On plantations where it is desirable to have passenger carriages, or where it is to be foreseen that the narrow-gauge line maybe required for the regular transport of passengers and goods, the 20 in. line is replaced by one of 24 in.

The transport of the refuse of sugar cane is effected by means of tilting basket carts; the lower part of which consists of plate iron as in earthwork wagons, while the upper part consists of an open grating, offering thus a very great holding capacity without being excessively heavy. The content of these wagons is 90 cubic feet (2,500 liters). To use it for the transport of earth, sand, or rubbish, the grating has merely to be taken off. In the case of the transport of sugar cane having to be effected by steam power, the most suitable width of road is 24 in., with 19 lb. rails; and this line should be laid down and ballasted most carefully. The cost of one mile of the 20 in. gauge road, with 14 lb. rails, thirty basket wagons, and accessories for the transport of sugar cane, is 700l., and the total weight of this plant amounts to 35 tons.

Owing to the great lightness of the portable railways, and the facility with which they can be worked, the attention of explorers has repeatedly been attracted by them. The expedition of the Ogowe in October, 1880, that of the Upper Congo in November, 1881, and the Congo mission under Savorgnan de Brazza, have all made use of the Decauville narrow-gauge railway system.

During these expeditions to Central Africa, one of the greatest obstacles to be surmounted was the transport of boats where the river ceased to be navigable; for it was then necessary to employ a great number of negroes for carrying both the boats and the luggage. The explorers were, more or less, left to the mercy of the natives, and but very slow progress could be made.

On returning from one of these expeditions in Africa, Dr. Balay and M. Mizon conceived the idea of applying to M. Decauville for advice as to whether the narrow-gauge line might not be profitably adapted for the expedition. M. Decauville proposed to them to transport their boats without taking them to pieces, or unloading them, by placing them on two pivot trollies, in the same manner as the guns are transported in fortifications and in the field. The first experiments were made at Petit-Bourg with a pleasure yacht. The hull, weighing 4 tons, was placed on two gun trollies, and was moved about easily across country by means of a portable line of 20 in. gauge, with 14 lb. rails. The length of the hull was about 45 ft., depth 6 ft. 7 in., and breadth of beam 8 ft. 2 in., that is to say, five times the width of the narrow-gauge, and notwithstanding all this the wheels never came off the line. The sections of line were taken up and replaced as the boat advanced, and a speed of 1,100 yards per hour was attained. Dr. Balay and M. Mizon declared that the result obtained exceeded by far their most sanguine hopes, because during their last voyage, the passage of the rapids had sometimes required a whole week for 1,100 yards (1 kilometer), and they considered themselves very lucky indeed if they could attain a speed of one kilometer per day. The same narrow gauge system has since been three times adopted by African explorers, on which occasions it was found that the 20 in. line, with 9 lb. or 14 lb. rails, was the most suitable for scientific expeditions of this nature.

The trucks used are of the kind usually employed for military purposes, with wheels, axles, and pivot bearings of steel; on being dismounted the bodies of the two trucks form a chest, which is bolted together and contains the wheels, axles, and other accessories. The total weight of the 135 yards of road used by Dr. Balay and M. Mizon during their first voyage was 2,900 lb., and the wagons weighed 5,000 lb. Hence the expedition had to carry a supplementary weight of 3½ tons; but at any given moment the material forming this burden became the means of transporting, in its turn, seven boats, representing a total weight of 20 tons.

It is impossible to enumerate in this paper all the various kinds of wagons and trucks suitable for the service of iron works, shipyards, mines, quarries, forests, and many other kinds of works; and we therefore limit ourselves to mentioning only a few instances which suffice to show that the narrow gauge can be applied to works of the most varied nature and under the most adverse circumstances possible.

It therefore only remains to mention the various accessories which have been invented for the purpose of completing the system. They consist of off-railers, crossings, turntables, etc.

The off railer is used for establishing a portable line, at any point, diverging to the right or left of a permanent line, and for transferring traffic to it without interruption. It consists of a miniature inclined plane, of the same height at one end as the rail, tapering off regularly by degrees toward the other end. It is only necessary to place the off-railer (which, like all the lengths of rail of this system, forms but one piece with its sleepers and fish-plates) on the fixed line, adding a curve in the direction it is intended to go, and push the wagons on to the off-railer, when they will gradually leave the fixed line and pass on the new track.

The switches consist of a rail-end 49 in. in length, which serves as a movable tongue, placed in front of a complete crossing, the rails of which have a radius of 4, 6, or 8 meters; a push with the foot suffices to alter the switch. There are four different models of crossings constructed for each radius, viz.:

1. For two tracks with symmetrical divergence.

2. For a curve to the right and a straight track.

3. For a curve to the left and a straight track.

4. For a meeting of three tracks.

When a fixed line is used, it is better to replace the movable switch by a fixed cast-iron switch, and to let the workmen who drive the wagon push it in the direction required. Planed switch tongues are also used, having the shape of those employed on the normal tracks, especially for the passage of small engines; the switches are, in this case, completed by the application of a hand lever.

The portable turntable consists of two faced plates laid over the other, one of thick sheet iron, and the other of cast iron. The sheet-iron plate is fitted with a pivot, around which the cast iron one is made to revolve; these plates may either be smooth, or grooved for the wheels. The former are used chiefly when it is required to turn wagons or trucks of light burden, or, in the case of earthworks, for trucks of moderate weight. These plates are quite portable; their weight for the 16 in. gauge does not exceed 200 lb. For engineering works a turntable plate with variable width of track has been designed, admitting of different tracks being used over the same turntable.

When turntables are required for permanent lines, and to sustain heavy burdens, turntables with a cast iron box are required, constructed on the principle of the turntables of ordinary railways. The heaviest wagons may be placed on these box turntables, without any portion suffering damage or disturbing the level of the ground. In the case of coal mines, paper mills, cow houses with permanent lines, etc., fixed plates are employed. Such plates need only be applied where the line is always wet, or in workshops where the use of turntables is not of frequent occurrence. This fixed plate is most useful in farmers' stables, as it does not present any projection which might hurt the feet of the cattle, and is easy to clean.

The only accident that can happen to the track is the breaking of a fish-plate. It happens often that the fish-plates get twisted, owing to rough handling on the part of the workmen, and break in the act of being straightened. In order to facilitate as much as possible the repairs in such cases, the fish-plates are not riveted by machinery, but by hand; and it is only necessary to cut the rivets with which the fish-plate is fastened, and remove it if broken: A drill passed through the two holes of the rail removes all burrs that may be in the way of the new rivet. No vises are required for this operation; the track to be repaired is held by two workmen at a height of about 28 in. above the ground, care being taken to let the end under repair rest on a portable anvil, which is supplied with the necessary appliances. The two fish-plates are put in their place at the same time, the second rivet being held in place with one finger, while the first is being riveted with a hammer; if it is not kept in its place in this manner it may be impossible to put it in afterward, as the blows of the hammer often cause the fish-plate to shift, and the holes in the rail are pierced with great precision to prevent there being too much clearance. No other accident need be feared with this line, and the breakage described above can easily be repaired in a few minutes without requiring any skilled workman.

The narrow-gauge system, which has recently received so great a development on the Continent, since its usefulness has been demonstrated, and the facility with which it can be applied to the most varied purposes, has not yet met in England with the same universal acceptance; and those members of this Institution who crossed the sea to go to Belgium were, perhaps, surprised to see so large a number of portable railways employed for agricultural and building purposes and for contractors' works. But in the hands of so practical a people it may be expected that the portable narrow gauge railway will soon be applied even to a larger number of purposes than is the case elsewhere.

GERARD'S ALTERNATING CURRENT MACHINE.

The machine represented in the annexed engravings consists of a movable inductor, whose alternate poles pass in front of an armature composed of a double number of oblong and flat bobbins, that are affixed to a circle firmly connected with the frame. There is a similar circle on each side of the inductor. The armature is stationary, and the wires that start from the bobbins are connected with terminals placed upon a wooden support that surmounts the machine.

AUTOMATIC FAST SPEED TELEGRAPHY.

By THEO. F. TAYLOR.

Since 1838 much has been done toward increasing the carrying capacity of a single wire. In response to your invitation I will relate my experience upon the Postal's large coppered wire, in an effort to transmit 800 words per minute over a 1,000 mile circuit, and add my mite to the vast sum of knowledge already possessed by electricians.

As an introduction, I shall mention a few historical facts, but do not propose to write in this article even a short account of the different automatic systems, and I must assume that my readers are familiar with modern automatic machines and appliances.

In 1870, upon the completion of the Automatic Company's 7 ohm wire between New York and Washington, it happened that Prof. Moses G. Farmer was in the Washington office when the first message was about to be sent, and upon being requested, he turned the "crank" and transmitted the message to New York, at the rate of 217 words per minute.

Upon his return to New York he co-operated with Mr. Prescott in experiments on W.U. wires, their object being to determine what could be done on iron wires with the Bain system. A good No. 8 wire running from New York to Boston was selected, reinsulated, well trimmed, and put in first-class electrical condition, previous to the test. The "Little" chemical paper was used.

The maximum speed attained on this wire was 65 words per minute.

About the same time George H. Grace used an electro magnet on the automatic line with such good effect that the speed on the New York-Washington circuit was increased to 450 words per minute.

Then a platina stylus or pen was substituted for the iron pen in connection with iodide paper, and the speed increased to 900 words per minute.

In 1880, upon the completion of the Rapid Company's 6 ohm wire, between New York and Boston, 1,200 words per minute were transmitted between the cities above named.

In 1882, I was employed by the Postal Telegraph Company to put the Leggo automatic system into practical shape, and, if possible, transmit 800 words per minute between New York and Chicago.

It was proposed to string a steel-copper wire, the copper on which was to weigh 500 lb. to the mile.

When complete, the wire was rather larger than No. 3, English gauge, but varied in diameter, some being as large as No. 1, and it averaged 525 lb. of copper per mile and = 1.5 ohms. The surface of this wire was, however, large.

Dr. Muirhead estimated its static capacity at about 10 M.F., which subsequent tests proved to be nearly correct.

It will be understood that this static capacity stood in the way of fast transmission.

Resistance and static capacity are the two factors that determine speed of signaling.

The duration of the variable state is in proportion to the square of the length of the conductor, so that the difficulties increase very greatly as the wire is extended beyond ordinary limits. According to Prescott, "The duration of the variable condition in a wire of 500 miles is 250,000 times as long as in a wire of 1 mile."

In other words, a long line retains a charge, and time must be allowed for at least a falling off of the charge to a point indicated by the receiving instrument as zero.

In the construction of the line care was taken to insure the lowest possible resistance through the circuit, even to the furnishing of the river cables with conductors weighing 500 lb. per mile.

Ground wires were placed on every tenth pole.

When the first 100 miles of wire had been strung, I was much encouraged to find that we could telegraph without any difficulty past the average provincial "ground," provided the terminal grounds were good.

When the western end of this remarkable wire reached Olean, N.Y., 400 miles from New York, my assistant, Mr. S.K. Dingle, proceeded to that town with a receiving instrument, and we made the first test.

I found that 800 words, or 20,000 impulses, per minute, could be transmitted in Morse characters over that circuit without compensation for static.

In other words, the old Bain method was competent to telegraph 800 words per minute on the 400 miles of 1.5 ohm wire.

The trouble began, however, when the wire reached Cleveland, O., about 700 miles from New York.

Upon making a test at Cleveland, I found the signals made a continuous black line upon the chemical paper. I then placed both ends of the wire to earth through 3,000 ohms resistance, and introduced a small auxiliary battery between the chemical paper and earth.

The auxiliary or opposing battery was placed in the same circuit with the transmitting battery, and the currents which were transmitted from the latter through the receiving instrument reached the earth by passing directly through the opposing battery.

The circuit of the opposing battery was permanently completed, independently of the transmitting apparatus, through both branch conductors and artificial resistances.

The auxiliary battery at the receiving station normally maintained upon the main line a continuous electric current of a negative polarity, which did not produce a mark upon the chemical paper.

When the transmitting battery was applied thereto, the excessive electro-motive force of the latter overpowered the current from the auxiliary battery and exerted, by means of a positive current, an electro-chemical action upon the chemical receiving paper, producing a mark.

Immediately upon the interruption of the circuit of the transmitting battery, the unopposed current from the auxiliary battery at the receiving station flowed back through the paper and into the main line, thereby both neutralizing the residual or inductive current, which tended to flow through the receiving instrument, and serving to clear the main line from electro-static charge.

The following diagram illustrates my method:

Referring to this diagram, A and B respectively represent a transmitting and a receiving station of an automatic telegraph. These stations are united in the usual manner by a main line, L. At the transmitting station, A, is placed a transmitting battery, E, having its positive pole connected by a conductor, 2, with the metallic transmitting drum, T. The negative pole of the battery, E, is connected with the earth at G by a conductor, 1. A metallic transmitting stylus, t, rests upon the surface of the drum, T, and any well known or suitable mechanism may be employed for causing an automatic transmitting pattern slip, P, to pass between the stylus and the drum. The transmitting or pattern slip, P, is perforated with groups of apertures of varying lengths and intervals as required to represent the dispatch which it is desired to transmit, by an arbitrary system of signs, such, for example, as the Morse telegraphic code.

At the receiving station, B, is placed a recording apparatus, M, of any suitable or well known construction. A strip of chemically prepared paper, N, is caused to pass rapidly and uniformly between the drum, M', and the stylus, m, of this instrument in a well known manner. The drum, M', is connected with the earth by conductors, 4 and 3, between which is placed the auxiliary battery, E, the positive or marking pole of this battery being connected with the drum and the negative pole with the earth. The electro-motive force of the battery, E', is preferably made about one-third as great as that of the battery, E.

Extending from a point, o, in the main line, near the transmitting station, to the earth at G, is a branch conductor, l, containing an adjustable artificial resistance, R. A similar conductor, ll, extends from a point, o', near the receiving terminal of the line, L, to the conductor, 3, in which an artificial resistance, R', is also included, this resistance being preferably approximately equal to the resistance, R. The proportions of the resistance of the main line and the artificial resistances which I prefer to employ may be approximately indicated as follows: Assuming the resistance of the main line to be 900 ohms, the resistance, R, and R', should be each about 3,000 ohms. The main battery, E, should then comprise about 90 cells, and the auxiliary battery, E', 30 cells.

The operation of my improved system is as follows: While the apparatus is at rest a constant current from the battery, E', traverses the line, L, and the branch conductors, l, and ll, dividing itself between them, in inverse proportion to their respective resistances, in accordance with the well-known law of Ohm. When the transmitting pattern strip, P, is caused to pass between the roller, T, and the stylus, t, electric impulses will be transmitted upon the line, L, from the positive pole of the battery, E, which will traverse the main line, L, the two branch lines, l, and ll, and their included resistances, and also the receiving instrument, M. The greater portion of this current will, however, on account of the less resistance offered, traverse the receiving instrument, M, and the auxilary battery, E'. The current from the last-named battery will thus be neutralized and overpowered, and the excess of current from the main battery, E, will act upon the chemically prepared paper and record in the form of dots and dashes or like arbitrary characters the impulses which are transmitted.

Immediately on the cessation of each impulse, the auxiliary battery, E', again acts to send an impulse of positive polarity through the receiving paper and stylus in the reverse direction and through the line, L, which returns to the negative pole of the battery by way of the artificial resistances, R and R'. Such an impulse, following immediately upon the interruption of the circuit of the transmitting battery, acts to destroy the effect of the "tailing" or static discharge of the line, L, upon the receiving instrument, and also to neutralize the same throughout the line. By thus opposing the discharge of the line by a reverse current transmitted directly through the chemical paper, a sharply defined record will in all cases be obtained; and by transmitting the opposing impulse through the line, the latter will be placed in a condition to receive the next succeeding impulse and to record the same as a sharply defined character.

This arrangement was made on the New York-Cleveland circuit, and the characters were then clearly defined and of uniform distinctness. The speed of transmission on this circuit was from 1,000 to 2,000 words per minute.

Upon the completion of the wire to Chicago, total distance 1,050 miles, including six miles of No. 8 iron wire through the city, the maximum speed was found to be 1,200 words per minute, and to my surprise the speed was not affected by the substitution of an underground conductor for the overhead wire.

The underground conductor was a No. 16 copper wire weighing 67 pounds per mile, in a Patterson cable laid through an iron pipe.

I used 150 cells of large Fuller battery on the New York-Chicago circuit, and afterward with 200 cells in first class condition, transmitted 1,500 words, or 37,000 impulses, per minute from 49 Broadway, New York, to our test office at Thirty-ninth Street, Chicago.

The matter was always carefully counted, and the utmost care taken to obtain correct figures.

It may be mentioned as a curious fact that we not only send 1,200 words per minute through 1,050 miles of overhead wire and five miles of underground cable, but also through a second conductor in No. 2 cable back to Thirty-ninth Street, and then connected to a third underground conductor in No. 1 cable back to Chicago main office, in all about fifteen miles of underground, through which we sent 1,200 words per minute and had a splendid margin.--Electrical World.

[ELECTRICAL REVIEW].

THEORY OF THE ACTION OF THE CARBON MICROPHONE--WHAT IS IT?

A careful examination of the opinions of scientific men given in the telephone cases--before Lord McLaren in Edinburgh and before Mr. Justice Fry in London--leads me to the conclusion that scientific men, at least those whose opinions I shall quote, are not agreed as to what is the action of the carbon microphone.

In the Edinburgh case, Sir Frederick Bramwell said: "The variations of the currents are effected so as to produce with remarkable fidelity the varied changes which occur, according as the carbon is compressed or relieved from compression by the gentle impacts of the air set in motion by the voice."

"The most prominent quality of carbon is its capability, under the most minute differences of pressure, to enormously increase or decrease the resistances of the circuit." "That the varying pressure of the black tension-regulator (Edison's) is sufficient to cause a change in the conducting power." Sir Frederick also said "he could not believe that the resistance was varied by a jolting motion; could not conceive a jolting motion producing variation and difference of pressure, and such an instrument could not be relied on, and therefore would be practically useless."

Sir William Thomson, in the same case, said: "The function of the carbon is to give rise to diminished resistance by pressure; it possesses the quality of, under slight degrees of pressure, decreasing the resistance to the passage of the electric current;" and, also, "the jolting motion would be a make-and-break, and the articulate sounds would be impaired. There can be no virtue in a speaking telephone having a jolting motion." "Delicacy of contact is a virtue; looseness of contact is a vice." "Looseness of contact is a great virtue in Hughes' microphone;" and "the elements which work advantages in Hughes' are detrimental to the good working of the articulating instrument."

Fig. 1.

Fig. 1.

Mr. Falconer King said: "There would be no advantage in having a jolting motion; the jolting motion would break the circuit and be a defect in the speaking telephone," and "you must have pressure and partially conducting substances."

Professor Fleeming Jenkin said, "The pressure of the carbons is what favors the transmission of sound."

All the above named scientific men agree that variations of a current passing through a carbon microphone are produced by pressure of the carbons against one another, and they also agree that a jolting motion could not be relied upon to reproduce articulate speech.

Mr. Conrad Cooke said, "The first and most striking principle of Hughes' microphone is a shaking and variable contact between the two parts constituting the microphone." "The shaking and variable contact is produced by the movable portion being effected by sound." "Under Hughes' system, where gas carbon was used, the instruments could not possibly work upon the principle of pressure." "I am satisfied that it is not pressure in the sense of producing a change of resistance." "I do not think pressure has anything to do with it."

Professor Blyth said: "The Hughes microphone depends essentially upon the looseness or delicacy of contact." "I have heard articulate speech with such an instrument without a diaphragm." "There is no doubt that to a certain extent there must be a change in the number of points of surface contact when the pencil is moved." "The action of the Hughes microphone depends more or less upon the looseness or delicacy of the contact and upon the changes in the number of points of surface contact when the pencil is moved."

Mr. Oliver Heaviside, in The Electrician of 10th February last, writes: "There should be no jolting or scraping." "Contacts, though light, should not be loose."

Fig. 2.

Fig. 2.

A writer, who signs "W.E.H.," in The Electrician of 24th February last, says: "The variation of current arises from a variation of conductivity between the electrodes, consequent upon the variation of the closeness or pressure of contact;" and also, "there must be a variation of pressure between the electrodes when the transmitter is in action."

It seems, then, that some scientific men agree that variation of pressure is required to produce action in a microphone, and some of them admit that a microphone with loose contacts will transmit articulate speech, while others deny it, and some admit that a jolting or shaking motion of the parts of the microphone does not interfere with articulate speech, while others say such motion would break the circuit, and cannot be relied on.

I will now describe two microphones in which there is a shaking or jolting motion, and loose contacts, and no variation of pressure of the carbons against one another, and both of these microphones when used with an induction coil and battery give most excellent articulation. One of these microphones is made as follows: Two flat plates of carbon are secured to a block of cork, insulated from each other; into a hole of each carbon a pin of carbon fits loosely, projecting above the carbons; another flat piece of carbon, having two holes in it, bridges over the two lower carbons, being kept in its place by the pins of carbon which fit loosely in the holes in it, the bottom carbons being connected with the battery; a block of cork has a flat side of it cut out so as when secured to the lower cork the carbons will not come in contact with it, yet be close enough to it to keep the carbons from falling apart. The cork covering the carbons forms a dome.

Any good telephone receiver when used in connection with this microphone, reproduces articulate speech with remarkable distinctness, especially hissing sounds, and with a loud and full tone.

A description of this microphone was published in La Lumiere Electrique, of 15th April, 1882, and a drawing thereof on 29th April of same year.

Another form of microphone is made as follows: Two blocks of gas carbon, C, B, each about one and a half inches long and one inch square, having each a circular hole one and a quarter inches deep and half inch in diameter; these two blocks are embedded in a block of cork, C, about one-quarter of an inch apart, these holes facing each other, each block forming a terminal of the battery and induction coil; a pencil of carbon, C, P, about three-eighths of an inch in diameter, and two inches long, having a ring of ebonite, V, fixed around its center, is placed in the holes of the two fixed blocks; the ebonite ring fitting loosely in between the two blocks so as to prevent the pencil from touching the bottom of the holes in the blocks. The space between the blocks is closed with wax, W, to exclude the air, but not to touch the ring on the pencil. A block of cork fitting close to the carbon blocks on all sides is then firmly secured to the other block of cork. The microphone should lie horizontally or at a slight angle.

This microphone produces in any good telephone perfect articulation in a loud and full tone. In these microphones there is certainly "looseness and delicacy of contact," and there is a "jolting or shaking motion," and it does not seem possible that there can be any "pressure of one carbon against another."

I repeat the question I asked at the beginning of this communication, and hope that it may elicit from you, or some of our scientific men, an explanation of the theory of the action of this form of microphone.

W.C. BARNEY.