Barbed wire

“ The point where the barbs are located seems to rust more quickly than do other parts of the wire. In some cases barbed guard wires that have given trouble by breaking have been taken down and smooth wires put up instead. If a guard wire is well grounded at least as often as every other pole, its size may be determined largely on considerations of mechanical strength and lasting qualities. ”

“ In one case a flat bit of metal is used, of an elongated diamond shape, through which a hole is pierced, by means of which it is strung upon the wire, requiring something more than the aid of a second wire twisted upon the first to render it immovable; in the other, the barb is a piece of wire coiled about one of the fence-wires, and held rigidly in place by the twisting of another wire about the first. ”

“ He says of this in his specification: 'I can, where it is desirable to increase the strengh of the wire, lay another wire of the same of a different size along-side of a thorn-wire, and can twist the two together by any suitable mechanism.' No claim was made for this method of construction in the original patent, although it seems to have been made the principal feature of a reissue obtained in 1876, which was not made an exhibit in this case. In this reissue he made a claim for twisting two wires and a series of thorns strung upon one of the wires, and held in position by them. ”

“ At one time it was thought very desirable to have barbs on guard wires, but now the better opinion seems to be that, as barbs tend to weaken the wire, they lead to breaks and cause more trouble than they are worth. ”

“ Who has not seen men in the streets dragging huge pipes of lead through the open manholes from big wooden spools? These are the cables you talk over. They have been papered and clothed—and tarred and feathered, maybe—and then encased in lead by a process that is so easy as to be laughable, and yet as ingenious as any one thing the wire miller does. Unrolling slowly from its spool, the heavy cable moves up to a machine built strong and four-legged from the floor. ”

“ Iron seems to be the most desirable material for guard wires because it gives the required mechanical strength and sufficient conductivity at a less cost than copper, aluminum, or bronze, and is easier to handle and less liable to break than steel. It was formerly the practice to staple guard wires to the tops of poles or to the ends of cross-arms, but it was found that the wire was more apt to rust and break at the staple than elsewhere, and in the better class of work such wires are now mounted on small insulators. ”

“ The piles of this equipment, waiting shipment in the Roebling storerooms, give proof that the satire of the cartoonist and the mockery of the funny writer cannot destroy an ancient faith.
The telephone and telegraph companies use uncountable miles of copper wire in line service and other miles in fine sizes for instrument coils and divers other functions. Electricity as an agent would be a halting cripple without wire. The dynamo would have little more utility than a washtub. Armatures, frames for which are formed from flat steel wire, are wound in the Roebling plant in impressive number. ”

“ The insulated wires being drawn into them, any short circuit or heating of the wire cannot give rise to a fire, as it can only take place in the interior of a non-inflammable tube. A third system of electric light wiring is the safety concentric system, in which concentric conductors are used. The inner one, which is well insulated, consists of a copper-stranded cable. The outer may be a galvanized iron strand, a copper tape or braid, or a brass tube, and is therefore necessarily connected with the earth. ”

“ In some of the newer cables wires covered with cotton soaked in paraffine are used instead of gutta-percha-covered wires. The distances within this city are so short that neither induction nor retardation has to be considered in the telegraph wires. Electric-lighting wires, we have seen, are not affected. The telephone wires are in Paris protected from these evils by an extremely simple though expensive device. Instead of a single wire for each circuit, two wires twisted together are used, the current going out over one and returning over the other. ”

“ When wire is wound by hand from a spool into a coil, or around a core, it soon becomes twisted and tangled. Make a winder. This will keep the wire straight and save much time.
APPARATUS 81.
Fig. 54.
108. Electro-Magnet. Fig. 54. Drive a nail into a board so that it will project about 3⁄4 of an inch. A soft, or wrought-iron, nail is best, but a short, thick wire-nail will do. If you do not have a thick nail, use an iron screw. Wind 3 or 4 layers of insulated copper wire around it, and fasten the bare ends of the wire down with bent pins. ”

“ It is all like a Maypole, and the bobbins go in and out like children carrying each its ribbon. As the wire climbs, the whirling fingers braid around it a coating, tight fitting and impervious. Sometimes, where double insulation is required, there are two sets of arms, one above the other, the upper one putting on a second covering outside the first, of cotton of one color or another, or hemp or whatever else the experimentalists have found best for the purpose. You wonder how the bellcord in the railroad train can ever stand the pulling and jerking and wear and tear it gets. ”

“ HOW THE GREAT CABLES WERE MADE Each of these cables consists of nineteen strands of about two hundred and seventy-eight No. 8 B. W. G. wires each, and each wire is continuous in its strand, like the yarns in a skein, traveling eternally to Brooklyn and back, up over the top of one tower, down in a long curve above the tideway, up to the other tower and down again, to be gripped and carried by links, like a chain, down to the everlasting clutch of the rock and concrete-bound anchorage. Each skein is a million feet long—nearly two hundred miles—and still men talk of “Oriental patience.” ”

“ In the making of wire screens the wire men have taken a leaf from the cloth-mill book, but in weaving a casing of cotton or other fibre around the wire for insulation the process is strongly reminiscent of some of the New England textile mills. Long rows of machines, black and silent and swift, reaching upward toward the ceiling, revolving rapidly on an upright shaft; long arms trailing downward, with wheels and bobbins like fingers plying dizzily but swiftly in and out around the wire which unwinds from its spool and keeps forever climbing. ”

“ In 1850 a cable twenty-five miles in length was laid from Dover to Calais, only to prove [Pg 40] worthless from faulty insulation and the lack of armour against dragging anchors and fretting rocks. In 1851 the experiment was repeated with success. The conductor now was not a single wire of copper, but four wires, wound spirally, so as to combine strength with flexibility; these were covered with gutta-percha and surrounded with tarred hemp. As a means of imparting additional strength, ten iron wires were wound round the hemp—a feature which has been copied in every subsequent cable (Fig. 58) . ”

“ Before me on the table is a spiral of copper wire, and in this wire, by special means, I can create what we call an electric current. I shall ask you to notice that when this is done two effects are immediately produced. In the first place, the wire becomes hot, and, secondly, it becomes magnetic. The fact that it is hot is evident, because it is now nearly red hot, and is visibly incandescent in the dark. If we dip the wire in iron filings, you will see that these cling to the wire and are taken up by it, just as when an ordinary steel magnet is substituted for the wire. ”

“ The wires should be attached with tie wires having an insulation equal to that of the conductor which it secures to the knob. The use of split knobs does away with the necessity of using tie wires. The conductors must be at least 5 inches apart and it is better to support them on separate beams when possible. Each wire must be encased in a piece of flexible tube at all switches, outlets, etc., and this piece of tubing should be sufficiently long to extend from the last insulator and project at least one inch beyond the outlet. ”

“ It is wire, from the huge three-inch cable that pulls the loads of mountain haulways or moves the thousand cars of a city transit system, down to the gossamer that jingles the bell in the telephone or the infinitesimal hair that in the eyepiece of a telescope helps the astronomer to mark the movement of a distant world. There is hardly a thing in the nature of wire, round, flat or irregular, that the Roeblings do not manufacture or have not at some time manufactured, whether for the world’s standard uses or the numberless special purposes hidden in inventive minds. ”

“ A piece of gutta-percha should then be taken and placed upon the joint while warm, and with the aid of the spirit lamp and wet fingers, moulded round until a firm and perfect covering has been formed. On no account use spirits in soldering. With the line wire, it is best, as far as possible, to convey it all the way from the push to the signal box or bell in one continuous length. Of course, when two or more pushes are required to the same wire, a junction is unavoidable. The same process of joining and covering, as given for the battery wire, applies to the line wire. ”

“ Whenever possible, the wiring of a house, etc., for bell work, should be done as soon as the walls are up and the roof is on. The shortest and straightest convenient route from bell to battery, etc., should always be chosen where practicable to facilitate drawing the wire through and to avoid the loss of current which the resistance of long lengths of wire inevitably entails. The wires should be run in light zinc tubes nailed to the wall. ”

“ This continual making and breaking of the circuit keeps up as long as the push is pressed, a ball mounted on A by means of a rod strikes against the gong G causing a continuous ringing of the bell. The wires leading between the bell, battery cell and push must all be insulated, that is, covered with cotton, rubber, etc., which prevents the leakage of current should two wires cross each other. Copper wire is mostly used for circuits indoors, the details of the kind and size of wire will be given later on. ”

“ Wires having figure 8 or elliptical grooved sections have been employed, and have the advantage of allowing the use of a mechanical clip ear which is clear of the trolley wheel. The ordinary round wire is usually supported by a gun-metal or gun-metal and iron ear grooved to fit the wire, which is soldered or sweated to it. In Great Britain the overhead conductors are required by the board of trade to be divided into half-mile sections. The wires on adjoining sections are connected by section insulators. ”

“ Each conductor of this cord is made up of several fine copper wires, instead of one solid wire, which makes it very flexible. But whether the cord or separate single wires are used, the connections with the zincs and carbons are the same. It is understood, of course, that it is necessary to have two wires to connect the battery and lamp. One end of each of the wires is connected with the lamp, and the other ends with the battery—one with the zincs and the other with the carbons. ”

“ Underground cables, cables formed of rubber insulated wires, and interior wiring which is properly done, all may be considered to be wiring which is unexposed, that is, not exposed to foreign high potentials, discharges, sneak, or abnormal currents. All other wiring, such as bare wires, aërial cables, etc., should be considered as exposed to such hazards and a fuse should exist in each wire between its exposed portion and the central office or subscriber's instrument. ”

“ It is evident that by merely depressing the handle till the upper lever comes in contact with the lower bar of metal at the point A, a current of electricity will flow through the point of contact from the battery wire to the telegraph wire. In order to break the contact or circuit, the operator has simply to desist from depressing the handle of the upper lever, which is instantly raised from contact by the action of the spring at the other end. ”

“ The resistance of this wire, when added to that of lamps, permits not more than one fifth of an ampere to pass, and this warms the wire slightly. The bar a b is composed of two strips of metal, brass above and iron below. Heat expands brass more than iron. The result is that when the current is turned on, the bar begins to curve downward until presently it touches the metal base of c. Then the full current required to light the lamps which are in circuit passes. While the circuit is closed through the large metal strips not enough passes through the fine wire to warm it. ”

“ The finer the wire, the more its resistance. The large wire that you see on the poles connects directly with this fine relay wire. When the electric circuit is complete, the soft iron bars are magnets; when it is broken, they are not. Thus is produced a backward and a forward movement of the armature which opens and closes a second or local circuit, in which is placed the sounder, having two similar coils, but wound with comparatively coarse wire. ”

“ It is well to have 1⁄2 lb. of No. 24 or 25 for electro-magnets, current-detectors, etc., etc. 1⁄2 lb. of No. 30 will not be too much, if you make induction coils. If you handle your wire carefully, single cotton-covered will do. Double cotton-covered is better than single, but it costs more. Be careful not to injure the covering. (See below for splicing wire.) Look out for broken wire.
288. Splicing Wire. Fig. 125. Do not simply touch [Pg 140] two wires together and imagine that you have a good connection; a mere twist is not sufficient. ”