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Stretching Barbed Wire

to drive through this steam. It often Could you suggest how to make a stretcher is unable to do this; and, as a result, for barbed wire?-F. W. G.

work is brought to an abrupt standstill. Saw from hickory, oak, or other hardwood a piece three-quarters of an inch

Operation of Electric Bell 2 Please explain with diagrams the operation

of an electric bell.–S. E. G. SIMPLE WIRE-STRETCHER.

The operation of an electric bell de

pends upon the principle that if a current thick by two and a-half or three inches

of electricity flows through a coil of wire wide, and of convenient length. Be sure

wound upon an iron core, the core bethere is no knot in the wood that can

comes magnetized and will attract any weaken it. At one end, fasten an iron magnetic substance to itself. A diagramplate containing a notch the width of a matic representation of an electric bell barb. Now catch in the notch a barb is shown in Fig. 1, in which M is the close to a post, and brace the plated end of the stick against the post. An excellent leverage can thus be secured and the wire will be tightened.

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For a Pinched Tube How can I prevent the pinching of inner tubes in tires ?-C. R. K.

The tube should first be carefully wiped with a clean cloth that has been well charged with talc powder. Then slightly inflate the tube, to remove folds and wrinkles. In introducing it into the shoe, feel inside around the rim, and underneath the tube, to be sure all is smooth and right. If a fold is discovered that refuses to yield to rubbing, remove the tube and repeat the process.

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Pumping Hot Water Why is it that hot water canrot be successfully drawn through a pump?-W. H. A.

Under proper conditions, there is no reason why hot water cannot be pumped. But when the pump is not placed below the level of the supply, so that the water enters with little or no pressure, difficulty is likely to be experienced. When the piston rises, the pressure is reduced and the vacated space is flooded with steam. The reason for this is that a liquid will boil at a lower temperature than in the surrounding atmosphere if the pressure is reduced. This well-known fact is taken advantage of in the boiling of syrups, etc. On its return, the piston is obliged

Fig. 1.

electro-magnet composed of a soft iron core of horseshoe shape wound with copper wire. The armature of the bell is mounted on a spring K, and carries a hammer H for striking the gong. On the back of the armature is a spring which makes contact at point D with a backstop T. The action of the bell is as cuit with which it is connected in series. follows: When the circuit is closed Normally the springs are separated as through the bell, a current flows from shown, and the circuit is open. The bell terminal 1 around the cores of the elec- and the push-button are connected up in tro-magnet, through the spring K and series with the batteries as illustrated in contact-point D, then through backstop Fig. 3, in which P is the push, B the bell, T and terminal 2. The current magne

and C the battery.

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Use of Soldering Paste
What is soldering paste, and how is it used ?
-W. S. C.

Soldering paste consists of a mixture of grease and chloride of zinc. Vaseline or petrolatum is the grease commonly used, the latter being probably just as effective and costing less. The composition is mixed as follows: One pound of petrolatum, one fluid ounce saturated solution chloride of zinc. The chloride of zinc solution is made by dissolving as much zinc in strong hydrochloric acid as it will take up. A thick, oily solution is the result. This is mixed with the petrolatum by vigorous stirring.

The mixture is used in electrical work as a flux for soldering, especially for soldering copper wires. It is also used in other fields where corrosion is not desirable.

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tizes the core, which causes it to attract : the armature, and the hammer strikes

the gong. While in this position, however, the contact at D is broken, the current ceases to flow, and the cores lose their attractive force. The armature is, therefore, carried back to its original position by the spring K, making contact again, and the process is repeated. The bell will, therefore, continue to ring as long as the circuit is closed.

The bell-push, or means of closing the circuit, is shown in Fig. 2. P is the push

Tropenas Process of Making Steel

Castings Please explain or describe the Tropenas process of making steel castings?-W. A. H.

The difference between this method and the ordinary method is that instead of having the tuyères at the very bottom of the converter so that the blast goes up through the metal, the air is blown at a low pressure upon the surface of the molten metal. At a point 4 to 7 inches above this set of tuyères, is another set which supplies air to burn the carbon monoxide coming out of the metal. In this method there is a great increase in the amount of heat produced, and the steel is much hotter than if blown in the usual (Bessemer) way. These converters are better adapted than an open-hearth furnace for making very small charges.

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Fig. 3.

button; and when this is pressed upon, it brings the point of the spring S in contact with the spring R, thus closing the cir

Longest Subsurface Phone

By W. T. Walsh

nor

B

ETWEEN the two great service rendered. Wind, nor rain,

cities on Lake Michigan, storm can disturb the cables. “A heavy Chicago and Milwaukee, snowfall brings down wires,” will never

, there will soon be in op- be said of the Chicago-Milwaukee teleeration the longest under- phone line. Moreover, many fine towns,

ground telephone system surburban in character, along the route, in the world. The feat of laying cables are preserved from the disfigurement of that would be capable of electrically unsightly poles and webs of tangled wire. transmitting the voice eighty-five miles, The work of construction is divided the distance from the Illinois to the Wis- between the Chicago and the Wisconsin consin city, would have been considered telephone companies. The southern problematical several years ago; thirty limits of Kenosha, Wis., indicate where

one shall leave off and the other continue the labor. Trenching and laying the cables are not the only things that have to be accomplished. An adequate system of drainage also is provided for, and this through a rolling country traversed by ravines and varying considerably in the character of the soil.

Several gangs of men, ranging in numbers from fifty to 100, began the work simultaneously at various points. Excavation, of course, was the first step. Ordinarily, two feet is the depth of the

ditch; but conditions are occasionally MEN LAYING CONDUITS. Chicago-Milwaukee telephone line.

such as to render three times this depth

necessary. Gullies, so frequently enmiles was something of which to boast. countered, must be filled; rivers and ra. But in 1900, Prof. M. I. Pupin of Co- vines crossed by means of viaducts. lumbia University, invented the load coil This initial work completed, all was that bears his name, by which self-induc- ready for the installation of the conduits. tion is almost entirely overcome—that is, the current of one cable is prevented from setting up an induced current in a parallel cable. Professor Pupin's invention may be compared to a balance, for it acts in such a way that both cables remain about equally charged, rendering "cross-talk” impossible. The appliance has often been used in the past for longdistance overhead systems; for subsurface cables, however, the construction of the Chicago-Milwaukee line marks an epoch.

The advantages of the conduit method lie in the lessened cost of maintenance,

CONCRETE MANHOLE ON LINE OF CHICAGO-MILWAUKEE and in the increased efficiency of the

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TELEPHONE

Where concrete alone is used, the conduits are encased in a three-inch layer of the substance. In cross-country work, a four-inch bed of concrete is first laid. Upon this the conduits are placed, and covered with two inches of earth. Finally, a plank one and one-half inches in thickness, thoroughly impregnated with creosote, is set over all. Thus, in ordinary cases, the sides of the tile are protected only by the earthy walls of the trench itself. But where there is any likelihood of current interruption, as has been stated, the tile conduits rest securely encased in concrete armor, safe from water and surface pressure, and, in fact, from any danger except the unforeseen.

The drainage system has been alluded to. At all hazards, the subtle trickle of water that steals electricity, the life of the

telephone, must be prevented. At every CONDUITS IN TRENCH.

two hundred yards' distance is placed a Chicago-Milwaukee telephone line.

concrete basin. From 100 yards either

way, the trench is drained into these baThese are constructed of vitrified clay, sins. The fall is gradual, two inches in and have four ducts. At this stage of 100 feet. Town sewers, where available, the work, concrete and creosote proved afford valuable assistance in this drainthemselves invaluable allies. The former ing. is used solely under paved streets, over At intervals of a mile and a-quarter, steep hills, and, in fact, wherever the the Pupin load coils, the secret of the current is likely to be interrupted; the successful operation of the long-distance latter, used as a wood preservative, underground telephone line, are set in in conjunction with concrete, is em

manholes of unusual size. Iron pots proployed in the more open country.

tect the coils.

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Gold in the Appalachians

By Richard Hamilton Byrd

OLD is mined within the District of Columbia was a part of

sight of the Washing Maryland. There are great auriferous ton Monument and the fields throughout the Appalachian moundomes and steeples of tains, and the foothills of that great the capital of the range extend through Maryland to the United States. Though District of Columbia. The Heights of no effort has ever been Washington are really a part of the Apmade to keep this a palachian system. Before the outbreak

secret, it is a fact that of the gold fever in California and is not generally known. It is true for all its spread to other parts of the West, all that. The hilly country of Maryland and the gold produced in the United States Virginia is gold-bearing, and what is now came out of the Appalachian mines. Only the ores that contained free milling gold could, with the crude processes, be worked. Where the gold was incorporated with other metals, it had to be passed by as unworkable. Then, because of the presence of subterranean streams, mining could not be carried on at any considerable depth. Nevertheless,

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TYPICAL GROUP or MINERS.

gold mines are in profitable operation to-day in Maryland and southwestern Virginia; and these gold veins, badly broken and dis- panning, get a "color.” It has not been integrated, are being worked down found in sufficient quantities to make through the Carolinas and into Georgia placer mining attractive, though many and Alabama.

men have washed out enough gold to There is not a ravine or gulch in the have a ring or charm made for them

selves or a favored girl.

A few miles west of Washington, a man may see several small mines, some in operation and some abandoned. A great deal of money has been sunk, and it is believed that some has been made. Great areas of gold-bearing rock have been uncovered or blocked out. Gold is obtained, but in many instances it has cost more to extract it than the gold was worth. Every now and then some small capitalist will take over one of the old mines and seek to make it pay.

At present there is one mine in which extensive operations are being carried on; and though the operators do not talk for publication, the belief is general that they are making a good profit from the mine. There are thousands of tons of

ore in sight; and if you take a pound of PANNING GOLD NEAR WASHINGTON, D. C.

the ore, crush it, and wash it, a fair

amount of gold is obtained. Much of environs of Washington City, where, if the ore assays high, but getting the yela man dig down to the gravel and black low stuff out in paying quantities is the sand that lie over bed-rock, he cannot, by problem.

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