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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

dis land the chrough Mare Heights AS

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

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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, gold mines are in profitable operation to-day in Maryland and southwestern Virginia; and these gold veins, badly broken and disintegrated, are being worked down through the Carolinas and into Georgia and Alabama.

There is not a ravine or gulch in the

TYPICAL GROUP OF Miners.

panning, get a "color.” It has not been found in sufficient quantities to make placer mining attractive, though many men have washed out enough gold to have a ring or charm made for themselves 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 the ore, crush it, and wash it, a fair amount of gold is obtained. Much of the ore assays high, but getting the yellow stuff out in paying quantities is the problem.

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Sanitation at Panama houses are, in general, built of wood,

with lower floor more than a yard above ONE of the great difficulties and the ground. For each person, 500 cubic

sources of expense in building the feet of air space is provided. Panama Canal is the problem of sanita- Another important question is the suption. The overlooking of this feature by ply of pure drinking water. There is an the old French company cost many lives. abundance of the latter high up on the The many thousands of workers must not hills. From there it is now pumped in only be housed and fed, but also pro- large pipes to the houses. A thorough tected against those terrible enemies, yel- system of drainage also has been installed low fever and malaria. That our Gov- in Panama, Colon, and other cities. The ernment has not underestimated the im- cleaning of the streets is carried on sysportance of the hygienic problem, is seen tematically. Many swampy localities have from the many sanitary installations to been elevated with sand and gravel. be found on the Isthmus.

Against yellow fever and malaria and There were a few thousand little their chief propagators, the mosquitoes, houses left by the French company, of a real war has been raging. In the early which some have been restored and made months of the American occupation, both fit for human habitation. Also new diseases prevailed to some extent on the houses and hotels have been built. The Isthmus. Now, however, they have been brought under control. The principal method of combating them is to screen completely all houses and receptacles containing food, and to fumigate all rooms. This kills the insects inside. It was found, also, that the blood of most of the negroes contained malaria bacilli, and that any insect biting an infected negro could easily infect others, especially the whites. By destroying the mosquitoes through fumigation, and by the use of internally administered drugs in the case of the negroes, the malaria was also practically stamped out. It is estimated that $2,000,000 will be needed for completing the sanitary work in the Canal Zone.—Max BRUNNER.

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TYPICAL GROUP OF HOUSES, HOTELS, AND HOSPITALS IN THE CANAL ZONE, PANAMA.

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Pike's Peak Locomo

tive N EW engines of a very interesting type

are being built for use in climbing Pike's Peak. The railroad which traverses the sides of this great mountain is known as the Manitou & Pike's Peak

ALTERNATING-CURRENT DETECTOR.

600 gallons. The capacity for oil is 325 gallons. Beneath the cab floor are the oil tanks, from which the oil is fed through a heater on one side of the engine,consisting of a 17/4-inch oil pipe inside a larger pipe. The space between these pipes is filled with steam. The boilers of this odd-appearing locomotive are so set that when the engine is upon a 16 per cent gradethe tubes are horizontal.-W. FRANK MCCLURE.

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An A-C Detector New LOCOMOTIVE FOR Pike's Peak Railway.

IT is a well-known fact that electric cir

cuits have mostly to be switched out, Railway, and is one of the most novel thus interrupting the service, whenever roads in the world. The new locomo- the existence of an alternating current is tives, one of which is shown in the to be ascertained or its intensity measaccompanying photograph, differ from ured. An instrument recently contheir predecessors chiefly in that they structed, called an “applier,” will show burn oil instead of coal; that each of the presence of alternating currents of their axles is fitted with a driving gear, any kind, and may serve to determine which, as can be seen, lies unusually close their intensity, merely by being applied to the roadbęd; and that the high- outside the circuit, thus in no way interpressure cylinders are one inch greater in fering with the service. diameter and of two inches longer stroke. This apparatus consists of a small The weight of the new engine is 60,000. transformer, the iron core of which is pounds. The tank capacity for water is divided into two pieces forming a kind from any iron protection. This condition is best complied with by applying the apparatus to safety fuses. The apparatus will prove very useful in locating ground connections for short circuits.

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House Moving by

Water
CHICAGO still has so many frame

houses that house-moving is fre

quently undertaken. The crowded conHouse-MOVING ON CHICAGO River.

dition of the streets, with both elevated

and trolley lines, is, however, a heavy of tongs, the jaws of which are opened obstacle. Consequently, when the buildby a pressure exerted on the legs, and

ings are near the water, they are often are automatically closed again as the carried to their new destination on scows. pressure is removed. To insure a safe The accompanying illustration shows a magnetic closure, the jaws of the tongs house being towed on the Chicago river should entirely encircle the conductors.

to its new location.—W. HILD. The circuit encircled by the back part of the jaws constitutes the primary coil of the transformer; while the secondary coil,

Trackless Trolley-Car in the shape of a small bobbin, is solidly fitted to the back bolts of the jaws, being THE trackless trolley is a French and connected to the measuring instrument - German novelty which is offering proper by a fine electric cable. The meas- serious competition to the regular lines. uring instrument consists of either a tele- The advantage of such a motor-car lies phone or a heating coil instrument, the in the saving in the cost of track laying former being suitable for ascertaining the and maintenance. In Germany the conexistence of considerably weaker cur- struction of a two-mile trackless trolley rents than the latter.

line cost but $35,000, as against $87,500 Whenever the intensity of a current is for the regular system between the same to be measured, the line should be free points. Moreover, in country districts

having good roads, the trackless trolleys perform a service in the marketing of farm products that the track lines cannot do. The cost of operation is low. In winter the energy required for a distance of some 28 miles is said to be about 40 cents per car

-considerably less than with the usual tracklines. The rate of speed is about 512 miles per hour. The trackless trolley is almost impracticable, however, where the road surface is much

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broken by ruts or other Trackless TROLLEY-CAR AND TRAILER,

irregularities.

COUNT LOY OF " ELECTRICAL WORLD AND ENGINEER.

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