Part 34

The car consists of heavy steel plate structure, erected upon a flat car of standard type. The interior is divided into three compartments. The end compartments are for use of troops operating machine guns and rifles through the port-holes shown on side of car. The center compartment, which is not the full height of the car, is used for ammunition storage, and is capable of holding a large quantity of ammunition, either for small arms or for the rapid-fire gun which is mounted on top of the car. The rapid-fire gun here shown is a model of a three-inch field gun mounted upon a special carriage. The well in which the gun is located may also be used as a fighting top for troops armed with rifles or machine guns.

This car is known as a light-armored car. It is armed with a three-inch rapid-fire gun, two machine guns and any number of rifles which the troops occupying it may carry. The service for which this car is intended is primarily to guard railroads and depots adjacent to railroads. It is not ordinarily to be employed in aggressive movements. In effect, it is a movable block-house which may be used at any point along the line, or it may be used as a retreat for troops when necessary. It may also be used for transporting troops past danger points, and for transporting explosives or other perishable material which might be damaged by fire from the ends. The car as constructed weighs 86,200 pounds. It is 47 feet long, 9 feet 3 inches wide, and 7 feet high at the ends. When used for transportation of troops, it will accommodate a company of infantry seated on camp stools or benches. When used for patrol purposes, there would not be more than twelve men in the car, to operate the rapid-fire gun and machine guns.

The car was shipped to the Sandy Hook proving grounds to be equipped with rapid-fire guns and ammunition and thoroughly tested and inspected by the Engineer and Ordnance Officer of the U. S. Army.

What is an “Electric Eel”?

This is an eel abundant in the fresh waters of Brazil and the Guianas, which possesses organs capable of developing a strong electric current and thus of giving a violent shock to any one touching the eels. These organs replace the lower muscles along the sides of the tail. The eels can be taken by driving horses into the water to be shocked and seizing them when thus weakened.

The Story of Salt[56]

Salt is a chemical compound composed of two elements, sodium and chlorine. Chemically it is known as sodium chloride.

It is one of the things which comes into our lives daily, perhaps more than any other, with the exception of water. Probably no other thing than water is used more by all civilized people than salt.

Nature provides salt for us in three different forms. First, in sea water in solution; second, in salt springs; and third, in the form of salt rock.

From time immemorial man has obtained salt from sea water. This is still being done on our sea coasts, but the salt obtained by evaporating the water is very crude and usually contains many impurities.

It has been possible to obtain a large supply of salt from what are known as salt springs. These springs are usually the result of water flowing over a deposit of salt rock. The amount of salt obtained from evaporating this spring water is, however, so small that salt springs are an impractical source of supply when it comes to making salt for commercial purposes.

Rock salt forms the most common and practical source of supply. It is found in all parts of the world and reasonably near the surface. The deposit is said to be what is left of ancient salt seas. In the United States the largest deposits of salt are found in the states of Michigan, New York, Ohio, Utah, Louisiana, Kansas, Texas and California. The above-mentioned states are the largest producers of salt in this country.

One of the largest sources of salt supply in Europe is at Wielizka in Poland. This deposit of salt is said to be the largest in the world, the bed of salt rock being 500 miles long, 20 miles wide and 1,200 feet thick. Some of the salt mines in Poland are so extensive that it is said some of the miners spend all of their lives in them, never coming to the surface of the earth.

Most of the deposits of salt rock contain impurities which need to be removed before the salt is fit for use commercially; however, some deposits show a very pure salt rock and when ground up this rock salt is suitable for table use. In general, however, the salt made from crude salt rock is only fit for the crudest commercial uses. The most common impurity is gypsum and it is necessary to remove this gypsum before the salt can be considered pure.

The general way of obtaining salt from the earth is by means of salt wells. These wells are drilled in the same way that wells are bored for oil and gas. A pipe about six inches in diameter is lowered to the surface of the salt rock and then an inside pipe is put down, water is forced down between the two pipes and the pressure exerted brings up the dissolved rock or salt brine through the inside pipe.

As the salt brine reaches the surface the salt is extracted from it in various ways. At present the crude open-pan system, where the brine was poured into open pans and fires were built below the pans, is almost obsolete. The most practical methods of refining salt today are known as the Grainer, Vacuum Pan and Alberger systems.

The Grainer system is similar in its operation to the old open-pan system. The brine is run through long, shallow tanks and the heat is applied through steam pipes inside of the pan. The salt settles to the bottom of the pan and large rakes operated either by hand or machinery collect the salt.

In the Vacuum Pan process tiny cubes of salt are formed and settle to the bottom of the pan in which a vacuum has been created. The salt is then drained out and is ready for drying.

Variations of the two above processes make possible the production of certain grades of table salt. Oftentimes the brine is relieved of impurities through the action of certain chemicals. In some instances a chemical known as “barium chloride” is used, but the wisdom of this process has been much questioned, owing to the fact that barium chloride is a deadly poison.

The Alberger system of salt manufacture is a mechanical process which subjects the salt brine to a much higher temperature and removes the impurities by means of mechanical filters. This process is known to make a very pure salt and has been used for some time as a practical method for manufacturing high-grade dairy and table salt. Unlike the other two common methods of making salt, it forms tiny salt flakes instead of the usual cubes or lumps.

After manufacturers obtain the salt from the brine they usually put it through drying processes. After drying, the salt is sifted and the fine table salt is separated from the coarser products. When salt is sifted it is ready for packing in bags or packages suitable for shipment to the consumer.

According to recent government reports, it is estimated that the average consumption of salt per capita for all purposes is about 100 pounds per year. The salt industry is now said to have reached a very stable basis and the demand for salt in the United States is practically all supplied by American manufacturers. Salt can be put to a great many uses in addition to the usual requirements for table and cooking. It is used by food manufacturers and performs highly important functions in certain commercial fields.

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Why do We Call it “Denatured Alcohol”?

Under a law passed by the United States Congress in 1907, on alcohol intended for use as fuel or for illuminating purposes, or other mechanical employment, the internal tax need not be paid. But to avoid taxation it must be rendered unfit for drinking by the addition of such unpalatable substances as wood alcohol, pyridin, benzola, sulphuric ether or animal oil. Thus treated, it is spoken of as denatured.

What is the Difference Between a Cruiser and a Battleship?

A cruiser is a vessel built to secure speed and fuel capacity at the expense of armor and battery strength.

The modern cruiser may be regarded as the offspring of the frigate of the eighteenth and nineteenth centuries. The later construction has been designed for a minimum speed of twenty-five knots an hour, with a possible attainment of thirty knots or over, under favorable conditions.

The battleship and one form of cruiser were evolved from the conflicting opinions of two opposite schools of design. The battleship is the expression of the thoughts of those who stood for extremely developed battery power, great thickness of armor plate, and moderate speed. The cruiser is the result of the triumph of those who contended for high speed at the sacrifice of heavy armor protection and excessive battery strength.

The armored cruiser was the particular development of the antagonistic views prevailing among naval architects. The type of this class in the United States navy was the “Brooklyn,” which figured prominently in the war with Spain in 1898.

Recently the armored cruiser has been superseded by the battle cruiser. The armor protection in this type of ship is much lower than that of the battleship, while the ordnance, on the other hand, is practically the same. High speed, wide radius of action and great battery strength are the characteristics of this type; and to meet these requirements the battle cruiser is planned of a size considerably larger than the battleship.

The protected cruiser is a later development of naval construction. Its distinguishing features are certain modifications in the distribution of the mass of protective armor of the ship.

Light cruisers are vessels of from 1,500 to 7,500 tons, used in scouting, as commerce destroyers, etc. They are outside the armored class.

The Story of the Growth of the Motor Truck[57]

While exact dates are not easily obtainable, it is thought to be quite within the bounds of reasonable accuracy to say that the motor truck only began to be recognized as a practical vehicle for commercial purposes in 1905.

Today motor vehicles, both pleasure and commercial, are such a common sight in every city and town, and even throughout the rural districts, that one can scarcely believe that they were a novelty such a little time ago.

The statistics show, however, that in 1906 the total registrations of both pleasure and commercial vehicles, as reported by the various states, was 48,000--about one month’s production today of one well-known pleasure-car maker.

In 1915 the registrations totaled nearly 2,500,000, and every day has added to the number.

It can be truthfully said that the pleasure car is the father of the truck or commercial car.

The application of the internal combustion engine to the use of propelling vehicles was the beginning of a new era in that world. The idea, born, one might say, with the new century, has already done more to revolutionize transportation than all of the inventions of all the centuries that have gone before.

The automobile, first looked upon as a freak, then “a rich man’s plaything,” has in a few years come to be recognized as a necessity, and literally millions of people are employed in its production and dependent on the industry for support.

To trace the ramifications of the industry back through the mills, mines and factories that produce the iron, steel, copper, brass, zinc, aluminum, lead, leather, lumber, glass, celluloid, etc., would make a long and interesting story, but this chapter deals with the motor vehicle as a commercial car or truck and the part it is playing in transportation of the world’s goods.

While the first commercial vehicles to come into use were electrically propelled, and while the electric truck has become a factor in the large cities, the gasoline power vehicles are, as yet, the dominant factor.

At the first, business men were slow to take up the use of trucks for delivery and hauling purposes and one of the specialties of early factories was the making of “sight-seeing” cars which were sold to enterprising individuals in cities and summer resorts for the purpose of showing visitors the sights. These wagons became popular throughout the country and are still being used in many places.

Little by little, however, progressive business men saw the advantages to be gained by motor delivery and the motor truck began to gain favor. Several of the pleasure-car manufacturers took advantage of the awakening interest and added a commercial vehicle section to their plants.

Others began to see visions of the day when horses would no longer be used for other than strictly farm work, and motor-truck factories sprang up here and there, even faster than pleasure-car plants.

Like the seed mentioned in the parable of the sower, some fell on good ground and grew to produce a bountiful harvest, but many withered by the wayside.

In the early days of the motor-truck industry men bought the finished vehicle, but later on the practice of selling chassis only became popular, and while today some manufacturers cater to the body trade, a large percentage of trucks are sold to the purchaser without the body, this being built by a local builder, the truck manufacturer furnishing a body builder’s blue-print.

As in everything else, it has taken time to overcome the faults of the early trucks. Most all trucks above 1,500 pounds capacity are equipped with solid rubber tires, and while the solid rubber tires and the springs on the trucks give a great deal of resiliency, it was discovered that the steady pounding over all kinds of pavements soon racked a truck to pieces and that pleasure-car practice could not be followed successively in building motor trucks.

In the earlier days truck buyers made many mistakes in selecting the size or capacity of trucks. Some made the mistake of buying trucks too light for their work. Others selected trucks large enough to provide for exceptional or emergency loads, and would, for example, buy a truck of 3-1/2-tons capacity when 90 per cent of their hauling was loads not exceeding 1-1/2 or 2 tons. Thus they not only had a greater investment than necessary in the truck itself, but were paying an exclusive charge in the way of operating costs and depreciation.

But the experimental days have passed, both in the manufacture of motor trucks and in their adaption to various lines of work. If the buyer has not determined by experience and investigation the kind and capacity of truck he should use, the older manufacturers are able to step in and analyze the work to be done and to intelligently recommend to the buyer what he should have.

That motor trucks not only furnish cheaper transportation than horse-drawn vehicles, but greatly extend the radius of operation, is quite generally conceded. This is shown by the enormous increase in the demand for motor trucks in all lines of business where goods of any kind are to be moved over any considerable distance.

With motor trucks, merchants have extended their deliveries to reach territory they could not touch under the horse-delivery system.

Market gardeners, who must have their product in the city markets early and have it fresh, can now sell their high-priced land adjoining the cities and go miles back in the country where as good ground can be bought for from one-tenth to one-fourth the price their suburban property will bring--and still be closer to market with their motor trucks than they were before with their horses.

Contractors can transport material long distances and save both time and money. Dairymen collect milk over a radius of thirty or forty miles and get it to market fresh. Freight and passenger lines are possible with motor trucks where a steam railroad or trolley system would not be practicable.

In short, the motor truck is revolutionizing transportation. As made today by the leading manufacturers, it is simple, durable and easy to operate and care for.

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What is a Diving Bell?

Diving, aside from the pleasure afforded to good swimmers, is important in many different industries, particularly in fishing for pearls, corals, sponges, etc.

Without the aid of artificial appliances a skilful diver may remain under water for two, or even three minutes; accounts of longer periods are doubtful or absurd.

Various methods have been proposed and engines contrived to render diving more safe and easy. The great object in all these is to furnish the diver with fresh air, without which he must either make but a short stay under water or perish.

Diving bells have been used very effectively. A diving bell is a contrivance for the purpose of enabling persons to descend, and to remain, below the surface of water for a length of time, to perform various operations, such as examining the foundations of bridges, blasting rocks, recovering treasure from sunken vessels, etc.

Diving bells have been made of various forms, more especially in that of a bell or hollow truncated cone, with the smaller end closed, and the larger one, which is placed lowermost, open.

The air contained within these vessels prevents them from being filled with water on submersion, so that the diver may descend in them and breathe freely for a long time provided he can be furnished with a new supply of fresh air when the contained air becomes vitiated by respiration. This is done by means of a flexible tube, through which air is forced into the bell.

A form, called the “nautilus,” has been invented which enables the occupants, and not the attendants above, to raise or sink the bell, move it about at pleasure, or raise great weights with it and deposit them in any desired spot.

How are Harbors Dredged Out?

There are several forms of mechanical, power-operated dredges. One of the most common is the “clam-shell” dredge, consisting of a pair of large, heavy iron jaws, hinged at the back, in general form resembling a pair of huge clam shells. This with its attachments is called the grapple. In operation it is lowered with open jaws, and by its own weight digs into the ground that is to be excavated. Traction is then made on the chains controlling the jaws, which close; the grapple is hoisted to the surface and its contents discharged into scows alongside the dredge.

The dipper dredge, an exclusively American type, has a bucket rigidly attached to a projecting timber arm. In operation the bucket is lowered and made to take a curving upward cut, thus dipping up the bottom material, which is discharged through the hinged bottom of the bucket. The pump or suction dredge operates by means of a flexible pipe connected with a powerful centrifugal pump. The pipe is lowered into contact with the bottom to be excavated and the material is pumped into hopper barges or into a hopper-well in the dredge itself.

The center ladder bucket dredge operates by means of an endless chain of buckets moving over an inclined plane, which in structure is a strong iron ladder, one end of which is lowered to the sea bottom. The steel buckets scoop up the material at the bottom of the ladder, which they then ascend, and are discharged by becoming inverted at the upper end of the ladder. This dredge is the only one found satisfactory in excavating rock.

How is a Razor Blade Made?

The best scissors, penknives, razors and lancets are made of cast steel. Table knives, plane irons and chisels of a very superior kind are made of shear steel, while common steel is wrought up into ordinary cutlery.

In making razors, the workman, being furnished with a bar of cast steel, forges his blade from it. After being brought into true shape by filing, the blade is exposed to a cherry-red heat and instantly quenched in cold water. The blade is then tempered by first brightening one side and then heating it over a fire free from flame and smoke, until the bright surface acquires a straw color (or it may be tempered differently). It is again quenched, and is then ready for being ground and polished.

The Story of the Tunnels Under the Hudson River[58]