carried on poles by men over trails where wheels would be impossible, is the source of power.

Subterranean Passages of Naours

BENEATH the village of Naours in Picardy, France, there are extensive subterranean galleries dating from an unknown period, and resembling the catacombs of Rome and Paris. They are located beneath the great Guet hill, and were excavated partly for the excellent building stone of the underlying rock, and partly to form places of refuge in time of foreign invasion. There are twenty-eight galleries in all, having a total length of about 6,500 feet, with a width of from 6 to 61⁄2 feet, with an average height of 64 feet. In addition to the

ful explorations have been made of them all. In the course of this work, wheat has been found which has been indisputably proven to have lain there for more than 200 years, and which, when planted, has germinated and borne fruit. This discovery of the germinative power of wheat, has been said by an eminent professor of agriculture to be one of the most valuable services that archæology has ever rendered to botany. Coins were

regular galleries, there are about 300 chambers or cells, having an average length of about 23 feet and a width of nearly 10 feet. A dozen or more are as large as the nave of a church, and a few are like public squares where a number of galleries converge. There are six chimneys used for ventilation and for the escape of smoke from the fires used for cooking. No fire could have been needed for heating, as the temperature does not vary much from 48° F. the year through. Finally, there are three chapels cut in the solid rock.

The chimneys are among the most interesting features of the excavation, and show the skill with which the openings were concealed. The illustration shows how the main chimney was covered with an arch of masonry and the opening hidden, while a horizontal gallery leads off to an outlet at some distance, which comes through the floor of a miller's house.

These excavations were lost sight of from 1825 to 1887; and since 1895, care

also found dating from the reigns of Henry IV., Louis XII., and Louis XIV., and evidence collected to show that a certain chamber was used as a storehouse for contraband salt, to escape the famous gabelle that figures so prominently as one of the bitter grievances of the French peasants prior to the Revolution.

Now, however, these silent, subterranean galleries are interesting only to the antiquarian, as their value as a place of refuge has long since passed away with the marauding armies that so often swept over the face of the country leaving a trail of misery and desolation behind them. They are mute evidences of the constructive ingenuity and engineering skill of the people of a bygone age.

F all the metals, iron in its various forms-cast iron, wrought iron, and steel-is the most abundant and of the greatest utility. On account of its strength, hardness, and elasticity, it has an almost endless variety of uses.

Iron is seldom found free or native, i. e., as a metal; but is combined chemically with other substances and with earthy matter. Iron combines readily with oxygen; therefore the most common ores (compounds) are composed largely of iron and oxygen. These ores, of which there are half a dozen, contain from 50 to 75 per cent of metallic iron, the remainder being oxygen and small quantities of alumina, calcium, silica, sulphur, and phosphorus.

The Reduction of the Ore

To get the iron into a metallic state and sufficiently pure for commercial uses, the impurities and the oxygen must be taken from the ore. This, briefly stated, is done as follows:

The ore, with limestone added, is heated with coke or charcoal for fuel. The limestone unites with the earthy impurities, and forms a slag which is lighter than the molten iron; as this slag collects and floats on the surface of the iron, it is easily drawn off. To get rid of the oxygen, the ore is heated to a high temperature, the separation being facilitated by mixing with carbon (coke or charcoal), because at high temperatures oxygen has a greater affinity for carbon than for iron. Therefore the oxygen leaves the iron, and combines with the carbon, forming carbon monoxide or carbon dioxide according to the amount of air present. These two substances are gases, the former combustible.

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Thus we see that the earthy impurities unite with the limestone and pass away as slag, and the oxygen unites with the carbon, passing off as a gas. The molten iron is left. This iron is by no means pure; it contains from 3 to 10 per cent of carbon and some silicon, manganese, sulphur, and phosphorus.

In actual practice the process is not so simple; but, before considering the process further, let us discuss the furnace in which the smelting is accomplished.

The Blast Furnace

The blast furnace is a circular iron shell lined with fire brick. At the bottom, called the hearth, the sides are straight; above this (at the boshes), the sides diverge rapidly, and then converge gradually to the throat. Near the top an opening allows the gases to leave the furnace. At the top is a hopper which allows the charges of fuel, limestone, and ore to fall into the furnace without the escape of gas.

The hearth is perforated about six feet from the bottom, with several holes, for the admission of hot air under pressure; this air enters through pipes T called tuyeres (pronounced tweers). The large pipe B which supplies the tuyeres, encircles the furnace, and is called the bustle pipe. The hot air is supplied under pressure of 5 to 15 pounds per square inch by a blowing engine.

Below the tuyeres is the crucible; in this portion, the molten metal collects; and, as the walls are very hot, they are cooled by water which circulates around them. In the crucible wall are two openings; the one near the top is for the removal of the slag or cinder, and is called the cinder notch or slag eye (S). A little below is the tap-hole (H), through which the molten iron flows.

Stoves

conducted through the pipe P and the dustcatcher D. Some of the gas then goes to boilers, gas engines, or other machinery, and the rest to the stoves. These stoves are filled with "checkerwork" (blocks of refractory material), and through them is passed all the air for the blast.

At the stoves, the waste gases are mixed with air, and, as they are at high temperature, the oxygen from the air unites with the carbon monoxide, and combustion takes place. The heated products of combustion pass through the checkerwork until it is raised to the temperature of combustion. The valves are then changed, and air from the blowing engine passes through the checkerwork and becomes heated to 1,000° to 1,500° F.; it then passes to the tuyeres. This is continued until the refractory material becomes cool. Meanwhile the hot gases are heating another stove.

At least three stoves should be used, two for alternate working (one being heated by hot gases while the other is giving heat to the blast), and a third to be idle for repairs or cleaning. Often four stoves are installed.

Operation

After the interior of the blast furnace is dry, it is filled with wood to about half-way up the boshes. On this wood is placed coke; and then layers of coke, limestone, and ore. After kindling the wood, the blast is turned on. As the fuel burns, the charge slowly descends to the crucible. When the temperature reaches about 400°, the carbon begins to unite with the oxygen to form carbon monoxide gas, and the iron oxide (the ore) is slowly reduced to metallic iron.

In the furnace, a current of hot gases is ascending and a current of solids is descending. When the temperature of the ore reaches 1,100 the oxygen has left it, and it is like a sponge. The limestone now unites with the silica and alumina; and when the temperature is sufficiently high, these substances melt, and form the slag. The slag floats on the metallic iron and is drawn off; then the iron itself is allowed to flow from the tap-hole to channels formed in sand. These channels are called pigs; and the iron, pig-iron.

A MINISTER's wife, a doctor's wife, and a traveling man's wife met one day recently, and were talking about the forgetfulness of their husbands. The minister's wife thought her husband was the most forgetful man living, because he would go to church and forget his notes and no one could make out what he was trying to preach about. The doctor's wife thought her husband was the more forgetful still, for he would often start out to see a patient, and would forget his medicine case and travel nine miles for nothing. "Well," said the traveling man's wife, "my husband beats that. He came home the other day and patted me on the cheek and said: 'I believe I have seen you before-what is your name?"

In Boston

MRS. TWITTER-I never was so provoked in all my life. The conductor of that car saw me plainly enough; but he permitted his car to go right by without stopping.

MR. STREETER - Of course you signaled to him?

Casting Pearls

BOB-"What did the lecturer say when you threw those cabbages at him?"

DICK "O, he said he had hoped the audience would be pleased, but he really hadn't expected they would entirely lose their heads." -Louisville Courier-Journal.