the rollers into the screen, and thence into the shareholders. Their main trunks connect the shutes. The screen is divided into four with the Reading Railroad and the docks of the sections, and, being in a slightly inclined po- canal, from which they diverge and radiate into sition, receives the coal from the hopper (fig- numerous branches to the mines. There are ure 2) at its elevated end. Figure 1 shows the more than one hundred such branches, having rollers, the upper one being solid, and the other an aggregate length of 500 miles, including perforated between the teeth. This is to avoid, about 150 miles under ground. as much as possible, the crushing or grinding of the coal. Figure 4 is the shaft which turns the screen. Now the screen being divided into sections, the net-work of the first produces the smallest size of coal, called "pea," which falls into the proper compartment of the shutes below (9). The net-work of the second section is a little larger, and furnishes the size known as "egg coal," which, in turn, falls into shute 8. The third section is again larger, and produces "stove coal," which is received into shute 7. The fourth section furnishes "broken coal," and it falls into 6, while the remainder, being too large in size to penetrate the net-work, passes out of the end of the screen, and falls into the shute 5. This variety is known as "lump coal." As the coal falls from the screen boys are stationed in the shutes to pick out the slate and impure coal, and it is truly astonishing to observe with what activity they will discover and seize the proscribed intruders. They often perform their work carelessly, however, and then the consumer commits the egregious blunder of denouncing the quality of the coal instead of the culpable slate-pickers. There are usually two sets of screens and shutes at every breaker, so that in case of accident to one the other may be used. The shutes will hold from three to five hundred tons, and they are filled at least once a day during the season of navigation.

The cars of the Reading Railroad and of the Schuylkill Navigation are sent over the lateral railways to the several mines, where they are drawn under the shutes of the breakers and filled. They are then brought back to the landings at Port Carbon or Schuylkill Haven, and if the coal is to be shipped by canal, it is dumped into the dock shutes or directly into the boats; and if by railway, then the cars are rearranged into trains for Port Richmond, Philadelphia, or intermediate-stations. The cars being labeled in numerical order, are consigned by the operator by the numbers which they respectively bear. Two tickets are filled up, one of which is taken by the conductor of the train, and serves to identify the cars and the coal at the weighscales, while the other is retained by the operator. After the weight is ascertained new bills are made out, one of which goes to the receiver of the coal, and the other to the proper officers of the railroad at the point of delivery. cost of transportation over the Reading road is usually about two cents per ton per mile, and is always collected from the receiver of the coal; while that of the lateral roads, varying from ten to thirty cents per ton, according to the distance, is paid by the operators. There are five or six of these lateral roads owned by as many different companies, and all operated with profit to

The

But let us return to the mine. Below the turning platform at the foot of the slope is a sump from thirty to forty feet in depth, and of the same width as the slope, into which the water from all the avenues of the mine is drained. The pipes through which the water is pumped up extend from the sump to the mouth of the slope, and their diameter ranges from twelve to eighteen inches. There is also a considerable variation both in the length of stroke of the engine and the number of revolutions per minute. However, the amount of water raised from some of the mines is almost incredible. In rainy seasons they are frequently overflowed, and it taxes the strength of the pumping machinery to relieve them. Four thousand hogsheads of water have, in some cases, been pumped up in eight hours; while the aggregate amount raised each day, from the seventy-five slopes now in operation, is estimated at 385,725 hogsheads. Indeed, the amount of water from each mine is much more than sufficient to float away the coal, and the upper levels of Schuylkill, during times of drought, are often sustained solely by the supplies thus received. The entire coalbasin being porous or cellular, like a sponge, nearly all the water that falls into it sinks into the mines, whence it is furnished in regular supplies to the canal without any appreciable loss by evaporation.

The coal strata of the Schuylkill are somewhat impaired in value by the frequent occurrence of "faults," and especially the veins of the upper or red-ash group. When the continuity of a vein is destroyed or interrupted by the intrusion of rock or dirt, or by a deposit of soft and impure coal, it is termed a Fault. And

Sv

these foreigners present themselves in various forms, in nearly every mine in the basin. Sometimes the vein has been fractured, and the dissevered and irregularly-shaped fragments are like a broken sheet of glass; sometimes it is rolled or doubled up, affording an immense quantity of coal in a particular spot, while

again the vein often pinches out into a mere | poses of the miner. It is too expensive and thread; but the most common kind is the in- too inefficient as a light. As nothing short of trusion of rock and dirt in the body of the vein. an open flame will suffice, the absolute danger These constitute one of the most troublesome is probably as great as ever. Nevertheless the and expensive contingencies in mining opera- Davy lamp is usetions, and have wrecked the fortunes of many ful in its way, in an operator, and caused the abandonment of enabling one to many a mine otherwise good. examine the condition of the mine, and to apply the needful remedies; but beyond this it subserves no important end. It is surrounded by a thin wire gauze, having about 750 holes to the square inch, and its peculiar merit consists in the discovery that the explosive mixture in the air will not penetrate it so as to affect the flame inside. An explosion is thus impossible, and it is this beautiful discovery that constitutes the value of the lamp.

Another serious difficulty is that of ventilation, and this unfortunately increases with the depth of the workings. Thus far, however, the matter has occasioned no particular embarrassment, since the mines themselves have attained no great depth. The deepest in the region hardly exceeds a thousand feet perpendicular, while in England some of the collieries are nearly two thousand feet deep. The ventilation is consequently expensive and difficult of attainment. Besides the evils flowing from an impure air the coal itself constantly discharges gases which, in a certain state of combination with the atmosphere, produce what are termed "fire-damp explosions." Their escape from the breasts of coal creates a peculiar hissing sound, and when the ventilation is imperfect the liability to danger is always present. An explosion of fire-damp is similar to that of powder, except that it is often far more violent and terrific. The air is converted into a cloud of fire, and every thing is dashed to atoms that falls within its grasp. The fiery tempest seizes the rubbish of the mine, the timbers, and fragments of loose coal, and hurls them against the sidewalls; the men, if they elude the sirocco blast, have their ears, mouth, and nostrils filled with sand and dust, and sustain more or less bodily injury from the mere violence of the atmospheric concussion. They often avoid the fire by falling on their faces and letting the demon ride over them, for if caught within its range death is the almost certain result. The fire-damp is generally succeeded by the "choke-damp," unless the ventilating current is strong. The atmospheric air being destroyed by the explosion, for a time there is left nothing to breathe but poisonous vapor-hence suffocation commonly ensues. In England, on one occasion, out of 200 men in the mine during an explosion, 196 were instantly killed. In France, on a Monday morning, when the miners, one after the other, were descending to their work, the first fell dead, seized with asphyxia; the next one attempted to aid him, and, coming within the stratum of carbonic acid, also fell dead; the third, fourth, and fifth shared a like fate, and there is no telling where the evil would have stopped had not the sixth turned round and forced the others to return up the shaft. The number of victims to these terrible casualties in the coal-mines of England became so alarming that the Government, some years ago, instituted measures for the better security of life; for although the safety-lamp invented by Sir Humphrey Davy enables one to explore the mine and penetrate the fiery accumulations with impunity, it can not be conveniently used for the ordinary purVOL. XV.-No. 88.-G G

THE DAVY LAMP.

The common mode of ventilating the mines of this region is upon the principle of withdrawing. For this purpose air-shafts are pierced from the breasts of coal to the surface, directly over which, or some of them, fires are constantly maintained. The draft thus occasioned creates a strong current of air in the mine below, and generally secures the object desired. But while the air in the gangways is nearly always good, that of the breasts is more or less defective, owing to the difficulty of forcing or conducting the atmospheric currents through them; and it therefore often becomes necessary to employ fans and banners, either to drive the foul air out or the pure air in. Explosions of fire-damp have been increasing with alarming rapidity; but in most cases they are the results of sheer carelessness on the part of the miners themselves. It is a lamentable fact-and to such as have occasion to descend into mines whose ventilation is imperfect, it is by no means a pleasant reflection-that out of a gang of fifty or sixty men you can always count on a certain proportion of ignorant and reckless characters, who hold the lives and limbs of all the others in the tenure of their criminal folly and stupidity.

Although the social and moral condition of our mining population is not as good as many of us would like to see it, it is yet infinitely superior to that of the same class in Europe. It is composed almost exclusively of foreigners, and includes representatives in about equal proportions from England, Ireland, Scotland, Wales, and Germany. When engaged in the mines the miner attaches his lamp to the side of his cap, and there is probably nothing peculiar in his appearance except that his face and hands

COAL-MINER.

are blackened and his clothes all wet and besmeared with coal mud. His shoes are coarse and heavy-the soles being very thick and completely covered with little broad-headed nails, to resist the encroachments of water and the sharp edges of the coal débris. Apart from the accidents to which they are exposed, they are otherwise extremely healthy. They know dittle but what pertains to their subterraneous employment, and in connection with it some of them have ideas of geological order of far more practical value than the high-strung theories of the learned professors. They are to some extent superstitious-as, for example, it is regarded as an evil omen for a visitor in the mine to whistle or hum an air. Some of their technical words indicate their apprehension of supernatural spirits and evil genii as existing in the mines. The Cornish miners, who are usually found in lead and copper regions, have a most ridiculous habit of giving a loud grunt with every blow of the pick or hammer.

dense variety on the Lehigh (and this is the strongest anthracite coal ever found on the face of the globe).

North of the Schuylkill are the basins of the Mahanoy and Shamokin; while east of them are several small detached ones, as the Hazleton, Beaver Meadow, Buck Mountain, etc., all of whose coal (except the two former) is shipped over the Lehigh Canal and the Valley Railroad. The coal of the Mahanoy is drawn over the Broad Mountain by means of steam inclined planes, and reaches the Atlantic markets via the Schuylkill; that of Shamokin descends the Susquehanna River, or goes north via the Sunbury and Elmira railways. North of all these basins lies that of Wyoming-beautiful alike for its unsurpassed scenery, its romantic settlement and history, and, to the geologist, for the regularity of its coal measures. Like the Schuylkill basin, it is about five miles in width by nearly seventy in length. The Lackawanna Creek drains the eastern portion, and meets the Susquehanna River in the centre of the basin. Entering the valley from the north, the river abruptly changes its course toward the west, and then glides down the middle of it some ten miles below Wilkesbarre, where it again deviates from the canal, and passes through the Nanticoke Mountains. The coal of the Lackawanna has several outlets: the Railway of the Pennsylvania Coal Company, the Delaware and Hudson Canal, and the Delaware, Lackawanna, and Western Railroad, just completed, are the avenues to the Atlantic markets, while the North Branch Canal supplies the interior country north and west of Scranton. A cross-section of the Wyoming basin in the vicinity of Wilkesbarre exhibits five or six distinct but gently-sloping axes, the southern one being comparatively level, and the coal lying near to the surface. The whole basin appears to be remarkably free from disturbance of any kind. In the vicinity of the Nanticoke, where the measures begin to rise toward their western termination, the veins of coal occur in great purity and extraordinary thickness; and the excavations of the Grand Tunnel, and those of the Baltimore Company near Wilkesbarre, are nothing short of a physical phenomenon. A stage-coach, a locomotive and train might be driven through the ex

The Schuylkill coal basin is supposed to contain thirteen distinct seams of coal. At one time it was thought to embrace a hundred or more, but this originated in mistaking the different out-crops, where they only described saddles, for so many veins. The combustible qualities of the coal are divided into three classes, determined by the color of their ashes-the low-cavated avenues of these mines. The principal er veins producing white, the middle gray or pink, and the upper red ashes. The first is preferred for smelting and puddling iron; the second for heating furnaces in houses, and the third for grates and cooking. But besides the marked differences in these three varieties in the economy of combustion, there is also a local difference in the character of the coal from the same veins; there is, in fact, all the difference in the qualities of coal that we find in different kinds of wood. Besides the distinguishing color of the ash, the coal graduates from a soft, semi-bituminous at the Susquehanna, to a free burner on the Swatara-a fine, compact and hard coal at the Schuylkill, to an exceedingly

vein at Nanticoke is thirty-five feet thick, at Wilkesbarre twenty-eight, Pillston fourteen, and Scranton about ten feet. The veins, it thus appears, thin out toward their eastern termini, and most likely come closer together. The Baltimore mines have been worked for many years, and it is worth a journey across the Atlantic to see them. The great vein was at first operated in open quarry, but the top covering having increased in thickness with the slope of the strata, it was found more economical to pursue the coal under ground, as in the case of the Lehigh mines. The measures having been thus cut down perpendicularly, six or seven openings were made into the coal, and up to the present

as this body of coal land seems some of the other States exceed it, though none of them have any thing like the number of distinct coal veins or aggregate thickness of coal. It is estimated that we have in all the States of the Union upward of 150,000 square miles of coal; but Pennsylvania is the only State which affords all the different varieties, as red, gray, and white ash anthracite, and semi-bituminous, bituminous, and cannel coal. Our anthracite fields are the great depositories of that description of fossil fuel on the globe, and as they are nowhere surpassed in quality, quantity, or accessibility of the coal, they must ultimately be looked to for the supplies of a large portion of the civilized world.

with carbon, and while it was thus unfit for the support of animal life (except a few species of the lower type), it could hardly have been better adapted for the rapid growth and development of vegetable matter. As the estuaries of the sea received the debris of the then higher points, they ultimately filled up and became shallow, thus forming the layers now constituting the old red sandstone group. These deposits in time must have formed low bottoms, islands, or peninsulas, and when emerged from the water their soft mud afforded an excellent soil for the most luxuriant vegetation, beginning with aquatic weeds, grass, and creepers, and ending with gigantic vines and trees rearing their dense foliage hundreds of feet in the air. The trees consisted, for the most part, of arborescent ferns, and several hundred specimens have been identified in the coal formation. We can readily imagine, as stretching along the margin of a primitive ocean, groups of islands or low marshy bottoms covered with the rankest and most luxuriant vegetation. Constantly drinking in the vapors of a hot and humid climate, the stupendous mass would ultimately break down by its own weight, but only to be succeeded by a fresh growth:

"The penetrating sun,

His force deep darting to the dark retreat
Of vegetation, set the steaming power
At large, to wander o'er the vernant earth
In various hues."

But what is coal? Our disquisition would most likely be thought incomplete were this question left unanswered. A chemist defines it to be "the result of the decomposition of the compound of bodies from which it is obtained. It consists for the greatest part of the earthy principle of these compound bodies, with which a part of the saline principle and some of the phlogiston of the decomposed oil are fixed and intimately combined. Coal can never be formed but by the heat of a body which has been in an oily state; hence it can not be formed by sulphur, phosphorus, metal, nor by any other substance the phlogiston of which is not in an oily state. Every oily matter, treated with fire in close vessels, furnishes true coal, so that whenever a charry residuum is left, we may be certain that the substance employed contains oil. But the inflammable principle of coal, although it proceeds from oil, certainly is not oil, but pure phlogiston; since coal, added to sulphuric acid, can form sulphur-to phosphoric acid, can form phosphorus-and since oil can produce none of these effects until it has been decomposed and reduced to a condition of coal." Be-are more or less distinct seams of coal, alternasides, the phenomena accompanying the burning coal are different from those which happen when oily substances are burned. The flame of charcoal is not so bright as that of oil, and produces no smoke or soot.

But how was it formed? After the convulsions which terminated the primitive period the earth seems to have enjoyed a long season of repose, and it was during this time that the coal materiel was deposited. That it is of the same age as the mountains which inclose it, is very certain from the fact that the layers are in conformable order with the stratification. That these mountains were at one period the bottoms of great seas or lakes is also very certain, since the rocks all point to a sedimentary origin, are full of marine shells, and contain strata of enormous thickness composed wholly of rounded and angular pebbles, which have undoubtedly been worn down by the attrition of water.

Previous to the elevation of the Appalachian chain of mountains, the climate was not only of an even temperature throughout the globe, but it was probably quite as warm as it now is in the torrid zone. The atmosphere was charged

Upon the accumulation, in this manner, of more or less vegetable material, we must suppose that, either by the subsidence of the strata of mud beneath, or by the overflow of the sea (most likely both), it would be covered over with a layer of mud and sand, which, in turn, would again rise from the water to sustain another vegetable crop. In every coal basin there

ting with seams of slate or mud and sand; and it is hard to believe that this mechanical operation had been repeated again and again. Yet, when we come to consider all the circumstances -the soft yielding nature of the ground, and the proximity of the sea exposing it to repeated overflow-we must adopt it as the most probable theory which our limited experience in geological science can put forward.

The question now presents itself as to how this vegetable matter was converted into coal; and it has already been partially elucidated by the chemical assay. But it appears from the researches of Liebig and others, that when wood and similar vegetable substances are buried in the earth, exposed to moisture, and partially or entirely excluded from the air, they decompose slowly, and evolve carbonic acid gas, thus parting with a portion of their original oxygen. By this means they become gradually converted into lignite, or wood-coal, which contains a larger proportion of hydrogen than wood. A continuance of decomposition changes this lignite into common bituminous coal, chiefly by the discharge of carbureted hydrogen, or the gas