A REIGN OF TERROR.

The great loss of life was due to the vast fall of ashes, which crushed in hundreds of roofs and buried the occupants within the ruins of their homes. In all the neighboring towns buildings were destroyed in great numbers, an early estimate being that fully 5,000 houses had been partly crushed or utterly destroyed. On the Ottajano side of the mountain, where the ashes fell in greatest profusion, all the houses of the villages were damaged, and Ottajano itself was left a wreck, several hundred dead bodies being taken from its ruins. In Naples the ash fall was so incessant that those who could afford it wore automobile coats, caps and goggles, while the people generally sought to save their eyes and faces by the aid of paper masks and umbrellas. The drivers of trolley cars were obliged to wear masks of some transparent material under the vizors of their caps.

DISASTERS AT SAN GIUSEPPE AND NAPLES.

There were two special disasters attended by serious loss of life. On the 9th, while a congregation of two hundred or more were attending mass in the church at San Giuseppe, the roof crushed in from the weight of ashes upon it and fell upon the worshippers below, few or none of whom escaped unhurt. Fifty-four dead bodies were taken from the ruins and a large number were severely injured. The Mayor of the town was dismissed from his office for leaving his post of duty in the face of danger.

The second disaster, one of the same character, took place at Naples. This was on Tuesday, April 10th. Just previous to it the people had been marching in religious processions through the streets, to render thanks for the apparent cessation of the activity of Vesuvius. Motley but picturesque processions were these, headed by boys carrying candles, which burned simply in the full sunshine and bearing aloft images of the Madonna or saints, clad in gorgeous robes of cheap blue or yellow satin. Their joy was suddenly changed to grief by tidings of a frightful disaster. The roof of the Monte Oliveto market, fronting on the Toledo, the main thoroughfare, had suddenly crushed in, burying more than 200 people beneath its heavy fall.

The market had been crowded with buyers and their children, and it was the busiest hours of the day in the great roofed courtyard, covering a space 600 feet square, when, with scarcely a tremor of warning, there came a frightful crash and a dense cloud of dust covered the scene, from out of which came heartrending screams of agony. The volcanic ash which, unnoticed, had gathered thickly on the roof, had broken it in by its weight.

The news set the people frantic with grief and indignation. They insisted that the authorities knew that the roof was unsafe and had neglected their duty. Cursing and screaming in their intense excitement, they surrounded the market, endeavoring with frantic haste to remove the heavy beams from beneath which came the appealing calls for help, many of the rescuers sobbing aloud as they worked. It required a large force of police and soldiers to keep them back and permit the firemen and other trained workers to carry on more systematically the work of relief. Twelve persons proved to have been killed, two fatally injured, twenty-four seriously hurt and over a hundred badly bruised and cut. Among these were many children, whose parents had sent them to do the marketing without a dream of danger, and the grief of the parents was intense. The Duke of Aosta, Prefect of Naples, directed the work of rescue, while his wife assisted in the care of the injured. As the Duchess bent in the hospital to give a cooling drink to a badly bruised little girl she felt a kiss upon her hand. Looking down, she saw a woman kneeling at her feet, who gratefully said: "Your Excellency, she is all I have. I am a widow. May God reward you."

While this scene of horror was taking place in Naples the fate of the town and villages grouped around the foot of the volcano seemed as hopeless as ever. Early on the 10th the showers of ashes and streams of lava diminished and almost ceased, but later the same day they began again, and the terrified inhabitants feared that a catastrophe like that which buried Pompeii and Herculaneum was about to visit them. The lava which reached the cemetery of Torre Annunziata turned in the direction of Pompeii as if to freshly entomb that exhumed city of the past. A violent storm of sulphurous rain fell at San Giuseppe, Vesuviana and Sariano, and on all sides the fall of sand and ashes came on again in full strength. Even with the sun shining high in the heavens the light was a dim yellow, in the midst of which the few persons who still haunted the stricken towns moved about in the awful stillness of desolation like gray ghosts, their clothing, hair and beards covered with ashes.

THE ERUPTION RESUMED.

A typical case was that of Torre del Greco. Though for thirty hours the place had been deserted, a few ghostly figures could be seen at intervals when the vivid flashes of lightning illuminated the gloom-covered scene, wandering desolately about, hungry and thirsty, their throats parched by smoke and dust, yet unable to tear themselves away from the ruins of their late comfortable homes.

So deep was the ash fall that railway or tramway travel to the inner circle of towns was impossible, and the great depth of fallen dust choked the roads so as to render travel by carriage or on foot very difficult. A party of officials made a tour of inspection by automobile, visiting a number of the town, but were prevented by the state of the roads from reaching others. Ottajano was thus cut off from travel, and a heavy fall of ashes followed the officials in their retreat. At Bosco Trecase the lava had gathered into a lake, already growing solid on top, but a mass of liquid rock beneath.

The lava carried vast masses of burnt stone and sulphur on its surface, like dross on melted lead, and nothing was visible toward Bosco Trecase but endless acres of dark scoriae, broken here and there by the greenish, curling smoke of sulphur. At one point a great cone pine tree, torn up by its roots and turned to black charcoal, stuck out of the mass at a sharp angle. The air was almost unbearable, the heat intense, and few could long bear the dangers and discomfort of the situation.

SCENES OF HORROR.

The greatest depth of ashes encountered was in the vicinity of Ottajano. Here large areas were buried to a depth of several feet. Soldiers had been sent there with military carts, carrying provisions and surgical appliances, with orders to lend their aid in the work of relief. They found it almost impossible to make their way through the deep fine dust, and the tales of horror and heroism they had to tell resembled those that must of old have been borne to Rome by the fleeing inhabitants of Pompeii.

Efforts were made to remove the children and old persons in the carts, but when these had gone a few hundred feet it was found that, although there were four horses harnessed to each vehicle, they could not pull their loads through the ashes. This caused a panic among the children, who expected to be buried in the incessant fall from the volcano, and they fled in all directions in the darkness and blinding rain. Searching parties went after them, but in spite of continuous shouting and calling no trace was found of the little ones, and numbers of the children were undoubtedly smothered by the ashes and sand.

Many of the inhabitants had been buried in the ruins of their houses, and the scenes when the victims were unearthed were often piteous and terrible. The positions of the bodies showed that the victims had died while in a state of great terror, the faces being convulsed with fear. Three bodies were found in a confessional of one of the fallen churches. One body was that of an old woman who was sitting with her right arm raised as though to ward off the advancing danger. The second was that of a child about eight years old. It was found dead in a position, which would indicate that the child had fallen with a little dog close to it and had died with one arm raised across its face, to protect itself and pet from the crumbling ruins. The third body, that of a woman, was reduced to an unrecognizable mass. These three victims were reverently laid side by side while a procession of friends and relatives offered up prayers beside them.

One soldier rode his horse through the ashes reaching up to its flanks, calling out, "Who wants help?" He was rewarded by hearing a woman's voice reply in weak tones and, springing from his horse, he floundered through the ashes to the ruined walls of a house from which the voice seemed to come. As he made his way through the soft, treacherous layer of scoriae which surrounded the destroyed habitation, and with difficulty worked his way toward the building the soldier shouted words of encouragement and, climbing over a heap of ruins and braving a toppling wall, entered the building. In the cellar he found the bodies of three children. Near them was a woman, barely alive, who by almost superhuman efforts for hours had succeeded in freeing herself from a mass of debris which had fallen upon her. The soldier picked the woman up in his arms and carried her to a place of safety. It was found that both legs were broken and that she had been badly crushed about the body.

Some extraordinary escapes from death took place. A man and his four children were rescued after having been lost in the ash-covered wilderness for fifty-six hours. They were terribly exhausted, and were reduced almost to skeletons.

Robert Underwood Johnson, one of the editors of the "Century Magazine", who happened to be in Rome at the time of the eruption, made one of a party who ventured as near the scene of destruction as they could safely approach. From his graphic story of his experiences we copy some of the most interesting details.

AN AMERICAN OBSERVER.

"We caught a train for Torre Annunziata, three miles this side of Pompeii and two miles from the southern end of the wedge of lava which destroyed Bosco Trecase. We had a magnificent view of the eruption, eight miles away. Rising at an angle of fifty degrees, the vast mass of tumult roundness was beautifully accentuated by the full moon, shifting momentarily into new forms and drifting south in low, black clouds of ashes and cinders reaching to Capri. At Torre del Greco we ran under this terrifying pall, apparently a hundred feet above, the solidity of which was soon revealed in the moonlight. The torches of the railway guards added to the effect, but greatly relieved the sulphurous darkness.

"We reached Torre Annunziata at three in the morning. There was little suggestion of a disaster as we trudged through the sleeping town to the lava, two miles away. The brilliant moon gave us a superb view of the volcano, a gray-brown mass rising, expanding and curling in with a profile like a monstrous cyclopean face. But nothing in mythology gives a suggestion of the fascination of this awful force, presenting the sublime beauty above, but in its descent filled with the mysterious malignance of God's underworld.

"We reached the lava at a picturesque cypress-planted cemetery on the northern boundary of Torre Annunziata. It was as if the dead had effectually cried out to arrest the crushing river of flames which pitilessly engulfed the statue of St. Anne with which the people of Bosco Reale tried to stay it, as at Catania the veil of St. Agathe is said to have stayed a similar stream from Mount Etna.

"We climbed on the lava. It was cool above but still alive with fire below. We could see dimly the extent of the destruction beyond the barrier of brown which had enclosed the streets, torn down the houses, invaded the vineyards and broken Cook's railways. A better idea of the surroundings was obtained at dawn from the railway. We saw north what was left of Bosco Trecase—a great, square stone church and a few houses inland in a sea of dull, brown lava. North and east rose a thousand patches of blue smoke like swamp miasma. All was dull and desolate slag, with nowhere the familiar serpentine forms of the old lava streams. In terrible contrast with the volcanic evidences were strong cypresses and blooming camelias in a neighboring cemetery.

"We ate a hasty luncheon before sunrise, when the great beauty of the scene was revealed. The column now seemed higher and more massive, rising to three times the height of Vesuvius. Each portion had a concentric motion and new aspects. The south edges floating toward the sea showed exquisite curved surfaces, due to the upper moving current. It was like the decoration of the side of a great sarcophagus. As a yellow dust hangs over Naples and hides the volcano, I count myself fortunate to have seen all day from leeward this spectacle of changing, undiminishing beauty.

"The wedge of cultivated land ruined east of the volcano extended at least ten miles, with a width of twenty or thirty miles. Fancy a rich and thickly populated country of vineyards lying under three to six inches of ashes and cinders of the color of chocolate with milk, while above, to the west, the volcano in full activity is distributing to the outer edges of the circle the same fate, and you will get an idea of the desolate impression of the scene, a tragedy colossal and heartrending. Like that of Calabria, it enlists the sympathy of the civilized world. It takes time for such a calamity to be realized.

"Two miles below San Giuseppe we struck cinders which the soldiers were shoveling, making a narrow road for the refugees. Our wagon driver begged off from completing his contract to take us to San Giuseppe. We had not the heart to insist, so the rest of the journey to the railway at Palma, eight miles, was made laboriously on foot for three hours through sliding cinders.

"In many places temporary shelters had been built by the roadside, like children's playhouses. Here women were huddled with their bedding, awaiting the coming of supplies which the army had begun to distribute. The men were largely occupied with shoveling cinders from the stronger roofs and floors into heaps three to six feet deep along the roadside. Many two-wheeled carts loaded with salvage, drawn by donkeys or pushed by peasants, were making their way along, the women with bundles on their heads or carrying poultry.

"In the square of San Giuseppe was an encampment of soldiers, with low tents. Near a destroyed church, in coarse yellow linen shrouds, were the bodies of thirty-three of the persons who there lost their lives. The peasants were sad, but uncomplaining; in fact, for so excitable a people they were wonderfully calm. As evidence of the thrift and self-respect of these, we were not once asked for alms during the afternoon."

THE KING AT THE FRONT.

The Italian Government did all it could at the moment to alleviate the horrors of the situation, sending money to be expended in relief work and dispatching high officials of the government to give aid and encouragement by their presence. The King, Victor Emmanuel, and Queen Helene reached the scene of destruction as early as possible and lent their personal assistance to the work of rescue.

Obliged to leave his automobile, which could not move over the cinder-choked road, the King went forward with difficulty on horseback, the animal floundering through four feet of ashes, stumbling into holes, and half blinded by the fall of dust and cinders.

"How did you escape?" he asked a priest whom he met in his journey.

"I put myself in safety," was the reply.

"What do you mean?" asked the King.

"Realizing the danger, I left Nola."

"What!" cried the King, with a flush of anger. "You, a minister of God, were not here to share the danger of your people and administer the last sacraments? You did very wrong and forgot your duty."

Reaching Ottejano, the King did what he could to expedite the work of rescue at that central point of disaster, more than a hundred dead bodies being taken from the ruins in his presence. He stood with set pale face watching the removal of the victims and directing the movement of the workers. During his visit at the front he inspected the temporary camp hospitals, in which the soldiers were caring for the injured and suffering, speaking to the poor victims, giving them what comfort he could, and asking what he could do to relieve their distress. Every request or desire was received with sympathy and orders given to have it fulfilled.

A pitiful scene took place when the King bent over a poor man, whose right leg had been amputated, and asked what he could do to comfort and aid him in his affliction.

"Send me my son, who is serving as a soldier," said the maimed peasant.

The King, visibly affected, clasped the old man's hand and exclaimed:

"My poor fellow! I can do much, but to grant your request would mean breaking the laws, which I must be the first to respect. I would give anything I have were it possible by so doing to send your son to you, but I cannot do so."

While the King was thus engaged at the scenes of desolation, Queen Helene visited the charitable institutions at Naples and inspected the places where the refugees were housed, doing what she could to improve conditions and add to the comfort of the sufferers. The Princess of Schleswig-Holstein, who was in Naples, made an automobile visit to the afflicted towns, but the motor broke down, and she was forced to return on foot, walking a distance of twelve miles through the ashes and displaying a power of endurance that surprised the natives.

THE CANOPY OF DUST.

By Friday, April 13th, the eruption was practically at an end. Vesuvius had spent itself in the enormous convulsion of the 7th and 8th and the subsequent minor explosions and had returned to its normal state, ceasing to give any signs of life, except the cloud of smoke which still rose from its crater and spread like a thick curtain over and around the mountain. Looked at from Naples, there was none of the familiar aspects of the volcano, with its output of smoke and ashes by day and fiery gleam by night. Now it lay buried in darkness and obscurity, clothed in a dense pall of smoke. At Rome there was sunshine, but twenty miles south hung a misty veil, and twenty-five miles above Naples a zone of semi-obscurity began, blotting out the sun, whose light trickled through with a sickly glare. Everything was whitened with powdery dust; pretty white villas were daubed and dripping with mud, and people were busy shoveling the ashes from their roofs.

The crowds at the stations resembled millers, their clothes flour covered; the Campania presented the appearance of a Dakota prairie after a blizzard of snow, though everything was gray instead of white. The ashes lay in drifts knee deep. As the volcano was approached semi-night replaced the day, the gloom being so deep that telegraph poles twenty feet away could not be seen. Breathing was difficult, and the smoke made the eyes water. At Naples, however, a favorable wind had cleared the air of smoke, the sun shone brightly, and the versatile people were happy once more. The goggles and eye-screens had disappeared, but the streets were anything but comfortable, for some six thousand men were at work clearing the ashes from the roofs and main streets and piling them in the middle of the narrow streets, making the passage of vehicles very difficult and the sidewalks far from comfortable for foot passengers.

But while brightness and joy reigned at Naples, there were gruesome scenes within the volcanic zone. At Bosco Trecase soldiers carried on the work of exhumation, being able to work only an hour at a time on account of the advanced stage of decomposition of the bodies. Many of these were shapeless, unrecognizable masses of flesh and bones, while others were little disfigured. To lessen the danger of an epidemic the bodies were buried as quickly as possible in quicklime.

On Sunday, the 15th, the searchers at Ottejano were surprised at finding two aged women still alive, after six days' entombment in the ruins. They were among those who had been buried by the falling walls a week before. The rafters of the house had protected them, and a few morsels of food in their pockets aided to keep them alive. At some points there the ashes were ten feet deep. At San Giuseppe bodies of women were found in whose hands were coins and jewels, and one woman held a jewelled rosary. This recalls the results of exploration at Herculaneum and Pompeii, where were similar instances of death overtaking the victims of the volcano while fleeing with their jewels in their hands.

It is interesting to learn that two men stood heroically to their post of duty during the whole scene of the explosion, Professor Matteucci, Director of the Royal Observatory, and his American assistant, Professor Frank A. Perret, of New York. Though the building occupied by them was exposed to the full force of the rain of stones from the burning mountain, they remained undauntedly at their post through that week of terror. On the 14th some of that venturesome fraternity, the newspaper correspondents, reached their eyrie on the highest habitable point on Vesuvius and heard the story of their experiences.

THE HEROES OF THE OBSERVATORY.

For several days Professors Matteucci and Perret and their two servants had been cut off from the outside world and bombarded by the volcano, their rations consisting of bread, cheese and dried onions, until on Friday a hardy guide was induced to push through to them with some provisions. During the eruption the Professor had kept at his instruments, taking observations day and night and making calculations in the midst of the inferno. Roughly dressed, he looked like a Western cowboy after a hard ride in a dust storm. The portico where he stood was knee deep in ashes, and from the observatory terrace narrow paths had been cut through the ashes, but as far as the eye could reach an ocean of ashes and twisted rivers were alone visible, with Vesuvius rising grimly in the midst. The great monster was enveloped in a cloak of white, as if buried under a snowstorm, its surface being here and there slit with gulches in which lava ran. At the bottom of one of those gulches lay the wrecked remnants of the peninsular railway, a portion of its twisted cable protruding through the ashes. As the correspondents ascended the mountain they were surprised by the apparition of natives, men wrinkled with age, who emerged from dugouts just below the observatory and offered them milk and eggs, just as if they were ordinary visitors to the volcano. As they descended they heard the sound of a mandolin from one of these dugouts. Evidently Vesuvius had no terrors for these case-hardened veterans.

We have already told the story gleaned by the correspondents from the daring scientists. Matteucci completed his record of boldness on Friday, the 13th, by climbing to a point far above the observatory, at the imminent risk of his life, to observe the conditions then existing. From what he says he believed the end of the disturbance near, though he did not venture to predict. As for the ashes, which a light wind was then blowing in a direction away from Naples, he said: "The ill wind is now blowing good to other places, for ashes are the best fertilizer it is possible to use. It is merely a question just now of having too much of a good thing."

This is a fact so far as the volcanic ash is concerned. An examination of the ashes a few days ago shows that they will prove an active and valuable fertilizer. The fertile slopes of Vesuvius have ever been an allurement to the vine-grower, four crops a year being a temptation no possible danger could drive him from, and as soon as the mountain grows surely peaceful after this eruption, we shall find its farmers risking again the chance of its uncertain temper. But this is not the case with the land covered with lava and cinders. Time for their disintegration is necessary before they can be brought under cultivation, and this is a matter of years. After the great eruption of 1871-72 the land covered with cinders did not bear crops for seven years, and there is no reason that they will do so sooner on the present occasion. So for years to come much of the volcanic soil must remain a barren and desert void.



CHAPTER XVI.

The Great Lisbon and Calabrian Earthquakes.

To our account of the great earth convulsions of San Francisco it is in place to append a description of some similar events of older date. It is due to the same causes, whatever these causes may be, the imprisoned forces within the earth acting over great distances during the earthquake, while they are concentrated within some limited space when the volcano begins its work. The earthquake is the most terrible to mankind of all the natural agencies of destruction. While the volcano usually has a greater permanent effect upon surface conditions, it is, as a rule, much less destructive to human life, the earthquake often shaking down cities and burying all their inhabitants in one common grave. Violent earthquakes are also of far more frequent occurrence than destructive volcanic eruptions, many hundreds of them having taken place during the historic period.

While the earthquake is only indirectly connected with the subject of our work, it seems desirable to make some mention of it here, at least so far as relates to those terrible convulsions whose destructiveness has given them special prominence in the history of great disasters. Ancient notable examples are those which threw down the famous Colossus of Rhodes and the Pharos of Alexandria. The city of Antioch was a terrible sufferer from this affliction, it having been devastated some time before the Christian era, while in the year 859 more than 15,000 of its houses were destroyed. Of countries subject to earthquakes, Japan has been an especial sufferer, in some cases mountains or islands being elevated in association with shocks; in others, great tracts of land being swallowed up by the sea. The number of deaths in some of these instances was enormous.

Numerous thrilling examples of the destructive work of the earthquake at various periods are on record. Of these we have given elsewhere a tabular list of the more important, and shall confine ourselves to a few striking examples of its destructive action. In the record of great earthquakes, one of the most famous is that which in 1755 visited the city of Lisbon, the capital of Portugal, and left that populous, place in ruin and dire distress. It may be well to recall the details of this dire event to the memories of our readers.

THE GREAT LISBON EARTHQUAKE

On the night of the 31st of October, 1755, the citizens of the fair city of Lisbon lay down to sleep, in merciful ignorance of what was awaiting them on the morrow. The morning of the 1st of November dawned, and gave no sign of approaching calamity. The sun rose in its brightness, the warmth was genial, the breezes gentle, the sky serene. It was All Saints' Day—a high festival of the Church of Rome. The sacred edifices were thronged with eager crowds, and the ceremonies were in full progress, when the assembled throngs were suddenly startled from their devotions. From the ground beneath came fearful sounds that drowned the peal of the organ and the voices of the choirs. These underground thunders having rolled away, an awful silence ensued. The panic-stricken multitudes were paralyzed with terror. Immediately after the ground began to heave with a long and gentle swell, producing giddiness and faintness among the people. The tall piles swayed to and fro, like willows in the wind. Shrieks of horror rose from the terrified assembly. Again the earth heaved, and this time with a longer and higher wave. Down came the ponderous arches, the stately columns, the massive walls, the lofty spires, tumbling upon the heads of priests and people. The graven images, the deified wafers, and they who had knelt in adoration before them—the worshipped and the worshippers alike—were in a moment buried under one undistinguishable mass of horrible ruins. Only a few, who were near the doors, escaped to tell the tale.

It fared no better with those who had remained in their dwellings. The terrible earth-wave overthrew the larger number of the private houses in the city, burying their inhabitants under the crumbling walls. Those who were in the streets more generally escaped, though some there, too, were killed by falling walls.

The sudden overthrow of so many buildings raised vast volumes of fine dust, which filled the atmosphere and obscured the sun, producing a dense gloom. The air was full of doleful sounds—the groans of agony from the wounded and the dying, screams of despair from the horrified survivors, wails of lamentation from the suddenly bereaved, dismal howlings of dogs, and terrified cries of other animals.

In two or three minutes the clouds of dust fell to the ground, and disclosed the scene of desolation which a few seconds had wrought. The ruin, though general, was not universal. A considerable number of houses were left standing—fortunately tenantless—for a third great earth-wave traversed the city, and most of the buildings which had withstood the previous shocks, already severely shaken, were entirely overthrown.

WATER ADDS TO THE DESTRUCTION

The last disaster filled the surviving citizens with the impulse of flight. The more fortunate of them ran in the direction of the open country, and succeeded in saving their lives; but a great multitude rushed down to the harbor, thinking to escape by sea. Here, however, they were met by a new and unexpected peril. The tide, after first retreating for a little, came rolling in with an immense wave, about fifty feet in height, carrying with it ships, barges and boats, and dashing them in dire confusion upon the crowded shore. Overwhelmed by this huge wave, great numbers were, on its retreat, swept into the seething waters and drowned. A vast throng took refuge on a fine new marble quay, but recently completed, which had cost much labor and expense. This the sea-wave had spared, sweeping harmless by. But, alas! it was only for a moment. The vast structure itself, with the whole of its living burden, sank instantaneously into an awful chasm which opened underneath. The mole and all who were on it, the boats and barges moored to its sides, all of them filled with people, were in a moment ingulfed. Not a single corpse, not a shred of raiment, not a plank nor a splinter floated to the surface, and a hundred fathoms of water covered the spot. To the first great sea-wave several others succeeded, and the bay continued for a long time in a state of tumultuous agitation.

About two hours after the first overthrow of the buildings, a new element of destruction came into play. The fires in the ruined houses kindled the timbers, and a mighty conflagration, urged by a violent wind, soon raged among the ruins, consuming everything combustible, and completing the wreck of the city. This fire, which lasted four days, was not altogether a misfortune. It consumed the thousands of corpses which would otherwise have tainted the air, adding pestilence to the other misfortunes of the survivors. Yet they were threatened with an enemy not less appalling, for famine stared them in the face. Almost everything eatable within the precincts of the city had been consumed. A set of wretches, morever, who had escaped from the ruins of the prisons, prowled among the rubbish of the houses in search of plunder, so that whatever remained in the shape of provisions fell into their hands and was speedily devoured. They also broke into the houses that remained standing, and rifled them of their contents. It is said that many of those who had been only injured by the ruins, and might have escaped by being extricated, were ruthlessly murdered by those merciless villains.

The total loss of life by this terrible catastrophe is estimated at 60,000 persons, of whom about 40,000 perished at once, and the remainder died afterwards of the injuries and privations they sustained. Twelve hundred were buried in the ruins of the general hospital, eight hundred in those of the civil prison, and several thousands in those of the convents. The loss of property amounted to many millions sterling.

WIDE-SPREAD DESTRUCTION

Although the earth-wave traversed the whole city, the shock was felt more severely in some quarters than in others. All the older part of the town, called the Moorish quarter, was entirely overthrown; and of the newer part, about seventy of the principal streets were ruined. Some buildings that withstood the shocks were destroyed by fire. The cathedral, eighteen parish churches, almost all the convents, the halls of the inquisition, the royal residence, and several other fine palaces of the nobility and mansions of the wealthy, the custom-houses, the warehouses filled with merchandise, the public granaries filled with corn, and large timber yards, with their stores of lumber, were either overthrown or burned.

The king and court were not in Lisbon at the time of this great disaster, but were living in the neighborhood at the castle of Belem, which escaped injury. The royal family, however, were so alarmed by the shocks, that they passed the following night in carriages out of doors. None of the officers of state were with them at the time. On the following morning the king hastened to the ruined city, to see what could be done toward restoring order, aiding the wounded, and providing food for the hungry.

The royal family and the members of the court exerted themselves to the uttermost, the ladies devoting themselves to the preparation of lint and bandages, and to nursing the wounded, the sick, and the dying, of whom the numbers were overwhelming. Among the sufferers were men of quality and once opulent citizens, who had been reduced in a moment to absolute penury. The kitchens of the royal palace, which fortunately remained standing, were used for the purpose of preparing food for the starving multitudes. It is said that during the first two or three days a pound of bread was worth an ounce of gold. One of the first measures of the government was to buy up all the corn that could be obtained in the neighborhood of Lisbon, and to sell it again at a moderate price, to those who could afford to buy, distributing it gratis to those who had nothing to pay.

For about a month afterward earthquake shocks continued, some of them severe. It was several months before any of the citizens could summon courage to begin rebuilding the city. But by degrees their confidence returned. The earth had relapsed into repose, and they set about the task of rebuilding with so much energy, that in ten years Lisbon again became one of the most beautiful capitals of Europe.

CHARACTERISTICS OF THE LISBON EARTHQUAKE

The most distinguishing peculiarities of this earthquake were the swallowing up of the mole, and the vast extent of the earth's surface over which the shocks were felt. Several of the highest mountains in Portugal were violently shaken, and rent at their summits; huge masses falling from them into the neighboring valleys. These great fractures gave rise to immense volumes of dust, which at a distance were mistaken for smoke by those who beheld them. Flames were also said to have been observed: but if there were any such, they were probably electrical flashes produced by the sudden rupture of the rocks.

The portion of the earth's surface convulsed by this earthquake is estimated by Humboldt to have been four times greater than the whole extent of Europe. The shocks were felt not only over the Spanish peninsula, but in Morocco and Algeria they were nearly as violent. At a place about twenty-four miles from the city of Morocco, there is said to have occurred a catastrophe much resembling what took place at the Lisbon mole. A great fissure opened in the earth, and an entire village, with all its inhabitants, upwards of 8,000 in number, were precipitated into the gulf, which immediately closed over its prey.

EARTHQUAKES IN CALABRIA

Of the numerous other examples of destructive earthquakes which might be chosen from Old World annals, it will not be amiss to append a brief account of those which took place in Calabria, Italy, in 1783. These, while less wide-spread in their influence, were much longer in duration than the Lisbon cataclysm, since they continued, at intervals, from the 5th of February until the end of the year. The shocks were felt all over Sicily and as far north as Naples, but the area of severe convulsion was comparatively limited, not exceeding five hundred square miles.

The centre of disturbance seems to have been under the town of Oppido in the farther Calabria, and it extended in every direction from that spot to a distance of about twenty-two miles, with such violence as to overthrow every city, town and village lying within that circle. This ruin was accomplished by the first shock on the 5th of February. The second, of equal violence, on the 28th of March, was less destructive, only because little or nothing had been left for it to overthrow.

At Oppido the motion was in the nature of a vertical upheaval of the ground, which was accompanied by the opening of numerous large chasms, into some of which many houses were ingulfed, the chasms closing over them again almost immediately. The town itself was situated on the summit of a hill, flanked by five steep and difficult slopes; it was so completely overthrown by the first shock that scarcely a fragment of wall was left standing. The hill itself was not thrown down, but a fort which commanded the approach to the place was hurled into the gorge below. It was on the flats immediately surrounding the site of the town and on the rising grounds beyond them that the great fissures and chasms were opened. On the slope of one of the hills opposite the town there appeared a vast chasm, in which a large quantity of soil covered with vines and olive-trees was engulfed. This chasm remained open after the shock, and was somewhat in the form of an amphitheatre, 500 feet long and 200 feet in depth.

MOST CALAMITOUS OF THE LANDSLIPS

The most calamitous of the landslips occurred on the sea-coast of the Straits of Messina, near the celebrated rock of Scilla, where huge masses fell from the tall cliffs, overwhelming many villas and gardens. At Gian Greco a continuous line of precipitous rocks, nearly a mile in length, tumbled down. The aged Prince of Scilla, after the first great shock on the 5th of February, persuaded many of his vassals to quit the dangerous shore, and take refuge in the fishing boats—he himself showing the example. That same night, however, while many of the people were asleep in the boats, and others on a flat plain a little above the sea-level, another powerful shock threw down from the neighboring Mount Jaci a great mass, which fell with a dreadful crash, partly into the sea, and partly upon the plain beneath. Immediately the sea rose to a height of twenty feet above the level ground on which the people were stationed, and rolling over it, swept away the whole multitude. This immense wave then retired, but returned with still greater violence, bringing with it the bodies of the men and animals it had previously swept away, dashing to pieces the whole of the boats, drowning all that were in them, and wafting the fragments far inland. The prince with 1,430 of his people perished by this disaster.

It was on the north-eastern shore of Sicily, however, that the greatest amount of damage was done. The first severe shock, on the 5th of February, overthrew nearly the whole of the beautiful city of Messina, with great loss of life. The shore for a considerable distance along the coast was rent, and the ground along the port, which was before quite level, became afterwards inclined towards the sea, the depth of the water having, at the same time, increased in several parts, through the displacement of portions of the bottom. The quay also subsided about fourteen inches below the level of the sea, and the houses near it were much rent. But it was in the city itself that the most terrible desolation was wrought—a complication of disasters having followed the shock, more especially a fierce conflagration, whose intensity was augmented by the large stores of oil kept in the place.

IMMENSE DESTRUCTION

According to official reports made soon after the events, the destruction caused by the earthquakes of the 5th of February and 28th of March throughout the two Calabrias was immense. About 320 towns and villages were entirely reduced to ruins, and about fifty others seriously damaged. The loss of life was appalling—40,000 having perished by the earthquakes, and 20,000 more having subsequently died from privation and exposure, or from epidemic diseases bred by the stagnant pools and the decaying carcases of men and animals. The greater number were buried amid the ruins of the houses, while others perished in the fires that were kindled in most of the towns, particularly in Oppido, where the flames were fed by great magazines of oil. Not a few, especially among the peasantry dwelling in the country, were suddenly engulfed in fissures. Many who were only half buried in the ruins, and who might have been saved had there been help at hand, were left to die a lingering death from cold and hunger. Four Augustine monks at Terranuova perished thus miserably. Having taken refuge in a vaulted sacristy, they were entombed in it alive by the masses of rubbish, and lingered for four days, during which their cries for help could be heard, till death put an end to their sufferings.

Of still more thrilling interest was the case of the Marchioness Spastara. Having fainted at the moment of the first great shock, she was lifted by her husband, who, bearing her in his arms, hurried with her to the harbor. Here, on recovering her senses, she observed that her infant boy had been left behind. Taking advantage of a moment when her husband was too much occupied to notice her, she darted off and, running back to the house, which was still standing, she snatched her babe from its cradle. Rushing with him in her arms towards the staircase, she found the stair had fallen—cutting off all further progress in that direction. She fled from room to room, pursued by the falling materials, and at length reached a balcony as her last refuge. Holding up her infant, she implored the few passers-by for help; but they all, intent on securing their own safety, turned a deaf ear to her cries. Meanwhile the mansion had caught fire, and before long the balcony, with the devoted lady still grasping her darling, was hurled into the devouring flames.



CHAPTER XVII.

The Charleston and Other Earthquakes of the United States.

The twin continents of America have rivalled the record of the Old World in their experience of earthquakes since their discovery in 1492. The first of these made note of was in Venezuela in 1530, but they have been numerous and often disastrous since. Among them was the great shock at Lima in 1746, by which 18,000 were killed, and those at Guatemala in 1773, with 33,000, and at Riobamba in 1797, with 41,000 victims. It will, however, doubtless prove of more interest to our readers if we pass over these ruinous disasters and confine ourselves to the less destructive earthquakes which have taken place within our own country.

The United States, large a section of North America as it occupies, is fortunate in being in a great measure destitute of volcanic phenomena, while destructive earthquakes have been very rare in its history. This, it is true, does not apply to the United States as it is, but as it was. It has annexed the volcano and the earthquake with its new accessions of territory. Alaska has its volcanoes, the Philippines are subject to both forms of convulsion, and in Hawaii we possess the most spectacular volcano of the earth, while the earthquake is its common attendant. But in the older United States the volcano contents itself with an occasional puff of smoke, and eruptive phenomena are confined to the minor form of the geyser.

We are by no means so free from the earthquake. Slight movements of the earth's surface are much more common than many of us imagine, and in the history of our land there have been a number of earth shocks of considerable violence. Prior to that of San Francisco, the most destructive to life and property was that of Charleston in 1886, though the 1812 convulsion in the Mississippi Valley might have proved a much greater calamity but for the fact that civilized man had not then largely invaded its centre of action.

As regards the number of earth movements in this country, we are told that in New England alone 231 were recorded in two hundred and fifty years, while doubtless many slighter ones were left unrecorded. Taking the whole United States, there were 364 recorded in the twelve years from 1872 to 1883, and in 1885 fifty-nine were recorded, more than two-thirds of them being on the Pacific slope. Most of these, however, were very slight, some of them barely perceptible.

Confining ourselves to those of the past important in their effects, we shall first speak of the shocks which took place in New England in 1755, in the year and month of the great earthquake at Lisbon. On the 18th of November of that year, while the shocks at Lisbon still continued, New England was violently shaken, loud underground explosive noises accompanying the shocks. In the harbors along the Atlantic coast there was much agitation of the waters and many dead fish were thrown up on the shores. The shock, indeed, was felt far from the coast, by the crew of a ship more than two hundred miles out at sea from Cape Ann, Massachusetts.

This event, however, was of minor importance, being much inferior to that of 1812, in which year California and the Mississippi Valley alike were affected by violent movements of the earth's crust. The California convulsions took place in the spring and summer of that year, extending from the beginning of May until September. Throughout May the southern portion of that region was violently agitated, the shocks being so frequent and severe that people abandoned their houses and slept on the open ground. The most destructive shocks came in September, when two Mission houses were destroyed and many of their inmates killed. At Santa Barbara a tidal wave invaded the coast and flowed some distance into the interior.

It may be said here that California has proved more subject to severe shocks than any other section of our country. In 1865 sharp tremors shook the whole region about the Bay of San Francisco, many buildings being thrown down. Hardly any of brick or stone escaped injury, though few lives were lost. In 1872 a disturbance was felt farther west, the whole range of the Sierra Nevada mountains being violently shaken and the earth tremblings extending into the State of Nevada. The centre of activity was along the crest of the range, and immense quantities of rock were thrown down from the mountain pinnacles. A tremendous fissure opened along the eastern base of the mountain range for forty miles, the land to the west of the opening rising and that to the east sinking several feet. One small settlement, that of Lone Pine, in Owen's Valley, on the east base of the mountains, was completely demolished, from twenty to thirty lives being lost. Luckily, the region affected had very few inhabitants, or the calamity might have been great.

The earthquakes of 1812 in the Mississippi Valley began in December, 1811, and continued at intervals until 1813. As a rule they were more distinguished by frequency than violence, though on several occasions they were severe and had marked effects. They extended through the valleys of the Mississippi, Arkansas and Ohio, and their long continuance was remarkable in view of the territory affected being far from any volcanic region.

The surface of the valley of the Mississippi was a good deal altered by these convulsions—several new lakes being formed, while others were drained. Several new islands were also raised in the river, and during one of the shocks the ground a little below New Madrid was for a short time lifted so high as to stop the current of the Mississippi, and cause it to flow backward. The ground on which this town is built, and the bank of the river for fifteen miles above it, subsided permanently about eight feet, and the cemetery of the town fell into the river. In the neighboring forest the trees were thrown into inclined positions in every direction, and many of their trunks and branches were broken. It is affirmed that in some places the ground swelled into great waves, which burst at their summits and poured forth jets of water, along with sand and pieces of coal, which were tossed as high as the tops of trees. On the subsidence of these waves, there were left several hundreds of hollow depressions from ten to thirty yards in diameter, and about twenty feet in depth, which remained visible for many years afterward. Some of the shocks were vertical, and others horizontal, the latter being the most mischievous. These earthquakes resulted in the general subsidence of a large tract of country, between seventy and eighty miles in length from north to south, and about thirty miles in breadth from east to west. Lakes now mark many of the localities affected by the earthquake movements. It is only to the fact that this country was then very thinly settled that a great loss of life was avoided.

New Madrid, Missouri, was a central point of this earthquake, the shocks there being repeated with great frequency for several months. The disturbance of the earth, however, was not confined to the United States, but affected nearly half of the western hemisphere, ending in the upheaval of Sabrina in the Azores, already described. The destruction of Caracas, Venezuela, with many thousands of its inhabitants, and the eruption of La Soufriere volcano of St. Vincent Island were incidents of this convulsion. Dr. J. W. Foster tells us that on the night of the disaster at Caracas the earthquake grew intense at New Madrid, fissures being opened six hundred feet long by twenty broad, from which water and sand were flung to the height of forty feet.

The most destructive of earthquakes in our former history was that which visited Charleston, South Carolina, in 1886, the injury caused by it being largely due to the fact that it passed through a populous city. As it occurred after many of the people had retired, the confusion and terror due to it were greatly augmented, people fleeing in panic fear from the tumbling and cracking houses to seek refuge in the widest streets and open spaces.

South Carolina had been affected by the wide-spread earthquakes of 1812. These in some cases altered the level of the land, as is related in Lyell's "Principles of Geology." But the effect then was much less than in 1886. Several slight tremors occurred in the early summer of that year, but did not excite much attention. More distinct shocks were felt on August 27th and 28th, but the climax was deferred till the evening of August 31st. The atmosphere that afternoon had been unusually sultry and quiet, the breeze from the ocean, which generally accompanies the rising tide, was almost entirely absent, and the setting sun caused a little glow in the sky.

"As the hour of 9.50 was reached," we are told, "there was suddenly heard a rushing, roaring sound, compared by some to a train of cars at no great distance, by others to a clatter produced by two or more omnibuses moving at a rapid rate over a paved street, by others again, to an escape of steam from a boiler. It was followed immediately by a thumping and beating of the earth beneath the houses, which rocked and swayed to and fro. Furniture was violently moved and dashed to the floor; pictures were swung from the walls, and in some cases turned with their backs to the front, and every movable thing was thrown into extraordinary convulsions. The greatest intensity of the shock is considered to have been during the first half, and it was probably then, during the period of its greatest sway, that so many chimneys were broken off at the junction of the roof. The duration of this severe shock is thought to have been from thirty-five to forty seconds. The impression produced on many was that it could be subdivided into three distinct movements, while others were of the opinion that it was one continuous movement, or succession of waves, with the greatest intensity, as already stated, during the first half of its duration."

Twenty-seven persons were killed outright, and more than that number died soon after of their hurts or from exposure; many others were less seriously injured. Among the buildings, the havoc, though much less disastrous than has been recorded in some other earthquakes in either hemisphere, was very great. "There was not a building in the city which had escaped serious injury. The extent of the damage varied greatly, ranging from total demolition down to the loss of chimney tops and the dislodgment of more or less plastering. The number of buildings which were completely demolished and levelled to the ground was not great; but there were several hundreds which lost a large portion of their walls. There were very many also which remained standing, but so badly shattered that public safety required that they should be pulled down altogether. There was not, so far as at present is known, a brick or stone building which was not more or less cracked, and in most of them the cracks were a permanent disfigurement and a source of danger and inconvenience." In some places the railway track was curiously distorted. "It was often displaced laterally, and sometimes alternately depressed and elevated. Occasionally several lateral flexures of double curvature and of great amount were exhibited. Many hundred yards of track had been shoved bodily to the south eastward."

The ground was fissured at some places in the city to a depth of many feet, and numerous "craterlets" were formed, from which sand was ejected in considerable quantities. These are not uncommon phenomena, and were due, no doubt, to the squirting of water out of saturated sandy layers not far below the surface; these being squeezed between two less pervious beds in the passage of the earthquake wave. The ejected material in the Charleston earthquake was ordinary sand, such as might exist in many districts which had been quite undisturbed by any concussions of the earth.

Captain Dutton made a careful study of the observations collected by himself and others concerning this earthquake, and came to the conclusion that the Charleston wave traveled with unusual speed, for its mean velocity was about 17,000 feet a second. The focus of the disturbance was also ascertained. Apparently it was a double one, the two centres being about thirteen miles apart, and the line joining them running nearly the same distance to the west of Charleston. The approximate depth of the principal focus is given as twelve miles, with a possible error of less than two miles; that of the minor one as roughly eight miles.

The Charleston earthquake was felt as a tremor of more or less force through a wide area, embracing 900,000 square miles, and affecting nearly the whole country east of the Mississippi. It is said that the yield of the Pennsylvania natural gas wells decreased, and that a geyser in the Yellowstone valley burst into action after four years of rest. The movement of the earth-wave was in general north and south, deflected to east and west, and the snake-like fashion in which rails on the railroad were bent indicated both a vertical and a lateral force.

This earthquake has been attributed to various causes, but geological experts think that it was due to a slip in the crust along the Appalachian Mountain chain. There is a line of weakness along the eastern slope of this chain, characterized by fissures and faults, and it was thought that a strain had been gradually brought to bear upon this through the removal of earth from the land by rains and rivers and its deposition in thick strata on the sea-bottom. It is supposed that this variation in weight in time caused a yielding of the strata and a slip seaward of the great coastal plain. Professor Mendenhall, however, thinks it was due to a readjustment of the earth's crust to its gradually sinking nucleus.



CHAPTER XVIII.

The Volcano and the Earthquake, Earth's Demons of Destruction.

To most of us, dwellers upon the face of the earth, this terrestrial sphere is quite a comfortable place of residence. The forces of Nature everywhere and at all times surround us, forces capable, if loosened from their bonds, of bringing death and destruction to man and the work of his hands. But usually they are mild and beneficent in their action, not agents of destruction and lords of elemental misrule. The air, without whose presence we could not survive a minute, is usually a pleasant companion, now resting about us in soft calm, now passing by in mild breezes. The alternation of summer and winter is to us generally an agreeable relief from the monotony of a uniform climate. The variation from sunlight to cloud, from dry weather to rainfall, is equally viewed as a pleasant escape from the weariness of too great fixity of natural conditions. The change from day to night, from hours of activity to hours of slumber, are other agreeable variations in the events of our daily life. In short, a great pendulum seems to be swinging above us, held in Nature's kindly hand, and adapting its movements to our best good and highest enjoyment.

But has Nature,—if we are justified in personifying the laws and forces of the universe,—has mother Nature really our pleasure and benefit in mind, or does she merely suffer us to enjoy life like so many summer insects, until she is in the mood to sweep us like leaves from her path? It must seem the latter to many of the inhabitants of the earth, especially to the dwellers in certain ill-conditioned regions. For all the beneficent powers above named may at a moment's notice change to destructive ones.

THE WIND IS A DEMON IN CHAINS

The wind, for instance, is a demon in chains. At times it breaks its fetters and rushes on in mad fury, rending and destroying, and sweeping such trifles as cities and those who dwell therein to common ruin. Sunshine and rain are subject to like wild caprices. The sun may pour down burning rays for weeks and months together, scorching the fertile fields, drying up the life-giving streams, bringing famine and misery to lands of plenty and comfort, almost making the blood to boil in our veins. Its antithesis, the rainstorm, is at times a still more terrible visitant. From the dense clouds pour frightful floods, rushing down the lofty hills, sweeping over fertile plains, overflowing broad river valleys, and, wherever they go, leaving terror and death in their path. We may say the same of the alternation of the seasons. Summer, while looked forward to with joyous anticipation, may bring us only suffering by its too ardent grasp; and winter, often welcomed with like pleasurable anticipations, may prove a period of terror from cold and destitution.

Such is the make-up of the world in which we live, such the vagaries of the forces which surround us. But those enumerated are not the whole. Can we say, with a stamp of the foot upon the solid earth, "Here at least I have something I can trust; let the winds blow and the rains descend, let the summer scorch and the winter chill, the good earth still stands firm beneath me, and of it at least I am sure?"

Who says so speaks hastily and heedlessly, for the earth can show itself as unstable as the air, and our solid footing become as insecure as the deck of a ship laboring in a storm at sea. The powers of the atmosphere, great as they are and mighty for destruction as they may become, are at times surpassed by those which abide within the earth, deep laid in the so-called everlasting rocks, slumbering often through generations, but at any time likely to awaken in wrath, to lift the earth into quaking billows like those of the sea, or pour forth torrents of liquid fire that flow in glowing and burning rivers over leagues of ruined land. Such is the earth with which we have to deal, such the ruthless powers of nature that spread around us and lurk beneath us, such the terrific forces which only bide their time to break forth and sweep too-confident man from the earth's smiling face.

THE SUBTERRANEAN POWERS

The subterranean powers here spoken of, those we had denominated earth's demons of destruction, are the volcano and the earthquake, the great moulding forces of the earth, tearing down to rebuild, rending to reconstitute, and in this elemental work often bringing ruin to man's boasted fanes and palaces.

No one who has ever seen a volcano or "burning mountain" casting forth steam, huge red-hot stones, smoke, cinders and lava, can possibly forget the grandeur of the spectacle. At night it is doubly terrible, when the darkness shows the red-hot lava rolling in glowing streams down the mountain's side. At times, indeed, the volcano is quiet, and only a little smoke curls from its top. Even this may cease, and the once burning summit may be covered over with trees and grass, like any other hill. But deep down in the earth the gases and pent-up steam, are ever preparing to force their way upward through the mountain, and to carry with them dissolved rocks, and the stones which block their passage. Sometimes, while all is calm and beautiful on the mountains, suddenly deep-sounding noises are heard, the ground shakes, and a vast torrent tears its way through the bowels of the volcano, and is flung hundreds of feet high in the air, and, falling again to the earth, destroys every living thing for miles around.

It is the same with the earthquake as with the volcano. The surface of the earth is never quite still. Tremors are constantly passing onward which can be distinguished by delicate instruments, but only rarely are these of sufficient force to become noticeable, except by instrumental means. At intervals, however, the power beneath the surface raises the ground in long, billow-like motions, before which, when of violent character, no edifice or human habitation can for a moment stand. The earth is frequently rent asunder, great fissures and cavities being formed. The course of rivers is changed and the waters are swallowed up by fissures rent in the surface, while ruin impends in a thousand forms. The cities become death pits and the cultivated fields are buried beneath floods of liquid mud. Fortunately these convulsions, alike of the earthquake and volcano, are comparative rarities and are confined to limited regions of the earth's surface. What do we know of those deep-lying powers, those vast buried forces dwelling in uneasy isolation beneath our feet? With all our science we are but a step beyond the ancients, to whom these were the Titans, great rebel giants whom Jupiter overthrew and bound under the burning mountains, and whose throes of agony shook the earth in quaking convulsions. To us the volcanic crater is the mouth from which comes the fiery breath of demon powers which dwell far down in the earth's crust. The Titans themselves were dwarfs beside these mighty agents of destruction whose domain extends for thousands of miles beneath the earth's surface and which in their convulsions shake whole continents at once. Such was the case in 1812, when the eruption of Mont Soufriere on St. Vincent, as told in a later chapter, formed merely the closing event in a series of earthquakes which had made themselves felt under thousands of miles of land.

ANCIENT AWE OF VOLCANOES

In olden times volcanoes were regarded with superstitious awe, and it would have been considered highly impious to make any investigation of their actions. We are told by Virgil that Mt. Etna marks the spot where the gods in their anger buried Enceladus, one of the rebellious giants. To our myth-making ancestors one of the volcanoes of the Mediterranean, set on a small island of the Lipari group, was the workshop of Vulcan, the god of fire, within whose depths he forged the thunderbolts of the gods. From below came sounds as of a mighty hammer on a vast anvil. Through the mountain vent came the black smoke and lurid glow from the fires of Vulcan's forge. This old myth is in many respects more consonant with the facts of nature than myths usually are. In agreement with the theory of its internal forces, the mountain in question was given the name of Volcano. To-day it is scarcely known at all, but its name clings to all the fire-breathing mountains of the earth.

As before said, at the present day we are little in advance of the ancients in actual knowledge of what is going on so far beneath our feet. We speak of forces where they spoke of fettered giants, but can only form theories where they formed myths. Is the earth's centre made up of liquid fire? Does its rock crust resemble the thick ice crust on the Arctic Seas, or is the earth, as later scientists believe, solid to the core? Is it heated so fiercely, miles below our feet, that at every release of pressure the solid rock bursts into molten lava? Is the steam from the contact of underground rivers and deep-lying fires the origin of the terrible rending powers of the volcano's depths? Truly we can answer none of these questions with assurance, and can only guess and conjecture from the few facts open to us what lies concealed far beneath.

RARITY OF ANCIENT ACCOUNTS

In the history of earthquakes nothing is more remarkable than the extreme fewness of those recorded before the beginning of the Christian era, in comparison with those that have been registered since that time. It is to be borne in mind, however, that before the birth of Christ only a small portion of the globe was inhabited by those likely to make a record of natural events. The vast apparent increase in the number of earthquakes in recent times is owing to a greater knowledge of the earth's surface and to the spread of civilization over lands once inhabited by savages. The same is to be said of volcanic eruptions, which also have apparently increased greatly since the beginning of the Christian era. There may possibly have been a natural increase in these phenomena, but this is hardly probable, the change being more likely due to the increase in the number of observers.

The structure of a volcano is very different from that of other mountains, really consisting of layers of lava and volcanic ashes, alternating with each other and all sloping away from the center. These elevations, in fact, are formed in a different manner from ordinary mountains. The latter have been uplifted by the influence of pressure in the interior of the earth, but the volcano is an immediate result of the explosive force of which we have spoken, the mountain being gradually built up by the lava and other materials which it has flung up from below. In this way mountains of immense height and remarkable regularity have been formed. Mount Orizabo, near the City of Mexico, for instance, is a remarkably regular cone, undoubtedly formed in this way, and the same may be said of Mount Mayon, on the Island of Luzon.

In many cases the irregularity of the volcano is due to subsequent action of its forces, which may blow the mountain itself to pieces. In the case of Krakatoa, in the East Indies, for instance, the whole mountain was rent into fragments, which were flung as dust miles high into the air. The main point we wish to indicate is that volcanoes are never formed by ordinary elevating forces and that they differ in this way from all other mountains. On the contrary, they have been piled up like rubbish heaps, resembling the small mountains of coal dust near the mouths of anthracite mines.

It is to the burning heat of the earth's crust and the influence of pressure, and more largely to the influx of water to the molten rocks which lie miles below the surface, that these convulsions of nature are due. Water, on reaching these overheated strata, explodes into volumes of steam, and if there is no free vent to the surface, it is apt to rend the very mountain asunder in its efforts to escape. Such is supposed to have been the case in the eruption of Krakatoa, and was probably the case also in the recent case of Mt. Pelee.

GENERAL DESCRIPTION OF ERUPTIONS

If we should seek to give a general description of volcanic eruptions, it would be in some such words as follows: An eruption is usually preceded by earthquakes which affect the whole surrounding country, and associated with which are underground explosions that seem like the sound of distant artillery. The mountain quivers with internal convulsions, due to the efforts of its confined forces to find an opening. The drying up of wells and disappearance of springs are apt to take place, the water sinking downward through cracks newly made in the rocks. Finally the fierce unchained energy rends an opening through the crater and an eruption begins. It comes usually with a terrible burst that shakes the mountain to its foundation; explosions following rapidly and with increasing violence, while steam issues and mounts upward in a lofty column. The steam and escaping gases in their fierce outbreaks hurl up into the air great quantities of solid rock torn from the sides of the opening. The huge blocks, meeting each other in their rise and fall, are gradually broken and ground into minute fragments, forming dust or so-called ashes, often of extreme fineness, and in such quantities as frequently to blot out the light of the sun. There is another way in which a great deal of volcanic dust is made; the lava is full of steam, which in its expansion tears the molten rock into atoms, often converting it into the finest dust.

The eruption of Mt. Skaptar, in Iceland, in 1783, sent up such volumes of dust that the atmosphere was loaded with it for months, and it was carried to the northern part of Scotland, 600 miles away, in such quantities as to destroy the crops. During the eruption of Tomboro, in the East Indies, in 1815, so great was the quantity of dust thrown up that it caused darkness at midday in Java 300 miles away and covered the ground to a depth of several inches. Floating pumice formed a layer on the ocean surface two and a half feet in thickness, through which vessels had difficulty in forcing their way.

The steam which rises in large volumes into the air may become suddenly condensed with the chill of the upper atmosphere and fall as rain, torrents of which often follow an eruption. The rain, falling through the clouds of volcanic dust, brings it to the earth as liquid mud, which pours in thick streams down the sides of the mountain. The torrents of flowing mud are sometimes on such a great scale that large towns, as in the instance of the great city of Herculaneum, may be completely buried beneath them. Over this city the mud accumulated to the depth of over 70 feet. In addition to these phenomena, molten lava often flows from the lip of the crater, occasionally in vast quantities. In the Icelandic eruption of 1783 the lava streams were so great in quantity as to fill river gorges 600 ft. deep and 200 ft. wide, and to extend over an open plain to a distance of 12 to 15 miles, forming lakes of lava 100 feet deep. The volcanoes of Hawaii often send forth streams of lava which cover an area of over 100 square miles to a great depth.

GREAT OUTFLOWS OF LAVA

In the course of ages lava outflows of this kind have built up in Hawaii a volcanic mountain estimated to contain enough material to cover the whole of the United States with a layer of rock 50 feet deep. These great outflows of lava are not confined to mountains, but take place now and then from openings in the ground, or from long cracks in the surface rocks. Occasionally great eruptions have taken place beneath the ocean's surface, throwing up material in sufficient quantity to form new islands.

The formation of mud is not confined to the method given, but great quantities of this plastic material flow at times from volcanic craters. In the year 1691 Imbaburu, one of the peaks of the Andes, sent out floods of mud which contained dead fish in such abundance that their decay caused a fever in the vicinity. The volcanoes of Java have often buried large tracts of fertile country under volcanic mud.

An observation of volcanoes shows us that they have three well marked phases of action. The first of these is the state of permanent eruption, as in case of the volcano of Stromboli in the Mediterranean. This state is not a dangerous one, since the steam, escaping continually, acts as a safety valve. The second stage is one of milder activity with an occasional somewhat violent eruption; this is apt to be dangerous, though not often very greatly so. The safety valve is partly out of order. The third phase is one in which long periods of repose, sometimes lasting for centuries, are followed by eruptions of intense energy. These are often of extreme violence and cause widespread destruction. In this case the safety valve has failed to work and the boiler bursts.

OFTEN REST FOR LONG TERMS OF YEARS

Such are the general features of action in the vast powers which dwell deep beneath the surface, harmless in most parts of the earth, frightfully perilous in others. Yet even here they often rest for long terms of years in seeming apathy, until men gather above their lurking places in multitudes, heedless or ignorant of the sleeping demons that bide their time below. Their time is sure to come, after years, perhaps after centuries. Suddenly the solid earth begins to tremble and quake; roars as of one of the buried giants of old strike all men with dread; then, with a fierce convulsion, a mountain is rent in twain and vast torrents of steam, burning rock, and blinding dust are hurled far upward into the air, to fall again and bury cities, perhaps, with all their inhabitants in indiscriminate ruin and death.



CHAPTER XIX.

Theories of Volcanic and Earthquake Action.

Though the first formation of a volcano (Italian, vulcano, from Vulcan, the Roman god of fire) has seldom been witnessed, it would seem that it is marked by earthquake movements followed by the opening of a rent or fissure; but with no such tilting up of the rocks as was once supposed to take place. From this fissure large volumes of steam issue, accompanied by hydrogen, nitrogen, carbon dioxide, hydrochloric acid, and sulphur dioxide. The hydrogen, apparently derived from the dissociation of water at a high temperature, flashes explosively into union with atmospheric oxygen, and, having exerted its explosive force, the steam condenses into cloud, heavy masses of which overhang the volcano, pouring down copious rains. This naturally disturbs the electrical condition of the atmosphere, so that thunder and lightning are frequent accompaniments of an eruption. The hydrochloric acid probably points to the agency of sea-water. Besides the gases just mentioned, sulphuretted hydrogen, ammonia and common salt occur; but mainly as secondary products, formed by the union of the vapors issuing from the volcano, and commonly found also in the vapors rising from cooling lava streams or dormant volcanic districts. It is important to notice that the vapors issue from the volcano spasmodically, explosions succeeding each other with great rapidity and noise.

All substances thrown out by the volcano, whether gaseous, liquid or solid, are conveniently united under the term ejectamenta (Latin, things thrown out), and all of them are in an intensely heated, if not an incandescent state. Most of the gases are incombustible, but the hydrogen and those containing sulphur burn with a true flame, perhaps rendered more visible by the presence of solid particles. Much of the so-called flame, however, in popular descriptions of eruptions is an error of observation due to the red-hot solid particles and the reflection of the glowing orifice on the over-hanging clouds.

ENORMOUS FORCE DISPLAYED

Solid bodies are thrown into the air with enormous force and to proportionally great heights, those not projected vertically falling in consequence at considerable distances from the volcano. A block weighing 200 tons is said to have been thrown nine miles by Cotopaxi; masses of rock weighing as much as twenty tons to have been ejected by Mount Ararat in 1840; and stones to have been hurled to a distance of thirty-six miles in other cases. The solid matter thrown out by volcanoes consists of lapilli, scoriae, dust and bombs.

Though on the first formation of the volcano, masses of non-volcanic rock may be torn from the chimney or pipe of the mountain, only slightly fused externally owing to the bad conducting power of most rocks, and hurled to a distance; and though at the beginning of a subsequent eruption the solid plug of rock which has cooled at the bottom of the crater, or, in fact, any part of the volcano, may be similarly blown up, the bulk of the solid particles of which the volcano itself is composed is derived from the lake of lava or molten rock which seethes at the orifice. Solid pieces rent from this fused mass and cast up by the explosive force of the steam with which the lava is saturated are known as lapilli. Cooling rapidly so as to be glassy in texture externally, these often have time to become perfectly crystalline within.

Gases and steam escaping from other similar masses may leave them hollow, when they are termed bombs, or may pit their surfaces with irregular bubble-cavities, when they are called scoriae or scoriaceous. Such masses whirling through the air in a plastic state often become more or less oblately spheroidal in form; but, as often, the explosive force of their contained vapors shatters them into fragments, producing quantities of the finest volcanic dust or sand. This fine dust darkens the clouds overhanging the mountain, mixes with the condensed steam to fall as a black mud-rain, or lava di aqua (Italian, water lava), or is carried up to enormous heights, and then slowly diffused by upper currents of the atmosphere. In the eruption of Vesuvius of A.D. 79, the air was dark as midnight for twelve or fifteen miles round; the city of Pompeii was buried beneath a deposit of dry scoriae, or ashes and dust, and Herculaneum beneath a layer of the mud-like lava di aqua, which on drying sets into a compact rock. Rocks formed from these fragmentary volcanic materials are known as tuff.

VOLCANIC CONES HAVE SIMILAR CURVATURES

It is entirely of these cindery fragments heaped up with marvellous rapidity round the orifice that the volcano itself is first formed. It may, as in the case of Jorullo in Mexico in 1759, form a cone several hundred feet high in less than a day. Such a cone may have a slope as steep as 30 or 40 degrees, its incline in all cases depending simply on the angle of repose of its materials; the inclination, that is, at which they stop rolling. The great volcanoes of the Andes, which are formed mainly of ash, are very steep. Owing to a general similarity in their materials, volcanic cones in all parts of the world have very similar curvatures; but older volcanic mountains, in which lava-streams have broken through the cone, secondary cones have arisen, or portions have been blown up, are more irregular in outline and more gradual in inclination.

In size, volcanoes vary from mere mounds a few yards in diameter, such as the salses or mud volcanoes near the Caspian, to Etna, 10,800 feet high, with a base 30 miles in diameter; Cotopaxi, in the Andes, 18,887 feet high; or Mauna Loa, in the Sandwich Isles, 13,700 feet high; with a base 70 miles in diameter, and two craters, one of which, Kilauea, the largest active crater on our earth, is seven miles in circuit. Larger extinct craters occur in Japan; but all our terrestrial volcanic mountains are dwarfed by those observed on the surface of the moon, which, owing to its smaller size, has cooled more rapidly than our earth. It is, of course, the explosive force from below which keeps the crater clear, as a cup-shaped hollow, truncating the cone; and all stones falling into it would be only thrown out again. It may at the close of an eruption cool down so completely that a lake can form within it, such as Lake Averno, near Naples; or it may long remain a seething sea of lava, such as Kilauea; or the lava may find one or more outlets from it, either by welling over its rim, which it will then generally break down, as in many of the small extinct volcanoes ("puys") of Auvergne, or more usually by bursting through the sides of the cone.

LAVA VARIES VERY MUCH IN LIQUIDITY

It is not generally until the volcano has exhausted its first explosive force that lava begins to issue. Several streams may issue in different directions. Their dimensions are sometimes enormous. Lava varies very much in liquidity and in the rate at which it flows. This much depends, however, upon the slope it has to traverse. A lava stream at Vesuvius ran three miles in four minutes, but took three hours to flow the next three miles, while a stream from Mauna Loa ran eighteen miles in two hours. Glowing at first as a white-hot liquid, the lava soon cools at the surface to red and then to black; cinder-like scoriaceous masses form on its surface and in front of the slowly-advancing mass; clouds of steam and other vapor rise from it, and little cones are thrown up from its surface; but many years may elapse before the mass is cooled through. Thus, while the surface is glassy, the interior becomes crystalline.

As to what are the causes of the great convulsions of nature known as the volcano and the earthquake we know very little. Various theories have been advanced, but nothing by any means sure has been discovered, and considerable difference of opinion exists. In truth we know so little concerning the conditions existing in the earth's interior that any views concerning the forces at work there must necessarily be largely conjectural.

Sir Robert S. Ball says, in this connection: "Let us take, for instance, that primary question in terrestrial physics, as to whether the interior of the earth is liquid or solid. If we were to judge merely from the temperatures reasonably believed to exist at a depth of some twenty miles, and if we might overlook the question of pressure, we should certainly say that the earth's interior must be in a fluid state. It seems at least certain that the temperatures to be found at depths of two score miles, and still more at greater depths, must be so high that the most refractory solids, whether metals or minerals, would at once yield if we could subject them to such temperatures in our laboratories. But none of our laboratory experiments can tell us whether, under the pressure of thousands of tons on the square inch, the application of any heat whatever would be adequate to transform solids into liquids. It may, indeed, be reasonably doubted whether the terms solid and liquid are applicable, in the sense in which we understand them, to the materials forming the interior of the earth.

"A principle, already well known in the arts, is that many, if not all, solids may be made to flow like liquids if only adequate pressure be applied. The making of lead tubes is a well-known practical illustration of this principle, for these tubes are formed simply by forcing solid lead by the hydraulic press through a mould which imparts the desired shape.

"If then a solid can be made to behave like a liquid, even with such pressures as are within our control, how are we to suppose that the solids would behave with such pressures as those to which they are subjected in the interior of the earth? The fact is that the terms solid and liquid, at least as we understand them, appear to have no physical meaning with regard to bodies subjected to these stupendous pressures, and this must be carefully borne in mind when we are discussing the nature of the interior of the earth."

THE VOLCANO A SAFETY VALVE

Whatever be the state of affairs in the depths of the earth's crust, we may look upon the volcano as a sort of safety-valve, opening a passage for the pent-up forces to the surface, and thus relieving the earth from the terrible effects of the earthquake, through which these imprisoned powers so often make themselves felt. Without the volcanic vent there might be no safety for man on the earth's unquiet face.

Professor J. C. Russell, of Michigan University, presents the following views concerning the status and action of volcanoes:—

"When reduced to its simplest terms, a volcano may be defined as a tube, or conduit, in the earth's crust, through which the molten rock is forced to the surface. The conduit penetrates the cool and rigid rocks forming the superficial portion of the earth, and reaches its highly heated interior.

"The length of volcanic conduits can only be conjectured, but, judging from the approximately known rate of increase of heat with depth (on an average one degree Fahrenheit for each sixty feet), and the temperature at which volcanic rocks melt (from 2,300 to 2,700 degrees Fahrenheit, when not under pressure), they must seemingly have a depth of at least twenty miles. There are other factors to be considered, but in general terms it is safe to assume that the conduits of volcanoes are irregular openings, many miles in depth, which furnish passageways for molten rock (lava) from the highly-heated sub-crust portion of the earth to its surface. . . ."

ERUPTIONS OF QUIET TYPE

"During eruptions of the quiet type, the lava comes to the surface in a highly liquid condition—that is, it is thoroughly fused, and flows with almost the freedom of water. It spreads widely, even on a nearly level plain, and may form a comparatively thin sheet several hundred square miles in area, as has been observed in Iceland and Hawaii. On the Snake River plains, in Southern Idaho, there are sheets of once molten rock which were poured out in the manner just stated, some four hundred square miles in area and not over seventy-five feet in average thickness. When an eruption of highly liquid lava occurs in a mountainous region, the molten rock may cascade down deep slopes and flow through narrow valleys for fifty miles or more before becoming chilled sufficiently to arrest its progress. Instances are abundant where quiet eruptions have occurred in the midst of a plain, and built up 'lava cones,' or low mounds, with immensely expanded bases. Illustrations are furnished in Southern Idaho, in which the cones formed are only three hundred or four hundred feet high, but have a breadth at the base of eight or ten miles. In the class of eruption illustrated by these examples, there is an absence of fragmental material, such as explosive volcanoes hurl into the air, and a person may stand within a few yards of a rushing stream of molten rock, or examine closely the opening from which it is being poured out, without danger or serious inconvenience.

"The quiet volcanic eruptions are attended by the escape of steam or gases from the molten rock, but the lava being in a highly liquid state, the steam and gases dissolved in it escape quietly and without explosions. If, however, the molten rock is less completely fluid, or in a viscous condition, the vapors and gases contained in it find difficulty in escaping, and may be retained until, becoming concentrated in large volume, they break their way to the surface, producing violent explosions. Volcanoes in which the lava extruded is viscous, and the escape of steam and gases is retarded until the pent-up energy bursts all bounds, are of the explosive, type. One characteristic example is Vesuvius.

"When steam escapes from the summit of a volcanic conduit—which, in plain terms, is a tall vessel filled with intensely hot and more or less viscous liquid—masses of the liquid rock are blown into the air, and on falling build up a rim or crater about the place of discharge. Commonly the lava in the summit portion of a conduit becomes chilled and perhaps hardened, and when a steam explosion occurs this crust is shattered and the fragments hurled into the air and contributed to the building of the walls of the inclosing crater.

"The solid rock blown out by volcanoes consists usually of highly vesicular material which hardened on the surface of the column of lava within a conduit and was shattered by explosions beneath it. These fragments vary in size from dust particles up to masses several feet in diameter, and during violent eruptions are hurled miles high. The larger fragments commonly fall near their place of origin, and usually furnish the principal part of the material of which craters are built, but the gravel-like kernels, lapilli, may be carried laterally several miles if a wind is blowing, while the dust is frequently showered down on thousands of square miles of land and sea. The solid and usually angular fragments manufactured in this manner vary in temperature, and may still be red hot on falling.

"Volcanoes of the explosive type not uncommonly discharge streams of lava, which may flow many miles. In certain instances these outwellings of liquid rock occur after severe earthquakes and violent explosions, and may have all the characteristics of quiet eruptions. There is thus no fundamental difference between the two types into which it is convenient to divide volcanoes."

MOUNTAINS BLOW THEIR HEADS OFF

"In extreme examples of explosive volcanoes, the summit portion of a crater, perhaps several miles in circumference and several thousand feet high, is blown away. Such an occurrence is recorded in the case of the volcano Coseguina, Nicaragua, in 1835. Or, an entire mountain may disappear, being reduced to lapilli and dust and blown into the air, as in the case of Krakatoa, in the Straits of Sunda, in 1883.

"The essential feature of a volcano, as stated above, is a tube or conduit, leading from the highly heated sub-crust portion of the earth to the crater and through which molten rock is forced upward to the surface. The most marked variations in the process depend on the quantity of molten rock extruded, and on the freedom of escape of the steam and gases contained in the lava.

"The cause of the rise of the molten rock in a volcano is still a matter for discussion. Certain geologists contend that steam is the sole motive power; while others consider that the lava is forced to the surface owing to pressure on the reservoir from which it comes. The view perhaps most favorably entertained at present, in reference to the general nature of volcanic eruptions, is that the rigid outer portion of the earth becomes fractured, owing principally to movements resulting from the shrinking of the cooling inner mass, and that the intensely hot material reached by the fissures, previously solid owing to pressure, becomes liquid when pressure is relieved, and is forced to the surface. As the molten material rises it invades the water-charged rocks near the surface and acquires steam, or the gases resulting from the decomposition of water, and a new force is added which produces the most conspicuous and at times the most terrible phenomena accompanying eruptions."

The active agency of water is strongly maintained by many geologists, and certainly gains support from the vast clouds of steam given off by volcanoes in eruption and the steady and quiet emission of steam from many in a state of rest. The quantities of water in the liquid state, to which is due the frequent enormous outflows of mud, leads to the same conclusion. Many scientists, indeed, while admitting the agency of water, look upon this as the aqueous material originally pent up within the rocks. For instance Professor Shaler, dean of the Lawrence Scientific School, says:

"Volcanic outbreaks are merely the explosion of steam under high pressure, steam which is bound in rocks buried underneath the surface of the earth and there subjected to such tremendous heat that when the conditions are right its pent-up energy breaks forth and it shatters its stone prison walls into dust. The process by which the water becomes buried in this manner is a long one. Some contend that it leaks down from the surface of the earth through fissures in the outer crust, but this theory is not generally accepted. The common belief is that water enters the rocks during the crystalization period, and that these rocks through the natural action of rivers and streams become deposited in the bottom of the ocean. Here they lie for many ages, becoming buried deeper and deeper under masses of like sediment, which are constantly being washed down upon them from above. This process is called the blanketing process.

"Each additional layer of sediment, while not raising the level of the sea bottom, buries the first layers just so much the deeper and adds to their temperature just as does the laying of extra blankets on a bed. When the first layer has reached a depth of a few thousand feet the rocks which contain the water of crystalization are subjected to a terrific heat. This heat generates steam, which is held in a state of frightful tension in its rocky prison. Wrinklings in the outer crust of the earth's surface occur, caused by the constant shrinking of the earth itself and by the contraction of the outer surface as it settles on the plastic centers underneath. Fissures are caused by these foldings, and as these fissures reach down into the earth the pressure is removed from the rocks and the compressed steam in them, being released, explodes with tremendous force."

This view is, very probably, applicable to many cases, and the exceedingly fine dust which so often rises from volcanoes has, doubtless, for one of its causes the sudden and explosive conversion of water into steam in the interior of ejected lava, thus rending it into innumerable fragments. But that this is the sole mode of action of water in volcanic eruptions is very questionable. It certainly does not agree with the immense volumes at times thrown out, while explosions of such extreme intensity as that of Krakatoa very strongly lead to the conclusion that a great mass of water has made its way through newly opened fissures to the level of molten rock, and exploded into steam with a suddenness which gave it the rending force of dynamite or the other powerful chemical explosives.

As the earthquake is so intimately associated with the volcano the causes of the latter are in great measure the causes of the former, and the forces at work frequently produce a more or less violent quaking of the earth's surface before they succeed in opening a channel of escape through the mountain's heart. One agency of great potency, and one whose work never ceases, has doubtless much to do with earthquake action. In the description of this we cannot do better than to quote from "The Earth's Beginning" of Sir Robert S. Ball.

CAUSE OF EARTHQUAKES

"As to the immediate cause of earthquakes there is no doubt considerable difference of opinion. But I think it will not be doubted that an earthquake is one of the consequences, though perhaps a remote one, of the gradual loss of internal heat from the earth. As this terrestrial heat is gradually declining, it follows from the law that we have already so often had occasion to use that the bulk of the earth must be shrinking. No doubt the diminution in the earth's diameter due to the loss of heat must be exceedingly small, even in a long period of time. The cause, however, is continually in operation, and, accordingly, the crust of the earth has from time to time to be accommodated to the fact that the whole globe is lessening. The circumference of our earth at the equator must be gradually declining; a certain length in that circumference is lost each year. We may admit that loss to be a quantity far too small to be measured by any observations as yet obtainable, but, nevertheless, it is productive of phenomena so important that it cannot be overlooked.

"It follows from these considerations that the rocks which form the earth's crust over the surface of the continents and the islands, or beneath the bed of the ocean, must have a lessening acreage year by year. These rocks must therefore submit to compression, either continuously or from time to time, and the necessary yielding of the rocks will in general take place in those regions where the materials of the earth's crust happen to have comparatively small powers of resistance. The acts of compression will often, and perhaps generally, not proceed with uniformity, but rather with small successive shifts, and even though the displacements of the rocks in these shifts be actually very small, yet the pressures to which the rocks are subjected are so vast that a very small shift may correspond to a very great terrestrial disturbance.

"Suppose, for instance, that there is a slight shift in the rocks on each side of a crack, or fault, at a depth of ten miles. It must be remembered that the pressure ten miles down would be about thirty-five tons to the square inch. Even a slight displacement of one extensive surface over another, the sides being pressed together with a force of thirty-five tons on the square inch, would be an operation necessarily accompanied by violence greatly exceeding that which we might expect from so small a displacement if the forces concerned had been of more ordinary magnitude. On account of this great multiplication of the intensity of the phenomenon, merely a small rearrangement of the rocks in the crust of the earth, in pursuance of the necessary work of accommodating its volume to the perpetual shrinkage, might produce an excessively violent shock, extending far and wide. The effect of such a shock would be propagated in the form of waves through the globe, just as a violent blow given at one end of a bar of iron by a hammer is propagated through the bar in the form of waves. When the effect of this internal adjustment reaches the earth's surface it will sometimes be great enough to be perceptible in the shaking it gives that surface. The shaking may be so violent that buildings may not be able to withstand it. Such is the phenomenon of an earthquake.