Organic life is the product of forces which arrive at the surface of the earth from two different directions; the one descending to us from the sun, the other coming up from the central regions of the earth. In the narrow zone, not over six miles thick, lying between the two great centres of energy, the one distant but a few hundred miles, the other nearly one hundred million, is developed that life which we are apt to deem the main object of the operation of the universe. The limitation of life in time is as great as its limitation in space; being dependent on two variable sources of force, the conditions which admit of its existence are inexpressibly precarious. A considerable increase in the amount of either force, or any considerable decrease in the amount of that received from the sun, would at once bring it to an end. At a recent period in the history of our solar system, the heat of the earth was so great that the zone now occupied by life was the scene of contending elements; and at a future time almost measurably distant, when the other great source of energy, the sun, shall become in like manner stilled, when the great struggle between matter and heat now going on there shall be over, this little oasis of life, in the midst of the expanse of matter which obeys only physical laws, will cease to be.
It is surprising to compare the relative character of the two sources of energy and the quantities of the force we receive from them. That which we receive from celestial sources comes to us softened and equalized by the distance it traverses. The inconceivable convulsions of the sun, the flames a million of miles high which burst from the fiery mass, the furious sounds which accompany this great struggle of matter with creative force, are quite lost in space, and there come to us only the equable and beneficent light and heat. We should have remained ignorant of the convulsions which attend the evolution of these properties, if we had been compelled to perceive them in their effects on the surface of the earth.
All the force which enters into the development of life has a celestial origin; and not only organic life, but all those symmetrical movements of matter upon the surface of the earth, which give a sort of life to the earth itself, have their source in the celestial bodies. The circulation of the waters from the oceans through the air to the lands, and back through the rivers to the sea, the currents of the air, and their product, the oceanic streams, are the direct result of solar heat. The whole structure of life, extending through a past of almost limitless duration, is scarcely more than embodied sunshine. The store of force contained within sedimentary strata, in the form of coal, is the product of solar action in past geological periods—is, in fact, fossil sunshine. The envelope of stratified rocks which has smoothed down the external irregularities of the earth, — giving us in place of a surface as rough as that the moon turns toward us, the regular combination of mountain and plain, of table-land and valley, — is the result of solar heat operating through the agency of water. It is now more than probable that the greater changes in the history of life on our earth, by which life has been advanced step by step from the simplicity of its origin to its present complication, are due to the combined effects of the attraction of the sun and planets upon the path of our earth around the sun.
According to this hypothesis, the varying position of the planets in relation to our earth has produced the alternations of temperature, which at many successive times have spread a glacial covering over the continents, extinguishing one assemblage of life to make way for another and higher development. If this be true, it is to celestial forces we must attribute the lifting and lowering of the great ice curtain, which has divided the successive acts of the drama of life.
The wildest dreams of the astrologers concerning the influence of the heavenly bodies over the destiny of living things are far surpassed by the truth if it be not true that our individual lives are the result of accidental influences of the stars, it is still unquestionable that we, as well as that life of which our lives are but a part, are the product of forces originating above the earth.
While the forces derived from celestial sources are uniform in their operation, those which come from beneath our feet are in the main irregular and spasmodic. Most of the phenomena which are referable to the action of telluric energy show the operation of discontinuous and violent forces. In the irregular action of earthquakes and volcanoes, or in the systems of mountains where the stratified materials laid down on old sea floors under the operation of uniform celestial forces are upheaved and contorted, we may see how different is the mode of action of the forces which originate within the earth, from that of the forces which come from above. Observations, which are too well verified to be questioned, show us that at the depth of a few miles the heat of the earth is sufficient to melt the most refractory materials, or convert them into gases, if it could be applied to them at the surface. If we made what is generally believed to be a legitimate inference from the phenomena, and concluded that an uniform increase of one degree of Fahrenheit attends every sixty feet of descent, then we should be compelled to suppose that the central region of the earth has a temperature of at least three hundred and thirty-three thousand degrees. Of this energy accumulated in the form of heat within the earth, we know happily but little from its immediate effects. Of the total supply of heat which the surface of the earth receives, not one thirty-fifth part comes from the interior, and of this fraction the greater part is so irregularly diffused, owing to the fact that it comes to the surface at a few points of volcanic eruption, that it cannot have any considerable influence on the development of life, or the production of movement in inorganic matter at the surface.1 The other chief element of vital activity, the chemical rays of sunshine, come entirely from the sun; so that there can be no doubt that no trace of life could ever have existed, had it depended on the forces originating on or within the earth. As yet we know too little of those forms of energies termed magnetism and electricity, to determine their effect in producing the organic and inorganic movements of matter, or the proportion in which they are produced by the two sources of force, the earth’s interior and the sun. There are some facts, however, which may fairly lead us to conclude it to be eminently probable that we owe at least the main part of these forces to the celestial centre. A relation has been observed between the great disturbances of the sun’s surface and the magnetic storms of our earth.
As far as all active influence in the production of vital activity on the surface of the earth is concerned, the focus beneath our feet may be regarded as practically inoperative; nor is it at all probable that, at any time in the past, it contributed anything towards the development of animal life; nor could it ever have had a share in the production of any of the constant movements of matter upon the earth’s surface, such as we find affecting the atmosphere or ocean. Unlike those features, which possess a certain symmetry, the movements produced by the energy which comes to us from the interior of the earth have all a convulsive character. It is as a disturbing agent, operating to produce interruptions in the even course of the action of the forces which come from without the earth, that the energy of the interior has its chief value. Considered from this point of view, it has a very great importance. The physical results of this collision between the forces derived from the two sources are apparent on every side. Their parts in the production of the great features of the earth are essentially antagonistic. While the telluric forces tend to give a great variety to the surface of the earth, producing the folds of the continents and the ridges of the mountain chains, the celestial forces, acting through the water which they cast upon the land in the form of rain and snow, or drive upon the shores by wind and tide, operate continually to reduce that surface to a uniform level. The effect of animal and vegetable life, the product as we have seen of solar forces, is to aid the great levelling process. The coral reefs and other products of the sea, the organic products of the land which are borne to the seas by the rivers, all tend to fill up the ocean basins which the telluric forces are always at work to deepen. When the waters first descended upon the surface of the earth, they doubtless formed a tolerably uniform expanse over the whole space now occupied by both land and water. In this condition of the earth, the solar forces would operate upon the air and ocean, uninterrupted by the action of the internal forces. The currents of both air and ocean would have over the universal sea the same uniformity of movement which we now find only in the Central Pacific Ocean. Two belts of trade-winds, one on either side of the equator, would form the only important atmospheric movements, and their product, a single equatorial oceanic current, would encircle the earth with its uniform stream. All the isothermal lines would be parallel with the equator, and each hemisphere would have the same conditions of climate under the same parallels. Animal life, the measure of climatic differences, would not present any great variety in a world of such uniformity of conditions; it would not advance beyond the simplicity which accorded with the conditions surrounding it. The knowledge, which the labors of the geologist have given us of the early life of our earth, assures us of the truth of this supposition. Into this uniformity the action of telluric forces soon began to introduce variety. As the heat flowed out from the interior of the earth, the crust had to accommodate itself to the diminished nucleus; to do this, the regions now occupied by the sea-floors bowed downwards, and the continental ridges lifted themselves upwards out of the sea. This at once broke the uniformity which prevailed during the uncontested reign of the solar forces. The equatorial ocean stream became broken into several smaller currents, forming a pair of vortical movements such as we now find in the Gulf Stream, wherever the uprising continent crossed its path. The regular course of the winds was broken up, each continent becoming the centre of meteorological disturbances, so that only in the remaining spaces of broad ocean could the typical regularity of movement of air and ocean be perceived. On the surface of the broad folds of the continents, the internal forces raised the mountain chains these break the movements of the aerial ocean, as the continents broke the currents of the sea.
Thus in the waters and in the air uniformity was replaced by variety, through the action of telluric forces. But the result of the intermixture of the effects of these internal forces with those coming from above is even greater in organic nature than upon the physical features of the earth’s surface. With varied climates came a varied life. In the range of conditions between the summits of the mountains and the bottoms of the sea’s life found a variety of circumstances influencing its development, and assumed a diversity of structure impossible before the telluric influences had given a greater variety to the theatre of life than was afforded by the uniform ocean floors. The influence of height alone in determining variety in both sea and land, animals and plants, is very great, but many other efficient causes, all operating in the same direction, were brought into action by the division of the universal ocean. The single equatorial stream girdling the earth favored the uniform development of life throughout the different zones. The closed currents, which were formed when this stream was broken up by the uprising continents, caused a limitation of life which could not have existed before. By carrying tropical warmth towards the poles, and in return bringing the temperature and creatures of the frozen regions towards the equator, the uniform zone, character of temperature, and life were greatly changed. Instead came the division of life by basins, which gives the complicated relations of the floras and faunas now existing.
Thus, on every side, we find the telluric forces operating to introduce variety into the previously more uniform conditions. Nor is this limited to the surface beneath it, on the rocks which are laid own on the ocean floors by the solar forces, the same diversifying agent is at work. In these beds of uniform materials the telluric heat begins to work, and gradually transforms them into very different substances.
Through the uniform limestones and sandstones fissures are riven; these, by the further working of the central heat, become filled with the varied materials which charge our mineral veins. So when the forces of the interior have completed their work of metamorphism, and have lifted into the atmosphere the beds which the celestial forces laid down on the ocean floors, the telluric forces have filled the originally uniform beds with varied substances, from which soils gain the variety enabling them to support a diversified life, and man will derive those materials which are to render possible his highest development. The way in which the uniform solar and irregular telluric forces co-operate in the production of their results is well illustrated by the history of the formation of our coal seams. First, the sunshine develops the plants, supplying the force necessary to separate the carbon from the atmosphere and its accumulation in the remains of a luxurious vegetation. Then, by the action of internal forces, the bed of vegetable matter is sunk beneath the sea. As it goes gradually down, the solar forces heap upon it sediment worn from the land, together with the remains of other organic forms. All the while the telluric forces are acting; and the heat which is drawn towards the original surface, by the newly deposited materials acting as a non-conductor, so increases the temperature of the buried plants that, combined with the moisture and pressure, it converts the bed of plants into coal. Now the variable internal forces cause the stratum of coal to begin to rise, and at length bring it again to the surface, where the solar forces, by rain or wave, sweep away the rocks which covered it, and thus, by undoing their work, render this store of solar force accessible to man.
If the telluric forces should ever cease to lift up the continents and deepen the seas, the solar forces acting in moving water would in time wear down the lands and restore the universal shallow ocean. The internal changes, on which the movements of the continental folds and sea floors depend, are likely to cease long before the solar force shall have become exhausted.
It is, then, by no means impossible that the complicated evolution of life may be succeeded by a gradual return to simplicity, brought about by a restoration of the uniform physical conditions which ushered life upon the earth’s surface. Universal ocean and simple forms of life may be the last stage of our earth’s organic history, as they were the first.
If this should be so, the whole life of our earth would only repeat what we find to be the history of every part of that life, — a progress from simplicity to variety in its growth, and a return to simplicity in its decline and death.
While there are, perchance, but few who feel much interest in tracing the share which the convulsive telluric forces have had in the development of the physical features or the extinct life of our earth, most persons will find some pleasure in observing how these convulsive forces have influenced the history of man.
The most important condition of the existence of civilized man is the stability of the land. He must have some basis for confidence that his structures will endure. Show him by experience that at any moment he is likely to be visited by a convulsion against which all resistance will be impossible, which shall destroy his most laborious works and bury his race in their ruins, and there is at once taken from him the basis of confidence on which his labor rested, and the incentive to toil is gone. It is on this account that the slightest operations of the internal forces, which have manifested themselves in those old ruptures of the earth’s crust we see on every side of us, have a very great value in the history of man. During all stages of the earth’s history before the coming of man, the ordinary earthquakes and volcanic eruptions exhausted their effects in their physical results; with his advent, fear became a power, and these convulsions had thenceforth a higher value.
It is not easy to say which of the two prominent manifestations of internal force have had the greatest effect on man, the volcano or the earthquake. Both possess the elements of the supernatural in the highest degree; both are so far isolated phenomena that the rude observer is thrown at once on his myth-making power, in order to gratify the natural demand for an explanation.
Volcanic phenomena, however, have some permanent features which render them less mysterious than the earthquake; and although, where they destroy, the ruin they make is more complete, their ravages are confined to a narrow range about their points of outbreak.
They present also something like a natural succession in their phenomena; their eruptions are always preceded by some external signs, which give time for flight, to save those who come within the range of their action. Of the coming earthquake there are probably no natural signs; except in so far as they attend volcanic outbreak, there is no trustworthy warning of its approach. In the midst of the most profound calm of nature, while every outward sign seems to betoken the uniform action of all forces, there may instantaneously appear the most frightful convulsion. The earth rocks to and fro; from its recesses there come the most appalling sounds; in an instant cities are shaken down, mountain summits are hurled into the sea, the rivers change their paths, and the ocean, as if to complete and cover the ruin the land has made, rises in an enormous wave and sweeps the shore.
When we consider that there are considerable portions of the earth’s surface where every generation experiences some of the terrible effects of these accidents, we can well believe they must affect the character of the peoples subjected to them. It is easy to trace the effect of a great and desolating war upon the development of a people; yet the immediate consequences of a war are rarely felt by any considerable portion of a people, and even with the actual combatants there is the roused spirit of the soldier to prevent the effects of paralyzing fear. But the earthquake may bring the worst consequences of war to every household; being irresistible, there can be no awakened courage to sustain the mind; being inscrutable, there are added the terrors of ignorance and superstition. The importance of earthquake phenomena on the development of man may be conceived by estimating the loss of human life caused by them. During the last two decades, the number of lives destroyed by earthquakes has certainly exceeded two hundred thousand. During this time, probably not over the usual rate of mortality from this cause has existed. Assuming this to be a fair measure of the loss of life produced by earthquakes, we should have a mortality of over one million for the last century, and since the beginning of the Christian era over eighteen millions would have perished from the direct action of this agent. But we must add to this appalling sum the probably greater number who have perished in the famines and pestilences which have almost always destroyed more than the convulsions they followed, before we can form a correct idea of the destroying power of earthquakes.
There are no sufficient data by which to compare the ravages of earthquakes with those of other destroying agents, such as epidemic diseases or war. Many earthquakes have certainly brought a greater loss of life on certain communities than any pestilence, as, for instance, the Calabrian earthquakes of 1783 and 1837, and the great Lisbon earthquake.
In addition to the loss of life, there is to be reckoned the destruction of property; this evil has probably as great effect upon the development of a community as the loss of human life. When a community is not only deprived of its laborers, as by pestilence, but is at the same time bereft of the accumulated toil of preceding generations stored in buildings, the shock is frequently too great for reparation.
The ordinary accidents which befall a community do not form any adequate measure of the effects of these convulsions. When fire or flood destroys a town, there remain the wealth and energy of the surrounding country, which by assuming the shape of charity or by giving the generally more efficient aid of enterprise afforded by the productive energy of the uninjured region acting through commercial channels, soon restore the loss. We can only compare the effect of the worst forms of earthquake violence with the ordinary accidents which befall communities, by supposing every house in a great area to be at once struck by lightning. If we can conceive of an electrical discharge of the most extreme destructive power hurled at once into every building in Massachusetts, kill the people, rendering the labor accumulated by half a dozen generations in the buildings and their furniture quite useless, bringing in the train of the convulsion famine and pestilence, so as to render immediate restorative effort impossible, we may then estimate the effect of severe earthquakes on the character of a people. How long would even New England energy remain unshaken under a succession of such calamities? Would this people have retained the courage to battle with the evils of its own community, crush out its ignorance, struggle with its vices, and have enough force to spare to produce an impression throughout the social and political movements of forty millions of Americans, if in the two centuries of its growth each generation had been a sufferer by some such devastation?2 Can we believe that even the native courage and sense of duty could prevail over the certainty that before the present century closed this desolation would be repeated, or that the work of material and moral advance would still go on without interruption? To any one who has considered how far the conviction that bricks and mortar will hold together underlies all human progress, the continued advance of this community under such conditions must appear very questionable. There can be no doubt that the Yankees would meet the question of dealing with earthquakes as it has never been met before. The Patent Office would be besieged with inventions calculated to give better assurance of safety to life and property. Houses would be constructed on new principles, with elastic joints and floors independent of gravity; the legislature would give us committees of investigation, and the whole range of questions connected with these convulsions would be studied as they have never yet been. The people of Massachusetts would never have their chimney-pots brought down on their heads every quarter of a century, without knowing something about the reasons therefor.
It may be that the world would have been a gainer if the portent of the Newbury earthquake of 1727 had ushered in a series of convulsions such as have desolated Calabria or Peru. We certainly should have known more of the nature of the causes and the means of obviating the worst effects of the convulsions. Maybe we should have learned the true character of the indications, if such there be, of the coming earthquake. We may even imagine that this people would have devised some method of helping Nature out of her difficulty by creating some convenient outlets whereby this pent-up force could escape without destructive effects.
However successful all these efforts to deal with the terrible enemy, and whatever the glory to have been gained thereby, there can be no doubt that the whole nation would have lost by every earthquake which might have devastated New England. We may be with reason thankful that Nature contented herself with giving to this land a meagre soil and a rigorous climate, but left its granite hills so steadfast that the living may sleep quietly in their beds, and the dead rest in peace in their graves.
By such a comparison between the condition of a community exempt from, with another subjected to, the action of these convulsions, we may gain a conception of their influence on the development of man, and be prepared to find distinctive marks of their effects in the character of every people long exposed to their ravages.3
Two results may evidently be expected. First, the effect of these convulsions will be to develop those insuperable bars to progress—superstition, and the conviction that the powers of nature contending against man are too great for his efforts. Then there must arise, from the constant destruction of architectural and other records, and the obliteration of traditions which crumble almost as easily as brick and mortar under these convulsions, a sundering of all that connects one generation with another. This destroys all that continuity of effort which is indispensable in the building up of a civilization. If we could construct a map which would represent the relative superstition of the inhabitants of different parts of the earth, or the energy with which they contended against natural obstacles, and could compare the indications thus obtained with those of another map, where the shading exhibited the relative frequency and violence of earthquake disturbances at different points, a striking correspondence would be perceived. Under the shading which indicated the maximum of earthquake activity, would be found the peoples on which superstition has stamped its evil effects most deeply. Beneath the shading which indicates the greatest intensity of seismic activity lie the greater part of Southern Italy and Sicily, Syria, a good part of Persia, the greater portion of Hindostan, the whole crescent of the Malayan Archipelago, from Singapore through the Spice Islands, and up to Manila. Most of Japan and much of the shores of the Chinese Empire are shadowed in the same manner. On our own pair of continents, we find Mexico, a good part of the Antilles, Central America, the whole northern and western shore of South America, lying within the region of maximum earthquake activity. The whole periphery of the Pacific Ocean, except Australia and the northern half of the American Continent, is thus subjected to the agent the most effective in hindering human advancement, — an unfortunate circumstance, which may have done much to prevent advancement among its original peoples, and may in the future prove a great bar to the progress of the transported races, which are rapidly fringing its shores with European colonies. In the Atlantic Ocean we find the last unfortunate land on our list Iceland, where earthquake activity is very great.
In each of these regions we may trace those indications which we expected would mark the work of this disturbing agent. In Iceland, for instance, we find a people who, although at first they seemed to develop an intellectual activity proportionate to the intensity of the movements of the physical world about them, are now reduced far below the position of the people of their race on the main-land. Their history, with its intense feuds, with every feature indeed indicating the predominance of those social evils which spring from superstition and the disturbed relations which these convulsions bring about, more resembles that of Southern Italy than that of any people of northern origin.
It is also instructive to compare the peoples occupying, at the present time and in the past, the three peninsulas of Southern Europe, — Spain, Italy, and Greece. These three regions are occupied, and have always been (excepting during the Moorish invasion of Spain), by peoples of the same race. Their climates do not vary widely, their productions are essentially the same, and their histories, as far as affected by external peoples, are as near alike as those of three states have ever been. Southern Italy and Sicily have been terribly devastated by earthquakes. The Spanish peninsula, excepting the strip known as Portugal, has been free from devastating convulsions. The greater part of Greece has also been exempt from the effects of severe convulsions. Shocks of moderate force have occurred frequently, but only a few devastating shocks have affected this peninsula. That part of Italy north of and including Rome has never been subject to the most destructive earthquake action, though often slightly shaken, and it is there that the civilizations of Italy, both ancient and modern, have been developed. These people have always exhibited, in common with the inhabitants of other centres of convulsive action, an utter inability for combined effort, a want of confidence in the future, and a degree of superstition we seek for in vain in the same race in better conditions.
That part of the Spanish peninsula included in Portugal, which lies beneath the deepest shades of our map, presents us with a people who show also in their history and character the unfortunate effects of this agent. The regions subject to the most intense earthquake activity on our own continents—Mexico, Central America, Venezuela, Peru, and other parts of the Pacific coast of South America—all exhibit in an unmistakable manner the peculiar effects which we may attribute to its existence. Superstition and a want of continuous effort characterize the inhabitants of all. It is not possible to set forth all the facts tending to support the conclusion that earthquakes have produced the peculiar features which we have claimed to be their effects in the people above named. One fact, however, is evident, that none of those peoples placed under the influence of the most extreme seismic activity have ever attained to greatness. The history of that portion of the Mediterranean region which has been subjected to the most destructive earthquakes may be removed from our annals without very materially affecting the record of the development of humanity around that sea; and the peoples occupying the same unfortunate position in the new world have not contributed much to the development of man, despite their great natural resources and generally favorable climate. It is extremely difficult to do anything toward unravelling the complicated system of causes which have made any people what they are, and impossible here to undertake the little that can be done. Without this analysis, however, it will not be difficult for the reader to perceive, in the character and history of many of the peoples dwelling within the regions where the most violent earthquakes occur, a strong confirmation of the hypothesis that these convulsions have had much to do with making that character and that history what they are.
The comparison of the characters of those peoples which have been subjected to earthquake ravages with those which have escaped these accidents naturally leads us to examine the character of the races of men in relation to the intensity of the subterranean disturbances of the regions they inhabit. If we lay before us an ethnographic map, and compare its indications with those given by our earthquake chart, we perceive some important relations. The Latin peoples of the Aryan race have developed over centres of earthquake action, while the northern members of that race, have inhabited regions quite exempt from devastating convulsions. The exceptions in the case of the Latin peoples are, that most of Spain proper, Northern Italy, Central and Northern France, Brazil, and Buenos Ayres have been exempt from the worst effects of these disturbances. Only the last two, however, have enjoyed the perfect immunity which has been happily allotted to most of Northern Europe and the greater part of our own continent. The only case of the subjection of a people of Northern European origin for many centuries to the action of earthquakes of great violence is found in Iceland. Jamaica presents us with a case where a small number of English have been similarly placed for about two centuries; but the continual change of population by immigration would invalidate any conclusions drawn from it. If we take the exceptions to the rule that the Latin peoples have generally been subjected to great earthquake convulsions, comparing the peoples of Central and Northern France, Spain proper, the Valley of the Po, in Northern Italy, the inhabitants of Eastern South America with those of Southern Italy, Sicily, Southern France, Portugal, Savoy, Mexico, Venezuela, and the western shore of South America, do we not see at once that there are differences in character between these two groups which cannot easily be attributed to climate? On the other hand, take the single exception in the case of Iceland, where a considerable mass of a Northern European people have been long exposed to severe earthquake action, do we not find a sufficient departure from the original stock to warrant us in supposing that the peculiar influences of these convulsions have had a great effect on the character of the inhabitants.
In the history of architecture, we find many features of interest in connection with earthquakes. An art which bases its work on the adherence of masonry cannot but have its history affected by such an agent. The style of architecture proper to the firm soil and Gothic peoples of Northern Europe differs as widely from that existing on the tremulous lands of the Latin peoples of the south, as the character and history of the nations among which they had their birth. Gothic architecture, with its aspiring lines, its slender steeples, its tall columns supporting a load of pointed arches and tracery, where every element of beauty would be an element of weakness in the earthquake’s shock, could never have developed in Calabria or Sicily, or any other region exposed to such convulsions. The massive walls, the narrow barrel arches, the dome in place of the spire, which we find in Southern Italy, are forms better suited to resist the frequent shocks to which they are exposed. Even these elements of arch and dome are less steadfast under such strains than those of the older orders of architecture, the Doric or Corinthian, whose crowded vertical supports hold up but little weight. Probably the most important architectural result of the action of earthquakes is the unequal degree in which their destruction operates on different sorts of buildings; while the temples and similarly solid public edifices may withstand severe shocks, the frailer buildings around them, constituting the private houses, are likely to be quite destroyed. Thus since the erection of the temples of Pæstum, over two thousand years ago, the dwellings of the people about them have been shaken into rubbish probably half a dozen times, while the firm-built temples have been little affected by the shocks. The natural result of this action is the more rapid alteration of domestic than religious architecture. The underground forces seem to have an especial antipathy to renaissance architecture; often the shock spares the heathen temple, to wreck the church beside it. If we could adopt that theory which attributed earthquake shocks to the struggles of the imprisoned gods of old in subterranean dungeons, we might suppose that there was some malice in the selection; but it is rather more likely that the better mortar and sounder principles of the ancient architecture are the real cause of the difference in durability.
When the process of decay begins to make serious ravages in any building in southern climes, the earthquake performs somewhat the same accessory work of destruction that the frost does in northern regions, — that of searching out all the opening joints and half-formed fissures, and, by developing them, hastening destruction. As soon as a column is loosened, or the adherence of masonry at any point materially weakened, some shock, incapable of overthrowing the whole structure, wrenches it from its position. Much of the work of demolition in Southern Italy and other earthquake centres, which is generally attributed to Robert Guiscard, or some other invading ravager, is really the work of earthquakes. Even in Rome, which, as before remarked, has escaped the worst effects of earthquakes, there is ample evidence in several of the great ruins that this agent has been an efficient destroyer. Mr. Mallet has recognized earthquake fissures in the ruined walls of the Baths of Caracalla. The same evidences are to be found in the Coliseum and other Roman structures, and are common in the mediæval buildings of the Imperial City.
It is unquestionably very difficult to trace in a satisfactory manner the effect of such a natural agent upon the development of a people. The foregoing inadequate presentation of the matter may serve, however, to call attention to the effects of subterranean forces upon the development of man within the regions affected by their convulsive action. In their direct action upon the development of the physical phenomena of the earth’s surface, these convulsive internal forces unquestionably contribute to an advance in the character of life, by varying the conditions to which it is exposed. Operating upon man, they doubtless tend to accomplish the same great end of diversification, by the same means of varied conditions; but they bring at the same time an amount of human suffering which transcends imagination.
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- Probably the most trustworthy estimate of the proportion of heat received from the sun and from the earth’s centre is that given by Mayer. According to this calculation, the sun gives us each day an amount of heat which would melt eight thousand cubic miles of ice at 32° Fahrenheit, while during the same time there would come up from the interior enough heat to melt only two hundred miles; and the greater part of this would be thrown out at points of volcanic eruption. ↩
- The earthquake shocks of 1638, 1663, 1727, and 1755, though violent, did not produce very destructive effects on the wooden houses and stout masonry of the then thinly peopled colony of Massachusetts Bay. ↩
- Buckle, in his History of Civilization, has incidentally referred to the influence of earthquakes on national character; but, so far as is known to the author, no careful effort has yet been made to determine the influence upon human development of this very important assemblage of phenomena. ↩