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formation of large hollow spaces beneath the surface. Again, the amount of solid material removed by springs, though it does not stand up before us as an enduring monument like Etna, is probably in reality greater in any one year over the whole globe, than all the lava and ashes which have been erupted by volcanic action during the same period. Every spring, even the clearest which comes welling out from the granite sides of a Highland hill, is slowly and silently conveying to the surface mineral materials which it has dissolved out of the rocks underneath. By some springs, such as those of a thermal kind, the quantity of these materials carried off in a single year would, if collected and rendered visible, make huge mounds, or even small hills. Alike, therefore, by the action of volcanos and the subterranean circulation of water, cavities must be produced within the interior of the earth. As these become enlarged, their roofs, from failure of support, will sometimes give way with a sudden collapse. Such is not impossibly the origin of many earthquake shocks. When we know that even on the surface the explosion of a powder-magazine sometimes gives rise to a tremor of the ground, which is felt at a distance of several miles, we may conceive how the collapse of one of these underground cavities, and the consequent rushing together of thousands of tons of rock, may send a pulsation for many miles through the elastic crust of the earth.
After a great earthquake, the ground affected by it, as we have seen above, is sometimes found to be permanently upheaved above its former level, or depressed beneath it. In the neighbourhood of active volcanos, similar results have been observed to be brought about more slowly; while in other tracts where volcanos do not occur, and where no very marked earthquake has ever been felt, the ground has nevertheless been found to be gradually rising or sinking. Such slow movements may all with much probability be referred to the agency of subterranean heat. It is a familiar fact that rocks increase in bulk with every increment of heat, while, on the other hand, they contract as they cool. It has been found, for example, that granite expands '000004825 for every degree Fahrenheit by which its temperature rises. Hence we may conceive that among the internal movements of the earth a great mass of rock may gradually have its temperature raised, and will in consequence push up the part of the crust lying above it. An area of granite, for instance, say 10,000 feet, or about two miles thick, having its temperature slowly increased 300° Fahrenheit, would cause a gradual elevation of the ground above it to the extent of 143 feet. So, on the other hand, if the rock cools down, a slow depression of the overlying region will be the result. If the rock were sandstone, the expansion would be about double that amount.
But what is the source of the underground heat? What force was it that lit those fires which have been burning under Etna for so many centuries, and how are they sustained? We cannot tell.
Some philosophers have tried to shew that the heat is due to constant chemical changes, such as the oxidation of potassium and sodium. Others have called in the aid of magnetic and electric forces. Others, again, suppose that the earth was once all liquid, and that, as above alluded to, there are still large reservoirs of melted rock in its interior not yet solidified. . But science is not yet far enough advanced to do more than suggest possible and partial explanations of the phenomena. What remains to be done is, in the meantime, diligently to study the facts which come within the sphere of actual observation, and doubtless in the end we shall come to know far more of the condition of our earth's interior, and of the changes which are passing there, than we do now.
This great truth, at least, science has already taught us, that the reaction of the interior upon the surface of our planet is necessary for the permanence of the present economy of nature. Everywhere, from pole to pole, the land is wasting away, and its detritus is carried out into the ocean. If no compensating element came into play, the land would inevitably disappear, and indeed must have disappeared long ago. But the crust of the globe is not an inert immovable mass; as we have seen in the previous pages, it is ever quivering and heaving in some part. Rains, streams, and waves may waste it, but an invisible power beneath is always somewhere pushing it up, and enabling it to compete successfully with the elements which seek its destruction. Terrible, therefore, as the earthquake and volcano are, they form but parts of a system of compensation by which the waste of the land is made good. The islands and continents may be wholly worn away, or may subside beneath the ocean, but as they disappear others rise in their stead. And thus the forces of nature, destructive though they often are in their first effects, work together harmoniously to preserve the balance of sea and land, and to fit our globe to be the abode of living and sentient beings.
AR distant from the many other islands with which the
Southern Pacific Ocean is studded, one stands alone, rich in natural beauty, and with a climate almost unrivalled.
This lovely island was visited by Captain Cook in 1774,
and named by him Norfolk Island; it was then uninhabited, and neither the vegetable nor the animal world had been disturbed. For about two hundred yards from the shore, the ground was covered so thickly with shrubs and plants as scarcely to be penetrable further inland. The account given by Cook led to an attempt at settlement on Norfolk Island; but this was attended with difficulty. The island is small, being only about six miles in length by four in breadth; and was therefore unavailable for a large or increasing population. Lying nine hundred miles from Port Jackson, in Australia, it was inconveniently remote from that country; and, worst of all, its cliffy and rocky shores presented serious dangers to mariners attempting a landing. Its general unsuitableness, however, for ordinary colonisation was considered to adapt it as a penal settlement, subordinate to New South Wales, and to which convicts could be sent who merited fresh punishment while in course of servitude. Thus, one of the loveliest of earthly paradises was doomed to be a receptacle for the very worst of malefactors. It was imagined that the beauty of Norfolk Island, and the fineness of its climate, would greatly tend to soothe the depraved minds of its unhappy tenants, and reconcile them to compulsory expatriation ; but such was not the case : the feeling uppermost in the minds of the convicts was to make their escape; and this, along with other circumstances,
caused the island, after a time, to be abandoned as a penal settlement. The narrative that follows, written by a gentleman personally acquainted with the convict system, bears on the case of an attempted escape, and the whole, as a warning to those who go astray,' may be relied upon as a true relation of facts.
'On the northern side of Norfolk Island, the cliffs rise high, and are crowned by woods, in which the elegant whitewood and gigantic pine predominate. A slight indentation of the land affords a somewhat sheltered anchorage-ground, and an opening in the cliffs has supplied a way to the beach by a winding road at the foot of the dividing hills. A stream of water, collected from many ravines, finds its way by a similar opening to a ledge of rock in the neighbourhood, and, falling over in feathery spray, has given the name of Cascade to this part of the island. Off this bay, on the morning of the 21st of June 1842, the brig Governor Philip was sailing, having brought stores for the use of the penal establishment. It was one of those bright mornings which this hemisphere alone knows, when the air is so elastic that its buoyancy is irresistibly communicated to the spirits. At the foot of the cliff, near a group of huge fragments of rock fallen from the overhanging cliffs, a prisoner was sitting close to the sea preparing food for his companions, who had gone off to the brig the previous evening with ballast, and who were expected to return at daylight with a load of stores. The surface of the sea was smooth, and the brig slowly moved on upon its soft blue waters. Everything was calm and still
, when suddenly a sharp but distant sound as of a gun was heard. The man, who was stooping over the fire, started on his feet, and looked above and around him, unable to distinguish the quarter from whence the report came. Almost immediately, he heard the sound repeated, and then distinctly perceived smoke curling from the vessel's side. His fears were at once excited. Again he listened; but all was hushed, and the brig still stood steadily in towards the shore. Nearer and nearer, she approached ; until, alarmed for her safety, the man ran to summon the nearest officer. By the time they returned, the vessel had wore, and was standing off from the land ; but while they remained in anxious speculation as to the cause of all this, the firing was renewed on board, and it was evident that some deadly fray was going on. At length a boat was seen to put off from the brig, and upon its reaching the shore, the worst fears of the party were realised. “The misguided prisoners on board had attempted to seize the vessel. They were but twelve in number, unarmed, and guarded by twelve soldiers, and a crew of eighteen men; yet they had succeeded in gaining possession of the vessel, had held it for a time, but had been finally overpowered, and immediate help was required for the wounded and dying.
June 21, 1842.—My duty as a clergyman called me to the scene of blood. When I arrived on the deck of the brig, it exhibited a frightful spectacle. One man, whose head was blown to atoms, was. lying near the forecastle. Close by his side a body was stretched, the face of which was covered by a cloth, as if a sight too ghastly to be looked upon ; for the upper half of the head had been blown off. Not far from these, a man badly wounded was lying on the deck, with others securely handcuffed. Forward, by the companion-hatch, one of the mutineers was placed, bleeding most profusely from a wound which had shattered his thigh ; yet his look was more dreadful than all-hate, passion, and disappointed rage rioted in his breast, and were deeply marked in his countenance. I turned away from the wretched man, and my eye shrunk from the sight which again met it. Lying on his back in a pool of blood, the muscular frame of a man whom I well knew was stretched, horribly mutilated. A ball had entered his mouth, and passing through his skull, had scattered his brains around. My heart sickened at the extent of carnage, and I was almost sinking with the faintness it produced, when I was roused by a groan so full of anguish and pain, that for a long time afterwards its echo seemed to reach me. I found that it came from a man lying further forward, on whose face the death-dew was standing, yet I could perceive no wound. Upon questioning him, he moved his hand from his breast, and I then perceived that a ball had pierced his chest, and could distinctly hear the air rushing from his lungs through the orifice it had left. I tore away the shirt, and endeavoured to hold together the edges of the wound until it was bandaged. I spoke to him of prayer, but he soon grew insensible, and within a short time died in frightful agony. In every part of the vessel, evidences of the attempt which had ended so fatally presented themselves, and the passions of the combatants were still warm. After attending those who required immediate assistance, I received the following account of the affair :
“The prisoners had slept the previous night in a part of the vessel appropriated for this purpose ; but it was without fastening or other means of securing them below. Two sentries were, however, placed over the hatchway. The prisoners occasionally came on deck during the night, for their launch was towing astern, and the brig was standing off and on until the morning. Between six and seven o'clock in the morning, the men were called to work. Two of them were up some time before the rest. They were struck by the air of negligence which was evident on deck, and instantly communicated the fact to one or two others. The possibility of capturing the brig had often been discussed by the prisoners, among their many other wild plans for escaping from the island, and recently had been often proposed by them. The thought was told by their looks, and soon spread from man to man. A few moments were enough ; one or two were roused from sleep, and the intention was hurriedly communicated to them. It was variously received. One of them distrusted the leader, and entreated his companions to desist from sọ mad an attempt. It