1. Of what they are composed?2. Whence they came?3. And how they came?
1. Of what they are composed?
2. Whence they came?
3. And how they came?
For the present we shall pass over these more humble whisperers of things curious and strange, and turn to those massive fragments of rocks which, far removed from their original site, are now scattered either singly or in groups over a large portion of the earth’s surface, resting sometimes on the slopes of hills composed of materials totally different from their own, seen sometimes on the sand and gravel of extensive plains, and distant from the mountains of which they were once a part, sometimes from one to three hundred miles: they are Boulders. Can we not picture to ourselves, in that remote period of our island’s history when forest and morass occupied the place of its bogs, and when the winds sighed over comparative desolation, an ancient inhabitant, imbued with nature’s living poetry, pausing before one of those grey lichen-covered masses which had withstood the warrings of the elements for perhaps thousands of years, and, as the awe of the surrounding solitude came like a charm over his soul, gazing with growing veneration at the venerable rock?—to him it would appear as if cast down from heaven, or planted where it now stands by some supernatural or giant hand. What spot, then, more fitted for the simple worship of nature’s child?—what temple, what altar more suited to his simple rites?
A rock such as we have here described may have been found supported in part by lesser fragments, or such supports may have been introduced by partial excavations under favourable projections of its surface; and in either case, the superfluous earth, sand, or stones under and about it, being removed, this ancient monument of the operations of Nature would henceforth become an instrument in the worship of Nature’s God—a Cromlech!
Whether, however, this be, or not, a correct view of the original impulse which led to the selection of these giant stones, or of the purpose to which they were applied, it is for our antiquarian friends to decide. Suffice it here to add, that the transportation of such huge masses from their native beds, by the power of man or of giants, was at such a remote epoch, and under the circumstances of the country, impossible; nor will I stop to inquire whether a work so mighty was performed by spirits light as air.
Let us turn to the consideration of the phenomenon of Boulders, as it has appeared to the eye of science. And perhaps there are no two facts which place it in so strong a light, and embrace so fully the reasonings founded upon it, as the dispersion of blocks of the granite and other rocks of Sweden overa large portion of Northern Europe, the boulders, either singly or in clusters, being disposed in long parallel lines or trainées, for upwards of two hundred miles from the mountains of Scandinavia, to which, by identity of mineral composition, they have been traced, although separated from them by the Baltic Sea; and the occurrence of boulders of alpine granite resting on the secondary rocks of the Jura chain, between which and the Alps are situated the deep valley of the Rhone, the Lakes of Geneva and Neufchatel, the distance travelled by the boulders being sixty miles. Saussure, struck by the spectacle of clusters of these fragments so far removed from any rock resembling them, declared that they looked as if rained down from heaven; a sentence strikingly expressive of the difficulties which attend on an explanation of their occurrence. De Luc rightly speaks of such travelled masses of stone as being “one of the most important of geological monuments, since they offer a rigorous criterion of the different systems concerning the revolutions which have happened on our globe;” and in describing the vicinity of Cuxhaven, situated at the extremity of the Bremen country, which lying between the Gulfs of the Elbe and Weser, is as it were a peninsula, he cites the very forcible example it affords of a vast abundance of boulders at a distance of more than two hundred miles from the Scandinavian chain, the outlet, itself sixty miles wide, of the Baltic, forming part of the intervening space.
At the time of De Luc’s visit to Cuxhaven (1797), a dike was constructing to secure the port from the violence of the sea, and the plan of employing blocks for this purpose was suggested by the quantity which were scattered over all the neighbouring country. From the vicinity alone of Hornburg, an inland town between the ports of Stade and Harborg, 600 lasts of blocks, amounting to 240,000 quintals, or 23,679 tons, had at that time been brought and consumed in the dike, which, with the thickness necessary to resist the utmost impetuosity of the waves, and a height of about eight feet, already extended three leagues to the westward of the town. The country in which these accumulations of erratic boulders had taken place, is an expanse of sand covered with heath, except where broken by cultivated patches around the scattered villages, the surface being undulated by hills composed either of sand or of heaps of boulders. De Luc adds, “that he travelled ten miles without perceiving in the whole horizon any house, or even a hovel, or a single tree”—desolate and dreary indeed to the eye of painter or poet, yet rich in all the elements of sublimity to the eye of the geologist.
It is quite unnecessary to adduce other and less imposing examples from Great Britain and Ireland of similar facts, the difficulties of explanation being fully embraced by those selected. How have they been brought to their present places? is then the question mentally asked, as well by the learned as the unlearned.
Saussure, celebrated for his examination of the Alps, imagined a great debacle and retreat of the sea from the strata that had been formed, as he supposed, by chemical precipitations; and to the violent rush of the vast current he ascribed the excavation of the valleys, and the transport of immense masses of stones from the central chain of the Alps, beyond the precincts of those mountains, to the Jura. Here, then, the excavation of the valleys of the Alps, and the transport of the boulders, are considered results of one great catastrophe, by which the bottom of the sea became hard dry land, its waters descending into huge abysses which had burst open around the Alps. The phenomenon of Boulders is general in a large portion of the northern hemisphere; the explanation however is local and hence insufficient; whilst the philosopher’s machinery, of huge abysses, like the peasant’s giant, is born of necessity, not deduced from experience.
Others, and even yet they are many, attribute the transport of both gravel and boulders to the Noachian deluge, which is their great geological catastrophe. The application, however, of that great historical event to such physical agencies, is beset with great difficulties. The words of scripture do not support, but rather oppose, the notion of a huge wave rising in the north to a great height, then rushing southwards over the dry land, and rooting up or sweeping before it, by hydrostatic pressure, fragments of the earth’s crust. Nor are facts more in accordance with that notion—the boulders of Scandinavia were moved from north to south—the boulders of the Alps from south to north, passing over the Jura mountains into Franchcomté—the stratification of many of the heaps of sand and gravel—the position of the boulders generally on the surface, whether of rocks, of sand, or of gravel—and the valleys, lakes, and seas now lying in the line of movement, which, if existing before the catastrophe, must have been filled up before the boulders could have travelled farther, if formed after, must have required the action of a second catastrophe of equal violence for their formation. And if, which is more in accordance with scripture, we consider the waters rising from the surrounding seas over the dry land, and then suppose them urged on with immense velocity, the effect would be a heaving up and moving forward of fragments from the lower land, by which the surface of the higher would be partly covered and protected; and at the return of the waters to their ancient beds, these fragments would be swept off, and carried back the same way they came. Neither, then, the words of scripture, nor the facts themselves, require us to seek in the Noachian deluge for an explanation of these phenomena. Another theory, still adhered to by many modern geologists, is, the action of submarine currents, at a time when the present dry land had only in part emerged from the sea. This theory has the advantage of dealing with bodies of diminished gravity, in consequence of their immersion in a fluid, and consequently of having to provide for the movement of weights less by one-half or one-third than they would have been in air. In conjunction with the theory of raised beaches, it explains many of the phenomena of accumulations of sand and gravel, but not all. And as regards the transport of boulders, it fails; the great size and angular form of some—their occurrence at various levels, resting on various strata—sometimes connected with, and sometimes unconnected with sand or gravel—their position frequently on the top of heaps and ridges of gravel, being facts in seeming opposition to such an explanation, even were it conceded that all the depressions now existing on the line of travel, as lakes and seas and valleys, were scooped out subsequently to their transport.
The geological system of the illustrious Hutton assumed as an essential principle, that as the present continents and dry land were once the bottom of the ocean, and have been formed, either in greater part or entirely, of fragments of pre-existing continents now submerged, so is the work of destruction and renewal still continuing, the substance of our present dry land being loosened, abraded, or worn down by meteoric agencies, and carried by torrents and rivers to the ocean, to be there by currents distributed over the bottom of the sea, and by internal heat consolidated into new strata, which in time will be elevated into new continents and islands. To apply this theory in the case of the Jura boulders, Playfair assigned their transport to an epoch anterior to the formation or excavation of the deep valleys and lakes which would now form an insurmountable obstacle to such transport, and thus obtained a greatly inclined plane, extending from the summit of the Alps to the Jura, on which to trundle the fragments gradually downwards, by aid of the numerous streams and torrents descending from the higher to the lower ground. But as this theory would, as thus applied, premise that the land had been raised above the sea-level prior to the transport of the boulders, no means of effecting the great excavations, including the Lakes of Geneva and Neufchatel, which are supposed to have been formed subsequently, are left, except the slow erosive action of rains, frost, torrents, and such-like agents—means which few will consider adequate to the desired object; and hence the explanation of Playfair, resting solely on a bold hypothesis, must be rejected. As most of the preceding theories referred to the usually rounded condition of the granite boulders (many boulders of other rocks are angular), as an evidence of movement through the agency of water, De Luc, preparatory to the promulgation of his own theory, thought it expedient to show that blocks of granite, even as they stand tranquilly braving the storms, are gradually weathered into a rounded form. He thus cites the granite of Darmstadt as an example:—“Here I found a striking example of the manner in which blocks and even rocks of granite are rounded by the decomposition of the angles of their masses. I perceived it first in some angular pieces that had been detached and lay at the foot of the rock, surrounded with rubbish; for, on giving them a strong blow with an iron at the end of my stick, the angles fell off, detaching themselves with a concave surface on their inner side; and I thus produced rounded blocks, exactly resembling those which I had seen scattered on the plains.” This spherical concretionary structure has been noticed in the granite of Dublin and Down, and is common in trap rocks. Having smoothed away this difficulty, De Luc tacks on the boulders as a corollary to his theoryof subsidences. Immense masses of strata, subsiding into huge caverns or hollows beneath them, fragments of the lower strata were broken off and blown upwards by the force of the pent-up air and gases rushing through the cracks of the sinking strata, the weight of which continued more and more to compress them, so that the boulders of M. De Luc came from below, and not from above. This is also a gratuitous hypothesis; and as the localities of many boulders exhibit no signs of such subsidences and explosions, it has obtained few if any adherents. So far, then, it would appear that philosophers, though armed with all the powers of mind invigorated by study and sharpened by research, have fought in vain against the difficulties which like a rampart fence in this rugged problem. For a moment they have appeared illumined by the light of knowledge, and have then sunk into the darkness of ignorance. But though philosophy may yield, she never will despair. And now, having marshalled new forces for the combat, we shall see her, with brighter hopes and prospects, again renew the assault. To the consideration, therefore, of a widely different class of explanations, I shall proceed to direct attention in a second paper.
J. E. P.
Intellectuality of Animals.—Father Bougeant, a Jesuit, was placed in confinement by his superior in the College of La Fleche, near Paris, for what he had written on the subject of the intellectuality of animals. His views, if not orthodox, were certainly curious and amusing, and there is a sprightliness in his mode of treating the subject, graceful at least in the Frenchman, if not conformable to the divine. The following observations, extracted from that section of his work which treats of the language of beasts, may amuse the reader:—“Our first observation upon the language of beasts is, that it does not extend beyond the necessaries of life. However, let us not impose upon ourselves with regard to this point. To take things right, the language of beasts appears so limited to us only with relation to our own; however, it is sufficient to beasts, and more would be of no service to them. Were it not to be wished that ours, at least in some respects, were limited too? If beasts should hear us converse, prate, lie, slander, and rave, would they have cause to envy us the use we make of speech? They have not our privileges, but in recompense they have not our failings. Birds sing, they say; but this is a mistake. Birds do not sing, but speak. What we take for singing is no more than their natural language. Do the magpie, the jay, the raven, the owl, and the duck, sing? What makes us believe that they sing is their beautiful voice. Thus, the Hottentots in Africa seem to cluck like turkey-cocks, though it be the natural accent of their language; and thus several nations seem to us to sing, when they indeed speak. Birds, if you will, sing in the same sense, but they sing not for singing’s sake, as we fancy they do. Their singing is always an intended speech; and it is comical enough that there should be thus in the world so numerous a nation which never speak otherwise but tunably and musically. But, in short, what do those birds say? The question should be proposed to Apollonius Tyaneus, who boasted of understanding their language. As for me, who am no diviner, I can give you no more than probable conjectures. Let us take for our example the magpie, which is so great a chatterer. It is easy to perceive that her discourses or songs are varied. She lowers or raises her voice, hastens or protracts the measure, lengthens or shortens her chit-chat; and these evidently are so many different sentences. Now, following the rule I have laid down, that the knowledge, desires, wants, and of course the expressions of beasts, are confined to what is useful or necessary for their preservation, methinks nothing is more easy than at first, and in general, to understand the meaning of these different phrases.”—Dublin University Magazine.
Atmospheric Resistance on Railways.—In Dr Lardner’s third lecture on railways at Manchester, he detailed a variety of experiments made in order to ascertain the source of resistance. “He found that an enlarged temporary frontage constructed with boards, of probably double the magnitude of the ordinary front of the train, caused an increase of resistance so trifling and insignificant as to be entirely unworthy of account in practice. Seeing that the source of resistance, so far as the air was concerned, was not to be ascribed to the form or magnitude of the front, it next occurred to him to inquire whether it might not arise from the general magnitude of the train front ends, top and all. An experiment was made to test this. A train of waggons was prepared with temporary sides and ends, so as to represent, for all practical purposes, a train of carriages, which was moved from the summit of a series of inclined planes, by gravity, till it was brought to rest; it was next moved down with the high sides and ends laid flat on the platform of the waggons, and the result was very remarkable. The whole frontage of the latter, including the wheels and every thing, a complete transverse section of the waggons, measured 24 feet square, and with the sides and ends up, so as to present a cross section, it amounted to nearly 48 square feet. The uniform velocity attained on a plane of 1 in 177, without the sides up, was nearly 23 miles an hour; whereas, with the sides up, it was only 17 miles an hour; so that, as the resistance would be in proportion to the square of the velocity, other things being the same, there would be a very considerable difference, due to that difference of velocity. Then, at the foot of the second plane, while the sides were down, an undiminished velocity remained of 19½ miles an hour, whereas, with the sides up, it was reduced to 8½ miles an hour; so that a very extensive difference was produced. They would see at once that this was a very decisive experiment to prove that the great source of resistance was to be found in the bulk, and not the mere section or the form, whether of the front or the back of a train; but simply in the general bulk of the body carried through the air. It was very likely to arise from the successive displacements of a quantity of the atmosphere equal to the bulk of the body; or still more probably, from the fact of the extensive sides of the train; and indeed there was little doubt that the magnitude of the sides had a very material influence; for if they consider what is going on in the body of air extending from either side of a train of coaches, they would soon see what a mechanical power must be exercised upon it. Thus, when a train is moving rapidly, the moving power had not only to pull the train on, but it had to drag a succession of columns of air, at different velocities, one outside the other, to a considerable extent outside the train; and it did more, for it overcame their friction one upon the other; for as these columns of air were at different velocities, the one would be rubbing against the other; and all this the moving power had to encounter. This would go far to explain the great magnitude of resistance found, and its entire discordance with any thing previously suspected.”
Gilding of Metals by Electro-Chemical Action.—M. de la Rive has succeeded in gilding metals by means of this powerful action. His method is as follows: he pours a solution of chloride of gold (obtained by dissolving gold in a mixture of nitric and muriatic acid) as neutral as possible and very dilute, into a cylindrical bag made of bladder; he then plunges the bag into a glass vessel containing very slightly acidulated water; the metal to be gilded is immersed in the solution of gold, and communicates by means of metallic wire with a plate of zinc, which is placed in the acidulated water. The process may be varied, if the operator pleases, by placing the acidulated water and zinc in the bag, and the solution of gold with the metal to be gilded in the glass vessel. In the course of about a minute, the metal may be withdrawn, and wiped with a piece of linen; when rubbed briskly with the cloth, it will be found to be slightly gilded. After two or three similar immersions the gilding will be sufficiently thick to enable the operator to terminate the process.—Athenæum.——[By referring to the article on the Electrotype which appeared in No. 20 of the Irish Penny Journal, the reader will be enabled clearly to understand the mode in which the gold is separated from the acid, which holds it in solution, and forced, or attracted, to deposit its particles upon the metallic surface; the solution of gold bearing in this case a precisely similar relation to the metal plate, as the solution of copper in the other.]
Definition of Cherub.—A lady (married of course) was once troubled with a squalling brat, whom she always addressed as “my cherub.” Upon being asked why she gave it that appellation, she replied—“Because that it is derived from cherubim, and the Bible says, ‘the cherubims continually do cry.’”
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