Histoire des principales découvertes scientifiques modernes: Volumes 4 à 5

Delevingne et Callewaert

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Delevingne et Callewaert
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Dec 31, 1852
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The observer who glances over a rich and fertile plain, watered by rivers and streams which have, during a long series of ages, pursued the same uniform and tranquil course; the traveller who contemplates the walls and monuments of a great city, the first founding of which is lost in the night of ages, testifying, apparently, to the unchangeableness of things and places; the naturalist who examines a mountain or other locality, and finds the hills and valleys and other accidents of the soil in the very spot and condition in which they are described by history and tradition—none of these observers would at first suspect that any serious change had ever occurred to disturb the surface of the globe. Nevertheless, the earth has not always presented the calm aspect of stability which it now exhibits; it has had its convulsions, and its physical revolutions, whose story we are about to trace. The earth, like the body of an animal, is wasted, as the philosophical Hutton tells us, at the same time that it is repaired. It has a state of growth and augmentation; it has another state, which is that of diminution and decay: it is destroyed in one part to be renewed in another; and the operations by which the renewal is accomplished are as evident to the scientific eye as those by which it is destroyed. A thousand causes, aqueous, igneous, and atmospheric, are continually at work modifying the external form of the earth, wearing down the older portions of its surface, and reconstructing newer out of the older; so that in many parts of the world denudation has taken place to the extent of many thousand feet. Buried in the depths of the soil, for example, in one of those vast excavations which the intrepidity of the miner has dug in search of coal or other minerals, there are numerous phenomena which strike the mind of the inquirer, and carry their own conclusions with them. A striking increase of temperature in these subterranean places is one of the most remarkable of these. It is found that the temperature of the earth rises one degree for every sixty or seventy feet of descent from its surface. Again: if the mine be examined vertically, it is found to consist of a series of layers or beds, sometimes horizontal, but more frequently inclined, upright, or contorted and undulating—even folded back upon themselves. Then, instances are numerous where horizontal and parallel beds have been penetrated, and traversed vertically or obliquely by veins of ores or minerals totally different in their appearance and nature from the surrounding rocks. All these undulations and varying inclinations of strata are indications that some powerful cause, some violent mechanical action, has intervened to produce them. Finally, if the interior of the beds be examined more minutely—if, armed with the miner’s pick and hammer, the rock is carefully broken up—it is not impossible that the very first efforts at mining may be rewarded by the discovery of some fossilised organic form no longer found in the living state. The remains of plants and animals belonging to the earlier ages of the world, are, in fact, very common; entire strata are sometimes formed of them; and in some localities the rocks can scarcely be disturbed without yielding fragments of bones and shells, or the impressions of fossilised animals and vegetables—the buried remains of extinct creations.
The important art of placing scientific knowledge, and especially new discoveries and topics of present controversy, within easy reach of educated readers not versed in their strictly technical details, is one which has for years been carried to remarkable perfection in France, in no small measure through the labours and example of M. Figuier himself. The present volume, one of his series, takes up the subject of Pre-historic Man, beginning with the remotely ancient stages of human life belonging to the Drift-Beds, Bone-Caves, and Shell-Heaps, passing on through the higher levels of the Stone Age, through the succeeding Bronze Age, and into those lower ranges of the Iron Age in which civilisation, raised to a comparatively high development, passes from the hands of the antiquary into those of the historian. The Author's object has been to give within the limits of a volume, and dispensing with the fatiguing enumeration of details required in special memoirs, an outline sufficient to afford a reasonable working acquaintance with the facts and arguments of the science to such as cannot pursue it further, and to serve as a starting-ground for those who will follow it up in the more minute researches of Nilsson, Keller, Lartet, Christy, Lubbock, Mortillet, Desor, Troyon, Gastaldi, and others.

The value of the work to English archæologists, however, is not merely that of a clear popular manual; pre-historic archæology, worked as it has been in several countries, takes in each its proper local colour, and brings forward its proper local evidence. It is true that much of its material is used as common property by scientific men at large. But, for instance, where an English writer in describing the ancient cave-men would dwell especially on the relics from the caves of Devon and Somerset as worked by Falconer and Pengelly, a French writer would take his data more amply from the explorations of caves of the south of France by De Vibraye, Garrigou, and Filhol—where the English teacher would select his specimens from the Christy or the Blackmore Museum, the French teacher would have recourse to the Musée de Saint-Germain. Thus far, the English student has in Figuier's 'Primitive Man' not a work simply incorporated from familiar materials, but to a great extent bringing forward evidence not readily accessible, or quite new to him.

Some corrections and alterations have been made in the English edition. The illustrations are those of the original work; the facsimiles of pre-historic objects have been in great part drawn expressly for it, and contribute to its strictly scientific value; the page illustrations representing scenes of primitive life, which are by another hand, may seem somewhat fanciful, yet, setting aside the Raffaelesque idealism of their style, it will be found on examination that they are in the main justified by that soundest evidence, the actual discovery of the objects of which they represent the use. 

What is man? A profound thinker, Cardinal de Bonald, has said: “Man is an intelligence assisted by organs.” We would fain adopt this definition, which brings into relief the true attribute of man, intelligence, were it not defective in drawing no sufficient distinction between man and the brute. It is a fact that animals are intelligent and that their intelligence is assisted by organs. But their intelligence is infinitely inferior to that of man. It does not extend beyond the necessities of attack and defence, the power of seeking food, and a small number of affections or passions, whose very limited scope merely extends to material wants. With man, on the other hand, intelligence is of a high order, although its range is limited, and it is often arrested, powerless and mute, before the problems itself proposes. In bodily formation, man is an animal, he lives in a material envelope, of which the structure is that of the Mammalia; but he far surpasses the animal in the extent of his intellectual faculties. The definition of man must therefore establish this relation which animals bear to ourselves, and indicate, if possible, the degree which separates them. For this reason we shall define man: an organized, intelligent being, endowed with the faculty of abstraction.

To give beyond this a perfectly satisfactory definition of man is impossible: first, because, a definition, being but the expression of a theory, which rarely commands universal assent, is liable to be rejected with the theory itself; and secondly, because a perfectly accurate definition supposes an absolute knowledge of the subject, of which absolute knowledge our understanding is incapable. It has been well said that a correct definition can be furnished by none but divine power. Nothing is more true than this, and were we able to give of our own species a definition rigorously correct, we should indeed possess absolute knowledge.

The trouble we have to define aright the being about to form the subject of our investigation is but a forecast of the difficulties we shall meet when we endeavour to reason upon and to classify man. He who ventures to fathom the problems of human nature, physical, intellectual or moral, is arrested at every step. Each moment he must confess his powerlessness to solve the questions which arise, and at times is forced to content himself with merely suggesting them. 

"Each facette, with its lens and nervous filament, separated from those surrounding them by the pigment in which they are enclosed, form an isolated apparatus, impenetrable to all rays of light, except those which fall perpendicularly on the centre of the facette, which alone is devoid of pigment. All rays falling obliquely are absorbed by that pigment which surrounds the gelatinous cone. It results partly from this, and partly from the immobility of the eye, that the field of vision of each facette is very limited, and that there are as many objects reflected on the optic filaments as there are corneæ. The extent, then, of the field of vision will be determined, not by the diameter of these last, but by the diameter of the entire eye, and will be in proportion to its size and convexity. But whatever may be the size of the eyes, like their fields of vision, they are independent of each other; there is always a space, greater or less, between them; and the insect cannot see objects in front of this space without turning its head. What a peculiar sensation must result from the multiplicity of images on the optic filaments! This is not more easily explained than that which happens with animals which, having two eyes, see only one image; and probably the same is the case with insects. But these eyes usually look in opposite directions, and should see two images, as in the chameleon, whose eyes move independently of each other. The clearness and length of vision will depend, continues M. Müller, on the diameter of the sphere of which the entire eye forms a segment, on the number and size of the facettes, and the length of the cones or lenses. The larger each facette, taken separately, and the more brilliant the pigment placed between the lenses, the more distinct will be the image of objects at a distance, and the less distinct that of objects near. With the latter the luminous rays diverge considerably; while those from the former are more parallel. In the first case, in traversing the pigment, they impinge obliquely on the crystalline, and consequently confuse the vision; in the second, they fall more perpendicularly on each facette.
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