Thus if we take the great masses of the Himalaya in Asia, the Andes in South America, or even such lesser ranges as the Pyrenees or the Great Atlas, we find that they interpose a far more absolute limit between the regions lying on their opposite flanks than occurs in respect to the Alps. These are formed of numerous ranges divided by comparatively deep valleys, which, with many local exceptions, tend towards parallelism with the general direction of the entire mass. This, between Dauphiné and the borders of Hungary, forms a broad band convex towards the north, and most of the main valleys lie between the directions west to east and south-west to north-east. But in many parts deep transverse valleys intersect the prevailing direction of the ridges, and facilitate the passage not only for purposes of human intercourse, but also for the migration of animals and plants, and for currents of air which mitigate the contrast that would otherwise be found between the climates of the opposite slopes.

The received opinion is, that the name Alps is derived from a Celtic root— alp or alb— signifying height. This has been connected by some writers with the Latin alb, albus, white, referring to the colour of the peaks. Strabo says that the name ῎Aλπια was formerly ῎Aλβια. Alp in south Germany— alpa in old High German—is exclusively applied to mountain pastures. For the present the derivation must remain somewhat uncertain.

To define the precise limits of the Alps, as will be seen fully in describing the several groups, is a somewhat arbitrary operation. To the W. they extend through a large portion of the French departments of Savoie, Haute-Savoie, Hautes Alpes, and Basses Alpes, being divided from the mountain district of the Cevennes by the broad and deep valley through which the Rhone flows from Lyons to the Mediterranean. The Jura range, usually regarded as distinct from the Alps, is nevertheless closely connected on one side with the outer ranges of the Alps of western Savoy, and on the other with those of northern Switzerland. On the N. side the Alps are definitely bounded by the lake of Constance, the plain of Bavaria, and the low country extending from Salzburg to the neighbourhood of Vienna. By these they are completely separated from the mountainous districts of central Germany, which extend through western Bohemia and Saxony in one direction to the Hartz mountains, and in the other to the Sudeten, or Riesengebirge, of Silesia. Hence it happens that the drainage of the northern slopes of the Alps flows either to the North Sea through the Rhine, or is diverted through the Danube to the Black Sea, and no portion of it reaches the Baltic. The eastern limit of the Alps is not easily defined with accuracy. The region of high hills, chiefly formed of tertiary strata, that extends from the left bank of the Mur into Hungary is continued by the north side of Lake Balaton to the Danube near Buda; and some geographers see in the hilly district that stretches thence to the northern Carpathians a connection between that range and the Alps. For practical purposes it seems that the line of depression, partly formed by the valley of the Mur, through which the railway is carried from Vienna to Laybach, may be considered as the eastern boundary of the Alpine chain. On the southern side the difficulty of fixing the precise limits of the Alpine chain is still more apparent. For a distance of some 350 miles, from the neighbourhood of Turm to that of Gorizia, the boundary is sufficiently obvious. The mountains subside into the continuous plain which includes the greater part of Piedmont, Lombardy, and Venetia; and their drainage is all borne eastward to the Adriatic. But on the west side of Piedmont the Alpine chain dividing Italy from France extends nearly due southward till it approaches to the Mediterranean in the neighbourhood of Nice. About 40 miles north of this city, that which, from its superior height and its geological structure, we call the main chain, is bent round from west to cast in a curve, slightly convex towards the south, till it becomes parallel to the Mediterranean shore, and is merged in the chain of the Apennines. For reasons hereafter mentioned it would appear that the limits of the Alps in this direction may best be fixed at the Col d’Altare, west of Savona, though the boundary commonly adopted is that of the Col di Tenda, lying considerably farther to the west. At the southeastern extremity of the Alpine chain the difficulty of fixing its limits arises rather from the vague use of geographical terms by ancient and modern writers than from the physical structure of the region. Taking no account of the arbitrary proceedings of geographers who have included in the Alps the mountains dividing Bosnia from Croatia and Dalmatia, and regarding only the natural features of the country, it seems clear that the south-eastern extremity of the Alps must be looked for in the group of lofty peaks between the head waters of the Isonzo and those of the Save, whose highest summit is the Terglou; and if we are not to include all the mountain ranges of European Turkey and Greece within the same designation, the plateau of the Karst must be held to form the boundary between these and the Alps. Within these limits the Alps extend from about the 44th to the 48th parallel of N. lat., and from about 5° 10' to 18° 10' E. long.

In every mountain system geographers are disposed to regard the watershed, or boundary dividing the waters flowing towards Opposite sides of the range, as marking the main chain; and this usage is often justified by the fact that the highest peaks lie on, or very near, the boundary so defined. In applying this term in the case of the Alps, there are, however, difficulties arising from their great extent and the number of their branches and ramifications. Many of the loftiest groups lie altogether on one side of that which we call the main chain, and at the eastern extremity, where all the drainage is ultimately borne to the Black Sea, we must be partly guided by geological considerations in deciding which of several ranges deserves to be considered pre-eminent.

Starting from the pass of Altare or Cadibona, west of Savona, the main chain extends first south-west, then nearly due west, to the Col di Tenda, but nowhere rising beyond the zone of coniferous trees. ^ Beyond that limit the range is more lofty, and includes four peaks exceeding 10,000 feet in height, till the line dividing the waters flowing to the Adriatic, through the Po, from the short streams that flow into the Gulf of Genoa, reaches the Mont Enchastraye. Beyond that point, although the line of watershed is very sinuous, its general direction for a distance of about 75 miles is nearly due north. On the east side the waters run to the Po; on the west they flow through the Durance to join the Rhone near Avignon. The most considerable peaks in the range immediately north of the Mont Enchastraye are the Grand Rioburent and the Aiguille de Chambeyron; but these are much surpassed by the Monte Viso, which is the highest peak in the range dividing Piedmont from Dauphiné. On the north side of Monte Viso the main chain diminishes much in average height, and presents no prominent peaks until we reach the Mont Tabor. That summit forms the apex of a salient angle which the main chain here presents on the side of France. For a distance of about 28 miles this extends eastward to the prominent peak of the Roche Melon, which may be considered as a re-entering angle in the great rampart by which Italy is guarded from her northern neighbours. Here the main chain resumes its northerly direction, and attains a greater average height than it had previously exhibited. Several of the prominent peaks in the range connecting the Roche Melon with Mont Blanc exceed 11,000 English feet in height, though they are much surpassed by the highest group of the Graian Alps, lying on the side of Piedmont, and that of the Tarentaise Alps in Savoy; while there is in this part of the main range but one considerable depression, which is that crossed by the road of the Little St Bernard. In the range crowned by the summit of Mont Blanc the Alpine chain attains its highest elevation. From thence to the Pass of St Gotthard its general direction varies between east and north-east. To the east of Mont Blanc a comparatively low tract allows of several comparatively easy passes between Switzerland and Piedmont, one of which has long been famous as the Pass of the Great St Bernard; but from that to the Simplon Pass, a distance of about 52 miles in a straight line, or about 75 miles if measured along the watershed, the main chain preserves a greater average height than in any other part. Several peaks lying in the dividing ridge, such as the Grand Combin, Matterhorn, Lyskamm, and Monte Rosa, exceed 14,000 feet in height; and these are rivalled by at least six summits on the north side of the same ridge, which at two points only sinks below the level of 10,000 feet. The Simplon Pass corresponds to what may be called a dislocation of the main chain. From thence to the St Gotthard the dividing ridge runs nearly due north-east, and does not present any dominant summit excepting the Monte Leone. On the east and south-east side of the St Gotthard Pass, as far as that of the Maloya, the line of watershed between the affluents of the Rhine and that of the Po is determined by what may be called accidental conditions. The chief mountain ridges, which culminate in the Cima Camadra, Piz Valrhein, and Tambohorn, instead of being arranged along the parting of the waters, lie in a transverse direction, and hence the natural frontier of Italy is here more broken and irregular than elsewhere; and it is only on the south side of the Maloya Pass that the main chain assumes a tolerably continuous direction from west-south-west to east-north-east, as between Piz Güz and the Bernina Pass it rises into the lofty group whose dominant peaks are Piz Tremoggia, Piz Bernina, and Piz Cambrena. Eastward of the Bernina Pass the same direction is preserved, and in the range including the Corno di Campo, Monte Zembrasca, and Monte Foscagno the level scarcely sinks below 9000 feet; but beyond the last-named summit, in the space lying between the Lower Engadine, the head waters of the Adige, and those of the Adda, the semblance of a continuous ridge forming the watershed between the Inn and the Adriatic altogether disappears. If we adhere to the usage of designating as the main chain the ridges which part the waters flowing in different directions, it must be owned that the disposition of the chief mountain masses has no connection with the direction of that chain. Lying between the great mass of the Orteles Alps to the south and the considerable group of the Silvretta Alps on the north side of the Inn, the greater part of the mass in question is drained by streams that flow into the latter river; but the arrangement of the valleys seems to be largely due to erosive action. Few summits in this part of the main chain exceed 10,000 feet, the highest being Piz Scesvenna, on the east side of Val Scarla.

The break in the continuity of the Alpine chain marked by the deep valley through which the main branch of the Adige descends, first southward and then eastward from its source to Meran and Botzen, is one of the most remarkable features in the orography of the Alps. The little lake which is regarded as the chief source of the river lies within less than five miles of the Inn, where that river enters the Tyrol, and no apparent barrier divides the lake from the Inn valley. Eastward of this limit the Alpine chain exhibits a degree of order in its general arrangement which it is impossible to trace in its western and central portions. For a distance of some 250 miles a broad zone of crystalline rocks extends from west to east, flanked on the north and south sides by parallel zones of sedimentary rocks, chiefly belonging to the older secondary formations. Two great valley systems on the opposite sides of the central zone closely coincide with those geological boundaries, and mark out in the physical aspect of this region the limits between the central and the secondary zones. In the former are situated all the highest peaks of the eastern Alps. For a distance of about 140 miles, from the Schafkogel, south-east of Nauders, to the Markkahrspitz, the average level of the main chain is nearly as high as in any equally long section of the central or western Alps. There is one very considerable depression which is marked by the Brenner Pass, but elsewhere in that long barrier there are but three points where the range is passable by beasts of burden. Between the two main sources of the Adige, at the Reschen Scheideck and the Brenner Pass, the considerable groups of the Oetzthal and Stubay Alps attain a great average elevation, though two points only—the Wildspitz and the Weisskugel—surpass the level of 12,000 feet. The drainage of these groups is mostly carried to the Inn, and the line of watershed, about 53 miles in length, is much less direct than in the more easterly portion of the chain. This extends nearly due east for about 90 miles from the Brenner Pass, nowhere falling below the level of 8000 feet, and in two prominent peaks—the Gross Venediger and the Gross Glockner—rising considerably above the limit of 12,000 feet. At a point somewhat north of the Markkahrspitz the central chain divides into two parallel ranges, between which lies the upper valley of the Mur. This river flows for a distance of fully 80 miles nearly due east, till at Bruck-an-der-Mur it turns southward to approach the Drave, and ultimately joins that stream. Various reasons combine to induce geographers to regard the more northern of the two ranges above mentioned, which divides the Enns and other minor tributaries of the Danube from those of the Drave, as constituting the eastern extremity of the main chain of the Alps. This extends a little north of due east for more than 110 miles, with a comparatively low mean elevation, from the Arlscharte to the Semmering Pass, which we regard as the eastern limit of the main chain of the Alps.

Measured along the watershed, as above defined, but without taking into account the minor sinuosities, which would considerably increase the total, the length of the main chain is about 790 English miles.

For ages before there existed any correct knowledge of the configuration of the Alpine chain, the needs of war and commerce had urged the people dwelling on the opposite sides of the great barrier to seek out the easiest and most direct routes for traversing it. Hence the chief passes of the Alps have been known and frequented from a period antecedent to authentic history, while until a quite modern period little attention was given to the parts of the chain which did not lie in or near the lines of traffic. It is highly probable that many other passes, affording the easiest means of communication between adjacent valleys, have been known and used by the native population from a very remote period, but only those which served for international purposes of war or peace became known at a distance, and are alluded to by ancient writers. A pass is a depression between two adjacent mountains, and the track is usually carried over the lowest part of that depression; but nevertheless nearly all the passes of the Alps involve a long ascent to reach the summit, and a long descent upon the opposite slopes. Hence the Romans, who were the first semi-civilised people to make extensive use of the Alpine passes, applied to each of them the term Mons. The same names, more or less modified in the middle ages, have been preserved in the dialects of Latin origin that prevail throughout the western half of the Alpine chain, and the modern name for the chief passes are still Mont Genévre, Mont Cenis, Mont Iséran, Petit Mont St Bernard, Grand Mont St Bernard, Monte Moro, and Monte San Gottardo. In more recent times, since geographers have attempted to fix the names and positions of the chief summits of the Alps, they have been continually misled by the supposition that a name of high antiquity designating a mountain must belong to some prominent peak. The errors arising from that source have not yet disappeared from geographical works of high repute, but in point of fact each of the names above enumerated belongs solely to the pass, and there is no neighbouring peak entitled to the same designation. The more important passes of the Alps are enumerated in the following description of the chief groups of the Alps; but it may be here remarked that the direction of the main routes for traffic is not exclusively determined by the position of the lowest and easiest passes over the main chain. The configuration of the mountains is such that a traveller proceeding from Italy to France, Switzerland, or Germany, after crossing a comparatively easy pass over the main chain, may find it necessary to traverse a second and loftier pass over a lateral chain, or else follow a circuitous route that may double the length of his journey. Thus a traveller going from Turin to Lyons, who should take what appears to be the direct course over the pass of Mont Genévre, the easiest in the whole range of the western Alps, will find on descending to Briançon that he must cross the much higher and more difficult pass of the Col de Lautaret, or else descend along the Durance till it emerges into the lower country near Gap, and thus more than double the length of his journey. Including the Semmering Pass, there are now not less than 60 Alpine passes that are traversed by carriage roads; and besides three lines of railway now open for traffic, several others are in course of construction.

From the time of Julius Caesar downwards, the Romans, in the prosecution of their policy of universal dominion, or for the purpose of maintaining communication with their military colonies, had become acquainted with all the easiest and most serviceable passes of the Alps, and were thus naturally led to attach names to the chief groups. As their acquaintance with the entire region was very incomplete, the exact boundaries of these groups were imperfectly understood, and the denominations adopted by them were never accurately defined. As might have been expected, the divisions thus roughly established had reference rather to the aspect of the mountains as presented to one travelling from Italy towards the north or west, than to a general view of the physical conformation of the...