JURA. This range may be roughly described as the block of mountains rising between the Rhine and the Rhone, and forming the frontier between France and Switzerland. The gorges by which these two rivers force their way to the plains cut of the Jura from the Swabian and Franconian ranges to the north and those of Dauphine to the south. But in very early days, before these gorges had been carved out, there were no openings in the Jura at all, and even now its three chief rivers - the Doubs, the Lone, and the Ain - flow down the western slope, which is both much longer and but half as steep as the eastern. Some geographers extend the name Jura to the Swabian and Franconian ranges between the Danube and the Neckar and the Main ; but, though these are similar in point of composition and direction to the range to the south, it is most convenient to limit the name to the mountain ridges lying between France and Switzerland, and this narrower sense will be adopted here.

The Jura has been aptly described as a huge plateau about 156 miles long and 38 miles broad, hewn into an oblong shape, and raised by internal forces to an average height of from 1950 to 2600 feet above the surrounding plains. The shock by which it was raised, and the vibration caused by the elevation of the great chain of the Alps, produced many transverse gorges or " cluses," while on the plateaus between these subaerial agencies have exercised their ordinary influence.

Geologically, the sedimentary rocks of the Jura belong to the Mesozoic age, and were deposited in a sea of variable depth, traces of which survive in the vast salt mines from which Salins and Lons-le Saunier derive their names. The special name of these fossiliferous strata is Oolitic ; the Jura. The action on these rocks of the carbonic acid gas discharged by all animals has been to transform them into bicarbonate of lime, a very soluble body, and hence the work of erosion has been much facilitated. The countless blocks of gneiss, granite, and other crystalline formations which are found in such numbers on the slopes of the diameter, and rests on the side of a hill 900 feet above mark on the Jura range itself in the shape of striations and moraines.

The general direction of the chain is from north-east to south-west, but a careful study reveals the fact that there 'were in reality two main lines of upheaval, viz., north to south and east to west, the former best seen in the southern part of the range and the latter in the northern ; and it was by the union of these two forces that the lines northeast to south-west (seen in the greater part of the chain), and south, while to the east the direction is north-east to south-west.

Before considering the topography of the interior of the Jura, it may be convenient to take a brief survey of its outer slopes.

The northern face dominates on one side the famous "Trunk:" (or Trench) of Belfort, one of the great geographical centres of Europe, whence routes run north down the Rhine to the North Sea, south-east to the Danube basin and Black Sea, and south-west into France and so to the Mediterranean basin. It is now so strongly fortified that it becomes a question of great strategical importance to prevent its being turned by means of the great central plateau of the Jura, which, as we shall see, is a network of roads and railways. On the other side it overhangs the " Troll& " of the Black Forest towns on the Rhine (Rheinfelden, Sackingen, Laufenbnrg, and Waldshut) through which the central plain of Switzerland is easily gained. On this north slope two openings offer routes into the interior of the chain, - the valley of the Doubs belonging to France, and the valley of the Birs belonging to Switzerland. 13elfort is the military, Midilhansen the industrial, and Basel the commercial centre of this slope.

The eastern and western faces offer many striking parallels. The plains through which flow the Aar and the Sa6ne have each been the bed of an ancient lake, traces of which remain in the lakes of Neuchatel, Bienne, and Morat. The west face runs mainly north and south like its great river, and for a similar reason the east face runs north-east to south-west. Again, both slopes are pierced by many transverse gorges or " dims " (due to fracture and not to erosion), by which access is gained to the great central plateau of Pontarlier, though these are seen more plainly on the east face than on the west; thus the gorges at the exit from which Lons le Saunier, l'oligny, Arbois, and Salins are built balance those of the Suze, of the Val de Ruz, of the Val de Travers, and of the Val d'Orbe, though on the east face there is but one city which commands all these important routes - Neuchatel. This town is thus marked out by nature as a great military and industrial centre, just as Besancon on the west, which has besides to defend the route from Belfort down the Doubs. These easy means of communicating with the Free County of Burgundy or Franche Comte accounts for the fact that the dialect of Neuchatel is Burgundian, and that it was held generally by Burgundian nobles, though most of the country near it was in the hands of the house of Savoy instil gradually annexed by Bern. The Chasscron (5286 feet) is the central point of the eastern face, commanding the two great railways which join Neuchatel and Pontarlier. It is in a certain sense parallel to the valley of the Lone on the west face, which flows into the Doubs a little to the south of Dole, the only important town of the central portion of the Saane basin. South of the Val d'Orbe the east face becomes a rocky wall crowned by all the highest summits of the chain - the Mont Tendrc (5512 feet), the Dole (5507 feet), the Reeulet (5643 feet), the Cr& dc in Neige (5653 feet), and time Grand Credo (5276 • feet), the uniformity of level being as striking as on the west edge of the Jura, though there the absolute height is far less. The position of the DOle is similar to that of the Chasseron, as along the sides of it run the great roads of the Col de St Cergues (4159 feet) and the Col de la Faucille (4341 feet), the latter leading through the Vallee des Dappes, which was divided in 1862 between France and Switzerland, after many negotiations. The height of these roads shows that they are passages across the chain, rather than through, natural depressions.

The Jura thus dominates on the north one of the great highways of Europe, on the east and west divides the valleys of the Saone and the Aar, and stretches out to the south so as nearly to join hands with the great mass of the Dauphine Alps. It therefore commands the routes from France into Germany, Switzerland, and Italy, and hence its enormous historical importance.

Let us now examine the topography of the interior of the range. This naturally falls into three divisions, each traversed by one of the three great rivers of the Jura--the Doubs, the Lone, and the Ain.

The first is the part east of the deep gorge of the Doubs after it turns south at St Hippolyte ; it is thus quite cut off on this side, and is naturally Swiss territory. It includes the basin of the river Birs, and the great plateau between the Doubs and the Aar, on which, at an average height of 2600 feet, are situated a number of towns, one of the most striking features of the Jura, These include Lode and La Chaux de Fonds, and are mainly occupied with watchmaking, an industry which does not require bulky machinery, and is therefore well fitted for a mountain district.

The part west of the " Cluse" of the Doubs. - Of this, the district east of the river Dessonbre, isolated in the interior of the range (unlike the Lode plateau), is called the "Haute Montagne," and is given up to cheese making, curing of hams, saw mills, &c. But little watchmaking is carried on there, Besancon being the chief French centre of this industry, and being connected with Geneva by a chain of places similarly occupied, which fringe the west plateau of the Jura. The part west of the Dessoubre, or the Moyenne Montagne, a huge plateau north of the Lone, is more especially devoted to agriculture, while along its north edge metal working and manufacture of hardware are carried on, particularly at Besancon and Audineourt.

The Ain rises on the south edge of this plateau, and on a lower shelf or step, which it waters, are situated two points of great military importance - Nozeroy and Champaguole. The latter is specially important, since the road leading thence to Geneva traverses one after auather, not far from their head, the chief valleys which run down into the South Jura, and thus commands the southern routes as well as those by St Cergucs and the Col de la Faucille from the Geneva region, and a branch route along the Orbe river from Jougne. The fort of Les ROUSSO, near the foot of the Dille, serves as an advanced post to Champagnole, just as the Fort de Joux does to l'ontarlier.

The above sketch will serve to show the character of the central Jura as the meeting place of routes from all sides, and the import auco to France of its being strongly fortified, lest an enemy approaching from the north-east should try to turn the fortresses of the " Trouee de Belfort." It is in the western part of the central Jura that the north and south lines first appear strongly marked. There are said to be in tlds district no less than fifteen ridges running parallel to each other, and it is these which force the Lone to the north, and thereby occasion its very eccentric course. The cultivation of wormwood wherewith to make the tonic " absinthe " has its headquarters at Pontarlier.

The Sienna, which flows from the fort of Les Rousses by St Claude, the industrial centre of the South Jura, famous for the manufacture of wooden toys, owing to the large quantity of boxwood in the neighbonrhood. Septmoncel is busied with cutting of gems, and Mores with watch and spectacle making. Cut off to the east by the great chain, the industrial prosperity of this valley is of recent origin.

The Gignon, which flows from south to north. It receives the drainage of the lake of Nantua, a town noted for combs and silk weaving, and which communicates by the " cheese " of the Lae de Silan with the Valserine valley, and so with the Rhone at Belle-garde, and again with the various routes which meet under the walls of the fort of Les Ramses, while by the Val homey and the Seran Culoz is easily gained.

The Albarine, connected with Culoz by the " cluse " of Virieu, and by the Ferran flowing south with Belley, the capital of the district of Bugey (the old name for the South Jura).

The " chases " of Nantua and Virieu are now both traversed by important railways ; and it is even truer than of old that the keys of the South Jura are Lyons and Geneva. But of course the strategic importance of these gorges is less than appears at first sight, because they can be turned by following the Rhone in its great bend to the south.

The name Jura, which occurs in Caesar and in Strabo, is a form of a word which appears under many forms (e.g., Jour, Jorat, Jorasse, Juriens), and is a synonym for a wood or forest. The German name is Leberberg, Leber being a provincial word for a hill.

Politically the Jura is French (departments of the Doubs, Jura, and Ain) and Swiss (parts of the cantons of Geneva, Vaud, Neuchatel, Bern, Solothurn, and Basel); but at its north extremity it takes in a small bit of Alsace (Pfirt or Ferrette). In the Middle Ages the southern, western, and northern sides were parcelled out into a number of districts, all of which were gradually absorbed by the French crown, viz., Gex, Val Homey, Bresse, and Bugey (exchanged in 1601 by Savoy for the marquisate of Saluzzo), Franche Comt6, or the Free County of Burgundy, an imperial fief till annexed in 1674, the county of Montholiard (Miimpelgard), acquired in 1793, and the county of Ferrette (French 1648-1871). The northern part of the eastern side was held by the bishop of Basel as a fief of the empire, but was given to Bern in 1S15 (as a recompense for its loss of Vaud), and now forms the Bernese Jura, a French-speaking district. The centre of the eastern slope formed the principality of Neuchatel and the county of Vallangin, which were generally held by Burgundian nobles, came by succession to the Icings of Prussia in 1707, and were formed into a .Swiss canton in ls 15, though they did not become free from formal Prussian claims until 1857. The southern part of the eastern slope originally belonged to the house of Savoy, but was conquered bit by bit by Bern, which was forced in 1815 to accept its subject district Vaud as a colleague and equal in the Swiss Confederation. It was Charles the Bold's defeats at Grandson and Morat which led to the annexation by the Confederates of these portions of Savoyard territory.

See E. P. Berlious, Le Jura, Paris, 1880 ; Adolphe Joanne, Jura et Japes Francaises, Paris, 1877 ; Id., Geographies apartementales (the Doubs, Jura, and Ain volumes) ; Charles Sauria, Le Jura pittoresque. (W. A. B. C.)