| Filar Mic. | Heliom. | |
| Equatorial diameter of Jupiter (Dist. 5.2028) | 38″.50 | 37″.50 |
| Polar diameter of Jupiter | 36″.02 | 35″.23 |
| Ellipticity | 1 ÷ 15.5 | 1 ÷ 16.5 |
| Theoretical ellipticity from motion of 900″ in the pericentre of Sat. V | 1 ÷ 15.3 | |
| Centrifugal force ÷ gravity at equator | 0.0900 | |
| Mass of Jupiter ÷ Mass of Sun, now used in tables | 1 ÷ 1047.34 | |
| Inclination of planet’s equator to ecliptic | 2° 9′.07 + 0.006t | |
| Inclination of planet’s equator to orbit | 3° 4′.80 | |
| Long. of Node of equator on ecliptic | 336° 21′.47 + 0′.762t | |
| Long. of Node of equator on orbit | 135°25′.81 + 0.729t | |
The longitudes are referred to the mean terrestrial equinox, and t is the time in years from 1900.0.
For the elements of Jupiter’s orbit, see Solar System; and for physical constants, see Planet. (S. N.)
JUR (Diur), the Dinka name for a tribe of negroes of the
upper Nile valley, whose real name is Luoh, or Lwo. They
appear to be immigrants, and tradition places their home in
the south; they now occupy a district of the Bahr-el-Ghazal
between the Bongo and Dinka tribes. Of a reddish black
colour, fairer than the Dinka, they are well proportioned, with
the hair short. Tattooing is not common, but when found is
similar to that of the Dinka; they pierce the ears and nose, and
in addition to the ornaments found among the Dinka (q.v.)
wear a series of iron rings on the forearm covering it from
wrist to elbow. They are mainly agricultural, but hunt and fish
to a considerable extent; they are also skilful smiths, smelting
their own iron, of which they supply quantities to the Dinka.
They are a prosperous tribe and in consequence spinsters
are unknown among them. Their chief currency is spears and
hoe-blades, and cowrie shells are used in the purchase of wives.
Their chief weapons are spears and bows.
See G. Schweinfurth, The Heart of Africa: Travels 1868–1871, trans. G. E. E. Frewer (2nd ed., 1874); W. Junker, Travels in Africa (Eng. ed., 1890–1892).
JURA, a department of France, on the eastern frontier,
formed from the southern portion of the old province of Franche-Comté.
It is bounded N by the department of Haute-Saône,
N.E. by Doubs, E. by Switzerland, S. by Ain, and W. by Saône-et-Loire
and Côte d’Or. Pop. (1906), 257,725. Area, 1951 sq. m.
Jura comprises four distinct zones with a general direction from
north to south. In the S.E. lie high eastern chains of the central
Jura, containing the Crêt Pela (4915 ft.), the highest point in
the department. More to the west there is a chain of forest-clad
plateaus bordered on the E. by the river Ain. Westward
of these runs a range of hills, the slopes of which are covered
with vineyards. The north-west region of the department is
occupied by a plain which includes the fertile Finage, the northern
portion of the Bresse, and is traversed by the Doubs and
its left affluent the Loue, between which lies the fine forest of
Chaux, 76 sq. m. in area. Jura falls almost wholly within the
basin of the Rhone. Besides those mentioned, the chief rivers
are the Valouze and the Bienne, which water the south of the
department. There are several lakes, the largest of which is
that of Chalin, about 12 m. E. of Lons-le-Saunier. The climate
is, on the whole, cold; the temperature is subject to sudden and
violent changes, and among the mountains winter sometimes
lingers for eight months. The rainfall is much above the average
of France.
Jura is an agricultural department: wheat, oats, maize and barley are the chief cereals, the culture of potatoes and rape being also of importance. Vines are grown mainly in the cantons of Arbois, Poligny, Salins and Voiteur. Woodlands occupy about a fifth of the area: the oak, hornbeam and beech, and, in the mountains, the spruce and fir, are the principal varieties. Natural pasture is abundant on the mountains. Forests, gorges, torrents and cascades are characteristic features of the scenery. Its minerals include iron and salt and there are stone-quarries. Peat is also worked. Lons-le-Saunier and Salins have mineral springs. Industries include the manufacture of Gruyère, Septmoncel and other cheeses (made in co-operative cheese factories or fruitières), metal founding and forging, saw-milling, flour-milling, the cutting of precious stones (at Septmoncel and elsewhere), the manufacture of nails, tools and other iron goods, paper, leather, brier-pipes, toys and fancy wooden-ware and basket-work. The making of clocks, watches, spectacles and measures, which are largely exported, employs much labour in and around Morez. Imports consist of grain, cattle, wine, leaf-copper, horn, ivory, fancy-wood; exports of manufactured articles, wine, cheese, stone, timber and salt. The department is served chiefly by the Paris-Lyon-Méditerranée railway, the main line from Paris to Neuchâtel traversing its northern region. The canal from the Rhone to the Rhine, which utilizes the channel of the Doubs over portions of its course, traverses it for 25 m. Lons-le-Saunier is the chief town of Jura, which embraces four arrondissements named after the towns of Lons-le-Saunier, Dôle, Poligny and St Claude, with 32 cantons and 584 communes. The department forms the diocese of St Claude and part of the ecclesiastical province of Besançon; it comes within the region of the VIIth army corps and the educational circumscription (académie) of Besançon, where is its court of appeal. Lons-le-Saunier, Dôle, Arbois, Poligny, St Claude and Salins, the more noteworthy towns, receive separate notices. At Baume-les-Messieurs, 8 m. N.E. of Lons-le-Saunier, there is an ancient abbey with a fine church of the 12th century.
JURA (“deer island”), an island of the inner Hebrides, the
fourth largest of the group, on the west coast of Argyllshire,
Scotland. Pop. (1901), 560. On the N. it is separated from
the island of Scarba by the whirlpool of Corrievreckan, caused
by the rush of the tides, often running over 13 m. an hour,
and sometimes accelerated by gales, on the E. from the mainland
by the sound of Jura, and on the S. and S.W. from Islay
by the sound of Islay. At Kinuachdrach there is a ferry to
Aird in Lorne, in Argyllshire, and at Faolin there is a ferry to
Port Askaig in Islay. Its area is about 160 sq. m., the greatest
length is about 27 m., and the breadth varies from 2 m. to 8 m.
The surface is mountainous and the island is the most rugged
of the Hebrides. A chain of hills culminating in the Paps of
Jura—Beinn-an-Oir (2571 ft.) and Beinn Chaolais (2407 ft.)—runs
the whole length of the island, interrupted only by Tarbert
loch, an arm of the sea, which forms an indentation nearly 6 m.
deep and almost cuts the island in two. Jura derived its name
from the red deer which once abounded on it. Cattle and sheep
are raised; oats, barley and potatoes are cultivated along the
eastern shore, and there is some fishing. Granite is quarried
and silicious sand, employed in glass-making is found. The
parish of Jura comprises the islands of Balnahua, Fladda,
Garvelloch, Jura, Lunga, Scarba and Skervuile.
JURA, a range which 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 off
the Jura from the Swabian and Franconian ranges to the north
and those of Dauphiné 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 Loue 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 m. long and 38 m. broad, hewn into an oblong shape, and raised by internal forces to an average height of from 1950 to 2600 ft. 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 Jura Mountains belong to the Alpine system; and the same forces which crumpled and tore the strata of the one produced the folds and faults in the other. Both chains
