same general direction in which they originally started, but following more or less the course of the great valleys. They only travel by night; and, staying in congenial places for considerable periods, with unaccustomed abundance of provender, notwithstanding the destructive influences to which they are exposed, they multiply excessively during their journey, having families more numerous and frequent than in their usual homes. The progress may last from one to three years, according to the route taken, and the distance to be traversed until the sea-coast is reached, which in a country so surrounded by water as the Scandinavian peninsula must be the ultimate goal of such a journey. This may be either the Atlantic or the Gulf of Bothnia, according as the migration has commenced from the west or the east side of the central elevated plateau. Those that finally perish in the sea, committing what appears to be a voluntary suicide, are only acting under the same blind impulse which has led them previously to cross shallower pieces of water with safety. In Eastern Europe, Northern Asia and North America the group is represented by the allied L. obensis, and in Alaska, by L. nigripes; while the circumpolar banded lemming, Dicrostonyx torquatus, which turns white in winter, represents a second genus taking its name from the double claws on one of the toes of the forefeet.
For habits of lemmings, see R. Collett, Myodes lemmus, its habits and migrations in Norway (Christiania Videnskabs-Selskabs Forhandlinger, 1895). (W. H. F.; R. L.*)
LEMNISCATE (from Gr. λημνίσκος, ribbon), a quartic curve
invented by Jacques Bernoulli (Acta Eruditorum, 1694) and
afterwards investigated by Giulio Carlo Fagnano, who gave its
principal properties and applied it to effect the division of a
quadrant into 2⋅2m, 3⋅2m and 5⋅2m equal parts. Following
Archimedes, Fagnano desired the curve to be engraved on his
tombstone. The complete analytical treatment was first given
by Leonhard Euler. The lemniscate of Bernoulli may be defined
as the locus of a point which moves so that the product of its
distances from two fixed points is constant and is equal to the
square of half the distance between these points. It is therefore
a particular form of Cassini’s oval (see Oval). Its cartesian
equation, when the line joining the two fixed points is the axis
of x and the middle point of this line is the origin, is (x2 + y 2)2 =
2a2(x2 − y 2) and the polar equation is r 2 = 2a2 cos 2θ. The curve
(fig. 1) consists of two loops symmetrically placed about the
coordinate axes. The pedal equation is r 3 = a2p, which shows
that it is the first positive pedal of a rectangular hyperbola with
regard to the centre. It is also the inverse of the same curve for
the same point. It is the envelope of circles described on the
central radii of an ellipse as diameters. The area of the complete
curve is 2a2, and the length of any arc may be expressed in the
form ∫(1−x4)−12dx, an elliptic integral sometimes termed the
lemniscatic integral.
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| Fig. 1. | Fig. 2. | Fig. 3. |
The name lemniscate is sometimes given to any crunodal quartic curve having only one real finite branch which is symmetric about the axis. Such curves are given by the equation x2 − y 2 = ax4 + bx2y 2 + cy 4. If a be greater than b the curve resembles fig. 2 and is sometimes termed the fishtail-lemniscate; if a be less than b, the curve resembles fig. 3. The same name is also given to the first positive pedal of any central conic. When the conic is a rectangular hyperbola, the curve is the lemniscate of Bernoulli previously described. The elliptic lemniscate has for its equation (x2 + y 2)2 = a2x2 + b2y 2 or r 2 = a2 cos2θ + b2 sin2θ (a > b). The centre is a conjugate point (or acnode) and the curve resembles fig. 4. The hyperbolic lemniscate has for its equation (x2 + y 2)2 = a2x2 − b2y 2 or r 2 = a2 cos2θ − b2 sin2θ. In this case the centre is a crunode and the curve resembles fig. 5. These curves are instances of unicursal bicircular quartics.
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| Fig. 4. | Fig. 5. |
LEMNOS (mod. Limnos), an island in the northern part of the Aegean Sea. The Italian form of the name, Stalimene, i.e. ἐς τὴν Λῆμνον, is not used in the island itself, but is commonly employed in geographical works. The island, which belongs to Turkey, is of considerable size: Pliny says that the coast-line measured 11212 Roman miles, and the area has been estimated at 150 sq. m. Great part is mountainous, but some very fertile valleys exist, to cultivate which 2000 yoke of oxen are employed. The hill-sides afford pasture for 20,000 sheep. No forests exist on the island; all wood is brought from the coast of Rumelia or from Thasos. A few mulberry and fruit trees grow, but no olives. The population is estimated by some as high as 27,000, of whom 2000 are Turks and the rest Greeks, but other authorities doubt whether it reaches more than half this number. The chief towns are Kastro on the western coast, with a population of 4000 Greeks and 800 Turks, and Mudros on the southern coast. Kastro possesses an excellent harbour, and is the seat of all the trade carried on with the island. Greek, English and Dutch consuls or consular agents were formerly stationed there; but the whole trade is now in Greek hands. The archbishops of Lemnos and Ai Strati, a small neighbouring island with 2000 inhabitants, resides in Kastro. In ancient times the island was sacred to Hephaestus, who as the legend tells fell on Lemnos when his father Zeus hurled him headlong out of Olympus. This tale, as well as the name Aethaleia, sometimes applied to it, points to its volcanic character. It is said that fire occasionally blazed forth from Mosychlos, one of its mountains; and Pausanias (viii. 33) relates that a small island called Chryse, off the Lemnian coast, was swallowed up by the sea. All volcanic action is now extinct.
The most famous product of Lemnos is the medicinal earth, which is still used by the natives. At one time it was popular over western Europe under the name terra sigillata. This name, like the Gr. Λημνία σφραγίς, is derived from the stamp impressed on each piece of the earth; in ancient times the stamp was the head of Artemis. The Turks now believe that a vase of this earth destroys the effect of any poison drunk from it—a belief which the ancients attached rather to the earth from Cape Kolias in Attica. Galen went to see the digging up of this earth (see Kuhn, Medic. Gr. Opera, xii. 172 sq.); on one day in each year a priestess performed the due ceremonies, and a waggon-load of earth was dug out. At the present time the day selected is the 6th of August, the feast of Christ the Saviour. Both the Turkish hodja and the Greek priest are present to perform the necessary ceremonies; the whole process takes place before daybreak. The earth is sold by apothecaries in stamped cubical blocks. The hill from which the earth is dug is a dry mound, void of vegetation, beside the village of Kotschinos, and about two hours from the site of Hephaestia. The earth was considered in ancient times a cure for old festering wounds, and for the bite of poisonous snakes.
The name Lemnos is said by Hecataeus (ap. Steph. Byz.) to have been a title of Cybele among the Thracians, and the earliest inhabitants are said to have been a Thracian tribe, called by the Greeks Sinties, i.e. “the robbers.” According to a famous legend the women were all deserted by their husbands, and in revenge murdered every man on the island. From this barbarous act, the expression Lemnian deeds, Λήμνια ἔργα, became proverbial. The Argonauts landing soon after found only women in the island, ruled over by Hypsipyle, daughter of the old king Thoas. From the Argonauts and the Lemnian women were descended the race called Minyae, whose king Euneus, son of Jason and Hypsipyle, sent wine and provisions to the Greeks at Troy. The Minyae were expelled by a Pelasgian tribe who came from Attica. The historical element underlying these traditions is probably that the original Thracian people were gradually brought into communication with the Greeks as navigation began to unite the scattered islands of the Aegean (see Jason); the Thracian inhabitants were barbarians in comparison with the Greek mariners. The worship of Cybele was characteristic of Thrace, whither it spread from Asia Minor at a very early period, and it deserves notice that Hypsipyle and Myrina (the name of one of the chief towns) are Amazon names, which are always connected with Asiatic Cybele-worship. Coming down to a better authenticated period, we find that Lemnos was conquered by Otanes, one of the generals of Darius
