Jena (Yay'na), a town of Saxe-Weimar, at the Leutra's influx to the Saale, 14 miles by rail SE. of Weimar, and 31 NNE. of Saalfeld. It lies 518 feet above sea-level, engirt by steep chalk-hills, of which the Hausberg (1069 feet) is crowned by the old Fuchsturm, and the Forstberg by a tower in memory of the Jena students who fell in the Franco-German war. It is still a quaint old-world place, with its ducal schloss, the ' Black Bear' inn where Luther halted on his flight from the Wartburg, and a church whose steeple is 311 feet high. Goethe here wrote his Hermann and Dorothea, Schiller his Wallenstein; and the houses of these and of other illustrious residents were marked with tablets in 1858, on occasion of the tercentenary of the university, when, too, was erected a bronze statue of its founder, the Elector John Frederick of Saxony. He founded it in 1547-58 to take the place of Wittenberg as a seat of learning and evangelical doctrine ; it attained its zenith in the days of Goethe's patron, Duke Karl August (1787-1806). To that period belong the names of Fichte, Schelling, Hegel, Schiller, the Schlegels, Voss, Fries, Krause, and Oken; to our own, of Hase and Haeckel. Jena now has 85 professors and lecturers, over 600 students, and a library of 200,000 volumes. In 1883 a memorial was erected of the Burschenschaft. Pop. (1875) 9020; (1900) 20,456. The battle of Jena is often applied as a collective name to two separate engagements fought on the same day, 14th October 1806 - one at Auerstadt, 14 miles to the north ; the other, on the heights round Jena, where Napoleon commanded in person. In both the Prussians were totally defeated.