Christian Ludwig Ideler (September 21, 1766 - August 10, 1846), German chronologist and astronomer, was born near Perleberg on the 21st of September 1766. After holding various official posts under the Prussian government he became professor at the university of Berlin in 1821, and eighteen years later foreign member of the Institute of France. From 1816 to 1822 he was tutor to the young princes William Frederick and Charles. He died in Berlin on the 10th of August 1846. He devoted his life chiefly to the examination of ancient systems of chronology. In 1825-1826 he published his great work, Handbuch der mathematischen und technischen Chronologie (2 vols.; 2nd ed., 1883), re-edited as Lehrbuch der Clironologie (1831); a supplementary volume, Die Zeitrechnung der Chinesen, appeared in 1839. Beside these important works he wrote also Untersuchungen über den Ursprung und die Bedeutung der Sternnamen and Über den Ursprung des Thierkreises (1838). With Nolte he published handbooks on English and French language and literature. His son, Julius Ludwig Ideler (1809-1842), wrote Meteorologia veterum Graecorum et Romanorum (1832).