Ludwig Alois Ferdinand Ritter von Köchel (January 14, 1800 - June 3, 1877) was a writer, composer, botanist and publisher. He was born in the small town of Stein, Lower Austria. He studied law in Vienna and for 15 years he was the tutor of the four sons of Archduke Charles.
Köchel's reward was a knighthood and a generous financial settlement which permitted him to spend the rest of his life as a private scholar. Scientists of his day were greatly impressed by his botanical researches in North Africa, the Iberian Peninsula, Great Britain, the North Cape[?] and Russia.
In addition to botany, he was interested in geology and mineralogy, but he also loved music, and as a member of the Salzburg Mozarteum he published in 1862 Chonologisch-thematisches Verzeichnis sämtlicher Tonwerke Wolfgang Amadé Mozarts, a chronological and thematic register of the works of Mozart. It is sometimes known today as "the Köchel catalogue".
This catalogue was the first on such a scale and with such a level of scholarship behind it. Köchel attempted to arrange the works in chronological order, but the dates of many of the pieces written prior to 1784 had to be guessed at. Subsequent editions, especially the third by Alfred Einstein[?] (1937), and the sixth by Franz Giegling[?], Gerd Sievers[?] and Alexander Weinmann[?] (1964, the most recent), included many corrections.
Köchel's catalogue included the opening bars of each piece and gave each work a number. Mozart's works are often referred to today by these numbers, known as the K number (see opus number) - for example, the Symphony No. 41[?] (the Jupiter symphony) is K. 551.
Köchel also arranged Mozart's works into 24 categories which were used by Breitkopf[?] when they published the first complete edition of Mozart's works from 1877 to 1905 (a venture funded in part by Köchel himself).