Ludwig Ritter von Köchel
Ludwig Alois Ferdinand Ritter von Köchel (IPA: [ˈkœçəl]) (January 14, 1800 – June 3, 1877) was a musicologist, writer, composer, botanist and publisher. He is best known for cataloguing the works of Mozart and originating the 'K-numbers' by which they are known (K for Köchel).
Born in the town of Stein, Lower Austria, he studied law in Vienna, and for fifteen years was tutor to the four sons of Archduke Charles of Austria. Köchel was rewarded with a knighthood and a generous financial settlement, permitting him to spend the rest of his life as a private scholar. Contemporary scientists were greatly impressed by his botanical researches in North Africa, the Iberian Peninsula, the United Kingdom, the North Cape, and Russia. Additional to botany, he was interested in geology and mineralogy, but also loved music, and was a member of the Mozarteum Salzburg.
Köchel catalogue
In 1862 he published the Köchel catalogue, a chronological and thematic register of the works of Mozart. This catalogue was the first on such a scale and with such a level of scholarship behind it; it has since undergone revisions. Mozart's works often are referred to their K-numbers (c.f. opus number); for example, the "Jupiter" symphony, Symphony No. 41 K. 551.
Moreover, Köchel arranged Mozart's works into twenty-four categories, which were used by Breitkopf & Härtel when they published the first complete edition of Mozart's works from 1877 to 1910, a venture partly funded by Köchel.
Ludwig Ritter von Köchel died at age 77 in Vienna.
Notes
Regarding personal names: Ritter is a title, translated approximately as Sir (denoting a Knight), not a first or middle name. There is no equivalent female form.