Jan LaRue, an expert on 18th-century music and an emeritus professor at New York University who compiled a colossal database of nearly 17,000 symphonic themes, died Sunday, the university announced.

For more than 50 years, Professor LaRue investigated and catalogued the classical idiom of Mozart, Haydn, and Beethoven, as well as the many lesser known composers of the 18th century. He tracked down information in libraries, archives, private basements, and attics in countries often deemed inaccessible because of the Cold War, LaRue and his research assistants scoured Europe and Russia in the 1950s, ’60s, and ’70s.

As he located symphonies, concertos, and other works by the great masters and their contemporaries, LaRue recorded thematic openings, scoring, source locations, and composer attributions. Using this information, he identified many new sources for works of the major composers of the period 1700-1800, corrected thousands of misattributions, and supplied composer names for many previously anonymous works.

LaRue’s work on watermark identification is still considered the cornerstone of all such work in the discipline of musicology.

The first volume of his “Catalogue of 18th Century Symphonies” containing nearly 17,000 entries, from Abel to Zumsteeg, was published by Indiana University Press in 1988. His work was greatly aided by the advent of computer databases for musicological research, a subject in which he was a pioneer.

In 1985, LaRue came to public attention as the most eminent authority when a suspected Mozart symphony was discovered lying in a bundle of old manuscripts in Odense, Denmark. “I’m happy to say that I enthusiastically believe that this is a work of Mozart,” LaRue told the Washington Post. Now generally accepted as early Mozart, the 15-minute symphony was composed when he was a precocious lad of 12, and constituted his first symphony in a minor key.

LaRue was born in Sumatra, where his father, the noted botanist Carl LaRue, was doing work with the variegated coleus. After graduating from Harvard in 1940, where he was a class mate of Leonard Bernstein’s, he received an M.F.A. from Princeton University in 1942 and taught at Wellesley College from 1942-43 before entering the Army and serving in the Pacific theater. Rising to the rank of captain, his time spent stationed on Okinawa led to some of the first investigations of native music there and the completion of one of the earliest American Ph.D. dissertations on an ethnomusicological subject, “Okinawan Classical Song.”

Larue returned to Wellesley to teach, and in 1957 joined the Department of Music at New York University, where he remained until his retirement in 1988.

While at NYU, LaRue served as dean of the Graduate School of Arts and Science and chair of the Department of Music. He was president of the American Musicological Society from 1967-68.

Until his death, LaRue was a member of the Salzburg Mozarteum, the central institute for Mozart research in Austria, and in 2003 he was elected to the American Academy of Arts and Sciences.

LaRue’s 1970 volume “Guidelines for Style Analysis” was recently translated into Spanish. He was the recipient of a festschrift on his 65th birthday, and a volume of his collected writings was published in 2001 by the Journal of Musicology in honor of his 80th birthday.

Jan LaRue

Born July 31, 1918 in Kisaran, Sumatra, Indonesia; died October 17 in Rye, N.Y.; predeceased by his first wife, Helen Robinson, in 1998; survived by his wife, Marian Green LaRue; two daughters, Charlotte Isaacs, and Christine Honig, and four grandchildren.