The Harvard College Library recently accepted an extraordinary collection of Mozart rariora, the Biblioteca Mozartiana Eric Offenbacher (BMEO), a gift from Eric Offenbacher given during a Nov. 4 program.

The collection contains autograph manuscripts of Wolfgang Amadeus Mozart and his son, Carl; more than 100 first and early editions of Mozart's music; early biographical materials regarding Mozart and his family; and hundreds of books and other research materials.

"Dr. Offenbacher's gift has been planned for more than a decade; some materials have been on deposit for some years, and others turned over to Harvard recently," explained John B. Howard, Harvard's Richard F. French Music Librarian. "On this occasion, Dr. Offenbacher has made a gift to Harvard of the last real jewels of the collection -- a manuscript section of Mozart's earliest Horn Concerto, K. 370b, and a letter written by his son, Carl, that refers to it."

In his presentation at the Houghton Library of the manuscript to Nancy Cline, Roy E. Larsen Librarian of Harvard College, Offenbacher recounted the circumstances under which he obtained the manuscripts.

"When I was still working in New York," he said, "Friday was the most expensive day of the week, because on Fridays I visited the antiquarian bookshops in Greenwich Village where treasures occasionally appear." On one such visit to a book dealer, he was shown the manuscript leaf from the Horn Concerto and the accompanying letter, but did not purchase it impulsively. "I called Robert Levin [now the Dwight P. Robinson Jr. Professor of Music at Harvard] and asked his opinion, who ventured the opinion that it was a part of a horn concerto." On a return visit Offenbacher purchased the manuscript.

The concerto manuscript, indeed, has had a difficult history. It came into the possession of Carl Mozart among documents inherited from his mother, Constanze, in an already incomplete state: the final fascicle was missing, and the manuscript was already separated from its second movement, a Rondo.

As explained by Christoph Wolff, the William Powell Mason Professor of Music and Dean of the Graduate School of Arts and Sciences, the manuscript was made even more incomplete through Carl Mozart's actions.

"During the centennial year of Mozart's birth and after, Carl cut the manuscript into ever smaller sections, distributing them as keepsakes to nobility and dignitaries." The manuscript was cut eventually into at least nine fragments, eight of which are now held by seven different libraries internationally.

When Offenbacher first discussed turning the manuscript over to Harvard, he mused that it would be an extraordinary task to reassemble all the missing fragments for exhibition. In the spirit of that idea, the Harvard College Library has published on the occasion of Offenbacher's gift a four-color facsimile of all the surviving fragments of the concerto, edited by John Howard with introductory commentary by Wolff and Levin.

In the process of assembling the edition, Wolff and Levin were able to demonstrate decisively that another work of Mozart's (the so-called "Concert Rondo," K. 371) formed part of the concerto. This movement, preserved in a privately owned manuscript, is reunited with K. 370b for the first time in the facsimile.

Wolff noted that Offenbacher's gift had contributed much to developing the "right climate" for serious Mozart research at Harvard, and that the scholarly contributions made by the edition help realize Offenbacher's goal of promoting the academic study of Mozart's life and works.

The evening concluded with a premiere performance of Levin's completion of the Horn Concerto, performed by renowned natural horn soloist Lowell Greer and members of Boston's Handel and Haydn Society orchestra.

The major part of the Biblioteca Mozartiana Eric Offenbacher is held at the Eda Kuhn Loeb Music Library; manuscript materials, including the Horn Concerto and part of Mozart's Sinfonie concertante, are kept at Houghton Library. An exhibit of selections from the BMEO is on display in the French Gallery at the Music Library through Dec. 31.