Of the more than 400 pieces written by 19th century German composer Felix Mendelssohn, only about 150 survive today in published form. A hundred of his pieces are believed to be completely lost, and the rest are missing.

Michael Cooper, an associate professor of music at Southwestern University, was browsing through an auction catalog in 1997 when he found a reference to one such missing piece at the St. Petersburg Conservatory in Russia. However, at that time the curators of the Conservatory’s music library were still hesitant about sharing their manuscripts with Westerners.

Cooper persisted, though, and in January 2003 the Conservatory finally sent him digital scans of the piece he was interested in. The piece, titled Fantasy and Variations for Two Pianos and Orchestra on the Gypsy March from Weber’s “Preziosa,” was jointly composed by Felix Mendelssohn and Ignaz Moscheles, a German pianist and composer who was a friend of Ludwig van Beethoven.

Central Texas residents will get the opportunity to hear the full version of the piece for the first time since 1833 when the Austin Civic Orchestra performs it at Southwestern on Saturday, Feb. 21. The piece will be performed as part of the orchestra’s winter concert, which begins at 7:30 p.m. in the Alma Thomas Theater.

The piece was originally commissioned in 1833 to be performed in a benefit concert for the Philharmonic Society of London. It was designed to feature Moscheles, who had moved to London and become a local piano celebrity. Mendelssohn helped Moscheles compose the piece after Moscheles fell ill just before the piece was to be performed.

After the piece premiered on May 2, 1833, the original score for the piece was never seen again. The work has been known only in an arrangement for two pianos without orchestra published by Moscheles in 1834.

Cooper said music historians now know that Moscheles bequeathed the original score to his son, Felix (who was named after Mendelssohn), who in turn gave it to the Russian pianist Anton Rubenstein in 1889. When Rubenstein died in 1894, he bequeathed his estate to the St. Petersburg Conservatory, which has thousands of historic music manuscripts.

“The St. Petersburg Conservatory didn’t know what they had,” said Cooper, who is one of the world’s leading authorities on Mendelssohn. “It was just something that existed in a card catalog and a weathered folder.”

Cooper said the Mendelssohn/Moscheles piece is based on a popular “Gypsies’ March” from a piece Carl Maria von Weber wrote in 1820. “At that time it was very popular for composers to take pieces that audiences already knew and put their own spin on them,” Cooper explained.

The 15-minute Mendelssohn/Moscheles piece features four variations on Weber’s theme, with the two pianos trading off starring roles. Mendelssohn and Moscheles each wrote a finale for the piece, and the ACO plans to perform both at the Feb. 21 concert to see which the audience prefers.

While the St. Petersburg Conservatory did have the full 69-page orchestral score for the piece, it did not have a complete score for the piano parts because Mendelssohn and Moscheles performed these parts themselves at the premier and did not record everything they played.

For assistance with recreating the piano parts, Cooper turned to Jonathan Bellman, a fellow musicologist from the University of Northern Colorado who also specializes in 19th century music. Bellman sent Cooper the recreated piano parts in the spring of 2006, just as Cooper was making plans to come to Southwestern to fill the Margarett Root Brown Chair of Fine Arts. When Cooper arrived at Southwestern in fall 2006, one of the first things he did was approach Kiyoshi Tamagawa, the chair of the Music Department and an accomplished pianist, about the possibility of performing one of the piano roles.

Tamagawa agreed, and Cooper then approached Lois Ferrari, associate professor of music at Southwestern and music director of the Austin Civic Orchestra, about having that orchestra accompany the pianists.

“We were very honored to have been asked to undertake this premiere and to have the opportunity to work with such distinguished and accomplished individuals,” Ferrari said.

Tamagawa will play the piano part Mendelssohn originally played and Bellman will play the piano part Moscheles originally played.

“The writing for the two pianos in these variations is brilliant and difficult,” Tamagawa said. “Both Mendelssohn and Moscheles were renowned as concert pianists and naturally composed parts that showed off their abilities.”

Tickets for the Feb. 21 concert may be purchased at the door the evening of the concert beginning at 6:30 p.m. Admission for the general public is $15. The concert is free for Southwestern students, faculty and staff.

“It will be nice to hear something that has been in the works for so long come to fruition,” Cooper said. “I know it will be a great performance.”

Cooper will give a brief talk before the concert about how the piece came into being and what he had to work with to recreate it.

Cooper wanted to have the piece performed this year to coincide with the 2009 bicentennial of the birth of Felix Mendelssohn, who is often considered to be the 19th century equivalent of Wolfgang Amadeus Mozart.

This is the third world premiere of a Mendelssohn piece Cooper has edited that will be performed in Central Texas. In 2006 the Austin Vocal Arts Ensemble performed an English version Cooper edited of Mendelssohn’s three Opus 69 motets. In 2007, there were performances in Austin and Georgetown of a new edition of Mendelssohn’s “St. Paul” oratorio that Cooper spent more than a decade recreating.

In all, Cooper has reconstructed seven Mendelssohn pieces that were believed to be missing.