Old Whalers’ Church will present two Sunday-afternoon organ recitals on the church’s historic Erben organ by organists Mark Thallander and Walter Klauss. On July 29, Mark Thallander, well known for his distinguished 18-year ministry at the Crystal Cathedral in Garden Grove, Calif., will play two organ duets with Andrew McKeon, organist at St. John’s Roman Catholic Church in Center Moriches, as well as other pieces. In spite of losing his left arm as a result of an automobile accident in 2003, Mr. Thallander has continued to inspire audiences with his mastery of the organ repertoire as well as telling his personal story in speaking engagements at schools and churches across the country. The recital will take place in the air-conditioned sanctuary and will be followed by a reception to meet Mr. Thallander. The tracker organ at Old Whalers' Church, built in 1845 by Henry Erben, is the oldest organ in a church on Long Island. Proceeds benefit the Community House at Old Whalers'.