Keyboard concertos by Johann Sebastian Bach left Weimar in 1717. Many of Bach's orchestral harpsichord concertos are adapted from a model with one or more violin solo parts. Several of these earlier models are extant. The oldest of these is Vivaldi's concerto for four violins, RV 580, published in 1711, model for Bach's concerto for four harpsichords, BWV 1065. Bach replaced the part of his fourth "Brandenburg Concerto", BWV 1049, composed in 1721 or earlier, by a harpsichord part when he reworked it to the harpsichord concerto BWV 1057. Bach's extant violin concertos BWV 1041–1043, two for a single violin soloist and one for two violin
Hansa-Brandenburg B.I Hansa-Brandenburg B.I The Hansa-Brandenburg B.I was an unarmed military trainer and reconnaissance biplane of World War I, flown by the Austro-Hungarian Air Service. Early models were known internally to the Hansa-Brandenburg firm as the type D, while later models with a more powerful engine were designated FD. This aircraft was one of the earliest designs of Ernst Heinkel, who was working for Hansa-Brandenburg at the time. It was an entirely conventional two-bay biplane with staggered wings of unequal span. The pilot and observer sat in tandem in a long open cockpit. The aircraft was produced under license by Aero, both