=Other Early Composers=.—Of these, =Gottfried Heinrich Stoelzel= (1690-1749), chapel-master at Saxe-Gotha, wrote an “enharmonic” clavier sonata in three parts, a Largo in C minor, in 4/4 time; a short fugue; and a 3/8 movement, in harmonic form, in which experiments in modulation were tried. His successor at Saxe-Gotha was =Georg Benda= (1721-95), who published a number of clavier pieces and sonatas, besides two concertos for clavier and string quartet, all of which show a desire for genuine expression in the harmonic form. The first four-hand sonatas seem to have been published by =Charles Heinrich Müller=, of Halberstadt, in 1783, and another appeared in 1784, by =Ernst Wilhelm Wolf= (1735-92), court chapel-master in Saxe-Weimar, the writer of numerous other clavier sonatas and concertos showing great purity and originality of style. At the court of Frederick the Great, at Berlin, =Christoph Nichelmann= (1717-62), a pupil of Bach, and =Carl Fasch= (1736-1800) were successively second harpsichordists. Both wrote sonatas, those of the former in two movements, while those of the latter had generally three, of a brilliant and attractive style. =Friedrich Wilhelm Marpurg= (1718-95), the distinguished Berlin theoretician, was more successful in contrapuntal work than in his sonatas, written in freer style. =Georg Christoph Wagenseil= (1715-77), pupil of J. J. Fux, court music teacher and celebrated clavier virtuoso, wrote sonatas for clavier and violin and a number for clavier alone. =Wilhelm Friedemann Bach=.—Perhaps the most striking developments, however, were at the hands of the sons of J. S. Bach, who were all, having come under his direct instruction, of refined musical judgment, while some of them possessed marks of his genius. Of these, =Wilhelm Friedemann Bach= (1710-84), the eldest, called the Bach of Halle, from his long residence there, studied at the University of Leipzig, distinguishing himself in mathematics; was organist at Dresden and Halle successively, and finally came to Frederick the Great’s court, at Berlin, through the influence of his brother Carl. Although he possessed great gifts as a player and composer, his dissipated habits brought him to disgrace, and he died in poverty. He wrote many clavier compositions, showing a bold use of harmonies, and including sonatas which have decidedly instrumental themes and development. A large number of his father’s manuscripts known to have been in his possession have been irretrievably lost.