George Joseph Vogler, known also as Abbé (or Abt) Vogler (1748-1816),
was a German musician. He composed operas and other musical pieces,
became famous as an organist, and invented an organ with pedals and
several keyboards. Browning seems to have in mind the complex musical
harmonies of which the instrument was capable. See lines 10, 13, 52,
55, and 84 of the poem. See also the _Encyclopædia Britannica_.
3. =Solomon=. Legends about Solomon and his power over the spirits of
earth and air are common in Jewish and Arabic literature.
9 ff. =building=. The idea of building by music is an old one. See
the classical story of Amphion and the walls of Thebes, Coleridge's
_Kubla Khan_, and Tennyson's _Gareth and Lynette_, lines
272-274.