engthened the tube and pierced another hole, the low E, covered by an
open key with a long lever which, when closed, gives the desired B as
its twelfth, thus forming a connexion between the two registers. A
clarinet with three keys, of similar construction (about 1750), marked
J.W. Kenigsperger, is preserved in the Bavarian national museum, at
Munich. Another in B flat marked Lindner[29] belongs to the collection
at Brussels. About the middle of the 18th century, the number of keys
was raised to five, some say[30] by Barthold Fritz of Brunswick
(1697-1766), who added keys for C# and D#. [Illustration] According to
Altenburg[31] the E flat or D# key is due to the virtuoso Joseph Beer
(1744-1811). The sixth key was added about 1790 by the celebrated French
virtuoso Xavier Lefebure (or Lefevre), and produced G#. [Illustration]
Anton Stadler and his brother, both clarinettists in the Vienna court
orchestra and instrument-makers, are said to have lengthened the tube of
the B flat clarinet, extending the compass down to C (real sound B
flat). It was for the Stadler brothers that Mozart wrote his quintet for
strings, with a fine obbligato for the clarinet in A (1789), and the
clarinet concerto with orchestra in 1791.

This, then, was the state of the clarinet in 1810 when Ivan Mueller, then
living in Paris, carried the number of keys up to thirteen, and made
several structural improvements already mentioned, which gave us the
modern instrument and inaugurated a new era in the construction and
technique of the clarinet. Mueller's system is still adopted in principle
by most clarinet makers. The instrument was successively improved during
the 19th century by the Belgian makers Bachmann, the elder Sax, Albert
and C. Mahillon, whose invention in 1862 of the C# key with double
action is now generally adopted. In Paris the labours of Lefebure,
Buffet-Crampon, and Goumas are pre-eminent. In 1842 H.E. Klose conceived
the idea of adapting to the clarinet the ingenious mechanism of movable
rings, invented by Boehm for the flute, and he entrusted the execution
of this innovation to Buffet-Crampon; this is the type of clarinet
generally adopted in French orchestras. From this adaptation has sprung
the erroneous notion that Klose's clarinet was constructed according to
the Boehm system; Klose's lateral divisions of the tube do not follow
those applied by Boehm to the flute.

In England the clarinet has also passed through several progressi