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No other work of this type makes use of thirteen instruments, a choice no
doubt determined by Mozart’s desire to demonstrate his virtuosity as a
composer, whilst paying tribute to the skills of the first-ratemusicians he had
at his disposal.
To the ‘traditional’ octet Mozart added two basset horns and two horns,
plus a double bass for additional depth (thus remedying a weakness of the
Harmonie). The presence of this string instrument refutes the common
description of K361 as a ‘Serenade for thirteen wind instruments’. For Mozart
undoubtedly wrote this part for a double bass, and not for a double bassoon,
as has sometimes been suggested. Indeed, he neither knew nor had access
to the latter instrument at the time — the double bass was the only very low-
pitched instrument that was available to him. He added two horns (which
are not used systematically) for the sake of variety, the natural horn being
restricted, at any given moment, to one pitch of the harmonic series.
The most unusual addition was undoubtedly that of the two basset horns,
instruments that were rarely used in musical compositions. The basset horn
was invented in the 1760s. The name derives from its basset (‘small bass’) pitch
and its original curved- horn shape (later supplanted by an angular form) and
brass bell. But it is in fact a clarinet pitched a fourth lower than the ordinary
B flat clarinet. Its sombre tone appealed to Anton Stadler, who adopted the
instrument and perfected it with Lotz’s help, making the low third completely
chromatic and therefore completely usable. It was no doubt Stadler who
introducedMozart to the basset horn, and for Stadler that Mozart composed
for the instrument (all his compositions for the basset horn date from the
Vienna period).
58 MOZART_ENSEMBLE PHILIDOR