The lowest octave is mainly used as a fundamental
octave bass to 'cello, bassoon or trombone. The tone of the
_pizzicato_ is full and rich owing to the slowness of the vibrations,
and it changes character according to the harmonies which lie above
it: with a chord of the diminished seventh above it, for instance, the
_pizzicato_ sounds like a menace, but with the common chord calm and
majestic. Both natural and artificial harmonics are possible on the
double bass, the former being the best; but they are seldom used in
orchestral works. As an instance of their use may be cited the scene
by the Nile at the beginning of the third act of Verdi's _Aida_, where
harmonics are indicated for both 'cellos and double basses.

The technical capabilities of the double bass are necessarily somewhat
more limited than those of the violoncello. Quick passages, though
possible, are seldom written for it; they cannot sound clear owing to
the time required for the strings to vibrate. An excellent effect is
produced by what is known as the _intermittent tremolo_: owing to the
elasticity of the bow, it rebounds several times on the strings when a
single blow is sharply struck, forming a series of short tremolos. The
double bass is the foundation of the whole orchestra and therefore of
great importance; it plays the lowest part, often, as its name
indicates, only doubling the 'cello part an octave lower. It is only
since the beginning of the 19th century that an independent voice has
occasionally been allotted to it, as in the Scherzo of Beethoven's
Fifth Symphony in C minor:--

[Illustration: CONTRABASSI.]

These opening bars are played _soli_ by 'cellos and double basses, a
daring innovation of Beethoven's which caused quite a consternation at
first in musical circles.

The remote origin of the double bass is the same as that of the
violin.[3] It was evolved from the bass viol; whether the transformation
took place simultaneously with that of the violin from the treble viol
or preceded it, has not been definitely proved, but both Gasparo da Salo
and Maggini constructed double basses, which were in great request in
the churches. De Salo made one with three strings for St Mark's, Venice,
which is still preserved there.[4] It was Dragonetti's favourite concert
instrument, presented to him by the monks of St Mark, and, according to
the desire expressed in his will, the instrument was rest