snares. The upper head, set in vibration by
direct percussion from the sticks, induces sympathetic vibrations in the
air contained within the resonating receptacle, and these vibrations are
communicated to the lower head. The presence of the snares across the
diameter of the latter produces a phenomenon which gives the side drum
its peculiar timbre, changing the nature of the vibrations, now no
longer free: the snares form a kind of nodal contact, inducing double
the number of vibrations and a sound approximately an octave higher than
would be the case were the heads left to vibrate freely. Moreover, the
vibrations of the upper head being weaker, the latter is compelled to
vibrate synchronously with the lower vellum.[1]

[Illustration: FIG. 2.--Guards pattern Side Drum (Besson & Co.).]

[Illustration: FIG. 3.--Regulation Side Drum (Besson & Co.).]

The side drum, so called because it is worn at the side, is struck in
the centre by two small wooden sticks with elongated heads or knobs of
hard wood, producing a hard rasping sound when the drum is played singly
and in close proximity to the hearer; when, however, several drums are
played simultaneously or with other instruments the effect is brilliant
and exhilarating. The roll is produced by striking two blows alternately
with each hand quite regularly and very rapidly, the result being a
rattling tremolo. This roll ("daddy-mammy") is very difficult to
acquire, and requires long practice. The side drum can be muffled by
loosening the snares or by inserting a piece of silk or cloth between
the snares and the parchment. An impressive effect is produced by a
continued roll on muffled drums in funeral marches. The notation for the
side drum is similar to that in use for the bass drum; the value of the
note is alone of importance; the place of the note on the staff is
immaterial and purely a matter of custom. In orchestral scores, a single
line is often used, or the part for side and bass drum is written on the
same staff. A great variety of rhythmical figures can be played on the
side drum, such as

[Illustration: notes]

The _tenor drum_ (Fr. _caisse roulante_; Ger. _Roll-_ or _Ruhrtrommel_;
Ital. _tamburo rulante_) is similar to the side drum but has a larger
cylinder of wood and no snares; consequently its timbre lacks the
brilliancy and incisiveness of the side drum. It is used for the roll in
military bands, in some theatre orchestras, and on the stage.

The _tamb