“The instruments were to have a bore slightly larger than that of the horns, but much less than that of the tubas. The instruments were to be arranged in two pairs—a small high-pitched pair and a large low-pitched pair. They are all _modified horns_, but Wagner called them _tenor-tuben_ and _bass-tuben_. This group of the so-called Wagner tubas is made up of two distinct types of instruments—a quartet of two high and two low _modified horns_ and _one true tuba_.” This is the bass tuba described above. [Illustration: BASS TUBA, SYMPHONY SOCIETY OF NEW YORK _Luca Del Negro_] CHAPTER VII PERCUSSION INSTRUMENTS _The kettledrums; the side-drum; the bass drum; the triangle; the cymbals; the tambourine; the tambourin; the castanets; the carillon, or glockenspiel; the celesta; the xylophone; the wind-machine; the rattle; the anvils; the cuckoo; the bells._ There are two kinds of percussion instruments: those which produce _musical_ notes; and those which only make _noise_. These instruments have neither strings, nor holes, nor keys. They are simply beaten, or shaken. In his definition of percussion instruments Gevaert subdivides them into two groups: Autophonic Instruments, and Membrane Instruments. Autophonic Instruments are those in which the tone is produced by the vibration of solid bodies (made of metal or wood), and which are of a nature sufficiently elastic to keep up the vibratory motion that has been given to them by the blow from the performer. These include instruments of _definite_ pitch, such as bells, _glockenspiel_ and celesta; and instruments of _indefinite_ pitch, such as the triangle, cymbals, gong, castanets, etc. Membrane Instruments are those that have a parchment, or skin, stretched, over them. These are the kettledrum, which has a _definite_ pitch, and the bass drum, side drum and tambourine, which have _indefinite_ pitch. THE KETTLEDRUMS The name of these instruments describes them precisely. We are perfectly familiar with these huge copper kettles that stand at the back of the Orchestra, adding no little to the picturesqueness of the stage. The kettledrum is a big copper bowl, or basin, across which a piece of parchment is tightly stretched to make the “head.” By means of screws with T-heads, the parchment can be tightened, or loosened, and thus the drum is tuned to a musical note of definite pitch. On the bottom of the shell a hole is pierced so that the air may escape when a heavy blow is struck. Otherwise the skin would split when the performer comes down with a vigorous thwack upon the “head” with his stick. Calfskin is usually employed for the “head,” and it has to be selected and prepared with great care. After being soaked in cold water until pliable, the “head” is tucked around the “flesh hoop,” and, upon drying, it holds as fast as if it were glued.