The glass harmonica was invented in 1761. Mozart wrote several pieces for this instrument. The hemispherical glass bowls which rotate around a horizontal axis driven by a pedal were rediscovered only in the last decades of the 19th century. Sounds are produced by touching the rotating glasses with moistened fingertips. Today, the glass harmonica is an absolute rarity, with roughly ten professional players world-wide. Another rather rarely encountered jewel is the verrophone (from the french word "la verre" for glass). The youngest of the glass instruments was developed only 20 years ago in Germany. Chromatically tuned glass tubes are rubbed with moistened fingers like the musical glasses, but are also struck with mallets. The lingering, atmospheric sound is highly esteemed by modern composers due to its extraordinary intensity. The musical glasses present one of the oldest forms of making music and sounds with glasses. The instrument consists of several custom-made wine glasses. In order to get different pitches the musical glasses are filled with varying amounts of water. The musical glasses sampled by the Vienna Symphonic Library have a chromatic range from G3 to G6. The glass instruments are rounded off by the bottles which are blown with VOLUME CONTENTS such as sustains and flutter tonguing.