(Fr. céleste).
A muting device that introduces a strip of cloth, felt or leather between the hammers and strings of a piano. Operated by a hand stop, knee lever or, especially in later examples, a pedal, it was commonly found on German and Austrian pianos of the 18th and early 19th centuries. From about 1810 to the 1830s Viennese grand pianos often had two moderator pedals, the second of which inserted an extra thickness of muting cloth to provide a third level of soft tone-colour in addition to the normal moderator and the Una corda. Moderators, which had almost never been included in French and English grand pianos, fell out of favour in Germany and Austria after about 1840. The device was also applied to square and upright pianos, in which it remained in occasional use throughout Europe and America until the early 20th century, since these instruments usually lacked una corda pedals.
EDWIN M. RIPIN/JOHN KOSTER