The bowed clavier is a keyboard instrument

Keyboard instrument

A keyboard instrument is a musical instrument which is played using a musical keyboard. The most common of these is the piano. Other widely used keyboard instruments include organs of various types as well as other mechanical, electromechanical and electronic instruments...

 strung with gut strings, the tone of which is produced by a steadily revolving well rosin

Rosin

.Rosin, also called colophony or Greek pitch , is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black...

ed cylinder (powered by a foot pedal), a mechanism not dissimilar to that found in the hurdy-gurdy

It was invented by Joh. Hohlfeld of Berlin

Berlin

Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

 in 1751

1751 in music

-Events:*1751 is the year commonly given as the beginning of the classical era*The "War of the Buffoons" , concerning the relative merits of French and Italian opera, divides Paris....

. This instrument and another one of his inventions, a device that records keyboard improvisations in real-time, were mentioned in the "Essay on the True Art of Playing Keyboard Instruments" by C. P. E. Bach.