Berlin Musical Instrument Museum Berlin Musical Instrument Museum The Berlin Musical Instrument Museum () is located at the Kulturforum on Tiergartenstraße in Berlin, Germany. The Museum holds over 3,500 musical instruments from the 16th century onward and is one of the largest and most representative musical instrument collections in Germany. Objects include a portable harpsichord once owned by Prussia’s Queen Sophie Charlotte, flutes from the collection of Frederick the Great, and Benjamin Franklin’s glass harmonica. The Museum was founded in 1888 at the Royal Academy of Music in Berlin from a collection assembled by Philipp Spitta and Joseph Joachim. Thirty-four instruments from the Museum
Proof that π is irrational In 1761, Lambert proved that is irrational by first showing that this continued fraction expansion holds: Then Lambert proved that if "x" is non-zero and rational then this expression must be irrational. Since tan(/4) = 1, it follows that /4 is irrational and therefore that is irrational. A simplification of Lambert's proof is given below. This proof uses the characterization of as the smallest positive number whose half is a zero of the cosine function and it actually proves that is irrational. As in many proofs of irrationality, the argument proceeds by reductio ad absurdum. Consider the sequences ("A") and