though at singers' insistence the Birmingham Festival pitch was lowered (and the organ retuned) at that time. At the Queen's Hall in London, the establishment of the diapason normal for the Promenade Concerts in 1895 (and retuning of the organ to A = 435.5 at 15 °C (59 °F), to be in tune with A = 439 in a heated hall) caused the Royal Philharmonic Society and others (including the Bach Choir, and the Felix Mottl and Arthur Nikisch concerts) to adopt the continental pitch thereafter. In England the term low pitch was used from 1896 onward to refer to the new Philharmonic Society tuning standard of A = 439 Hz at 68 °F, while "high pitch" was used for the older tuning of A = 452.4 Hz at 60 °F. Although the larger London orchestras were quick to conform to the new, low pitch, provincial orchestras continued using the high pitch until at least the 1920s, and most brass bands were still using the high pitch in the mid-1960s. Highland pipe bands continue to use an even sharper tuning, around A = 470–480 Hz, over a semitone higher than A440. As a result, bagpipes are often perceived as playing in B despite being notated in A (as if they were transposing instruments in D-flat), and are often tuned to match B brass instruments when the two are required to play together. The Stuttgart Conference of the Society of German Natural Scientists and Physicians in 1834 recommended C264 (A440) as the standard pitch based on Scheibler's studies with his Tonometer. For this reason A440 has been referred to as Stuttgart pitch or Scheibler pitch. In 1939, an international conference recommended that the A above middle C be tuned to 440 Hz, now known as concert pitch. As a technical standard this was taken up by the International Organization for Standardization in 1955 and reaffirmed by them in 1975 as ISO 16. The difference between this and the diapason normal is due to confusion over the temperature at which the French standard should be measured. The initial standard was A = , but this was superseded by A = 440 Hz, possibly because 439 Hz was difficult to reproduce in a laboratory since 439 is a prime number. Current concert pitches The most common standard around the world is currently A = 440 Hz. In practice most orchestras tune to a