Harrison & Harrison (McClure) organ

• Harrison and Harrison, 1949-50

An experimental organ of unequal temperament moved in 1977 from the Reid Concert Hall to Lecture Room B, Alison House, Nicolson Square.
This move was to make space for the new Ahrend organ (1977-78) and at the same time the wooden floor of the platform area in the Reid Concert Hall was replaced.

This unusual experimental instrument was designed by Dr A. R. McClure, and was one of the results of his experiments n keyboard temperaments. The organ has two pipes for each of the black keys, e.g. both D sharp and E flat; both G sharp and A flat, etc. are available; in other words there are 19 pipes to the octave rather than 12.  The temperament is close to mean tone, but it is thus possible to pay in more keys than are feasible with a normal mean-tone keyboard.  Dr McClure described it as an 'extended mean-tone organ' and intended it for 'experiments in plainsong accompaniment, as a continuo instrument for 16th- and 17th-century music and for experiments in original music'.  There is one manual and a full pedal-board permanently coupled to it..  Seven key-switches (like draw-stops) allow the player to choose the appropriate accidental.  There are six ranks of pipes, all of metal except for the stopped diapason. 

• Report on the McClure organ to Professor Sidney Newman, Reid Professor of Music (1941-1970)