Bosanquet's Enharmonic harmonium (4 1/2 octaves tuned in 53 equal temperaments with 84 keys per octave ), designed by R H M Bosanquet and constructed by T A Jennings of Hackney Road, London in 1872-3.

Enharmonic harmonium with 4 1/2 octaves tuned in 53 equal temperaments with 84 keys per octave, designed by R H M Bosanquet (1841-1912) of St John's College, Oxford, and constructed by T A Jennings of Hackney Road, London in 1872-3. Bosanquet’s research into musical intervals and temperaments was influential in determining the design of keyboards for modern musical instruments.