In 1834, Johann Scheibler (1777–1837) invented a musical instrument made of 54 tuning forks that vibrated between 220 cycles per second and 440 cycles per second. He made it

so that successive tuning forks had equal increases in cycles per second.

a What was the size of the increase between two successive tuning forks?

b Write down the cycles per second of the fi rst four notes of Scheibler’s instrument.

c What is the difference between Scheibler’s scale and a modern one?