'Attempt to explain the principles on which the science of music is founded' by Boyce, consisting of tables of intervals expressed numerically, an account of each interval and its place in ascending and descending scales, and rules for its treatment in composition, c. 1777-8. Notes by Overend and Callcott appear throughout. Letters from Boyce to Overend, 30 Aug. 1777 and 8 Oct. 1778, are on fols.iv and i. Copyright assigned to John Wall Callcott by Mary Overend, 20 April 1795.