Harmonics, or the Philosophy of Musical Sounds - BOUND WITH - A Postscript to Smith's Harmonics ... The Changeable Harpsichord ....

London: T & J Merrill, 1759 & 1762. Second Enlarged Edition / First Edition.. Full contemporary calf.. Good; binding cocked because of damp; title and four pages with damp mark; head band chipped.. 8vo, I - xx, [1] - 280, [14 - index] pp. + 29 engraved plates (plate #29 issued with the Postscript); 3 folding tables (two of the tables are printed in the text and have an additional marginal printed "flap" inserted and mounted along the vertical margin); II - 12 pp.

Both are controversial and important books. The Harmonics consists of 11 sections and an appendix in which the author asserts his theory of musical sound, harmony, and the nature and constitution of imperfect consonances. There are also detailed explanations for tuning systems. The first was issued in 1749 with another (unlocated, but advertised) in 1751. The second editon of 1759, offered here, demonstrated explicitly the properties of periods, beats, harmony, and imperfect consonances. In addition to this Smith drew attention to his theory of the senses in the last section of the book. There he hypothesized that all our senses and faculties seemed to depend on very minute vibrating motions and that his theory of vibrations might prove useful in promoting a philosophy of mind. Hartley may have adapted this idea for his own work published in the same year. The two knew one another at Cambridge during this period. The second work is an account of Smith's invention, ' The Changeable Harpsichord '. The new keyboard and stops are illustrated. The device was first mentioned in the second edition of the Harmonics but not fully explained. Kassler II, 948-953.