HARMONICS - MATHEMATICS Album of original harmonic diagrams, 89 original coloured (purples, reds and blues) ink drawings, each 85 x 115mm., window-mounted with ink caption ('5:3 Major Sixth', '7:4 Harmonic Seventh', '2:1 Octave Out of Tune', '3:1 Perfect Twelfth', etc.) on separately mounted label (5 missing), contemporary cloth, spine near detached, small 4to, [late nineteenth/early twentieth century] Footnotes: Album of 89 original coloured ink 'harmonographs', illustrating the different acoustic vibrations ('Superimposed Unison Curve', '3:2 Perfect Fifth', '7:3 Harmonic Minor Tenth', etc.) made by a pendulum curve machine. Derived from the invention made by Hugh Blackburn, Professor of Mathematics at Glasgow University, in the 1840s, the images in this album are similar to those reproduced by H. Irvine Whitty in his pioneering The Harmonograph, 1893. For further information on this lot please visit Bonhams.com