The second half of the seventeenth century was a period of considerable upheaval in
English music, not only because the political instability of the time altered the way
musicians were employed, but also because the era saw fundamental changes in the
construction and perception of music. The most important of these was a transition
between music conceived primarily according to horizontal (imitative) principles and
that founded on vertical (tonal) principles, which in turn allowed for vastly expanded
formal dimensions. The seventeenth century also witnessed the gradual replacement of
the remaining elements of mensural notation and proportional metrical relationships in
favour of free tempo with contrasts between duple and triple units, again influencing
the way in which works were structured. These elements are examined from the
viewpoint of the music theorist, by analysing the thirty-seven treatises which were in
circulation in manuscript or printed form during the century. However, the greater part
of the dissertation seeks to assess the impact of such profound alterations on the
composer himself, through detailed analysis of the music's notation and its
development in response to the changing styles and techniques; in order to be as certain as possible that such developments were genuine attempts to communicate new attitudes to music and its construction rather than simply the results of mistakes or
misunderstandings by copyists, the analysis is restricted to the ninety-four extant
autograph manuscripts of composers' own music copied during the period. These
primary sources include several previously unidentified sketches and working drafts of
pieces which reveal elements of the processes used by composers in the conception of
new pieces, as well as finished copies from which has been drawn information on the
status of metre, tonality and structure during the period