This is a micro-tonal piece (180 notes per octave) based on 'Fantazia
#8, in 4 parts Z.739', by Henry Purcell

Playing with Henry - 1

1-9. Primarily Henry (31 May 2006 - Pyhra)

This is the latest of an occasional ongoing series of works based on
the collection 'Fantazias and In Nomines, for strings' by Henry
Purcell. Started in 1988, the series so far consists of 13 pieces,
including several for ’tape’ and works for various small ensembles.
This piece is based on 'Fantazia #8, in 4 parts Z.739', it uses prime
numbers to determine structure and tuning (180 notes per octave).

Tuning:
There are 15 voices, each tuned to an individual setting:
0/+3 cents/-5 cents/+7/-11/+13/-17/+19/-23/+29/-31/+37/-41/+43 and
-47 cents.
A new line/voice entry is written in at every bar with a prime
number. The voices are introduced one at a time. The voice tuned 0
at bar 1, the next, tuned -5 cents, at bar 2, the next, tuned +3, at
bar 3, the next, tuned -11, at bar 5, the next, +7, at bar 7, the
next, -17 at 11, the next at 13 etc. After the fifteenth entry
additional lines are played by one of the previous voices.

Sound:
The prime numbered bars are also used as end or start points for
sound changes. These are staggered across the lines/voices to create
a pattern of slowly changing textures, the slowest change taking
fourteen minutes or so.

Structure:
The original Purcell (48 bars) is stretched to last 73 minutes (96
bars + 1 for fade out), these bars are used as reference points for
the voice entries.
These original Purcell four lines are the core of the piece, from
which is generated further material to allow for the 15 individually
tuned voices/lines. Four of these are simply the piece backwards,
four are an inversion around D2 and the further three (four) an
inversion around C3 (the sixteenth line is played by one of the
fifteen voices).
The process is manipulated and the pitches are transposed up or down
by octave as and when required.

With the exception of the first 4 lines (the original Purcell, with
each of the string lines slightly manipulated to conform to the first
4 voice entry points), each new line is stretched to fit the allowed
bar count (determined by prime numbers). i.e. the line entering at
bar 7 is stretched to fit 89 bars, the line entering at bar 11 is
stretched to fit 85 bars, etc. up to the required 15 voices. From
then on any new lines introduced are copies from the previous
fifteen, but stretched appropriately from their point of entry.
There are 25 entries/lines, determined by the 25 prime numbers
between 1 and 89 (inclusive).
The pitch material is aligned to produce a chord cluster at the end
of the piece that fades to bar/prime number 97 (73 minutes).