9 6 9 ), ▁and ▁The ▁P ì ob aire ach d ▁Society ▁Books ▁ ▁The ▁staff ▁notation ▁in ▁Ang us ▁Mac K ay ' s ▁book ▁and ▁subsequent ▁P ì ob aire ach d ▁Society ▁san ction ed ▁publications ▁is ▁character ised ▁by ▁a ▁simpl ification ▁and ▁standard isation ▁of ▁the ▁orn amental ▁and ▁rh yth mic ▁complex ities ▁of ▁many ▁p ib ro ch ▁compos itions ▁when ▁compared ▁with ▁earlier ▁un pub lished ▁manuscript ▁sources . ▁A ▁number ▁of ▁the ▁earliest ▁manuscript s ▁such ▁as ▁the ▁Campbell ▁Can nt aire ach d ▁MS ▁that ▁pre date ▁the ▁standard ▁edited ▁published ▁collections ▁have ▁been ▁made ▁available ▁by ▁the ▁Alt ▁P ib ro ch ▁Club ▁website ▁as ▁a ▁public ly ▁accessible ▁compar ative ▁resource . ▁ ▁P ib ro ch ▁is ▁difficult ▁to ▁document ▁accur ately ▁using ▁traditional ▁musical ▁notation , ▁and ▁early ▁attempts ▁suffered ▁from ▁convent ions ▁which ▁do ▁not ▁accur ately ▁convey ▁t une ▁expression . ▁ ▁More ▁contemporary ▁p ib ro ch ▁notation ▁has ▁attempted ▁to ▁address ▁these ▁issues , ▁and ▁has ▁produced ▁notation ▁much ▁closer ▁to ▁true ▁expression ▁of ▁the ▁t unes . ▁ ▁P ib ro ch ▁does ▁not ▁follow ▁a ▁strict ▁met re ▁but ▁it ▁does ▁have ▁a ▁rh yth mic ▁flow ▁or ▁pul se ; ▁it ▁does ▁not ▁follow ▁a ▁strict ▁beat ▁or ▁tempo ▁although ▁it ▁does ▁have ▁p acing . ▁The ▁written ▁notation ▁of ▁p ib ro ch ▁serves ▁mainly ▁as ▁a ▁rough ▁guide ▁for ▁the ▁pi per . ▁The ▁expression ▁of ▁the ▁rh yth