The Square and Compass is a Masonic symbol. Many influential early Scottish musicians were Freemasons (notably Robert Bremner). i. Robert Ross, 1778. ii. Kerrs 2 (circa 1880). iii. Athole Collection, 1884. iv. John A. MacDonald, LP, 1960s.    Notation above from The Cape Breton Scottish Collection.

Other Examples of Music Notation