Known as “the purple book,” this is a book of pieces in tenor and treble clef to be played in thumb position. If you are looking for instruction, principles, hand placement, posture, you need a precursor to this.
Starts with pieces in 1st position and goes through Grades 1 – 5, but the grading system is not specified. ABRSM, perhaps. All pieces are in bass clef, not exceeding 4th position, with a variety of keys and rhythmic challenges.