“Athair” is the Irish word for “father”, and the Anglicized title “Fr. Jack
Walsh” is often used as the title for this tune, as is “Tatter Jack Walsh”.
The tune is played in the D mixolydian mode and thus contains the same
notes as a G Major scale. A cursory glance at the chords used in the sheet
music should alert you to this. The two main chords used are D and C and
this combination in a “D” tune invariably tells you it’s mixolydian. The key
signature is one sharp (F#). If I used two sharps (F# and C#) then there would
be natural signs used for the C notes occurring in the tune.
Some tune books incorrectly notate the tune this way. Tony’s old copy of that
excellent small collection “Allan’s Irish Fiddler” has it in D Major with
natural signs for the C. Although the transcription still ends up with the same
notes it is not very good “musical grammar”. There are two accidentals in the
tune, both in the last bar of each section. In fact the last three bars of each
section are identical.