"Carolan's Cap", also known as "Carolan's Nightcap" is an Irish air in 2/4 time and G Mixolydian composed by Turlough O'Carolan (1670-1734). A "cap" is a dram of liquor, as in a 'nightcap'. The tune was originally published by Irish collector Edward Bunting in his General Collection of the Ancient Music of Ireland (1809), noted from the playing of one of the last of the ancient Irish harpers, Patrick Quinn. The Forde and Pigot manuscripts both have versions of this tune and Forde has entered the comment "Very Scottish" next to the tune. O'Sullivan notes that the opening phrase is "virtually identical" with "The Lass of Patie's Mill" published in Thomson's Orpheus Caledonius (1725). It is possible that O'Carolan adapted and modified that air for his own. Hardiman mentions a "Carolan's Nightcap" and O'Sullivan believes the 'cap' of the title indeed refers to a last drink before bed. It was printed in Complete Collection of Carolan's Irish Tunes (1984), Mulholland's Ancient Irish Airs (1810), O’Sullivan's Carolan: The Life, Times and Music of an Irish Harper (1958) and Ossian's The Complete Works of O'Carolan (1989). It was recorded by Derek Bell on Carolan's Receipt (1987) (Appears as "Carolan's Nightcap").