For an English translation of the lyrics, see here.
Here's an interesting extract from a documentary, showing how the singing of this song by the computer HAL in 2001: A Space Odyssey was inspired by early speech synthesis, and the 'first singing computer'.
Edited on June 8th 2013: Please note that the Grade 4 scales have been corrected. The older version included D major rather than E major - a rather embarrassing and problematic error!
This follows the new ABRSM violin syllabus for 2012 onwards, including the new option for even notes rather than long tonics. I've included the fingerings I prefer to teach, such as starting two octave scales high on the G string in later grades, and three octave arpeggios shifting across the perfect fourths.
"Ar Hyd y Nos is a Welsh folksong sung to a tune that was first recorded in Edward Jones' Musical and Poetical Relics of the Welsh Bards (1784). The Welsh lyrics were written by John Ceiriog Hughes, and has been translated into several languages, including English and Breton. The melody was used by John Gay in The Beggar's Opera. It is also used in the hymn "Go My Children With My Blessing." The song is highly popular with traditional Welsh male voice choirs, and is sung by them at festivals in Wales and around the world.