Dying declaration of Nicholas Fernandez, who with nine others were executed in front of Cadiz harbour, December 29, 1829 For piracy and murder on the high seas.

Some 30 odd pages of his life story (he was a young man) as how piracy led to his downfall and this it seems was published the year after he waswhanged with others (9) it was translated from his native Spanish and there should be some copies still availble to read per my google research in US libraries etc

This does not of course answer the question Who constructed the lengthy song? or if indeed this really was the source of the ballad/broadside of the Flying Cloud ~ those with good eye sight may want check this further

Ray