James, here is an article on it.
[url="http://vads.ahds.ac.uk/diad/article.php?title=291&year=1973&article=d.291.27"]http://vads.ahds.ac.uk/diad/article.php?ti...rticle=d.291.27[/url]
[url="http://vads.ahds.ac.uk/diad/article.php?title=291&year=1973&article=d.291.27"]http://vads.ahds.ac.uk/diad/article.php?ti...rticle=d.291.27[/url]