Sir, – The phenomenon of the untraceable “humming noise”, pitched at E flat, heard recently over parts of Kerry (Home News, April 17th James Pembroke, April 19th), can be easily explained if one remembers that this note is known to players of the uilleann pipes as the “ghost D”. Are we hearing the spirits of Gandsey, Micí Cumbá and Canon Goodman? Could the “days of the Kerry pipers” have returned? – Yours, etc,