Interesting lecture according this subject : moreover about the drones lines ! on http://www.beesource.com/pov/osterlund/bucprinc.htm other adresse, same article (european database) http://www.fundp.ac.be/~jvandyck/homage/artcl/EO99princBAen.html Jean-Marie Van Dyck Namur University, Belgium. Homage page to Brother Adam (with a lot of original articles) : http://www.fundp.ac.be/~jvandyck/homage.html :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::