Warning, if you like guns and click the link, you will spend at least a 1/2 hour of your life reading the article. No really, I am serious. The analysis and detailed breakdown of the operation of the air rifle is exhaustive, leaving no detail about the air rifle untouched.
Robert D. Beeman, Ph. D. has undertaken one of the most rigorous studies of the Giradoni and other air rifles. Their works are published on his website Beemans.net. While last updated in 2007 (and the whole website in 2009), its obvious that Dr. Beeman is an avid collector and student of air rifles.