The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Queens Self-Regulating X-Ray Tube Invented by Sayen, Probably the most desirable X-Ray tube to own for any collector Right angle Queens tube Regulator Of course Frank has more than one of these tubes!  (?!?!!) The famous regulator He even has one that doesn't work! The Queens tube was most often reproduced in colour for the finest X-Ray books. Above are examples from the Kassabian book, below is another self-regulating tube  from the Tousey book.   Tube functioning almost perfect, and keratoses (cancer) from over exposure to tubes by fluoroscopy. Tousey suffered from his early work, Kassabian actually died before the second edition of his book was published.