Five Recent Near-Perfect Perpetual Calendars From Patek Philippe, Lange, IWC, Baume & Mercer and Jaeger-LeCoultre
One of Martin Green’s favorite complications is the perpetual calendar, aka QP. While he knows that an annual calendar can do almost the same for a lot less, he is still mesmerized by the human ingenuity of being able to a miniature mechanical device that can even deal with leap years.