Escapement mechanics

One of the most difficult parts of designing a mechanical timepiece is the escapement, the interface between the regulation system (e.g., the pendulum) and the drive system, and to a great degree the history of clock design is really the history of escapement design. Unfortunately, I always find it pretty hard to visualize the operation of an escapement from the static diagrams in books. I was therefore very happy to find Matt Headrick's Horology Page, which not only has an 80+ page eBook on escapement design but also animated simulations of the operations of a number of major escapements.