The Duplex Escapement

Of the requirements that are expected of a watch, one jumps to mind immediately - the one that has preoccupied horologists as well as watch owners tremendously for centuries. A good watch should be "exact"! The exact definition has been defined by each age separately. Nowadays one could already have a crisis, if its watch runs fast by five seconds. Approximately 300 years ago, this were probably five minutes, that occupied the proud watch owner's mind. Five minutes? Five minutes were a technically/economically good compromise for sure. It consisted of building a Cylinder Escapement into the good watch at use and ignoring the influence of the temperature. Pierre le Roy was the man who probably wanted to correct this compromise into one minute.

On a razor-edge
Look at it - the Duplex Escapement. The locking teeth lie on the roller, lurking only waiting to dart through the little window that develops due the little break inside the roller. In just that moment the impulse pallet who is using the favourable moment to start moving while attaching itself to the locking teeth gives an impulse to the impulse teeth, that will pass it to the balance undeterred. It is the time when the locking teeth lie at the roller that causes butterflies in the stomach when looking at it. There isn't much space that prevents the tooth from sliding through. Only a touch of a distance more of escape wheel and balance and it would be over with the locking. And exactly this touch is, what made life so difficult for this astonishing, simple escapement. Too difficult to survive.
However
The Duplex Escapement was able to reach its target to rise the accuracy of the watch - it just had to be made perfectly. It could have been made that good, that it was able to show an error of temperature clearly. Then it almost asked for a compensation balance to display its capacity. One minute a day?