Anchor escapement it he showed that the wide pendulum swings of verge clocks caused them to be inaccurate, because the period of oscillation of the pendulum was not isochronous but varied to a small degree due to circular error with changes in the amplitude of the pendulum's swing, which occurred with unavoidable changes in drive force. The realization that only small pendulum swings were nearly isochronous motivated clockmakers to design small swing escapements. The chief advantage of the anchor was that by locating the pallets farther from the pivot, the swing of the pendulum was reduced from around 100° in verge clocks
Escapement to a point close to its unstable state, and is released with a snap each swing of the balance wheel to give the wheel an impulse, after which it is cocked again by the wheeltrain. The advantage claimed is that since the blade imparts the same amount of energy to the wheel each release, the balance wheel is isolated from variations in impulse force due to the wheeltrain and mainspring which cause inaccuracies in conventional escapements. Parmigiani Fleurier with its Genequand escapement and Ulysse Nardin with its Ulysse Anchor escapement have taken advantage of the properties of silicon flat springs.