Escapement wheels, which because they lacked a balance spring had no natural "beat", so there was not much incentive to improve the escapement. The great leap in accuracy resulting from the invention of the pendulum and balance spring around 1657, which made the timekeeping elements in both watches and clocks harmonic oscillators, focused attention on the errors of the escapement, and more accurate escapements soon superseded the verge. The next two centuries, the "golden age" of mechanical horology, saw the invention of perhaps 300 escapement designs, although only about 10 stood the test of time and were widely used in clocks
Escapement 'anchor' pallet locks the larger wheel and, on this being unlocked, a pallet on the end of the lever is given an impulse by the smaller wheel through the lever fork. The return stroke is 'dead', with the 'anchor' pallets serving only to lock and unlock, impulse being given in one direction through the single lever pallet. As with the duplex, the locking wheel is larger in order to reduce pressure and thus friction. The Daniels escapement, however, achieves a double impulse with passive lever pallets serving only to lock and unlock the larger wheel. On one side, impulse is