Verge escapement be mechanical, depending on which manuscript evidence they regard as conclusive. One candidate is the Dunstable Priory clock in Bedfordshire, England built in 1283, because accounts say it was installed above the rood screen, where it would be difficult to replenish the water needed for a water clock. Another is the clock built at the Palace of the Visconti, Milan, Italy, in 1335. However, there is agreement that mechanical clocks existed by the late 13th century. The earliest description of an escapement, in Richard of Wallingford's 1327 manuscript "Tractatus Horologii Astronomici" on the clock he built at the Abbey of
Escapement was recognized as a disturbing influence on the isochronism of the balance. Purchasers no longer buy mechanical watches primarily for their accuracy, so manufacturers had little interest in investing in the tooling required, although finally Omega adopted it in 1990. Although a highly ingenious escapement design, the Daniels coaxial nevertheless still needs lubrication to the lever pallet pivots. In addition, because of its geometry the impulse wheel can only have a limited number of teeth, thus it is necessary to have an extra wheel and pinion in the wheel train the pivots of which also need lubricating. Therefore, the advantages