This watch which appears to be unique, enforces if possible the mystery of the origins of the one tooth escape wheel lever, patented by Albert Potter on 5 April 1887. Just why it was eligible for a patent is a mystery as it had appeared at the Paris Exposition of 1827 as Deshay's escapement and again at the International Exhibition of 1851 as Charles MacDowall's (1790-1872) patent and was described by Saunier in his Treatise on Modern Horology in the French edition of 1861 and the English edition of 1878. Saunier says that it attracted considerable attention alter its first appearance and was well thought of, for the locking took place rmder favourable conditions and the method of applying the impulse presented the most direct action; that the faults were that it required an additional wheel in the train and that the excessive velocity and smallness of the force caused sluggishness and subjected it to every change in the condition of the oil. MacDowall's patent of 1851 was bought by E.J. Dent (1790-1853), who made a few of them but did not push them because, according to MacDowall, they would interfere with the sale of his large stock of the usual form of lever escapement. Although cased in England, the dedication on the back plate enables to think Thomas Robjohn certainly made it in New York and like Albert Potter, but 36 years before him, was convinced to be the real inventor!