The inscription ?Detach?d? on the balance cock, refers to the invention of the detached form of lever escapement patented by Edward Massey in 1815. Usually, examples of these watches are also inscribed with the word ?Patent? but the present watch only carries the inscription ?detach?d?. S.I. Tobias is recorded as working between 1811 & 1813 and therefore this would appear to be a very early example of the detached Massey escapement before it was actually patented in 1815. This escapement paved the way for the development of the single-roller lever escapement in the early 1820?s. Edward Massey (1772-1852), Son of Edward Massey, he was a Coventry maker. He invented, patented and manufactured various mechanical logs and sounding machines, which were used by mariners throughout the world during most of the 19th century. A comparable achievement was his invention and production of a series of detached lever escapements for watches and a means of winding a watch by depressing the pendant. His detached lever, patented in 1815, was the first, simple detached lever since the more complicated work of Mudge, Emery, Leroux and Grant. Its simplicity and good rate encouraged other English makers to take an interest in the lever escapement.