What his watches have in common is that they contain early examples of important innovations. Tompion was one of the first watchmakers to utilize balance springs in his watches, and Somlo’s example, made in the 1680s, is one of his earliest attempts (this was only a few decades after Huygens fitted a spiral balance spring to a timepiece for the first time, around 1657). He also has a watch made by Graham, Tompion’s apprentice, that contains a very early cylinder escapement, which Graham had introduced just two years earlier, in 1725.  The cylinder escapement was the first real alternative to the earlier verge, and became very popular for a time until being eclipsed by the lever and detent escapements. The watch dates to 1727.