Stud
A small piece of metal which is slotted to receive the outer coil of the hair spring. Any short rod or roller projecting from a part of a machine is termed a stud. To set with projecting jewels or pieces of metal, as watch cases are sometimes ornamented.
SULLY, HENRY. Born in 1680 and died in 1728. A celebrated watchmaker and the author of a work on horology. He was an Englishman by birth, though he resided most of the time in France, where he died.