Watch Glossary and Terms with Images

After the Second World War, atomic clocks became so accurate that they could demonstrate the infinitesimal irregularities (a few hundreths of a second per year) of the Earth's rotation about its own axis. It was then decided to redefine the reference standard; this was done by the 13th General Conference on Weights and Measures in 1967, in the following terms: "The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the fundamental state of the atom of caesium 133". Conventionally, the second is subdivised into tenths, hundredths, thousendths (milliseconds), millionths (microseconds), thousand-millionths (nanoseconds) and billionths (picoseconds).Secret springA spring that releases the cover on a hunter watch case.Setting (to time)Process of bringing the hands of a watch or clock to the position corresponding to the exact time.Shock AbsorberResilient bearing which, in a watch, is intended to take up the shocks received by the balance staff and thus protects its delicate pivots from damage.Simple calendar (watch)Watches that show the date, i.e. the number, in order, of each day in the month. Certain *** calendars also display the names of the months.Drilled and polished, they are used as bearings for the different pivots to minimize friction and wear. As a general rule, a *** mechanical watch, i.e. one that indicates hours, minutes and seconds, should have at least fifteen jewels at the points most exposed to friction.S ImagesSafety rollerIn a lever escapement, a disc which limits the fork;s movement.SecondBasic unit of time (abbr. s or sec), corresponding to one 86,000th part of the mean solar day, i.e. the duration of rotation, about its own axis, of an ideal Earth describing a circle round the Sun in one year, at a constant speed and in the plane of the Equator.