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Term Definition
ElinvarA nickel, steel alloy containing other additions such as chromium, manganese, titanium, tungsten or beryllium, which has a very low thermoelastic coefficient over the range of temperatures commonly encountered by a watch. Used in modern balances and springs, derived from the words "elasticity" and "invariable".
 
EscapementProvides the balance with fresh additions of energy at regular intervals, and simultaneously prevents the movement from racing ahead and expending all its energy in a few mad seconds.
 
FrequencyNumber of complete oscillations made by the balance & spring in one second.
Example: 18,000 Vibrations per hour = 2.5 cycles per second, (Also referred to as "Hertz" - 2.5Hz).
 
Galling

Galling is a cold welding phenomenon which can occur when uncoated stainless steel (or aluminium alloy parts), such as the threads of the case and case back are forced together. These materials owe their corrosion resistance to the ease with which they passivate, forming a thin protective oxide layer. The friction scrapes off this oxide layer from the surface asperities and exposes clean reactive metal. If the mating parts are of a sufficiently similar material, no additional activation energy is needed to cold weld them together.

Galling can occur even if the parts are brought together slowly, and it is prevented by the presence of grease or surface coatings, even if the surface coatings increase friction. It does not occur when joining dissimilar materials (for example threading 18-8 stainless into 17-4 stainless) even though both of those materials are susceptible to galling. Galling does not occur on carbon steel.

 
GravityThe attraction exerted by Earth on all bodies. Its value is defined by the acceleration it causes in a free falling body.
 
HorologyThe science and study of time measurement, the art of manufacturing or repairing timepieces.
 


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