WATCH GLOSSARY S-T-U-V-W-X-Y-Z

SCALE
Graduation on a measuring instrument, showing the divisions of a whole of values, especially on a dial, bezel. The scales mostly used in horology are related to the following measuring devices: tachometer (s.) (indicating the average speed), telemeter (s.) (indicating the distance of a simultaneously luminous and acoustic source, e.g. a cannon-shot or a thunder and related lightning), pulsometer (to calculate the total number of heartbeats per minute by counting only a certain quantity of them). For all of these scales, measuring starts at the beginning of the event concerned and stops at its end; the reading refers directly to the chronograph second hand, without requiring further calculations.
SECOND TIME-ZONE INDICATOR, s. GMT and World Time.
SECTOR, s. Rotor.
SELF-WINDING, s. Automatic.
SHOCKPROOF or SHOCK-RESISTANT
Watches provided with shock-absorber systems (e.g. Incabloc) help prevent damage from shocks to the balance pivots. Thanks to a retaining spring system, it assures an elastic play of both jewels, thus absorbing the movements of the balance-staff pivots when the watch receives strong shocks. The return to the previous position is due to the return effect of the spring. If such a system is lacking, the shock forces exert an impact on the balance-staff pivots, often causing bending or even breakage.
SKELETON, SKELETONIZED
Watches whose bridges and pillar-plates are cut out in a decorative manner, thus revealing all the parts of the movement.
SLIDE
Part of a mechanism moving with friction on a slide-bar or guide.
SMALL SECOND
Time display in which the second hand is placed in a small subdial.
SNAILING
Decoration with a spiral pattern, mainly used on the barrel wheel or on big-sized full wheels.
SONNERIE (EN PASSANT)
Function consisting of an acoustic sound, obtained by a striking work made up of two hammers (s.) striking gongs (s.) at set hours, quarter- and half-hours. Some devices can emit a chime (with three or even four hammers and gongs). By a slide (s.) or an additional pusher (s.) it is possible to exclude the sonnerie device and to select a so-called grande sonnerie.
SPLIT-SECOND CHRONOGRAPH
Chronographs with split-second mechanisms are particularly useful for timing simultaneous phenomena which begin at the same time, but end at different times, such as sporting events in which several competitors are taking part. In chronographs of this type, an additional hand is superimposed on the chronograph hand. Pressure on the pusher starts both hands, which remain superimposed as long as the split-second mechanism is not blocked. This is achieved when the split-second hand is stopped while the chronograph hand continues to move. After recording, the same pusher is pressed a second time, releasing the split-second hand, which instantly joins the still-moving chronograph hand, synchronizing with it, and is thus ready for another recording. Pressure on the return pusher brings the hands back to zero simultaneously, provided the split-second hand is not blocked. Pressure on the split pusher releases the split-second hand, which
instantly joins the chronograph hand if the split-second hand happens to be blocked.
STAFF or STEM, s. Arbor.
STRIKING WORK, s. Sonnerie and Repeater.
SUBDIAL, s. Zone.
SUPER-LUMINOVA, s. Luminescent.
SWEEP SECOND HAND
A center second hand, i.e. a second hand mounted on the center of the main dial.
TACHOMETER or TACHYMETER
Function measuring the speed at which the wearer runs over a given distance. The tachometer scale is calibrated to show the speed of a moving object, such as a vehicle, over a known distance. The standard length on which the calibration is based is always shown on the dial, e.g. 1,000, 200 or 100 meters, or—in some cases—one mile. As the moving vehicle, for instance, passes the starting-point of the measured course whose length corresponds to that used as the basis of calibration, the observer releases the chronograph hand and stops it as the vehicle passes the finishing point. The figure
indicated by the hand on the tachometer scale represents the speed in kilometers or miles per hour.
TELEMETER
By means of the telemeter scale, it is possible to measure the distance of a phenomenon that is both visible and audible. The chronograph hand is released at the instant the phenomenon is seen; it is stopped when the sound is heard, and its position on the scale shows, at a glance, the distance in kilometers or miles separating the phenomenon from the observer.
Calibration is based upon the speed at which sound travels through the air, viz. approximately 340 meters or 1,115 feet per second. During a thunderstorm, the time that has elapsed between the flash of lightning and the sound of the thunder is registered on the chronograph scale.
TONNEAU
Particular shape of a watchcase, imitating the profile of a barrel, i.e. with straight, shorter, horizontal sides and curved, longer, vertical sides.
TOURBILLON
Device invented in 1801 by A. L. Breguet. This function equalizes position errors due to changing positions of a watch and related effects of gravity. Balance, balance spring and escapement are housed inside a carriage (s.), also called a cage, rotating by one revolution per minute, thus compensating for all the possible errors over 360 degree
Although this device is not absolutely necessary for accuracy purposes today, it is still appreciated as a complication of high-quality watches.
VIBRATION
Movement of a pendulum or other oscillating bodies, limited by two consecutive extreme positions. In an alternate (pendulum or balance) movement, a vibration is a half of an oscillation (s.). The number of hourly vibrations corresponds to the frequency of a watch movement, determined by the mass and diameter of a balance (s.) and the elastic force of the balance spring. The number of vibrations per hour (vph) determines the breaking up of time (the “steps of a second hand). For instance, 18,000 vph equals a vibration duration of 1/5 second; in the same way 21,600 vph = 1/6 second; 28,800 vph = 1/8 second; 36,000 vph = 1/10 second. Until the 1950s, wristwatches worked mostly at a frequency of 18,000 vph; later, higher frequencies were adopted to produce a lower percentage of irregularities to the rate. Today, the most common frequency adopted is 28,800 vph, which assures a good precision standard and less lubrication problems than extremely high frequencies, such as 36,000 vph.
WATER RESISTANT or WATERPROOF
A watch whose case (s.) is designed in such a way as to resist infiltration by water (3 atmospheres, corresponding to a conventional depth of 30 meters; 5 atmospheres, corresponding to a conventional depth of 50 meters.)
WHEEL
Circular element, mostly toothed, combines with an arbor (s.) and a pinion (s.) to make up a gear (s.). Wheels are normally made of brass, while arbors and pinions are made of steel. The wheels between barrel (s.) and escapement (s.) make up the so-called train (s.).
WINDING STEM
Element transmitting motion from the crown (s.) to the gears governing manual winding and setting.
WINDOW
Aperture in the dial, that allows reading the underlying indication, mainly the date, but also indications concerning a second zone’s time or jumping hour (s.).
WORLD TIME
Additional feature of watches provided with a GMT (s.) function, displaying the 24 time zones on the dial or bezel, each zone referenced by a city name, providing instantaneous reading of the time of any country.
ZONE
Small additional dial or indicator that may be positioned, or placed off-center on the main dial, used for the display of various functions (e.g. second counters).