A.H.P. (Automatic High Precision) a swinging rotor drives a mini-generator. Its electric power is stored in a capacitor, which supplies energy to a quartz-controlled integrated circuit.

ALARM function that sounds an alarm at a pre-set time or at regular intervals.

ALTIMETER function that determines altitude based on changes in barometric pressure. In a pressurized airplane cabin, the altimeter registers as if on land. A rotating bezel is used to determine altitude.

A.M. ante meridian (before noon)

ANALOG watch with a dial, hands, and numbers or markers that display a 12-hour time period.

ANALOG DIGITAL has both a digital display and hands of a conventional analog watch.

ANCHOR ESCAPEMENT a feedback regulator that controls the speed of a mechanical clock.

ANTI-MAGNETIC unaffected by magnetism. If the parts most affected by a magnetic field (balance, balance spring and escapement) are made of non-magnetic materials the watch is called anti-magnetic. Bomb squad experts require this type of watch.

APERTURE small opening in the dial that displays certain information such as date, day, month, or moon phase.

APPLIQUE numerals or symbols cut out and stuck to dial.

ARMORED CRYSTAL a plastic crystal installed by compressing it to fit into a groove in the face of the watchcase, instead of cementing it into place. What distinguishes an armored crystal from a common snap crystal is a ring of metal at the base, meant to hold the crystal firmly in place.

A.S.S. servo-controlled motor drive that lengthens the duration of motor impulse when the mechanism meets resistance and reverts to normal duration when the resistance ends. This technique increases battery life by 30%.

ASSEMBLING process of fitting the components of a movement. Formerly done entirely by hand, but now mainly by machine.

ASTHOMETER function on a chronograph for measuring the rate of respiration.

ATM a measurement of pressure called an atmosphere. An atmospheric measure is the amount of air pressure at sea level that a watch can withstand. (1ATM= 1BAR= 10m= 33.3ft)

ATOMIC TIME Atomic Time Standard is provided by the U.S. National Institute of Standards and Technology, Time and Frequency Division in Boulder Colorado. Atomic time is measured through vibrations of atoms in a metal isotope that resembles mercury. The result is extremely accurate time that can be measured on instruments. Radio waves transmit this exact time throughout North America. Atomic watches and clocks can receive the signal.

AUTOMATIC MOVEMENT self-winding watch whose movement is mechanical. A weight (the rotor) turns by the motion of your arm and winds the mainspring. The energy generated by the movement is transferred into mechanical energy that creates the movement. These watches can be shaken or manually wound if the power reserve runs out.

AUTO REPEAT TIMER function that counts down time and then resets itself as soon as a preset time has elapsed. It repeats the countdown continuously until a button is pressed to stop the function.

BALANCE mechanical watches are regulated with the balance and balance spring. The mainspring provides energy. The hairspring, coupled to the balance, makes it swing to and fro, dividing into equal parts. Each to and fro of the balance is called oscillation. One oscillation equals 2 vibrations. (Heart of the mechanical watch)

BALANCE SPRING the (hair spring) is attached to the balance and cock, and made of metal alloys. Its length determines the amount that the balance regularly oscillates: the shorter the spring the faster the watch runs. It returns the balance wheel back to a neutral position.

BALANCE WHEEL regulating organ of the watch, vibrating on a spiral hairspring. Lengthening and shortening of the balance spring makes the balance wheel go faster or slower to advance or retard the watch.

BAR thin metal rod fixed between the horns that attaches the bracelet or strap to the watch. Also called a lug or spring bar.

BARREL cylindrical box containing the mainspring of a watch. The toothed rim of the barrel drives the train.

BARREL SPRING this spring's tension controls the amount of energy transmitted to the measurement. Hooked to the barrel and arbor, when it is tensed it releases energy.

BATTERY device that converts chemical energy into electricity. (Silver Oxide1.5V, Nickel Cadium 1.5V, Lithium 3V, Mercury 1.5V)

BEAT the number of times per second (BPS) or per hour (BPH) that a balance wheel goes through a full arc of motion or the vibrations per hour (VpH) (half oscillation, or "tick") of a movement.

BEVEL furrow or groove cut at an angle that is either over or under, but not equal to 90 degrees.

BEZEL the ring around the top of the crystal. Generally hold the glass or crystal in place. A rotating ratchet bezel moves in some watches as part of a complication. Rotating bezels either rotate clockwise, counter clockwise, or both to assist in calculations.

BI-DIRECTIONAL BEZEL a bezel that rotates clockwise or counter clockwise.

BOTTOM PLATE supports the bridges, which are often on the top of the plate, the movement, the dial, and the holes where the jewels are inserted.

BRACELET metal linked watchband.

BRAILLE WATCH crystal can be lifted. The numerals protrude allowing the time to be told by feel for visually impaired. Also called a "tact" watch.

BRIDGE the balance cock is attached to the bottom plate with pins. Fixed to the main plate to form the frame of a watch.

BUTTONS push piece controls, usually at 2'oclock and/or 4'oclock on the dial to control specific functions such as the chronograph or the alarm.

CALENDAR a simple calendar is a complication that shows the date of the month. A day/date shows the date of the month and the day of the week. A complete calendar shows the day, date, and the month or moon phase.

CALIBER the size and configuration of a watch movement. The diameter of the movement measured in "Parisian lines," where 1=2.256mm.

CAMBERED curved or arched dial or bezel.

CASE container protecting the dial and movement consisting of the case band, case back, and bezel.

CASEBACK bottom of the watch that lies against your skin.

CHAMFERING beveling the edges of bridges or screws.

CHRONOGRAPH stopwatch function that uses sub dials to keep track of second, minutes, and hours.

CHRONOMETER a very precise watch that is tested for 15 days and nights at 5 different positions and temperature ranges. The C.O.S.C. provides the manufacturer with a certificate verifying it has passed all tests.

CLASP a deployment buckle is a 3 folding enclosure that secures the 2 ends of the bracelet (fold over buckle, butterfly clasp). hook lock buckle is 2 separate units that fit on either end of the bracelet and allows the watch to be laid flat (eweler's clasp, sliding clasp).

COLUMN WHEEL upright castle shaped wheel in a chronograph that acts as a sliding link to operate the various levers that set the chronograph functions in motion, generally more accurate type of chronograph.

COMPLICATION any "function" added to a watch, such as a minute repeater, countdown timer, stop watch, altimeter, asthometer, pulsometer, calendar, moon phase indicator, split second chronograph, power reserve indicator, alarm, etc.

C.O.S.C. Controle Officiel Suisse des Chronometres (Official Swiss Chronometer Testing Institute) they test watches for 15 days and nights at 5 different positions and temperature ranges. They either pass or fail the watch movement. If the watch passes it is called a chronometer.

COUNTDOWN TIMER function which measures time remaining in preset period of time.

CROWN knob used to wind a mechanical watch and to set the time and/or calendar of a watch.

CRYSTAL the crystal is the cover the protects the face of the watch and allows you to see the dial. Most high-end watches use mineral glass or a synthetic sapphire crystal. Tempered mineral glass is 10 times harder than plexiglass, but cannot be buffed out if scratched. Synthetic sapphire crystals are nearly scratchproof, although they are extremely brittle and easy to shatter. They are 2-3 times harder than a mineral crystal and 20 times harder than plexigalss. Although plexiglass is sometimes required due to it's impact resistance, for example the brand name Hesalite crystal is used in Omegas' Moon watch because of it's resistance to temperature changes, high pressure, and force. Another non traditional brand name crystal is Sapphlex which is a combination saphhire and hardlex crystal.

CYCLOPS small lens on the crystal to magnify the date.

DAYLIGHT SAVINGS TIME adopted around WWI it is used to utilize more daylight hours in the spring and summer for daytime activities. It is also a fuel saving measure.

DEPTH ALARM a complication on a diver's watch that sounds an alarm when the wearer exceeds pre-set depth. The alarm stops when the diver ascends above pre-set depth.

DIACHRONIC a liquid crystal display (LCD), enabling color to appear or vanish on the surface.

DIAL face of the watch showing hours, minutes, and sometimes seconds.

DIGITAL watch that uses an LCD or LED to display a continuous reading.

DIRECT DRIVE seconds hand advances in intervals rather than a smooth sweeping motion.

DIRECTIONAL COMPASS function that uses the sun to determine the geographical direction.

DISPLAY BACK also called a skeleton back it is a caseback that is transparent so that movement may be viewed.

DIVE WATCH designed especially for divers whose lives depend on the reliability of their watch in the water.

DUAL TIME ZONE measures local time as well as time in another time zone.

EBAUCHE (raw movement) unassembled movement, without escapement, balance, hairspring, or mainspring.

END OF ENERGY the end of energy in a "mechanical" watch is indicated by the seconds hand, which jumps every 2, 3, or 4 seconds.

END OF LIFE the end of battery life in a "quartz" watch is indicated by the seconds hand, which jumps every 2, 3, or 4 seconds.

ESCAPEMENT mechanism made up of the escapement wheel, lever, and discharging roller, which act to control the wheel movement and to provide pulses to pallets and thus the balance. The most important part of the watch. Converts the energy of the mainspring into equal units of time. The escapement controls the amount of power released from the mainspring. The regularity is controlled by the balance and it's spring. The escapement controls the rotation of the wheels and thus the motion of the hands. It is fitted at the end of the gear train and is designed to interrupt the movement of thee wheels at regular intervals.

ESCAPE WHEEL a lever escapement this is the last gear in the gear train.

ETA leading manufacturer in Switzerland for movements used in many Swiss watch brands.

EQUATION OF TIME difference between clock time and the defined position of the sun.

EQUATOR line of latitude located halfway between the North and the South Pole.

EXHIBITION BACK same as a "skeleton" or "display" back.

FEET commonly used to measure water resistance.

FINE TIME ADJUSTMENT lever to adjust the daily time accurately.

FIVE-MINUTE REPEATER a function that strikes the hours and five-minute intervals past the hour.

FLANGE ring that separates the crystal from the dial.

FLYBACK function that allows a chronograph to be reset to zero without having to stop the chronograph first.

FOUDROYANTE small dial that is marked 0-8. The hand on the dial completes a sweep every second which is an elapsed time of 1/8th of second for each number.

FREQUENCY number of vibrations a second or oscillations per second, in hertz (Hz) of a quartz watch. The number of vibrations per hour (VpH) of a mechanical watch.

FULL ROTOR automatic watches with rotors that travel 360 degrees in both directions.

FUNCTION the same as a complication on a mechanical watch, but technically called a function on a quartz watch.

FUSEE grooved pulley that equalizes the mainspring by controlling its winding or unwinding.

GASKET most water resistant watches are equipped with gaskets to seal the caseback, crystal, and crown from water. Gaskets need to be checked every couple of years to maintain water resistance.

GENEVA SEAL quality seal the displays the City of Geneva coat of arms. Watches must meet eleven strict criteria to be awarded the Geneva seal.

GLUCYDUR copper and glucinum stainless, non-magnetic alloy used in watch making for internal parts. Anit-magnetic alloy that expands very little when exposed to heat. (Used for balances)

GMT Greenwich Mean Time, marking the middle of a solar day, is the time measured from zero degrees latitude in Greenwich, England. It is the standard for time keeping introduced in England in 1880 and used as the basis for calculating standard time throughout the world. It reflects the mean solar time along the Earth's prime meridian. (0 degrees longitude). The prime meridian runs through the Greenwich Observatory outside of London.

GOING TRAIN made up of the going barrel, which drive the center wheel. The center wheel drives the third wheel then the 3rd wheel drives the second wheel. The second wheel drives the escapement wheel. It is the system of gears that transmits power from the mainspring to the escapement.

GUILLOCHE decoration found on the dials of high-end watches.

HACKING a feature that stops the second hand when the stem is pulled out as far as it will go and allows you to set the exact time.

HAIRSPRING same as balance spring.

HALLMARK a mark stamped into the case of the watch to provide information about the degree of purity of the metal used, the country of origin, the country of origin, the year of manufacture, the identity of the case's maker, trademarks, reference numbers, and/or serial numbers.

HAND watches generally have three hands for seconds, minutes, and hours. They come in many different shapes: Pear, Breguet, Baton, Arrow, Skeleton, Luminous, Alpha, Dauphine, etc.

HAND-WOUND WATCH a watch that receives energy by hand winding the crown.

HARDBACK caseback made of metal.

HARD METAL scratch resistant metal comprised of binding several materials, including titanium and tungsten which are then pressed into an extremely hard metal and polished with diamond powder to add brilliance.

HELIUM ESCAPE VALVE a helium escape valve is required for divers who spend a long time in hyperbaric chambers and breath helium enriched gas. The helium molecules are lighter than air and can therefore penetrate the watch. When a pressurized enclosure, such as a diving bell, surfaces and is depressurized the helium rushes out of the watch so quickly that the crystal on the watch pops out. To avoid this the helium escape valve releases this helium from the watch while resurfacing. This allows helium to escape without water entering the watch.

HESALITE brand name acrylic crystal. Omega chose "Hesalite" for the crystal on their moon watch because of its resistance to shocks and extreme temperatures.

HIGH-TECH CERAMIC used as a shield for spacecraft reentering the earth's atmosphere, high tech ceramic is polished with diamond dust to create a highly polished finish. Usually found in black.

HORNS part of the case where the bracelet is attached by lugs or pins.

HOROLOGY science of time measurement, including the art of designing and constructing timepieces.

INCABLOC a brand of shock absorber for mechanical watches designed to protect pinions or jewels.

INDEX instead of a number, a marking indicating the hour and/or minutes.

INTERNAL BEZEL a bezel inside the watch case usually with a separate or additional crown.

INVAR special alloy related to beryllium and used for watch parts because it is anti-magnetic and resists rust.

ISOCHRONISM equal periods of time. A watch's ability to maintain it's rate as the mainspring unwinds.

JEWELS synthetic sapphires or rubies that are used in a watch movement to reduce friction. They help maintain the watch's lubrication.

JULIAN CALENDAR Julius Caesar introduced a calendar with 12 months and 365 days. Previously the calendar had 10 months of 30 days each. The Julian calendar introduced "leap year" stating that a day would be added to the calendar every 4 years. That is required because there are roughly 365.25 days in a year.

JUMP HOUR a spring that causes a hand or other part of a watch to suddenly advance. A jump hour watch displays the hour through a dial window.

KIF method of shock protection.

KINETIC quartz movement that does not use a battery. Energy is stored for a period of time though movement of the wrist that charges a capacitor. (Seiko Kinetic)

LAP TIMER a chronograph function that times segments of a race. At the end of a lap a push button stops the time and then returns to zero to time the next lap.

LCD liquid crystal display.

LEAP YEAR an extra day every 6 years Feb 29.

LED light emitting diode.

LEVER ESCAPEMENT 18th century invention which is made up of an escape wheel, a lever, and a balance wheel, the only one now used in making mechanical watches.

LIGHTED DIALS several types of lighted dials are used to read your watch in low light conditions.

LIGNE traditional unit of measurement used to measure the diameter of watch movements.

LUG (same as horn) part of case where bracelet or strap is attached.

LUMINOUS PAINT self-illuminating paint that is put on the hands and markers to read the time in low light situations.

MAIN PLATE the base plate on which all other parts of a watch movement are mounted.

MAIN SPRING the driving flat-coiled spring of a watch contained in the barrel, supplies power.

MANUAL-WINDING a hand wound mechanical watch.

MANUFACTURE factory that makes its' own components and assembles at least one complete movement (caliber). A manufacture produces the movement and then assembles it.

MARINE CHRONOMETER a highly accurate timepiece enclosed in a box that is used for determining the longitude on board a ship. A marine chronometer is mounted on gimbals so that they remain in a horizontal position to maintain their precision.

MECHANICAL describes a movement with a balance wheel. Wound by hand or rotor. Dates back to the 14th century about 130 parts plus 60 for complications.

METER a measurement used to measure water resistance. (10m= 33.3ft= 1ATM= 1BAR)

MICRON 1/1000mm (.001 millimetre)

MICRO ROTOR small rotor that is integrated into the movement and used on automatic watches. It allows the construction of very thin calibers.

MINERAL GLASS glass that has been tempered to resist scratching.

MINUTE REPEATER a function on a watch that can strike the time in hours, quarters, or seconds by means of a push piece.

MOON PHASE shows: new moon, first quarter moon, full moon, and last quarter moon by means of a disk that rotates beneath a small aperture. The 29 and 1/2 day cycle of the moon.

MOVEMENT the "motor" of a watch or the machinery that turn the hands, change the date, start/stop the chronograph. There are two classifications of movement, either mechanical or quartz electronic.

NO BACK one piece a caseback.

NON-MAGNETIC see anti-magentic.

NON SCREW LOCKED CROWN easier to set than a screw locked crown, but it is less water resistant.

OSCILLATING SYSTEM hairspring and balance form the oscillating system. Two vibrations of the balance make the tick-tack sound of a mechanical watch known as oscillation. The travel of the balance wheel from one extreme to the other and back again.

PALLADIUM a rare and lustrous metal that is slightly whiter than platinum and slightly harder. It is part of the platinum group of metals. Palladium is tarnish resistant, electrically stable and resistant to chemical erosion as well as intense heat.

PALLET meshes with the teeth of the escapement wheel and transmits an impulse to the balance.

PEDOMETER function that counts the number of strides taken by the wearer.

PULSIMETER a chronograph with an extra dial or timer that gives the rate of pulse per minute.

PERPETUAL CALENDAR extremely elaborate complication that keeps track of the day, month, date, and sometimes even the moon phase, zodiac signs, decade, century, and which adjusts for the length of the month and for leap years. (Accurate until 2100)

PINION toothed wheel usually made of steel with a small number of teeth.

PLATE metal piece that holds up the bridge and other parts of the movement. The bottom side is the dial side the top side is the bridge side.

PLATINUM one of the rarest precious metals as well as one of the strongest and heaviest.

PLEXIGLASS a clear lightweight type of plastic. Used for watch crystals it is least likely to shatter and most likely to scratch.

POINTER CALENDAR hands point to the date as opposed to appearing in an aperture.

POLISHED brilliant meal surface obtained on the watchcase with a fine abrasive.

POWER RESERVE INDICATOR a sub dial used to show how much power remains before the watch stops.

PULSOMETER scale on the dial or bezel of a watch that works in conjunction with the seconds hand to measure pulse rate. A reference number tells how many pulse beats to count. If the reference number is 15, the operator counts 15 pulse beats. At the last beat the seconds hand shows the pulse beat per minute.

PVD Physical Vapor Deposition method of coating thin watch cases by integrating titanium particles and then depositing gold for color. (Usually comes in black finish)

QUARTZ a natural or synthetic silicon dioxide crystal used in quartz analog or solid state digital watches when activated by a battery or solar power, the thin silver of the crystal very predictably vibrates at an extremely high frequency (32,768 times per second) step motor, electric circuit block.

QUICK SET DATE mechanism to set the date directly to avoid having to turn the hands over 24 hours.

RADIO CONTROLLED WATCH quartz watch that is controlled by a radio signal from a cesium atomic clock.

RATCHET BEZEL RING bezel ring which can either turn one way or both ways and generally clicks into place.

RATTRAPANTE addition of a second hand to measure split times.

REGULATOR device inside a watch that speeds it up or slows it down to allow the more precise setting of the watch.

REPEATER strikes the hour, half hour, minutes, seconds, or some combination of the two.

RETROGRADE mechanism that lets a hand quickly return to its original position, usually used to return to one after 60 seconds.

REVERSO dual dial reversible watch.

ROMAN CALENDAR calendar used in ancient Rome until 46 B.C. when it was replaced with the Julian calendar.

ROTOR part of an automatic watch that winds the mainspring. A flat piece of metal swivels on a pivot with the motion of the wrist. Its rotation continually winds the mainspring of the watch. It turns freely in both directions and uses the force of gravity to wind the mainspring. Some rotors only turn in one direction or less than 360 degrees. Each time it moves it advances the ratchet wheel, which keeps the spring wound.

RUBIES ruby is a very hard stone usually synthetic, which prevents the wear of gear train parts. Also called jewels.

SAND BLASTING creating a granular metal finish by using a high-pressure jet of sand.

SAPPHIRE synthetic corundum crystal with a hardness second only to a diamond. Transparent sapphire is used for a scratchproof watch glass. Made of crystallizing aluminum oxide at very high temperatures. Chemically the same as natural sapphire, but colorless. It is hard and brittle so it shatters easier than plexiglass or mineral glass. 9 on a mohs scale, a diamond is 10.

SAPPHLEX CRYSTAL combination of sapphire and hardlex crystals.

SCREW BACK caseback has a thread so that it can be screwed into the case.

SCREW DOWN CROWN seals the crown against the case to prevent water penetration.

SEAL synthetic gaskets that seal the joints between parts of the case and keep out the water.

SHOCK ABSORBERS spring devices in balance wheel bearings that divert shocks away from the fragile pivot to the sturdier parts of the balance staff. The springs allow the balance wheel to return to its original position after shocks.

SHOCK RESISTANCE ability to withstand accidental fall or shocks without being damaged.

SHOT BLASTING a satin finish obtained by using tiny glass pellets, one or two microns in diameter.

SKELETON MOVEMENT movement on a watch where the plates have been removed or trimmed so that you can see the gears and other parts.

SKELETON WATCH crystal on the front and back.

SLIDE RULE BEZEL a rotating bezel that is printed with a logarithmic scale and assorted other scales and is used in conjunction with fixed rules of mathematics to perform general mathematical calculations or navigational computations.

SOLAR DAY the length of time it takes the earth to rotate in one day using the sun as fixed reference point.

SOLAR POWERED batteries are recharged via solar panels on the watch face. (Citizen ECO-Drive)

SOLAR YEAR earth completes its orbit about the sun in 365 days, 5 hours, 48 minutes and 46 seconds.

SOLID STATE a timepiece with no moving parts. All digital watches are 100% solid state. Analog watches combine solid state circuits with moving parts.

SPLIT SECOND CHRONOGRAPH a split seconds chronograph or rattrapante (catch up in French) or doppelchrono (double chrono is German) has two seconds hands, the first push starts both hands together, the second push stops one hand while the other continues, and another push allows the stopped hand to catch up with the moving seconds.

SPRING BAR a spring loaded metal bar mounted between the case lugs used to attach the strap or bracelet.

STAINLESS STEEL extremely durable metal alloy consisting of steel, nickel, and composed mainly of chromium. It is virtually rustproof. It is also antimagnetic.

STANDARD TIME the time that is kept locally in each time zone when daylight savings time is not in use.

STEM the shaft that connects to the movement's winding mechanism, the crown is fitted to the opposite end.

STEPPING MOTOR part of a quartz movement that moves the gear train which in turn moves the watches hand.

STOP SECOND (same as hacking) crown which can be pulled out to set the seconds on a watch accurately.

STOP WATCH a watch with a seconds hand that measures intervals of time. When a stopwatch is incorporated into a standard watch, both the stopwatch function and the timepiece are referred to as a chronograph.

SUMMER SOLSTICE the summer solstice is the longest day of the year.

SUPER ACCURATE a watch that is accurate to +/- 10 seconds per year. A technology that uses quartz crystal oscillators working with an integrated circuit, assuring up to 10 times more accuracy than a conventional quartz watch.

SUB DIALS auxiliary dials.

SUPERLUMINOVA photo-luminescent non-radioactive material with a long period of phosphorescence.

SWISS MADE legally protected indication of Swiss origin. Under terms of the Swiss Federal Council ordinance of December 23, 1971, it can apply only to watches with: -Swiss Movement -Assembled in Switzerland - Final inspection must be done in Switzerland

SWISS MOVEMENT in order for a watch to state that it has Swiss Movement it must: -be assembled in Switzerland -be tested in Switzerland -have 50% of the parts from Swiss origin

TACHOMETER instrument for measuring speed over a measured distance. A racing car covers 1 mile in 30 seconds. The sweep second hand, when stopped at the end of the mile, would point to the 120 on the tachometer. The average speed in 120mph. Counts the number of rotations to see how fast you travel over a measured distance.

TANTULUM a grey, heavy, and very hard metal. Tantalum is used to make avariety of alloys at high melting point and high strength. Tantalum is completely immune to body liquids and is a non-irrititating material.

TELEMETER stopwatch or chronograph function with a scale that measures the distance of something from the wearer of the watch through the amount of time it takes for sound to travel.

TIDEGRAPH tides are the periodic rise and fall of the water of oceans, seas, bays and other bodies of water caused mainly by the gravitational interactions between the Earth, Moon and Sun. Tides rise and fall about every six hours. The tide graph indicates tidal movement based on the Moon's transit over the meridian and the lunitidal interval. (Also called Tide Function)

TIME ZONE the world is divided into 24 time zones spaced at intervals of 15 degrees in longitude. The zones start at 0 with Greenwich. Within each time zone, the hour and minute of the day is defined to be the same. Time zones are usually specified by the number of hours they differ from GMT. EST is GMT 5 hours.

TITANIUM a metal, gray in color, that is used for watch cases and bracelets. Much stronger and lighter than stainless steel and hypo-allergenic. It is 30% stronger and 50% lighter than steel. It is very resistant to salt water corrosion makes it useful in divers watches although since it can be scratched easily some manufacturers use a coating to resist scratching.

TOURBILLON eliminates errors of rate due to earth's gravity of vertical positions. "whirlwind" a complex mechanism requiring the highest watch making skills: consists of a mobile carriage carrying all the parts of the escapement. It is a regulating device which connects for the gravity-caused differences in run time in a mechanical watch. (Shifts of weight)

TRAIN the series of wheels in a watch: center wheel, third wheel, fourth wheel, and escape wheel.

TRIBOLOGY the study of the interaction of sliding surfaces.

TRIMMER found in expensive quartz movements it is a variable capacitor that changes the frequency of the oscillator in order to advance or retard the rate of the watch.

TRIPLE DATE CALENDAR complication that provides month, day and date.

TRITIUM a slightly radioactive substance that collects light and is used to allow the hands or hour markers to glow in the dark. The radiation is so low that there is no health risk. Watches with tritium must be marked with the letter T on the dial near the 6'oclock.

TROPIC OF CANCER located 23.5 degrees north of the equator. On June 21st, the sun is directly overhead the tropic of cancer at noon. This is the beginning of summer in the northern hemisphere and the beginning of winter in the southern hemisphere.

TROPIC OF CAPRICORN located 23.5 degrees south of the equator. On December 21st the sun is directly overhead of the tropic of Capricorn at noon. This is the beginning of winter in the northern hemisphere and the beginning of summer in the southern hemisphere.

UNI-DIRECTIONAL BEZEL a bezel that rotates clockwise and counter clockwise.

VHP very high precision is a quartz movement with a temperature sensor to keep variations within extremely narrow margins. The movement corrects itself to precision +/- 10 seconds per year.

VIBRATION movement of a pendulum limited by 2 extreme positions. The balance of a mechanical watch generally makes 5 or 6 vibrations per second (18,000-21,600 per hour.) A high frequency watch makes 8-10 vibrations per second (25,200 28,800 36000 per hour) The higher the number the smoother and more accurately the watch will run.

WATERPROOF no watch is 100% waterproof.

WATER RESISTANT water resistance is reduced by age, wear, extreme temperatures and high pressure. Water resistance is measured 4 ways where 1ATM= 1 BAR = 10m = 33.3ft In order to maintain stated water resistance the gaskets that seal out water must be checked and replaced regularly. 3 ATM or 3 BAR (30m or 100ft) can withstand gentle splash such as rain 5ATM or 5 BAR (50 or 165ft) suitable for showering or light moisture 10ATM or 10 BAR (100m or 330ft) swimming or snorkeling 15ATM or 15BAR (150m or 500ft) suitable swimming, snorkeling and low diving 20ATM or 20BAR (200m or 660ft) suitable for swimming, diving and high board diving 30ATM or 30BAR (300m or 990ft) suitable for swimming, diving and high board diving 100ATM or 100BAR (1000m or3300ft) suitable for deep sea diving

WHITE ON analog watch that is able to display functions at the touch of a button. An easily legible white numeric display appears on the inside surface of the crystal when any digital function is activated.

WHEEL pinion circular part revolving an axis to transmit power or motion. Center wheel, front wheel, hour wheel, minute wheel, third wheel, transmission wheel.

WORLD TIME WATCH 24 different time zones that can display the current time in any part of the world.

WRIST COMPUTER a watch that can directly interact with a computer.

YACHT TIMER a countdown timer that sounds warning signals during the countdown to a boat race.