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.

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 movement.

A/m (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. (same as "applied")

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 WATCH quartz watch that is controlled by a radio signal from a cesium atomic clock. The result is extremely accurate time that can be measured on instruments. (radio-controlled)

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 is transferred into mechanical energy that creates the watch movement. These watches can be shaken or manually wound if the power reserve runs out.

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 (or 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.

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 both clockwise and 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.

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.

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.

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

CHRONOMETER A chronometer is a high-precision watch capable of displaying the seconds and housing a movement that has been tested over several days, in different positions and at different temperatures, by an official neutral body (COSC). Each chronometer is unique, identified by a number engraved on its movement and a certification number given by the COSC. Each movement is individually tested for several consecutive days, in 5 positions and at 3 temperatures. Each movement is individually measured. Any watch with the denomination "chronometer" is provided with a certified movement.

CLASP used to secure the brcelet or strap of a wristwatch, to the wrist. There are three basic types of clasps; fold-over clasp, jewelery clasp and butterfly-clasp (aka deployant/deployment buckle, hidden deployant/deployment buckle, hidden double-locking 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 several consecutive days, in 5 positions and at 3 temperatures. They either pass or fail the watch movement. If the watch passes it is certified as 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.

CYCLOPS small lens on the crystal to magnify the date.

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.

DIAL face of the watch that generally displays hours, minutes, and seconds.

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

DISPLAY BACK it is a caseback that is transparent so that movement may be viewed. (also called: clear, see-thru, skeleton, exhibition)

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

DLC (Diamond Like Carbon) a metal coating that produces a grey/black finish that is very scratch resistant and corrosion resistant. This type of coating is like PVD, but even harder (and more expensive).

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.

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 the wheels at regular intervals.

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

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.

GEAR 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.

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 (GMT), a watch that has the capability of displaying two different time zones.

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 the (or balance 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.

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 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 and more.

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

HARDBACK a solid metal caseback.

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.

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.

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

JUMP HOUR a display in which the hour, shown through an aperture, instantly changes every 60 minutes.

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.

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. SuperLuminova is the most popular type of luminous paint.

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 a factory that makes its own components and assembles at least one complete movement (caliber), in-house.

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, or over 500 for the most complicated watches.

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

MINUTE REPEATER a function on a watch that can strike the time in hours, quarters, or seconds by means of a push piece. An extremely complicated function, cost is very high.

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. (Go to the "movements" page for more info.)

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.

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.

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.

PVD (Physical Vapor Deposition) method of coating watch cases by integrating titanium particles and then depositing gold for color. Generally comes in black finish, but other colors can be created. (Very similar to "titanium carbide".)

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.

RATTRAPANTE addition of a second hand to measure split times. (Also called split-second chronograph.)

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

REGULATOR DIAL a watch where the hour and minute hands are not on the same, but separate, pinions. Generally a "regulator watch" (not to be confused with "retrograde") has an hours subdial at 12 o'clock, a seconds subdial at 6 o'clock and a central seconds hand.

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

RETROGRADE an hour, minute, seconds or calendar hand which moves across a scale and, at the end of its cycle, returns immediately to zero to begin again (not to be confused with "regulator dial").

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.

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

SAPPHIRE CRYSTAL 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.

SCREW BACK caseback has a thread so that it can be screwed-in to 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.

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

SKELETON MOVEMENT/DIAL 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 POWERED batteries are recharged via solar panels on the watch face. (Citizen ECO-Drive)

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. 316L is the standard steel used in watchmaking, however Rolex uses a slightly harder and more corrosion resistant steel called 904L. 904L is generally used in chemical applications and it costs significantly more than 316L steel.

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

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

STOPWATCH 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).

SUB DIALS auxiliary dials or registers.

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.

TANTALUM 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, making it useful for diver's watches. Although, since it can be scratched easily, some manufacturers use a coating to resist scratching.

TOURBILLON (or whirlwind) eliminates errors of rate due to earth's gravity of vertical positions. 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 corrects 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.

UNI-DIRECTIONAL BEZEL a bezel that rotates only one way (a dive bezel, for example, only moves one way, because it is used to count how much air is left in your tanks, and you would not want your bezel to accidentally go back, because it could be extremely dangerous if you stay under too long).

VPH (Vibrations Per Hour) 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 (25,200/28,800/36000/43,200 per hour) The higher the number the smoother and more accurately the watch will run. (same as BPH "beats per hour")

WATERPROOF no watch is 100% waterproof.

WATER RESISTANT The ability of a watch to withstand water from entering the case. Water resistance is generally measured in four ways, where (1 ATM = 1 BAR = 10 METERS = 33.3 FEET).

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

WORLDTIMER 24 different time zones that can display the current time in any part of the world, without adjusting the crown.

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