1. The division of time – with which level of accuracy ?
Time is divided naturally by striking astronomical phenomena such as the periodical renewal of the seasons, the phases of the moon, or the regular succession of day and night.

To divide time into smaller fractions, artificial means are needed, such as sun dials which mark the movement of the shadow cast by the sun; or clepsydras which use a controlled flow of water. Since 1657, the oscillatory movements of a mechanical movement have been used to divide time.

The electronic age did not pass watches by. In the late 1960s, a Swiss research group designed and tested the first electronic watch movement, which later became known as the quartz movement. These battery-powered watches also permitted a deviation from the centuries-old analog display with the introduction of digital display.

Quartz watches are extremely accurate thanks to their high frequency of vibrations (32 kHz). Their daily variation is equivalent to much less than a second per day.

Comparatively speaking, the frequencies of oscillations (number of one-way movements of the regulating organ per hour) mainly used in mechanical watches range from 21,600 Ah (3 Hz) to 28,800 Ah (4Hz), allowing a variation of less than 10 seconds a day.

2. It says “water resistant”, but can I swim with it ?
Water resistance is measured in bars (unit of pression, 1 bar being equivalent to 1 atmosphere), and watches are tested at these pressures for certain period of time. Exceptional pressure, as when diving, may exceed those limits, so if you are a keen diver you will need a watch that can tolerate that pounding.

Translation varies and your best guide is your supplier as it will almost certainly be part of the guaranteee.

Manufacturers often measure water resistance to a number of feet (ft), meters (m) or atmospheres (atm). Watches marked “water resistant” with or without additional indication of high pressure must comply with NIHS 92-10 watch Standard (corresponding to ISO 2281 international Standard). Such watches are designed for everyday life and must be water resistant during exercices such as short swimmings. They can be worn in different temperature and pressure conditions but are under no circumstances designed for scuba diving.

Divers’ watches must be water resistant at 330 ft minimum. They must also feature a time controller and comply with standards provided by NIHS 92-11 (ISO 6425) : luminosity, shock resistance, anti-magnetism, band solidity.

Remember that if you are going to be moutain climbing, parachuting, sky diving, hang gliding, or skiing, it is advisable to use a watch that is atm damage-protected as pressures change both above and below sea level.

For regular water use, solid metal cases or specially constructed products are recommended, including screwed-in case backs and crowns.
Do not hesitate to ask your next dealer about water resistance functions, and remember that only professional changing battery will guarantee the seals and thus the water resistance of your timepiece.

3. Chronograph – Chronometer – Complications
A Chronograph is a timepiece equipped with additional time measurement functions independent of normal time-telling.

A Chronometer is a high-precision timepiece which movement, after rigorous testing, has received an official timing certificate from and official timing bureau.

Watches providing additional measurement functions to the hours, minutes and seconds are referred to as “Complications“. The best-known complication watches are calendar watch, the most common of which display only the date. There are also chronographs with a center seconds hand which can be started, stopped and brought back to zero using one or two push-button on the side of the watch. Other additional functions include second time zone, alarm, moonphase, repeater, perpetual calendar, etc.

4.How long is the lifetime of a watch battery ?
Usually between two and five years, depending on the type of the watch, its dimensions and the quantity of energy requested by the different functions. For instance, a chronograph will have a higher energy consumption than a watch indicating the hours and the minutes only.

Certain types of watches feature a power reserve indicator : when the seconds hand starts jumping every five seconds, it is time to have the battery replaced by a qualified watchmaker.Special lithium-iodine batteries reach a theoretical lifetime of ten years.

5.What is a unidirectional bezel ?
Often the bezel (top ring on the case), serves to record additional data, and can often move in both directions to provide a number of functions. A unidirectional bezel only turns one way to prevent any danger of false manoeuvre. Especially important when being used to measure diving times as even if the bezel is knocked and moved it will simply indicate the diver has less air or decompression time rather than more.