M

Main Plate - the base plate on which all the other parts of a watch movement are mounted.

Mainspring - the driving flat-coiled spring of a watch or clock, contained in the barrel.  Supplies power to the watch.

Manual-wind - a watch movement that must be wound manually every day or two to keep it running.

Manufacture - (Manufactory) a factory where watches are manufactured almost completely.

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

Mechanical watch - origin dates back to the 14th century. It is made up of about 130 parts assembled in the three main parts which are:

1. the source of energy
2. the regulating parts

3. the display.
    

The number of component parts is much higher in so-called complicated watches (date, phases of moon, fly-back hand, etc.). The "ébauche" (about 60 parts) fitted with the regulating and certain other parts, forms the movement, in other words the internal mechanism of the watch, which makes it possible to maintain a constant tension in the spring once it has been wound manually or automatically (by movements of the wrist) and to regulate the display by means of the hands (hours, minutes, seconds).

Mercury battery - 1.35 volt.

Micron - 1/1000 mm. (0.001 millimetre).  Used to measure the thickness of gold plating

Military time - time is measured in 24-hour segments

Mineral glass - ordinary glass that is used for windows. Mineral glass, even though it has been hardened by a tempering process, is more likely to break than Plexiglas. But it is also more scratch-resistant than Plexiglas.

Minute Repeater - a complication that can be made to strike the time in hours, quarters and minutes by means of a button or slide on the side of the case.

e.g.              Hour =                  Ding
                   Quarter Hour =     Ding Dong
                    Minutes =             Dong

Ding Ding Ding - Ding Dong - Dong Dong Dong Dong
indicates that the time is 3:19                

Montre à tact - the tactful watch. In Parisian society of the late 18th century it was considered unseemly to take out a pocket watch to tell the time. In 1796 Breguet invented a pocket watch whose user could "feel" the time.

Moon phase - shows what phase the moon is in by means of a disk that rotates beneath a small aperture. On the disk are painted two full moon faces. As the day of the month pass, one moon face indicates the phase of the real moon.    The 29 1/2 day cycle of the moon is displayed by the disc being moved by a gear-train. 

        

The four phases of the moon are:            
        - New moon,
        - First quarter moon,
        - Full moon,
        - Last quarter moon. 

Moon Watch - The Omega Speedmaster Professional with reference number 3570.50.00 is the original Moon Watch.
                        calibre 1861 manual-winding movement.
                        stainless steel 
                        stainless steel bracelet                                
                        black dial and a hesalite crystal
                        waterproof to 30 metres/100 feet 
                                                                 

Movement - The engine of a watch.  The machinery of any time piece that moves the hands and any complications.  Movements are either mechanical or quartz.  Consists of the winding mechanism, the mainspring, the train, the escapement and the regulating elements.