The tachometer is an additional scale on the outer edge of the facia or on the bezel of a chronograph. It is designed to help calculate speeds.
The Earth is divided into 24 time zones, each covers 15 degrees of longitude. The time in each of these zones is based upon the actual time at the null meridian (see GMT). The time gain or delay from one zone into another is always 1 hour. Since the Earth turns from east to west, to the east of the meridian the time is always later than it is at the null meridian, to the west it is always earlier. Seconds and minutes are always the same.
Titanium is a very light, very hard, metal. It is used in the watch industry to make watch housings and armbands. It has a low specific gravity of just 4,49 and a high melting point of 1,800 degrees Celsius. Titanium is a very reactive metal. Its typical grey colour is caused by a film of oxidisation, which builds up on the surface whenever it is exposed to oxygen. Although titanium is abundant in the earth’s crust, this reactivity (its tendency to easily form compounds with other materials) makes its production very elaborate and expensive.
The tourbillon is a device designed to equalise the inaccuracies that may occur, due to the force of gravity, in a vertically positioned timepiece. This invention consists of a cage with all the parts of the escapement mechanism and a regulating device in the centre. The gearwheel of the escapement turns about the fixed second-wheel and the cage turns itself once a minute about its own axis. In doing so, it equalises any functional effects that may be caused by gravity. Abraham Louis Breguet (1747-1823) invented the tourbillon in the year 1800.