The Earth makes an elliptical orbit around
the Sun; also, its axis is tilted from perpendicular to the plane of the
equator. For these two reasons, a "true" solar day, which is the
interval of time between two "true" noons when the Sun is at its
highest point in the sky, is never the same length over the course of the year.
It is exactly twenty-four hours long on just four days: April 15th, June 14th,
September 1st and December 24th. In an unchanging cycle, all the other days are
either longer or shorter. This difference, which ranges from less 16 minutes
and 23 seconds on November 4th to plus 14 minutes and 22 seconds on February
11th, is the "equation of time".
On the subject of innovations, watchmakers have devised systems for reading the
equation of time at a specific longitude and not for an entire time zone,
thereby further enhancing precision.
Flyback
A flyback chronograph is a chronograph with
a twist. Unlike typical chronographs which must be stopped before they can be
reset to zero a flyback can be returned to zero while it is moving enabling one
to time successive events without a undue lapse of time.
Foudroyante
A foudroyante uses a 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.
GMT
Universal time based on the Greenwich Meridian
used by the military and in aviation. Greenwich Mean Time (GMT) is a 24-hour
watch is a type of watch with an hour hand that completes a revolution every 24
hours. This type of watch is especially useful for airplane pilots, astronauts,
members of the military, or anyone who uses a 24-hour clock. Also referred to
as UTC: Universal Time Co-ordinate.Zulu Time: Yet another reference to GMT and
UTC! The use of this phrase is prevalent in civil aviation and military. Zulu
is the phonetic for Z which is for the Zero meridian.
Jump
Hour
Whereas a standard watch displays the time
by a pair (or sometimes three) hands pointing at fixed numbers, jump hour
watches have a wheel that rotates to display the correct time i.e. the numbers
themselves move. The watch will have a small window cutout on the dial so that
only the correct time is displayed.
Power
Reserve
The mechanical watch operated either by
automatic- or manual winding. In order to run at a regular rate a mechanical
timepiece needs to have at least 30 per cent of its mainspring wound]. An
automatic timepiece needs to be worn for about 1015 hours before it is fully
wound. The power reserve indicator displayed on the watch with automatic-
winding movement shows how long a watch will function when not worn. The one
displayed at a watch with the manual winding mechanism shows the time left for
its next winding.
Moon
phase
Simply, this is a cut-out on the dial with
a picture of the moon showing its current phase.
Regulator
A watch where the hour and minute hands are
not on the same, but separate, pinions; they are watches where the hour
function is off centre. Typically the watch will have a small 12 hour watch
face at the 12 position which denotes the hours, a minute hand central to the
watch face and usually a seconds hand in a circular face at the 6 position. The
watch is read by consulting each hand separately.
Repeater
The repeater strikes the number of hours
that have passed since 12 o'clock on a gong. Repeater watches were much harder
to make than repeater clocks; fitting the bells, wire gongs and complicated
striking works into a pocket watch movement was a feat of fine watch making. So
repeating watches were expensive luxuries and status symbols.
·
Hour Repeater
The term 'repeater', without qualifiers, usually
means an hour repeater. On pressing the lever or button, the repeater strikes
the number of hours that have passed since 12 o'clock on a gong. This is the
only type of repeater that needs a single gong. No distinction is usually made
between AM and PM, so whether the time shown is 2:00am, 2:17am, 2:59am, or
2:59pm, the repeater will chime twice.
·
Quarter Repeater
The quarter repeater strikes the number of
hours, and then the number of quarter hours since the last hour. The mechanism
uses 2 chimes of different tones. The low tone usually signals the hours, and
the high tone the quarter hours.
·
Half-quarter Repeater
The half-quarter repeater can sound the
time to half a quarter hour, or 7½ minutes. It strikes hours and then quarter
hours, like the quarter repeater, then it uses a single tone in order to signal
if more than half of the current quarter hour has passed. For example, if the
time is 3:41 the mechanism will strike 3 low tones ("bong") to
represent 3 hours, then 2 sequence tones ("bing-bong") to represent 2
quarter hours, then one high tone ("bing") to indicate that more than
half of the third quarter hour has passed.
·
Ten-minute Repeater
Conceived of as clock for the blindbefore
talking clocks, and patented (3,925,777) in 1974, this electronic repeater
called the Audocron was manufactured in the U.S. When touched it chimed out the
hour, then in a higher tone - the tens of minutes, followed by the minutes in
the original tone.
·
Five-minute Repeater
The minute repeater works like the quarter
repeater, with the addition that, after the hours and quarter hours are
sounded, the number of minutes since the last quarter hour are sounded. This
requires three different sounds to distinguish hours, quarters, and minutes.
Often the hours are signaled by a low tone, the quarters are signaled by a
sequence of two tones ("bing-bong"), and the minutes by a high tone.
·
Minute Repeater
The minute repeater works like the quarter
repeater, with the addition that, after the hours and quarter hours are
sounded, the number of minutes since the last quarter hour are sounded. This
requires three different sounds to distinguish hours, quarters, and minutes.
Often the hours are signaled by a low tone, the quarters are signaled by a
sequence of two tones ("bing-bong"), and the minutes by a high tone.
·
Grande Sonnerie
A Grande Sonnerie is a quarter striking
mechanism combined with a repeater. On each quarter hour, it sounds the hours
and then the quarters on two gongs. In addition it can strike the hours at the
push of a button.
·
Dumb Repeater
Used by the visually impaired and to tell
the time quietly in meetings and concerts, 'dumb' repeater watches did not
chime audibly, but instead produced vibrations. Instead of a gong, the hammer
struck the hours on a solid metal block attached to the case, producing a dull
'thud' that could be felt in the hand.
Retrograde
Rather than a typical display in which a
hand (such as a minute hand) completes a 360 degree revolution, a retrograde
display completes 180 degree journey before flying back instantaneously to
begin its travel once more.
Skeleton
Movement
The skeleton has had all excess metal
removed from its structure of plates and bridges transforming it into an
intricate artwork of beauty and delicacy that allows the movement to be seen
through the dial. Also sometimes referred to as exposition, which usually
referrers to only the back of the watch.
Rattrapante - Split Second Chronograph - Double
Chronograph
Split Second Chronograph is the most
complicated chronograph. Instead of the ordinary single central stopwatch hand,
two hands are superimposed over the other. When the chronograph is activated
both hands will start in unison. However upon pressing the split-second button
the lower hand will stop while the other hand continues forward enabling two
events to be timed at once. By pushing the button again, the stopped hand will
immediately catch up with the other hand and will continue to travel in unison.
This complex mechanism places great demands on watchmakers as this type of chronograph
undergoes much more violent mechanical stresses when used in its intended
manner.
Tachymeter
A scale used to measure units per hour.
Commonly found on the bezels of chronograph watches, an event is timed by using
the chronograph seconds hand. The hand is stopped when the event ends and the
hand will point to the number of units per hour that could be achieved.
Tourbillon
Considered a very special complication in a
mechanical watch. A Tourbillon mechanism compensates for the effects of gravity
on the balance thus improving the overall accuracy of the watch. Originally
invented by Abraham Louis Breguet, the watch's escapement (balance, lever and
escape wheel combined) is housed in a cage which rotates every 60 seconds.
Pocket watches were worn vertically and motionless in a gentleman's pocket, in
order to negate the effect of gravity, the Tourbillon originally was an attempt
to improve accuracy. The mechanism is usually exposed on the watch's face to
show it off.
·
Double Tourbillon
The Double Tourbillon 30° features one
tourbillion carriage rotating once per minute and inclined at 30°, inside
another carriage which is rotating every four minutes.
·
Gyrotourbillon or Double-axis Tourbillon
This Tourbillon turns around two axes, both
of which rotate once per minute. The whole Tourbillon is powered by a special
constant-force mechanism, called a remontoire. Thomas Prescher invented the
constant-force mechanism to equalize the effects of a wound and unwound
mainspring, friction, and gravitation. Thereby, even force is always supplied
to the oscillation regulating system of the double-axis Tourbillon
·
Triple-axis Tourbillon
In the three axis Tourbillon movement the
3rd (external) cage has a unique form which provides the possibility of using
jewel bearings everywhere - instead of ball-bearings.
·
Quadruple Tourbillon
Quadruple Tourbillon à Différentiel (QDT),
which uses two Double-Tourbillons working independently. A spherical
differential connects the four rotating carriages, distributing torque between
two wheels rotating at different speeds.
·
Flying Tourbillon
Rather than being supported by a bridge, or
cock, at both the top and bottom, the flying Tourbillon is cantilevered, being
only supported from one side.
·
Open Heart
There are many "Tourbillon"
fake/replicas of premium brand watches that emulate this feature with the
oscillating balance wheel visible through the watch dial; however, these are
not Tourbillons. This feature is often referred to as "open heart".
