 |
|
FACTS
ABOUT MECHANICAL TIMEKEEPING
The exceptional operating efficiency of a quality mechanical
watch movement can be summed up in a few single figures. Its
balance wheel oscillates at a rate of 28,000 vibrations per
hour, equivalent to 4 Hertz. Its rotational speed thus approximates
that of the wheel of a locomotive travelling at about 140
km/h (a little under 90 mph).
Weighing about two thousandths of a gram, the balance spring
connected to the balance wheel is three to four times thinner
than a hair. Nonetheless, it resist a tensile force of 600
grams. It contracts and expands over 200,000,000 times a year.
The escapement of a mechanical watch is a particularly hard
working component as well.
At the oscillation rate mentioned above, it advances the going
train no fewer than 691,200 times every 24 hours – more
than one billion impulses over four years, six times the rate
of a human heart. The mainspring is made of an alloy of iron
and chrome laced with cobalt, molybdenum and beryllium. All
but unbreakable, practically impervious to magnetic influence.
It resists warping and will not rust. As for the often debated
matter of precision, a brief example puts the matter in proper
perspective. A watch running fast or slow by 30 seconds a
day would have a rate drift of only 0.035% from absolute precision.
i.e. it would still be accurate to 99.965%. What’s more,
the finest mechanical movements built today do infinitely
better than that, with the precision of automatic chronometers
varying between only –4 and +6 seconds per day. |
|
|
|
|
