Girard-Perregaux Minute Repeater Tourbillon with Bridges, Instructions For Use Manual

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In these enhanced conditions, the delicate components of the striking-mechanism, each given their own
traditional finishing, wind up and then release the hammers so as to strike with absolute consistency first
the hours (in a low tone), then the quarter-hours (in a combination of high and low tones), and finally
the minutes (in a high tone).
The decision to position the two gongs facing the inner side of the hour circle and to also place here the
hammers (the shape of which is inspired by the Gold Bridges first patented in 1884), goes beyond mere
aesthetic considerations. This positioning enables the acoustic wave, duly regulated at a carefully
calibrated frequency, to reverberate harmoniously and not, as is only too often the case, to be confined
by the excessive proximity of surfaces such as the skin, well known as possessing a density that easily
absorbs sound waves. In addition to this, the relationship between the size of the case and that of the
calibre has been carefully studied so as to offer the best possible volumetric arrangement, as in the case
of musical string instruments. Even better, the inside of the case has been specially crafted and finished
so as to limit any acoustic interference that might arise. And since there is no room for false notes in a
musical performance, the sapphire crystal case-back has been crafted to give it the delicate curvature
found in the majority of musical instruments equipped with a sounding-box, and the aim of which is to
maximize the volume in which the sound can reverberate.
HALF MUSICAL INSTRUMENT, HALF KINETIC SCULPTURE
It is the highly unusual structure of the striking-mechanism, together with the adoption of a number of subtle
technical solutions for this complication that has allowed the Minute Repeater Tourbillon with Bridges to
perform so exceptionally well. Thus, in order to enhance the transmission of the sound wave between the
heels of the two gongs, the link between the main plate and the case-band has been stiffened. This is not
all, however. To increase the speed of the hammers and consequently their striking impact, they are each
mounted on a pair of jewels acting as ball-bearings so as to reduce friction. The design of this structure
has such a harmonious visual impact that it may seem simple.
However things that look easy are in fact often exceedingly complex to achieve. No fewer than 270 hours
of painstaking labour by a master watchmaker are required to assemble and adjust this magnificent
mechanism. This work is made all the more arduous by the fact that the method of production of the minute
repeater complication, with its hammers placed on the same plane as the racks used to wind them up prior
to striking, makes it necessary to adjust the hammers outside the movement using a special tool simulating
their future position. Nevertheless the final result is there for all to see, and these small components made
from black polished tempered steel and beveled to highlight their original design inspired by the Three
Gold Bridges, produce thanks to their high degree of inertia a clear, powerful note at each strike.