Letter from the Publisher

oPTIMAL READABILITy
In recent years, we have been seeing the grand return
of a function that is not specifically horological as such, but
is nonetheless extremely useful to divers: the depth gauge,
or bathymeter. It serves as an alternative to—or rather as
complementary to—the electronic wrist chronographs that
are pouring onto the market. The Master Compressor Diving Pro
Geographic Navy SEALs by Jaeger-LeCoultre is water resistant
to 300 meters and distinguished by a mechanical depth
gauge located on the left side of the case and fitted with a
membrane that expands or contracts according to the degree
of water pressure to which it is subjected. The movements of
this membrane act on a large arrow-tipped hand by means
of a clever transmission system that is partially visible on the
dial. The depths measured range from 0 to 80 meters. Jaeger-
LeCoultre has also paid tribute to its partnership with the
uS Navy SEALs—the elite American military combat divers’
unit—by creating two other divers’ watches in limited series:
the Master Compressor Diving Chronograph GMT Navy SEALs,
with chronograph and dual time zone display; and the Master
Compressor Diving Alarm Navy SEALs with alarm function.
• 480 Grand Complications, Vol. VII
Moreover, certain brands devote particular efforts to the
field of visibility. At depth of 75 meters and under, daylight
gives way to ever-greater darkness the further one descends.
Divers’ watches must thus ensure perfect readability by
means of large numerals and hour markers, as well as by
an effective luminescent substance. For its Engineer
hydrocarbon Spacemaster model, Ball Watch uses microtubes
of gas guaranteeing 20 years of luminosity one hundred
times more intense than other technologies. It is based on
cutting-edge Swiss technology consisting of capturing tritium
in a gaseous state within tiny glass tubes. Light energy is given
off by molecules striking the colorful inner surface of the
capsules. For its Deep Dive model, Luminox uses the same
micro-tubes tinted in blue, the very last color that the human
eye is capable of perceiving from a certain depth downwards.
below left
Jaeger-LeCoultre, Master Compressor Diving Pro Geographic
Navy SEALs
below right
Ball Watch , Engineer Hydrocarbon Spacemaster