158
Thc Last Resource
to work or to carry out studies has yet to be resolved. Parallel with
advances in diving and manned vehicles have come novel develop—
ments in instruments and remote—controlled machines. The under—
water camera, equipped with a special wide—angle lens, has already
proved a valuable tool in surveys of the sea oor, particularly when
used in conjunction with a grab. Underwater television and acoustic
‘imaging’ are other areas where considerable improvements can be
expected. Several remote—controlled machines have now been built
for underwater salvage work. However, these and other systems
need not come into direct conict with man’s underwater aspira—
tions. On the contrary, they offer the kind of choice which should
make possible further exploitation of ocean resources—they even
introduce the hazard of over—exploitation.
Towards the limit of diving
At the surface a diver can ll his lungs with about six litres of air,
but during a dive the water pressure, which increases by one
atmosphere for every 33 feet, gradually compresses the air in his
lungs until by about 100 feet its volume is reduced to about one and
a half litres. At the surface this is the volume of air remaining in the
lungs after breathing out completely. If the diver continues to
descend, he risks permanent lung damage and probably death. This
simple effect of increasing pressure on the volume of a gas,
summarized long ago in Boyle’s Law (the volume of a given mass of
gas at a constant temperature varies inversely with the pressure
exerted upon it), sets a natural limit to unaided diving. To go deeper
the diver must be supplied with air at the same pressure as his
surroundings—the ambient sea pressure—thus keeping changes in
lung volume the same as on the surface.
An early solution was to provide the diver With a helmet which
received air pumped down from the surface by a hand—operated
compressor, any excess air simply escaping from around the edge of
the headgear. An Englishman, John Deane, designed one of the
rst successful diving suits in the early 18oos. He eventually joined
forces with Augustus Siebe, a German engineer who had settled in
England, to produce a diving dress complete with a hard hat and a
watertight suit for the body. ln spite of distinct disadvantages, not
least being the cumbersome weights needed to keep the diver rmly
on the sea oor, the Siebe diving dress has persisted with few
modications up to modern times.
Thc Last Resource
to work or to carry out studies has yet to be resolved. Parallel with
advances in diving and manned vehicles have come novel develop—
ments in instruments and remote—controlled machines. The under—
water camera, equipped with a special wide—angle lens, has already
proved a valuable tool in surveys of the sea oor, particularly when
used in conjunction with a grab. Underwater television and acoustic
‘imaging’ are other areas where considerable improvements can be
expected. Several remote—controlled machines have now been built
for underwater salvage work. However, these and other systems
need not come into direct conict with man’s underwater aspira—
tions. On the contrary, they offer the kind of choice which should
make possible further exploitation of ocean resources—they even
introduce the hazard of over—exploitation.
Towards the limit of diving
At the surface a diver can ll his lungs with about six litres of air,
but during a dive the water pressure, which increases by one
atmosphere for every 33 feet, gradually compresses the air in his
lungs until by about 100 feet its volume is reduced to about one and
a half litres. At the surface this is the volume of air remaining in the
lungs after breathing out completely. If the diver continues to
descend, he risks permanent lung damage and probably death. This
simple effect of increasing pressure on the volume of a gas,
summarized long ago in Boyle’s Law (the volume of a given mass of
gas at a constant temperature varies inversely with the pressure
exerted upon it), sets a natural limit to unaided diving. To go deeper
the diver must be supplied with air at the same pressure as his
surroundings—the ambient sea pressure—thus keeping changes in
lung volume the same as on the surface.
An early solution was to provide the diver With a helmet which
received air pumped down from the surface by a hand—operated
compressor, any excess air simply escaping from around the edge of
the headgear. An Englishman, John Deane, designed one of the
rst successful diving suits in the early 18oos. He eventually joined
forces with Augustus Siebe, a German engineer who had settled in
England, to produce a diving dress complete with a hard hat and a
watertight suit for the body. ln spite of distinct disadvantages, not
least being the cumbersome weights needed to keep the diver rmly
on the sea oor, the Siebe diving dress has persisted with few
modications up to modern times.