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372 ILLUSTRATED WORLD
AFTER THE MERWA'S SILVER BULLION
For greater safety the divers work in pairs when seeking out the strong room of this treasure ship.
ten years ago that these were discovered
to be inefficient.
Through one cause or another pumps
leaked and air supply was insufficient
when the diver was toiling at his maximum
depth—100 to 150 feet below the
sea's surface. Not only that, but the
pressure gage, which served as a guide
for the men at the pump cranks, was
proved to be a treacherous index of the
measure of air being forced down into
the ocean's depths for the man or men
at the other ends of the armored hose.
No wonder, then, that divers found themselves
short of vitally necessary air when
slipping to added depths of only a few
feet while working around sunken
wrecks, or that the men thus were dazed
or made incapable of giving the proper
signals that might have saved them from
death.
Because of certain discoveries, the