How cables were laid across the floor of the Atlantic ocean

vacuum tubes resistors condensers all the essential parts for the repeater to do its job Beneath the Sea protection against being crushed by the tremendous pressures at Ocean depths was provided by interlocking steel rings a copper tube outside the steel rings would prevent a single drop of seawater from getting into the repeater and possibly silencing the cable the ends of the repeater were sealed under great Heat by a complex brazing process