Quotation from: People Out of Time

Written by: Edgar Rice Burroughs

Tyler and Hollis and Short and all the rest of us Americans nearly
worked our jaws loose on the march back to the village, and for
days afterward we kept it up. They told me how they had crossed
the barrier cliffs in five days, working twenty-four hours a day in
three eight-hour shifts with two reliefs to each shift alternating
half-hourly. Two men with electric drills driven from the dynamos
aboard the Toreador drilled two holes four feet apart in the face
of the cliff and in the same horizontal planes. The holes slanted
slightly downward. Into these holes the iron rods brought as
a part of our equipment and for just this purpose were inserted,
extending about a foot beyond the face of the rock, across these
two rods a plank was laid, and then the next shift, mounting to the
new level, bored two more holes five feet above the new platform,
and so on.