Joe said:

"Ten seconds. Nine ... eight ... seven ... six ... five ... four ...
three ... two ... one...."

He stabbed the master jato switch. And a monstrous jato rocket, built
into each and every one of the pushpots outside, flared chemical fumes
in a simultaneous, gigantic thrust. A small wire-wound jato for
jet-assisted-take-off will weigh a hundred and forty pounds and deliver
a thousand pounds of thrust for fourteen seconds. And that is for
rockets using nonpoisonous compounds. The jatos of the pushpots used the
beryllium-fluorine fuel that had lifted the Platform and that filled the
take-off rockets of Joe's ship. These jatos gave the pushpots themselves
an acceleration of ten gravities, but it had to be shared with the cage
and the ship. Still....

Joe felt himself slammed back into his seat with irresistible,
overwhelming force. The vibration from the jets had been bad. Now he
didn't notice it. He didn't notice much of anything but the horrible
sensations of six-gravity acceleration.

It was not exactly pain. It was a feeling as if a completely intolerable
and unbearable pressure pushed at him. Not only on the outside, like a
blow, but inside too, like nothing else imaginable. Not only his chest
pressed upon his lungs, but his lungs strained toward his backbone. Not
only the flesh of his thighs tugged to flatten itself against his
acceleration-chair, but the blood in his legs tried to flow into and
burst the blood-vessels in the back of his legs.