The attendant nodded indifferently, then helped Forster into the helmet of his pressure suit. He climbed up the steps into the chamber, pulling the airtight door shut behind him. He placed the box on the desk in front of the instrument panel, then turned back to push the door clamps into place.
For the first time in the hundreds of hours he'd spent in the tank, he knew the meaning of claustrophobia.
Mechanically, he plugged in his intercom and air lines, went through the other routine checks before ascent, tested communications with the lab attendant, then flicked the exhaust motor switch.
Now there was little to do except wait. He stared at the box; in the artificial light it seemed full of hidden menace, a knowing aliveness of its own....
Forster shrugged his shoulders impatiently, as though to throw off the vague blanket of uneasiness that was settling around him. So somebody had forgotten to send a covering message with the container, or else it had been mislaid—that could happen, although with security routine as strict as it was, the possibility was remote. All the same, it could happen. After all, what other explanation was there? What was it he was afraid of? There was something about it—
He glanced at the altimeter. The needle showed only 10,000 feet, and seemed to be crawling around the dial. He resolved not to look at it for three minutes by the clock on the panel.
When he checked the altimeter again, it registered just over 30,000 feet. Not even half way yet.
As the pressure in the tank decreased, he began to be conscious of the need for "reverse breathing"—and he concentrated on using his tongue to check the flow of air into his lungs, then using the thoracic muscles to exhale against the higher pressure inside the suit.
Time seemed to be passing in micro-seconds ... 25,000 feet ... 30,000 ... 40,000 ... 50,000.
At 62,500 feet he gently tested the cover of the container again; it lifted.