"We've no time to lose," he announced briskly. "That uranium cylinder in the tractor must be nearly exhausted. It had never been operated before at its maximum power, and we overestimated its life—a serious error. There is an automatic signal that shows you when ninety per cent. of it is gone. See? Only two per cent. left! I didn't like the idea of going outside to replace it, though, while we were driving through space. Hope our liquid-air suits will work. We'll be in a beastly fix if they won't. We ought to have tested them in a vacuum, but there were too many things to do."
He crossed the chart-room, and, unlocking a cupboard at the farther end, dragged forth the three suits of vacuum armor. They were of simple design, made of heavy rubber cloth and surmounted by copper helmets resembling those worn by divers. Each wearer carried a cylindrical tank, supported upon the shoulders, for his supply of liquid air.
"The first thing," continued Burke, "is to load up our knapsacks."
Bennie and Atterbury assisted him in unclamping the cover of one of the large retainers that supplied the Ring with fresh air. In appearance, it was not unlike a gigantic milk-can, and caused Burke to remark,
"I pity anyone who tried to steal that milk!"
Atterbury produced a metal ladle from the closet, while Bennie unfastened the tops of the cylinders, and Rhoda held her breath as she peered into the big retainer as the engineer thrust the ladle into its mysterious contents, which gave out dense clouds of white smoke.
"Hot stuff!" he grinned. "Look out!"
"Hot nothing!" replied Bennie. "It's over three hundred degrees below Fahrenheit!"
Bennie held the cylinder for Atterbury, while the latter attempted to pour it in through a funnel, but, in spite of all his care, some of the liquid fell upon the floor with a hiss like that of water dropping upon a red-hot stove.
"What makes it smoke like that?" asked Rhoda. "Of course, I know it isn't hot!"