"Yes." Professor Reuter, a big man, with folds of fat hanging from his cheeks, pursed his lips and blew through them. "At the time, I must confess, I really must confess, that I failed to consider the fact that the enveloping upper atmosphere of the planet would cause the surface temperature to be lower than that in the atmosphere itself. As a result, it is just cold enough to hold a certain amount of fluorine in solution in this cold ocean--" "And, in a nut-shell, we must turn back," said Adam. He appealed to Captain McCausland. "Isn't there anything aboard ship with which we could insulate the ports?" Scientists always made difficulties, he thought; an old space captain like McCausland would not be so hard to down. "We can try putting divers in space suits with double-thickness glass in the ports. That would last a couple of hours at all events. I don't doubt but we could get volunteers in _this_ crew." Reuter blew through his thick lips again. "Dangerous. As scientific head of the expedition I will permit nothing of the kind. Naturally, Captain, we are under your orders, but if you take such a step it will be without my authority." McCausland made a gesture of hopelessness. "Have you any other ideas to suggest, Mister Longworth?" Was "Old Steel-Wall" giving up this easily? Adam's thoughts wheeled, but he schooled himself to inquire mildly, "Have you thought of trying mica windows, sir?" "That would do it!" cried Dr. Perkins excitedly. "Fluorine doesn't attack mica--at least at Earth temperatures. I don't know about these sub-zero atmospheres, but it ought to work. Have we the mica?" "The ship is lined with it," remarked McCausland. "But we can't very well take the ship apart." "Compartment eighteen, sir!" Adam burst out. "Try it by all means: Hurry though, for we'll have to shutter the ship's ports within an hour or get out of here. I congratulate you, Mister Longworth. That was well thought of." Was there a touch of irony in the voice? As Adam saluted and withdrew, he wondered. Nobody else appeared to have noticed it, to have noticed that there was something in the Captain's voice that didn't somehow sound quite right. * * * * * Three men were grouped around the air lock at eighteen, and they looked up as the First Mate approached. "He's coming out now, sir," said one of them. "Been in already once, and Bjornsen fitted a mica shield over one of his helmet ports. He's trying that and the straight glass shield in comparison." Adam nodded wordlessly, watching the lock handle. Presently it turned and out stumbled a figure like a gnome, cased in hairy hoar-frost. "Pretty cold out there," said one of the men, as with gloved fingers he labored deftly at Burchall's helmet.