She pointed. "There's an open window."
They climbed in and found themselves in the principal's office. Three men with sledge hammers and crow-bars were knocking the knob off the safe. They turned menacingly.
"Go ahead." Groff shrugged. "I can't stop you."
"Get the hell out of here," one of them said.
"We came to get some oxygen," Polly said. "For the sick people across the river."
"Sick people? Okay."
They went into the corridor and wandered from room to room; on the second floor they found an old-fashioned lecture theater, bowl-shaped with steep rows of seats focusing on a laboratory bench piped for water and gas. There was a promising-looking door behind it.
It was locked. Groff kicked at the door and swore with pain; the building was old-fashioned brick and its woodwork was old-fashioned golden oak, the stuff you can hardly drive a nail into. He trudged down to the office again. The three men were gone; the door of the safe swung open. They had left one sledge; somehow he had expected to find all the tools dropped, but apparently they were going to work their way methodically through every safe they could find.
He returned with the sledge and bashed at the golden-oak door until its latch sprung and it swung open. It was the storeroom for lecture supplies and the gas flasks were neatly stacked on the top shelf. There was a complete carton of a dozen twelve-inch cylinders marked O2 and another carton with eight cylinders.
"Thank God," he said. "Let's go."