midnight
He stared out through one of his windows into the brilliant blue darkness , but did not turn on his flashlight . How near were these enemies of his , he wondered ? The presence of those menacing man-sharks , just outside the four-inch-thick steel shell , which withstood a ton of pressure for each square inch of its surface , began to obsess young Abbot . What were they doing out there in the watery-blue midnight ? Perhaps , having secured his sphere as a scientific specimen , they were already preparing to cut into it so as to see what was inside . That these fish could cut through four inches of steel was not so improbable as it sounded , for had they not already succeeded in severing a rubber cable an inch and a half thick , containing two heavy copper wires , and also two inches of the finest , non-kinking steel rope ! The young scientist flashed his pocket torch out through the thick quartz pane , but his enemies were nowhere in sight .