To Pratt these phenomena were at first merely sensations of sight, not perceptions of intelligence. But by and by he was struck by the fact that the glow always appeared at the same spot, not here and there, like a lamp carried by a person moving about a room. Then he found himself mentally measuring the intervals between its appearances, expecting their occurrence as regularly as the beats of a striking clock. It was with surprise and a sort of disappointment that he discovered that the intervals were irregular, and with curiosity, after a while, that they were regular and irregular both, as it seemed, fitfully; the glow appeared two or three times at equal intervals, then the intervals became shorter or longer. "Signals, of course," he thought, when the impression of order and purpose became fixed in him. "Who is it? Where is it? What's the game?"
The alternations continued for several minutes, then finally ceased. Pratt got up, left the ruins, and made his way with some difficulty back to camp.
"Armstrong back?" he asked.
"Not yet," replied Warrender. "Time he was. This is the darkest evening we've had. See any one?"
"Not a soul. All quiet here?"
"Absolute peace. You weren't here."
"Thanks. Glad you missed me. Will the sweet, melodious strains of my gentle banjo disturb your serenity?"
"Not a bit. Strum away. But hadn't you better turn in? It's past nine. Old Jack won't get much sleep before second watch if he isn't here soon; no reason why you shouldn't have your full whack, especially after last night's affair."
"I'll stay up till he comes."
Pratt softly thrummed his strings, musing on his discoveries. Half-past nine came; ten o'clock.