They went into the other room, and looked across the river into the darkness, faintly patterned by the nearer trees. Suddenly, high up, a glow appeared, shone for a second, disappeared, recurred. They watched in silence. Presently Armstrong spoke.
"They're certainly signals. Keep your eye on them; count them."
There was a period of complete darkness; it seemed that the signalling had ceased. Then the glow peered over the tree-tops again; it was repeated at regular intervals, at first short, then longer, then short again.
"It's like Morse," said Armstrong. "Did you count?"
"Nine times."
"In groups of three?"
"Four, three, and two, I thought."
"So did I. Well, if it's Morse, that spells VGI. What on earth does that mean?"
"Goodness knows. It's stopped. Wonder if it'll start again?"
A minute or two passed. Again the glow appeared, at intervals as before. Again they counted its appearances.