“My mercy me!” exclaimed Tom again. “What do you mean?”

Nan told him about the mystery. The fact that a column of smoke arose out of the top of the dead tree seemed to worry Tom. Nan became alarmed.

“Oh, dear, Tom! Do you really think it was afire?”

“I, don't know. If it was afire, it is afire now,” he said. “Show me, Nan.”

He turned the horses out of the beaten track through the brush and brambles, to the edge of the open place which had been heaped with sawdust from the steam-mill.

Just as they broke cover a vivid flash of lightning cleaved the black cloud that had almost reached the zenith by now, and the deep rumble of thunder changed to a sharp chatter; then followed a second flash and a deafening crash.

“Oh, Tom!” gasped Nan, as she clung to him.

“The flash you see'll never hit you, Nan,” drawled Tom, trying to be comforting. “Remember that.”

“It isn't so much the lightning I fear as it is the thunder,” murmured Nan, in the intermission. “It just so-o-ounds as though the whole house was coming down.”

“Ho!” cried Tom. “No house here, Nan.”