"It is again on this side, only higher up," announced Jim; "somebody going up those stairs, that's what it is."
In a few moments the powerful lamp illuminated an upper room and they saw the interior distinctly. But what fastened their attention was the sight of a head that showed just above the sill of the windows. It must be the head of a child to reach no higher. But what would a child be doing up in that lonely tower. Jim gripped his companion's arm.
"It's that infernal Mexican, Berwick!" he whispered.
"No other!" said his friend. "And that light is a signal."
"Can't be seen far even if the fog is thinner," objected Jim.
"Broome is close in," said the engineer decisively.
"It may be to serve as a guide for some party coming over the lonely moor," said Jim with much shrewdness.
"Go to the head of the class, James," remarked Berwick; "that's a sound guess for a fact."
"Guess nothing," retorted Jim; "that's a deduction as they say in the school books. What in the deuce is that up there now!"
A canine head was outlined in an open window and then the big hound gave tongue that went far into the night. His senses told him that an enemy was lurking near.