His eves, which were fixed too long on a luminous point of the binnacle, suddenly lost the power of vision, and he fell into a true anaesthetic sleep.
Not only was he incapable of seeing, but if one had touched or pinched him hard he would probably have felt nothing.
So he did not see a shadow which glided over the deck.
It was Negoro.
Arrived aft, the head cook placed under the binnacle a pretty heavy object which he held in hand.
Then, after observing for an instant the luminous index of the compass, he retired without having been seen.
If, the next day, Dick Sand had perceived that object placed by Negoro under the binnacle, he might have hastened to take it away.
In fact, it was a piece of iron, whose influence had just altered the indications of the compass.

The magnetic needle had been deviated, and instead of marking the magnetic north, which differs a little from the north of the world, it marked the northeast.

It was then, a deviation of four points; in other words, of half a right angle.
Tom soon recovered from his drowsiness.

His eyes were fixed on the compass.

He believed, he had reason to believe, that the "Pilgrim" was not in the right direction.