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. He then moved the helm so as to head the
ship to the east--at least, he thought so.

But, with the deviation of the needle, which he could not suspect, that
point, changed by four points, was the southeast.

And thus, while under the action of a favorable wind, the "Pilgrim" was
supposed to follow the direction wished for, she sailed with an error