For many days, what we have of the diary is little more than a log-book, giving the rate of sailing, or rather two rates, one for Columbus's own private heed, and the other for the sailors.

On the 13th of September it is noted that the needle declined in the evening to the north-west, and on the ensuing morning, to the north-east, the first time that such a variation had been observed, or, at least recorded by Europeans.

On the 14th, the sailors of the caravel "Nina" saw two tropical birds, which they said were never wont to be seen at more than fifteen or twenty leagues from shore.

On the 15th they all saw a meteor fall from heaven, which made them very sad.
PLAINS OF SEAWEED.
On the 16th, they first came upon those immense plains of seaweed (the fucus natans), which constitute the Mar de Sargasso, and which occupy a space in the Atlantic almost equal to seven times the extent of France.
The aspect of these plains greatly terrified the sailors, who thought they might be coming upon submerged lands and rocks; but finding that the vessels cut their way well through this seaweed, the sailors thereupon took heart.

On the 17th, they see more of these plains of seaweed, and thinking themselves to be near land, they are almost in good spirits, when finding that the needle declines to the west a whole point of the compass and more, their hopes suddenly sink again: they begin "to murmur between their teeth," and to wonder whether they are not in another world.
Columbus, however, orders an observation to be taken at day-break, when the needle is found to point to the north again; moreover he is ready with a theory sufficiently ingenious for that time, to account for the phenomenon of variation which had so disturbed the sailors, namely, that it was caused by the north star moving round the pole.