about twelve or fifteen feet above the water, and then, after flying
more than a distance of a hundred feet, dive down again for a moment
beneath the waves, to recommence directly afterwards: this occurs
most frequently when they are pursued by bonitos or other foes.
When they were flying at some distance from the ship they really
looked like elegant birds. We very frequently saw the bonitos also,
who were pursuing them, endeavour to raise themselves above the
water, but they seldom succeeded in raising more than their head.

It is very difficult to catch one of these little denizens of the
air, as they are to be secured neither by nets or hooks; but
sometimes the wind will drive them, during the night, upon the deck,
where they are discovered, in the morning, dead, not having
sufficient strength to raise themselves from dry places; in this way
I obtained a few specimens.

Today, August 15th, we enjoyed a most interesting sight. We
happened, exactly at 12 o'clock, to be in the sun's zenith, and the
sunbeams fell so perpendicularly that every object was perfectly
shadowless. We put books, chairs, ourselves in the sun, and were
highly delighted with this unusual kind of amusement. Luckily we
had chanced to be at the right spot at the right time; had we, at
the same hour, been only one degree nearer or one degree further, we
should have lost the entire sight; when we saw it we were 14 degrees
6' (a minute is equal to a nautical mile).

All observations with the sextant {9} were out of the question until
we were once more some degrees from the zenith.

17th August. Shoals of tunny-fish, (fish four and five feet long,