twopence, and as close as they can stick one by another: the belly,
thighs, sides, and inner part of the wings, are of a light grey. These
birds, of all these sorts, fly many together, never high, but almost
sweeping the water. We shot one a while after on the water in a calm, and
a water-spaniel we had with us brought it in: I have given a picture of
it, but it was so damaged that the picture doth not show it to advantage;
and its spots are best seen when the feathers are spread as it flies.

The petrel is a bird not much unlike a swallow, but smaller, and with a
shorter tail. It is all over black, except a white spot on the rump. They
fly sweeping like swallows, and very near the water. They are not so
often seen in fair weather; being foul-weather birds, as our seamen call
them, and presaging a storm when they come about a ship; who for that
reason don't love to see them. In a storm they will hover close under the
ship's stern in the wake of the ship (as it is called) or the smoothness
which the ship's passing has made on the sea; and there as they fly
(gently then) they pat the water alternately with their feet as if they
walked upon it; though still upon the wing. And from hence the seamen
give them the name of petrels in allusion to St. Peter's walking upon the
Lake of Gennesareth.

We also saw many bunches of seaweeds in the latitude of 39 32 and, by
judgment near, the meridian of the island Tristan d'Acunha: and then we
had about 2 degrees 20 minutes east variation: which was now again
decreasing as we ran to the eastward, till near the meridian of
Ascension; where we found little or no variation: but from thence, as we
ran farther to the east, our variation increased westerly.

OF A BIRD THAT SHOWS THE CAPE OF GOOD HOPE TO BE NEAR: OF THE
SEA-RECKONINGS, AND VARIATIONS: AND A TABLE OF ALL THE VARIATIONS