The captain told us that this was the fourteenth voyage he had made to the Brazils, during which time he had always found the heat very easily borne, and had never seen the sky otherwise than dull and lowering.  He said that this was occasioned by the damp, unhealthy coast of Guinea, the ill effects of which were perceptible much further than where we then were, although the distance between us was 350 miles.

In the tropics the quick transition from day to night is already very perceptible; 35 or 40 minutes after the setting of the sun the deepest darkness reigns around.  The difference in the length of day and night decreases more and more the nearer you approach the Equator.  At the Equator itself the day and night are of equal duration.

All the 14th and 15th of August we sailed parallel with the Cape de Verde Islands, from which we were not more than 23 miles distant, but which, on account of the hazy state of the weather, we could not see.

During this period we used to be much amused by small flocks of flying-fish, which very often rose from the water so near the ship’s side that we were enabled to examine them minutely.  They are generally of the size and colour of a herring; their side fins, however, are longer and broader, and they have the power of spreading and closing them like little wings.  They raise themselves 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.