_August 24th._—Yesterday afternoon we saw, on the north side of the river, the first elevations of any consequence one meets on the Amazons, the singular flat-topped hills of Almeirim. They are cut off as squarely on the top as if levelled with a plane, and divided from each other by wide openings, the sides being shaved down with the same evenness as the summits. Much has been said about the geology of these singular hills, but no one has fairly investigated it. Von Martius landed, and ascertained their height to be about eight hundred feet above the level of the river, but beyond this, no one seems to know anything of their real nature. They are generally represented as spurs of the higher table-land of Guiana.[55] Last evening was the most beautiful we have seen on the Amazons. We sat on the front upper deck as the crimson sun went down, his broad red pathway across the water followed presently by the pale trembling line of light from the crescent moon above. After the sun had vanished, broad rays of rose-color, shooting almost to the zenith, still attested his power, lending something of their glow also to a great mass of white clouds in the east, the reflection of which turned the yellow waters of the river to silver, while between glory and glory the deep blue sky of night gathered over the hills of Almeirim. This morning at dawn we stopped at the little settlement of Prainha, but did not land, and we are now on our way to Monte Alégre, where we shall pass a day and a half.