CHAP. 58. (57.)—RATTLING OF ARMS AND THE SOUND OF TRUMPETS HEARD IN THE SKY.
We have heard, that during the war with the Cimbri, the rattling of arms and the sound of trumpets were heard through the sky, and that the same thing has frequently happened before and since[426]. Also, that in the third consulship of Marius, armies were seen in the heavens by the Amerini and the Tudertes, encountering each other, as if from the east and west, and that those from the east were repelled[427]. It is not at all wonderful for the heavens themselves to be in flames[428], and it has been more frequently observed when the clouds have taken up a great deal of fire.
CHAP. 59. (58.)—OF STONES THAT HAVE FALLEN FROM THE CLOUDS[429]. THE OPINION OF ANAXAGORAS RESPECTING THEM.
The Greeks boast that Anaxagoras[430], the Clazomenian, in the second year of the 78th Olympiad, from his knowledge of what relates to the heavens, had predicted, that at a certain time, a stone would fall from the sun[431]. And the thing accordingly happened, in the daytime, in a part of Thrace, at the river Ægos. The stone is now to be seen, a waggon-load in size and of a burnt appearance; there was also a comet shining in the night at that time[432]. But to believe that this had been predicted would be to admit that the divining powers of Anaxagoras were still more wonderful, and that our knowledge of the nature of things, and indeed every thing else, would be thrown into confusion, were we to suppose either that the sun is itself composed of stone, or that there was even a stone in it; yet there can be no doubt that stones have frequently fallen from the atmosphere. There is a stone, a small one indeed, at this time, in the Gymnasium of Abydos, which on this account is held in veneration, and which the same Anaxagoras predicted would fall in the middle of the earth. There is another at Cassandria, formerly called Potidæa[433], which from this circumstance was built in that place. I have myself seen one in the country of the Vocontii[434], which had been brought from the fields only a short time before.
CHAP. 60. (59.)—THE RAINBOW.
What we name Rainbows frequently occur, and are not considered either wonderful or ominous; for they do not predict, with certainty, either rain or fair weather. It is obvious, that the rays of the sun, being projected upon a hollow cloud, the light is thrown back to the sun and is refracted[435], and that the variety of colours is produced by a mixture of clouds, air, and fire[436]. The rainbow is certainly never produced except in the part opposite to the sun, nor even in any other form except that of a semicircle. Nor are they ever formed at night, although Aristotle asserts that they are sometimes seen at that time; he acknowledges, however, that it can only be on the 14th day of the moon[437]. They are seen in the winter the most frequently, when the days are shortening, after the autumnal equinox[438]. They are not seen when the days increase again, after the vernal equinox, nor on the longest days, about the summer solstice, but frequently at the winter solstice, when the days are the shortest. When the sun is low they are high, and when the sun is high they are low; they are smaller when in the east or west, but are spread out wider; in the south they are small, but of a greater span. In the summer they are not seen at noon, but after the autumnal equinox at any hour: there are never more than two seen at once.
CHAP. 61.—THE NATURE OF HAIL, SNOW, HOAR, MIST, DEW; THE FORMS OF CLOUDS.
I do not find that there is any doubt entertained respecting the following points. (60.) Hail is produced by frozen rain, and snow by the same fluid less firmly concreted, and hoar by frozen dew[439]. During the winter snow falls, but not hail; hail itself falls more frequently during the day than the night, and is more quickly melted than snow. There are no mists either in the summer or during the greatest cold of winter. There is neither dew nor hoar formed during great heat or winds, nor unless the night be serene. Fluids are diminished in bulk by being frozen, and, when the ice is melted, we do not obtain the same quantity of fluid as at first[440].
(61.) The clouds are varied in their colour and figure according as the fire which they contain is in excess or is absorbed by them.