(4.) The water-supply of wells never fails in summer, but in all cases it falls low during four days at the rising of the constellation above-mentioned. Throughout the whole winter, on the other hand, many wells entirely fail; as in the neighbourhood of Olynthus, for example, where the water returns in the early days of spring. In Sicily too, in the vicinity of Messana and Mylæ, the springs are entirely dry throughout the winter, while in summer they overflow and form quite a river. At Apollonia in Pontus there is to be seen, near the sea-shore, a fountain which overflows in summer only, and mostly about the rising of the Dog-star; should the summer, however, not be so hot as usual, its water is less abundant. Certain soils become drier in consequence of rain, that in the territory of Narnia for example: a fact which M. Cicero has mentioned in his “Admiranda,” with a statement that drought is there productive of mud, and rain of dust.[3062]
CHAP. 29.—THE QUALITIES OF WATER AT THE DIFFERENT SEASONS OF THE YEAR.
Every kind of water is freshest in winter, not so fresh in summer, still less so in autumn, and least of all in times of drought. River-water, too, is by no means always the same in taste, the state of the bed over which it runs making a considerable difference. For the quality of water, in fact, depends upon the nature of the soil through which it flows, and the juices[3063] of the vegetation watered by it; hence it is that the water of the same river is found in some spots to be comparatively unwholesome. The confluents, too, of rivers, are apt to change the flavour of the water, impregnating the stream in which they are lost and absorbed; as in the case of the Borysthenes, for example. In some instances, again, the taste of river-water is changed by the fall of heavy rains. It has happened three times in the Bosporus that there has been a fall of salt rain, a phænomenon which proved fatal to the crops. On three occasions, also, the rains have imparted a bitterness to the overflowing streams of the Nilus, which was productive of great pestilence throughout Egypt.
CHAP. 30.—HISTORICAL OBSERVATIONS UPON WATERS WHICH HAVE SUDDENLY MADE THEIR APPEARANCE OR SUDDENLY CEASED.
It frequently happens that in spots where forests have been felled, springs of water make[3064] their appearance, the supply of which was previously expended in the nutriment of the trees. This was the case upon Mount Hæmus for example, when, during the siege by Cassander,[3065] the Gauls cut down a forest for the purpose of making a rampart. Very often too, after removing the wood which has covered an elevated spot and so served to attract and consume the rains, devastating torrents are formed by the concentration of the waters. It is very important also, for the maintenance of a constant supply of water, to till the ground and keep it constantly in motion, taking care to break and loosen the callosities of the surface crust: at all events, we find it stated, that upon a city of Crete, Arcadia by name, being razed to the ground, the springs and water-courses, which before were very numerous in that locality, all at once dried up; but that, six years after, when the city was rebuilt, the water again made its appearance, just as each spot was again brought into cultivation.
(5.) Earthquakes also are apt to discover or swallow[3066] up springs of water; a thing that has happened, it is well known, on five different occasions in the vicinity of Pheneus, a town of Arcadia. So too, upon Mount Coryeus,[3067] a river burst forth; after which, the soil was subjected to cultivation. These changes are very surprising where there is no apparent cause for them; such as the occurrence at Magnesia,[3068] for instance, where the warm waters became cold, but without losing their brackish flavour; and at the Temple[3069] of Neptune in Caria, where the water of the river, from being fresh, became salt. Here, too, is another fact, replete with the marvellous—the fountain of Arethusa at Syracuse has a smell of dung, they say, during the celebration of the games at Olympia,[3070] a thing that is rendered not improbable by the circumstance,[3071] that the river Alpheus makes its way to that island beneath the bed of the sea. There is a spring in the Chersonesus of the Rhodians[3072] which discharges its accumulated impurities every nine years.
Waters, too, sometimes change their colour; as at Babylon, for example, where the water of a certain lake for eleven days in summer is red. In the summer season, too, the current of the Borysthenes[3073] is blue, it is said, and this, although its waters are the most rarefied in existence, and hence float upon the surface of those of the Hypanis;[3074]—though at the same time there is this marvellous fact, that when south winds prevail, the waters of the Hypanis assume the upper place. Another proof, too, of the surpassing lightness of the water of the Borysthenes, is the fact that it emits no exhalations, nor, indeed, the slightest vapour even. Authors that would have the credit of diligent research in these enquiries, assure us that water becomes heavier after the winter-solstice.
CHAP. 31. (6.)—THE METHOD OF CONVEYING WATER.
The most convenient method of making a watercourse from the spring is by employing earthen pipes, two fingers in thickness, inserted in one another at the points of junction—the one that has the higher inclination fitting into the lower one—and coated with quick-lime macerated in oil. The inclination, to ensure the free flow of the water, ought to be at least one-fourth of an inch to every hundred feet; and if the water is conveyed through a subterraneous passage, there should be air-holes let in at intervals of every two[3075] actus. Where the water is wanted to ascend[3076] aloft, it should be conveyed in pipes of lead: water, it should be remembered, always rises to the level of its source. If, again, it is conveyed from a considerable distance, it should be made to rise and fall every now and then, so as not to lose its motive power. The proper length for each leaden pipe is ten feet; and if[3077] the pipe is five fingers in circumference its weight should be sixty pounds; if eight feet, one hundred; if ten, one hundred and twenty; and so on in the same proportion.