Near Harpasa, a town of Asia, there stands a terrific rock, which may be moved by a single finger; but if it be pushed by the force of the whole body, it resists[602]. In the Tauric peninsula, in the state of the Parasini, there is a kind of earth which cures all wounds[603]. About Assos, in Troas, a stone is found, by which all bodies are consumed; it is called Sarcophagus[604]. There are two mountains near the river Indus; the nature of one is to attract iron, of the other to repel it: hence, if there be nails in the shoes, the feet cannot be drawn off the one, or set down on the other[605]. It has been noticed, that at Locris and Crotona, there has never been a pestilence, nor have they ever suffered from an earthquake; in Lycia there are always forty calm days before an earthquake. In the territory of Argyripa the corn which is sown never springs up. At the altars of Mucius, in the country of the Veii, and about Tusculum, and in the Cimmerian Forest, there are places in which things that are pushed into the ground cannot be pulled out again. The hay which is grown in Crustuminium is noxious on the spot, but elsewhere it is wholesome[606].
CHAP. 99. (97.)—CONCERNING THE CAUSE OF THE FLOWING AND EBBING OF THE SEA.
Much has been said about the nature of waters; but the most wonderful circumstance is the alternate flowing and ebbing of the tides, which exists, indeed, under various forms, but is caused by the sun and the moon. The tide flows twice and ebbs twice between each two risings of the moon, always in the space of twenty-four hours. First, the moon rising with the stars[607] swells out the tide, and after some time, having gained the summit of the heavens, she declines from the meridian and sets, and the tide subsides. Again, after she has set, and moves in the heavens under the earth, as she approaches the meridian on the opposite side, the tide flows in; after which it recedes until she again rises to us. But the tide of the next day is never at the same time with that of the preceding; as if the planet was in attendance[608], greedily drinking up the sea, and continually rising in a different place from what she did the day before. The intervals are, however, equal, being always of six hours; not indeed in respect of any particular day or night or place[609], but equinoctial hours, and therefore they are unequal as estimated by the length of common hours, since a greater number of them[610] fall on some certain days or nights, and they are never equal everywhere except at the equinox. This is a great, most clear, and even divine proof of the dullness of those, who deny that the stars go below the earth and rise up again, and that nature presents the same face in the same states of their rising and setting[611]; for the course of the stars is equally obvious in the one case as in the other, producing the same effect as when it is manifest to the sight.
There is a difference in the tides, depending on the moon, of a complicated nature, and, first, as to the period of seven days. For the tides are of moderate height from the new moon to the first quarter; from this time they increase, and are the highest at the full: they then decrease. On the seventh day they are equal to what they were at the first quarter, and they again increase from the time that she is at first quarter on the other side. At her conjunction with the sun they are equally high as at the full. When the moon is in the northern hemisphere, and recedes further from the earth, the tides are lower than when, going towards the south, she exercises her influence at a less distance[612]. After an interval of eight years, and the hundredth revolution of the moon, the periods and the heights of the tides return into the same order as at first, this planet always acting upon them; and all these effects are likewise increased by the annual changes of the sun[613], the tides rising up higher at the equinoxes, and more so at the autumnal than at the vernal; while they are lower[614] about the winter solstice, and still more so at the summer solstice; not indeed precisely at the points of time which I have mentioned, but a few days after[615]; for example, not exactly at the full nor at the new moon, but after them; and not immediately when the moon becomes visible or invisible, or has advanced to the middle of her course, but generally about two hours later than the equinoctial hours[616]; the effect of what is going on in the heavens being felt after a short interval; as we observe with respect to lightning, thunder, and thunderbolts.
But the tides of the ocean cover greater spaces and produce greater inundations than the tides of the other seas; whether it be that the whole of the universe taken together is more full of life than its individual parts, or that the large open space feels more sensibly the power of the planet, as it moves freely about, than when restrained within narrow bounds. On which account neither lakes nor rivers are moved in the same manner. Pytheas[617] of Massilia informs us, that in Britain the tide rises 80 cubits[618]. Inland seas are enclosed as in a harbour, but, in some parts of them, there is a more free space which obeys the influence[619]. Among many other examples, the force of the tide will carry us in three days from Italy to Utica, when the sea is tranquil and there is no impulse from the sails[620]. But these motions are more felt about the shores than in the deep parts of the seas, as in the body the extremities of the veins feel the pulse, which is the vital spirit, more than the other parts[621]. And in most estuaries, on account of the unequal rising of the stars in each tract, the tides differ from each other, but this respects the period, not the nature of them; as is the case in the Syrtes.
CHAP. 100.—WHERE THE TIDES RISE AND FALL IN AN UNUSUAL MANNER.
There are, however, some tides which are of a peculiar nature, as in the Tauromenian Euripus[622], where the ebb and flow is more frequent than in other places, and in Eubœa, where it takes place seven times during the day and the night. The tides intermit three times during each month, being the 7th, 8th and 9th day of the moon[623]. At Gades, which is very near the temple of Hercules, there is a spring enclosed like a well, which sometimes rises and falls with the ocean, and, at other times, in both respects contrary to it. In the same place there is another well, which always agrees with the ocean. On the shores of the Bætis[624], there is a town where the wells become lower when the tide rises, and fill again when it ebbs; while at other times they remain stationary. The same thing occurs in one well in the town of Hispalis[625], while there is nothing peculiar in the other wells. The Euxine always flows into the Propontis, the water never flowing back into the Euxine[626].
CHAP. 101. (98.)—WONDERS OF THE SEA.
All seas are purified at the full moon[627]; some also at stated periods. At Messina and Mylæ a refuse matter, like dung[628], is cast up on the shore, whence originated the story of the oxen of the Sun having had their stable at that place. To what has been said above (not to omit anything with which I am acquainted) Aristotle adds, that no animal dies except when the tide is ebbing. The observation has been often made on the ocean of Gaul; but it has only been found true with respect to man[629].