4
Thereupon Ammonius the philosopher, who was present, exclaimed, Not for the sun only, but for the whole heavens. For the sun’s course in passing from solstice to solstice must inevitably become shorter and not continue to be so large a part of the horizon as the mathematicians say it is, since the southern portion is constantly subject to a contracting movement, which brings it closer to the northern portion; and so our summer must become shorter and its temperature lower, as the sun turns about within narrower limits and touches fewer parallels of latitude at the solstitial points; moreover, the phenomenon observed at Syenê,Syenê was on the Tropic of Cancer, and because of the fact that on the day of the summer solstice the sun was directly overhead it was used by Eratosthenes (third century b.c.) as one of the termini in calculating the circumference of the Earth. Cleomedes, On the Circular Movement of Heavenly Bodies, i. 10, describes Eratosthenes’ method. where the upright rods on the sun-dials cast no shadow at the time of the summer solstice, is bound to be a thing of the past; many of the fixed stars must have gone below the horizon, and some of them must be touching one another, or have become coalescent, as the space separating them has disappeared! But if, on the other hand, they are going to assert that, while all the other bodies are without change, the sun displays irregularity in its movements, they will not be able to state the cause of the acceleration which affects the sun alone among so many bodies, and they will throw into confusion almost all the celestial mechanics, and into complete confusion those relating to the moon, so that they will have no need of measures of oil to prove the difference. In fact, the eclipses will prove it, as the sun more frequently casts a shadow on the moon and the moon on the earth; the other facts are clear, and there is no need to disclose in further detail the imposture in the argument.
