Their setting. The rich train of marshall'd numbers
I taught them, and the meet array of letters.
the Rhodian, who flourished only 120 years before Christ, which was near 420 years after the birth of Æschylus, was the first who dared to undertake a thing, which, says Pliny, seemed to surpass the power of a divinity, that of wondering the stars for posterity, and reducing them to a rule. Because the civil year of the ancients did not correspond with the apparent annual motion of the sun, it was impossible by the calendar to ascertain the precise times for the purposes of agriculture, as the same day of the month would not happen in the same season of the year; it was necessary therefore to have recourse to more certain standards and invariable characters to distinguish times, which the risings and the settings of the stars naturally afforded; Prometheus, therefore, with great propriety might boast of this signal and important discovery to mankind: of which Virgil, in his first Georgic, when he delivers his poetical precepts nor the husbandman, makes a particular injunction.
Præterea tam sunt Arcturi sídera nobis,
Hædorumque dies servandi, et lucidus anguis, &c.
Hesiod had before given precepts of similar nature.
Now the rising of a star, as defined by Chrysippus, is its advancement above the earth, and its setting the occultation of it under the earth. (See Stanley's History of Philosophy, part vii. c. 8.) And astronomers have divided the risings and settings of stars, according to their technical expressions, into Cosmical, Achronical, and Heliacal, which are thus explained by Keil in his nineteenth lecture, p. 222. A star is said to rise or set cosmically, which rises or sets when the sun rises; achronically, when it rises while the sun sets, that iş in the evening, when it is in opposition to the sun, and is visible all night, heliacally, when after it has been in conjunction with the sun, and on that account invisible, it comes to be at such a distance from him as to be seen in the morning before sun rising, when the sun, by his apparent motion, recedes from the star towards the easts but the Heliacal setting is, when the sun approaches so near a star, that it hides it with its beams, which keep the fainter light of the star from being perceived" This I conceive to be the meaning of the poet in his epithet of , or
———an harder science yet,
Their setting.———
For by this philosophical solution the observation of the settings of the stars must be attended with more difficulty than that of the risings: this appears to me to be the most natural explication of this passage."
