#### CHAP. 21. (23.)—OF THE DIMENSIONS OF THE WORLD.

The stadium is equal to 125 of our Roman paces, or 625 feet1. Posidonius2 supposes that there is a space of not less than 40 stadia around the earth, whence mists3, winds and clouds4 proceed; beyond this he supposes that the air is pure and liquid, consisting of uninterrupted light; from the clouded region to the moon there is a space of 2,000,000 of stadia, and thence to the sun of 500,000,0005. It is in consequence of this space that the sun, notwithstanding his immense magnitude, does not burn the earth. Many persons have imagined that the clouds rise to the height of 900 stadia. These points are not completely made out, and are difficult to explain; but we have given the best account of them that has been published, and if we may be allowed, in any degree, to pursue these investigations, there is one infallible geometrical principle, which we cannot reject. Not that we can ascertain the exact dimensions (for to profess to do this would be almost the act of a madman), but that the mind may have some estimate to direct its conjectures. Now it is evident that the orbit through which the sun passes consists of nearly 366 degrees, and that the diameter is always the third part and a little less than the seventh of the circumference6. Then taking the half of this (for the earth is placed in the centre) it will follow, that nearly one-sixth part of the immense space, which the mind conceives as constituting the orbit of the sun round the earth, will compose his altitude. That of the moon will be one-twelfth part, since her course is so much shorter than that of the sun; she is therefore carried along midway between the sun and the earth7. It is astonishing to what an extent the weakness of the mind will proceed, urged on by a little success, as in the abovementioned instance, to give full scope to its impudence! Thus, having ventured to guess at the space between the sun and the earth, we do the same with respect to the heavens, because he is situated midway between them; so that we may come to know the measure of the whole world in inches. For if the diameter consist of seven parts, there will be twenty-two of the same parts in the circumference; as if we could measure the heavens by a plumb-line!

The Egyptian calculation, which was made out by Petosi- ris and Necepsos, supposes that each degree of the lunar orbit (which, as I have said, is the least) consists of little more than 33 stadia; in the very large orbit of Saturn the number is double; in that of the sun, which, as we have said, is in the middle8, we have the half of the sum of these numbers. And this is indeed a very modest calculation9, since if we add to the orbit of Saturn the distance from him to the zodiac, we shall have an infinite number of degrees10.

1 Hence the passus will be equal to 5 Roman feet. If we estimate the Roman foot at 11ċ6496 English inches, we shall have the miliare of 8 stadia equal to 1618 English yards, or 142 yards less than an English statute mile. See Adam's Roman Antiquities, p. 503; also the articles Miliare and Pes in Smith's Dictionary of Greek and Roman Antiquities; and for the varieties of the stadium, as employed at different periods and in different countries, see the article Stadium. The stadium which Herodotus employed in measurements of Babylon has been supposed to consist of 490 English feet, while that of Xenophon and Strabo has been estimated at 505; see Ed. Rev. xlviii. 190. The Abbé Barthelemi supposes the stadium to be equal to 604 English feet; Anach. Travels, vii. 284.

2 There appears to have been two individuals of this name, who have been confounded with each other; the one referred to by Pliny was an astronomer of Alexandria, who flourished about 260 years B.C.; the other was a native of Apamea, a stoic philosopher, who lived about two centuries later; see Aikin's Biog. in loco; also Hardouin's Index Auctorum, Lemaire, i. 209.

3 The terms in the original are respectively nubila and nubes. The lexicographers and grammarians do not appear to have accurately discriminated between these two words.

4 The terms in the original are respectively nubila and nubes. The lexicographers and grammarians do not appear to have accurately discriminated between these two words.

5 The words in the text are "vicies centum millia "and "quinquies millia."

6 Archimedes estimated that the diameter of a circle is to its circumference as 1 to 3ċ1416; Hutton's Diet. in loco. Ptolemy states it to be precisely as 1 to 3; Magn. Const. i. 12.

7 The author's reasoning is founded upon the supposition of the length of the sun's path round the earth being twelve times greater than that of the moon's; the orbit therefore would be twelve times greater and the radius in the same proportion.

8 "Non inter Lunam et Saturnum, sed inter Lunam et cœlum affixarum stellarum, medium esse Solem modo dixerat. Quam parum sui meminit! "Alexandre in Lem. i. 291.

9 "Qui computandi modus plurimum habet verecundiæ et modestiæ, quum ibi sistit, nec ulterius progreditur." Hardouin in Lemaire, i. 292.

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