54 
pliny's katueal histoet. [Book II. 
and thence to the sun of 500,000;000^ 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 geome- 
trical principle, which we cannot reject. !N'ot 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 circumference^. 
Then taking the half of this (for the earth is placed in the 
centre) it will follow, that nearly one-sixth part of the im- 
mense 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 earth ^. It 
is astonishing to what an extent the weakness of the mind 
will proceed, urged on by a little success, as in the above- 
mentioned 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. 
Por 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- 
1 The words in the text are "vicies centum miUia" and "qninquies 
miUia." 
2 Archimedes estimated that the diameter of a circle is to its circum- 
ference as 1 to 3 '1416 ; Hutton's Diet, in loco, Ptolemy states it to be 
precisely as 1 to 3 ; Magn. Const, i. 12. 
3 The author's reasoning is founded upon the supposition of the length 
o# 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. 
