TRANSLATIONS AND SELECTED ARTICLES. 299 
around which all the planetary movements are performed? Is it trues 
that in many respects we are not more advanced than the philoso- 
phers of ancient Greece?” 
It has been thought that these questions should meet a serious 
reply, and I have undertaken the task of supplying it, not concealing 
from myself the dryness which must needs pervade it, nor forgetting 
that details, which have become at the present day elementary truths, 
will force themselves prominently under my pen; yet I have thought 
that your indulgence will not fail to one who is in the performance of 
a duty. 
A general glance at the labors of ancient philosophers and modern 
observers, will readily prove that, if the sui kas been studied for two 
thousand years, the point of view has often changed, and that, during 
this interval, science has made immense steps in advance. 
Anaxagoras asserted that the sun was scarcely larger than the 
Peloponnesus. Eudoxus, who enjoyed a great reputation in antiquity, 
assigned to this star a diameter nine times greater than that of the 
moon. This was a great step, if we compare this value with that of 
Anaxagoras, but the number given by the philosopher of Cnidus 
was still enormously wide of the reality. Cleomedes, who wrote in 
the reign of Augustus, tells us that the Epicureans, his contempor- 
aries, regarding only appearance, maintai-ed that the real diameter of 
the sun did not exceed one foot. 
Let us now compare with these arbitrary guesses the value which is 
deduced from the labors of modern astronomers, executed with the 
most minute care, and by the aid of instruments of extreme delicacy. 
The sun has a diameter of 357,000 leagues (of 4 kilometres.) There 
is some difference, we see, between this number and that adopted by 
the Epicureans. 
Supposing the sun to be spherical, his volume is fourteen hundred 
thousand times that of the earth. 
_ Numbers so enormous not being frequently employed in common 
life, and failing to convey a precise conception of the magnitudes which 
they imply, I shall here recall a remark which will enable us better 
to grasp the immensity of this solar volume. Imagine the centre of 
the sun to coincide with that of the earth; his surface would then 
not merely extend to the orbit in which the moon revolves, but would 
reach nearly as far again beyond. 
These results, so remarkable for their immensity, possess all the 
