HIS HISTORY OF ASTRONOMY. 117 
the opposite point of view, and reflect on the extreme 
feebleness of the natural means by the help of which so 
many great problems have been attacked and solved; if 
we consider that to obtain and measure the greater part 
of the quantities now forming the basis of astronomical 
computation, man has had greatly to improve the most 
delicate of his organs, to add immensely to the power of 
his eye; if we remark that it was not less requisite for 
him to discover methods adapted to measuring very long 
intervals of time, up to the precision of tenths of seconds ; 
to combat against the most microscopic effects that con- 
stant variations of temperature produce in metals, and 
therefore in all instruments; to guard against the innu- 
merable illusions that a cold or hot atmosphere, dry or 
humid, tranquil or agitated, impresses on the medium 
through which the observations have inevitably to be 
made; the feeble being resumes all his advantage; by 
the side of such wonderful labours of the mind, what 
signifies the weakness, the fragility of our body; what 
signify the dimensions of the planet, our residence, the 
grain of sand on which it has happened to us to appear 
for a few moments! 
The thousands of questions on which Astronomy has 
thrown its dazzling light belong to two entirely distinct 
categories; some offered themselves naturally to the 
mind, and man had only to seek the means for solving 
them; others, according to the beautiful expression of 
Pliny, were enveloped in the majesty of nature! When 
Bailly lays down in his book these two kinds of problems, 
it is with the firmness, the depth, of a consummate 
astronomer; and when he shows their importance, their 
immensity, it is always with the talent of a writer of the 
highest order; it is sometimes with a bewitching elo- 
