Various estimates have been hazarded on the Number of Stars throughout
the whole heavens visible to us by the aid of our colossal telescopes.
Struve assumes for Herschel’s 20-feet reflector, that a magnifying
power of 180 would give 5,800,000 for the number of stars lying within
the zones extending 30° on either side of the equator, and 20,374,000
for the whole heavens. Sir William Herschel conjectured that 18,000,000
of stars in the Milky Way might be seen by his still more powerful
40-feet reflecting telescope.--_Humboldt’s Cosmos_, vol. iii.
The assumption that the extent of the starry firmament is literally
infinite has been made by Dr. Olbers the basis of a conclusion that the
celestial spaces are in some slight degree deficient in _transparency_;
so that all beyond a certain distance is and must remain for ever
unseen, the geometrical progression of the extinction of light far
outrunning the effect of any conceivable increase in the power of
our telescopes. Were it not so, it is argued that every part of the
celestial concave ought to shine with the brightness of the solar disc,
since no visual ray could be so directed as not, in some point or other
of its infinite length, to encounter such a disc.--_Edinburgh Review_,
Jan. 1848.