entury is one
of the most striking examples of intellectual progress and mastery in
the history of mankind. The first day of the century found us, not,
indeed, where we were left by Galileo and Copernicus in the knowledge
of the skies and in our ability to penetrate their depths, but it did
find us advanced by only moderate stages from the sky-lore of the
past.

The after half of the eighteenth century presents a history of
astronomical investigation and deduction which confirmed and amplified
the preceding knowledge; but that period did not greatly widen the
field of observation. If the sphere of space which had been explored
on the first day of January, 1801, could be compared with that which
is now known and explored by our astronomers, the one sphere would be
to the other even as an apple to the earth.

It is difficult to apprehend the tremendous strides which we have made
in the production of telescopes and the consequent increase in our
sweep of the heavens. It was only in 1774 that the elder Herschel
began his work in the construction of reflecting telescopes. These he
gradually increased in size, until near the close of the century, when
he produced an instrument which magnified two hundred and twenty-seven
diameters. In the course of his career he built two hundred
telescopes, having a seven-foot focus; 150 of ten feet and about
eighty of twenty feet each.

With these instruments the astronomical work in the last quarter of
the eighteenth century was mostly performed. The study of the heavens
at this epoch began to reach out from the planetary system to the
fixed stars. In this work Herschel led the way. The planet Uranus at
first bore the name of Herschel, from its discoverer. Sir John
Herschel, son of Sir William, was born in 1792. All of his
astronomical work was accomplished in our century. Following the line
of his father, he used the reflecting telescope, and it was an
instrument of this kind that he took to his observatory at the Cape of
Good Hope. Lord Rosse was born in the year 1800. Under his auspices
the reflecting telescope reached its maximum of power and usefulness.
His great reflector, built in his own grounds at Birr Castle, Ireland,
was finished in 1844. This instrument was the marvel of that epoch. It
had a focal distance of fifty-three feet, and an aperture of six feet.
With this great telescope its master reached out into the region of
the nebulae, and began the real work of exploring th