am Watson happened to pass by, and was
arrested by the unusual spectacle of an astronomer in the public street,
at the dead of night, using a large and quaint-looking instrument.
Having a taste for astronomy, Sir William stopped, and when Herschel
took his eye from the telescope, asked if he might be allowed to have a
look at the moon. The request was readily granted. Probably Herschel
found but few in the gay city who cared for such matters; he was quickly
drawn to Sir W. Watson, who at once reciprocated the feeling, and thus
began a friendship which bore important fruit in Herschel's subsequent
career.

At length the year 1781 approached, which was to witness his great
achievement. Herschel had made good use of seven years' practical
experience in astronomy, and he had completed a telescope of exquisite
optical perfection, though greatly inferior in size to some of those
which he afterwards erected. With this reflector Herschel commenced a
methodical piece of observation. He formed the scheme of systematically
examining all the stars which were above a certain degree of brightness.
It does not quite appear what object Herschel proposed to himself when
he undertook this labour, but, in any case, he could hardly have
anticipated the extraordinary success with which the work was to be
crowned. In the course of this review the telescope was directed to a
star; that star was examined; then another was brought into the field of
view, and it too was examined. Every star under such circumstances
merely shows itself as a point of light; the point may be brilliant or
not, according as the star is bright or not; the point will also, of
course, show the colour of the star, but it cannot exhibit recognisable
size or shape. The greater, in fact, the perfection of the telescope,
the smaller is the telescopic image of a star.

How many stars Herschel inspected in this review we are not told; but at
all events, on the ever-memorable night of the 13th of March, 1781, he
was pursuing his self-allotted task among the hosts in the constellation
Gemini. Doubtless, one star after another was admitted to view, and was
allowed to pass away. At length, however, an object was placed in the
field which differed from every other star. It was not a mere point of
light; it had a minute, but still a perfectly recognisable, disc. We say
the disc was perfectly recognisable, but we should be careful to add
that it was so in the excellent telescope of