Herschel alone. Other
astronomers had seen this object before. Its position had actually been
measured no fewer than nineteen times before the Bath musician, with his
home-made telescope, looked at it, but the previous observers had only
seen it in small meridian instruments with low magnifying powers. Even
after the discovery was made, and when well-trained observers with good
instruments looked again under the direction of Herschel, one after
another bore testimony to the extraordinary delicacy of the great
astronomer's perception, which enabled him almost at the first glance to
discriminate between it and a star.

If not a star, what, then, could it be? The first step to enable this
question to be answered was to observe the body for some time. This
Herschel did. He looked at it one night after another, and soon he
discovered another fundamental difference between this object and an
ordinary star. The stars are, of course, characterised by their fixity,
but this object was not fixed; night after night the place it occupied
changed with respect to the stars. No longer could there be any doubt
that this body was a member of the solar system, and that an interesting
discovery had been made; many months, however, elapsed before Herschel
knew the real merit of his achievement. He did not realise that he had
made the superb discovery of another mighty planet revolving outside
Saturn; he thought that it could only be a comet. No doubt this object
looked very different from a great comet, decorated with a tail. It was
not, however, so entirely different from some forms of telescopic comets
as to make the suggestion of its being a body of this kind unlikely; and
the discovery was at first announced in accordance with this view. Time
was necessary before the true character of the object could be
ascertained. It must be followed for a considerable distance along its
path, and measures of its position at different epochs must be effected,
before it is practicable for the mathematician to calculate the path
which the body pursues; once, however, attention was devoted to the
subject, many astronomers aided in making the necessary observations.
These were placed in the hands of mathematicians, and the result was
proclaimed that this body was not a comet, but that, like all the
planets, it revolved in nearly a circular path around the sun, and that
the path lay millions of miles outside the path of Saturn, which had so
long been reg