to him that it had
slightly moved westwards, and on the following night this suspicion was
confirmed. Remark that in this case no peculiar appearance in the star
suggested that it might be a comet or planet, as in the case of the
discovery of Uranus. We are not unfair in ascribing the discovery to pure
accident, although we must not forget that a careless observer might
easily have missed it. Piazzi was anything but careless, and watched the
new object assiduously till February 11th, when he became dangerously ill;
but he had written, on January 23rd, to Oriani of Milan, and to Bode at
Berlin on the following day. These letters, however, did not reach the
recipients (in those days of leisurely postal service) until April 5th and
March 20th respectively; and we can imagine the mixed feelings with which
Bode heard that the discovery which he had contemplated for fifteen years,
and for which he was just about to organise a diligent search, was thus
curiously snatched from him.

[Sidenote: Hegel's forecast.]

More curious still must have seemed the intelligence to a young
philosopher of Jena named Hegel, who has since become famous, but who had
just imperilled his future reputation by publishing a dissertation
proving conclusively that the number of the planets could not be greater
than seven, and pouring scorn on the projected search of the half-dozen
enthusiasts who were proposing to find a new planet merely to fill up a
gap in a numerical series.

[Sidenote: The planet lost again.]

The sensation caused by the news of the discovery was intensified by
anxiety lest the new planet should already have been lost; for it had
meanwhile travelled too close to the sun for further observation, and the
only material available for calculating its orbit, and so predicting its
place in the heavens at future dates, was afforded by the few observations
made by Piazzi. Was it possible to calculate the orbit from such slender
material? It would take too long to explain fully the enormous difficulty
of this problem, but some notion of it may be obtained, by those
unacquainted with mathematics, from a rough analogy. If we are given a
portion of a circle, we can, with the help of a pair of compasses,
complete the circle: we can find the centre from which the arc is struck,
either by geometrical methods, or by a few experimental trials, and then
fill in the rest of the circumference. If the arc given is large we can do
this with certainty