3, 6, 12, and
so on, each formed by doubling the last, we get numbers representing very
nearly the planetary distances, which are shown approximately in the
second column. But three points call for notice. Firstly, the number
before 3 should be 1-1/2, and not zero, to agree with the rest. Secondly,
there is a gap, or rather was a gap, after the discovery of Uranus,
between Mars and Jupiter; and thirdly, we see that when Uranus was
discovered, and its distance from the sun determined, this distance was
found to fall in satisfactorily with this law, which was first stated by
Titius of Wittenberg. This third fact naturally attracted attention. No
explanation of the so-called "law" was known at the time; nor is any
known even yet, though we may be said to have some glimmerings of a
possible cause; and in the absence of such explanation it must be regarded
as merely a curious coincidence. But the chances that we are in the
presence of a mere coincidence diminish very quickly with each new term
added to the series, and when it was found that Herschel's new planet
fitted in so well at the end of the arrangement, the question arose
whether the gap above noticed was real, or whether there was perhaps
another planet which had hitherto escaped notice, revolving in an orbit
represented by this blank term. This question had indeed been asked even
before the discovery of Uranus, by Bode, a young astronomer of Berlin; and
for fifteen years he kept steadily in view this idea of finding a planet
to fill the vacant interval. The search would be a very arduous one,
involving a careful scrutiny, not perhaps of the whole heavens, but of a
considerable portion of it along the Zodiac; too great for one would-be
discoverer single-handed; but in September 1800 Bode succeeded in
organising a band of six German astronomers (including himself) for the
purpose of conducting this search. They divided the Zodiac into
twenty-four zones, and were assigning the zones to the different
observers, when they were startled by the news that the missing planet had
been accidentally found by Piazzi in the constellation Taurus. The
discovery was made somewhat dramatically on the first evening of the
nineteenth century (January 1, 1801). Piazzi was not looking for a planet
at all, but examining an error made by another astronomer; and in the
course of this work he recorded the position of a star of the eighth
magnitude. Returning to it on the next night, it seemed