y of Uranus, at a distance falling but slightly
short of perfect conformity with the law of Titius, lent weight to a
seemingly hazardous prediction, and Von Zach was actually at the pains,
in 1785, to calculate what he termed "analogical" elements[200] for this
unseen and (by any effect or influence) _unfelt_ body. The search for
it, through confessedly scarcely less chimerical than that of alchemists
for the philosopher's stone, he kept steadily in view for fifteen years,
and at length (September 21, 1800) succeeded in organising, in
combination with five other German astronomers assembled at Lilienthal,
a force of what he jocularly termed celestial police, for the express
purpose of tracking and intercepting the fugitive subject of the sun.
The zodiac was accordingly divided for purposes of scrutiny into
twenty-four zones; their apportionment to separate observers was in part
effected, and the association was rapidly getting into working order,
when news arrived that the missing planet had been found, through no
systematic plan of search, but by the diligent, though otherwise
directed labours of a distant watcher of the skies.

Giuseppe Piazzi was born at Ponte in the Valtelline, July 16, 1746. He
studied at various places and times under Tiraboschi, Beccaria,
Jacquier, and Le Sueur; and having entered the Theatine order of monks
at the age of eighteen, he taught philosophy, science, and theology in
several of the Italian cities, as well as in Malta, until 1780, when the
chair of mathematics in the University of Palermo was offered to and
accepted by him. Prince Caramanico, then viceroy of Sicily, had
scientific leanings, and was easily won over to the project of building
an observatory, a commodious foundation for which was afforded by one of
the towers of the viceregal palace. This architecturally incongruous
addition to an ancient Saracenic edifice--once the abode of Kelbite and
Zirite Emirs--was completed in February, 1791. Piazzi, meanwhile, had
devoted nearly three years to the assiduous study of his new profession,
acquiring a practical knowledge of Lalande's methods at the Ecole
Militaire, and of Maskelyne's at the Royal Observatory; and returned to
Palermo in 1789, bringing with him, in the great five-foot circle which
he had prevailed upon Ramsden to construct, the most perfect measuring
instrument hitherto employed by an astronomer.

He had been above nine years at work on his star-catalogue, and was
still