divines of the fifth century, a man of learning,
piety, and judicial mind, and a champion of freedom of opinion in all
religious matters.

[746] He died in 417. He was a man of great energy and of high attainments.

[747] He died in 461, having reigned as pope for twenty-one years. It was
he who induced Attila to spare Rome in 452.

[748] He succeeded Leo as pope in 461, and reigned for seven years.

[749] Victorinus or Victorius Marianus seems to have been born at Limoges.
He was a mathematician and astronomer, and the cycle mentioned by De Morgan
is one of 532 years, a combination of the Metonic cycle of 19 years with
the solar cycle of 28 years. His canon was published at Antwerp in 1633 or
1634, _De doctrina temporum sive commentarius in Victorii Aquitani et
aliorum canones paschales_.

[750] He went to Rome about 497, and died there in 540. He wrote his _Liber
de paschate_ in 525, and it was in this work that the Christian era was
first used for calendar purposes.

[751] See note 259, page 126.

[752] Johannes de Sacrobosco (Holy wood), or John of Holywood. The name was
often written, without regard to its etymology, Sacrobusto. He was educated
at Oxford and taught in Paris until his death (1256). He did much to make
the Hindu-Arabic numerals known to European scholars.

[753] See note 36, page 44.

[754] See note 45, page 48.

[755] The Julian year is a year of the Julian Calendar, in which there is
leap year every fourth year. Its average length is therefore 365 days and a
quarter.--A. De M.

[756] Ugo Buoncompagno (1502-1585) was elected pope in 1572.

[757] He was a Calabrian, and as early as 1552 was professor of medicine at
Perugia. In 1576 his manuscript on the reform of the calendar was presented
to the Roman Curia by his brother, Antonius. The manuscript was not printed
and it has not been preserved.

[758] The title of this work, which is the authority on all points of the
new Calendar, is _Kalendarium Gregorianum Perpetuum. Cum Privilegio Summi
Pontificis Et Aliorum Principum. Romae, Ex Officina Dominici Basae. MDLXXXII.
Cum Licentia Superiorum_ (quarto, pp. 60).--A. De M.

[759] _Manuels-Roret. Theorie du Calendrier et collection de tous les
Calendriers des Annees passees et futures_.... Par L. B. Francoeur,...
Paris, a la librairie encyclopedique de Roret, rue Hautefeuille, 10 bis.
1842. (12mo.) In this valuable manual, the 35 possible almanacs are given
at length, with such preliminar