JOHANNES DE [Joni.' IIOLYWOOD] SACRO BOSCO (d. 1244 or 1256)  , astronomical author, studied at

Oxford and was afterwards professor of mathematics at the university of Paris . He wrote a treatise on spherical astronomy, Tractatus de sphaera, first printed at Ferrara in 1472 . This was the second astronomical work to be printed . Although recording no advance on the Arabian commentaries on Ptolemy, it gained a great reputation; twenty-four editions appeared before 1500, and at least forty between 1 500 and 1647, in which year the last edition was published, at Leiden . About the year 1232 he wrote De anni ratione or De eomputo ecclesiastico (printed editions at Paris in 1538 (?), 1550, 1572 and at Antwerp in 1547 and 1566), in which he points out the increasing error of the Julian calendar, and suggests a remedy which is nearly the same as that actually used under Gregory XIII. three hundred and fifty years later . He also wrote Algorismus or De arte numerandi, printed in 1490 (?), in 1517 (Vienna), 1521 (Cracow), 1523 (Venice) ; De astrolabio and Breviarum juris .