INIERCATOR, GERARDUS (Latinized form of Gerhard Kramer) (1512-1594), mathematician and geographer, was born at Rupelmonde in Flanders, May 5, 1512. Hav- ing completed his studies at Louvain, he devoted himself to geography, and, after being for some time attached to the household of Charles V., he was appointed cosmographer to the duke of Juliers and Cleves in 1559, taking up his residence at Duisburg, where he died December 2, 1594. One of his earliest cartographical works was a terrestrial globe (1541), followed in 1551 by a celestial globe. In 1552 he published a treatise De usu annuli astronomici (Louvain), and at Cologne in 1569 his Chronologic, hoc est temporum demo-nstratio . . . ab initio mundi usque ad Annum Domini 1568, ex eclipsibus et observationibus astronomicis, sacris quopte Bibliis, &c. In the same year was published the first map on Mercator's well-known projection, with the parallels and meridians at right angles, for use in navigation. At Cologne, in 1578, appeared his Tabulx geographicx ad mentem Ptolemxi restitutx et emendatm. The work by which he is chiefly known is his atlas, published in 1594 at Duisburg, in folio, under the title of Atlas, sive Cosmographicx meditationes de fabrica munch.. It contains, besides the maps, cosmographical and other dissertations, some of the theological views in which were condemned as heretical ; it was completed by Hondius in 1607. Several of the maps had been previously published separately, the atlas being delayed to allow Ortelius to complete his. Mercator also published in 1592 a liarmonia Evangeliorum.