2 works bound together. [4], 36; 24 pp. BOUND WITH: Compendium Euclidis curiosi: Dat is, Meetkonstigh Passer-werck..., published in Amsterdam by Waesberge in 1673. Illustrated with 4 folding engraved plates (3 of which are in Mohr's volume). (Small 4to) 7½x6, early vellum, spine lettered in manuscript. First Edition, Dutch Issue.

Rare first edition of the celebrated work by one of the most famous of Danish mathematicians, possibly signed. Mohr was the first to prove that all Euclidean constructions can be carried out with compasses alone (instead of compasses and rulers), a result now known as the Mohr-Mascheroni theorem. Mohr's work, being published in only Danish and Dutch rather than Latin and apparently in quite a small printing, was largely forgotten and so the theorem was acribed to Mascheroni who proved it about 125 later. In 1928, a Danish student discovered a copy of the Danish issue of the first edition in a bookstore and revived Mohr's reputation. He published a critical facsimile edition, a copy of which is also present in this lot. This copy is in fine condition and bears the author's name in period manuscript on the title-page, apparently his signature authorizing sale.