2 parts in one volume. 4to (180 x 136mm). Engraved frontispiece, 17 engraved plates (including a duplicate of plate facing page 48 attached to fore-edge on leaf F4). (Browned and spotted, lacking final blank.) Contemporary vellum, yapp edges (soiled). Provenance: ownership inscription on title, dated 1720; Björn Kjellström (bookplate).

 

One of three editions of Welper’s work on dialing published in 1672. In the first part Welper describes the process and illustrates details for quadrant and instruments for measuring circle of declination. The second part by Johann Christoph Sturm (1635-1703) provides additional mathematical information and instructions in the use of horizontal and vertical dials. Wellcome V, 412 (containing a third part published in 1681). RARE: According to online records no copies have appeared at auction in at least the past 45 years.