THE DESCRIPTION AND USE OF A PORTABLE INSTRUMENT, vulgarly known by the name of GUNTER'S QUADRANT 1721, BOUND WITH, THE ART OF NUMBRING BY SPEAKING-RODS, Vulgarly termed NEPEIRS BONES 1685. by LEYBOURN, William. 2 WORKS BOUND TOGETHER.:

London, J. Wilcox, 1721.. By which is perform'd most propositions in Astronomy; as, the altitude, azimuth, right ascension and declination of the sun, &c. also his rising and setting and amplitude, together with the hour of the day or night, and other conclusions exemplified at large. To which is added THE USE OF NEPEIRS BONES 1685, In multiplication, division and extraction of roots; also the nocturnal, the ring-dyal, and Gunter's line... Collected and digested into this portable volume for the use of young practitioners. SECOND EDITIONS, 1721 (actually a reissue of the first edition of 1685 with a cancel title page). THE ART OF NUMBRING BY SPEAKING-RODS, Vulgarly termed NEPEIRS BONES, title page dated 1685, second edition. London, printed by T[homas]. B[raddyll]. for H[annah]. Sawbridge, at the Bible on Ludgate-Hill, first published 1667, 2 works bound together, 12mo, approximately 130 x 75 mm, 5¼ x 3 inches, a folding plate to each volume, pages: [2], 1-70; [8], 1- 86, [2] last leaf bears advertisement on recto and errata on verso. A1 & E10 both blanks are missing and A1 blank is missing to second part, bound in full sheep, blind rules to covers, no label or lettering to spine, stab hole in the inner margins of Nepiar's Bones, probably issued as a pamphlet before being bound with Quadrant. Small chip to head of spine, 1 scuff mark to lower cover, corners slightly worn, lacking free endpapers, pencil calculations on pastedowns, those on front pastedown partially erased, 1 page darkened in fore-edge margin, small ink correction to text on 1 page, 2 very small closed edge tears neatly repaired, no loss of text. Binding tight and firm. A very good copy. Portable Instrument ESTC T139825 listing 2 copies of this edition, 1 in UK & 1 in USA. Nepiers Bones, ESTC R20104 . William Leybourn (1626-1719) mathematician, was in his time a distinguished land and quantity surveyor (although he began his working life as a printer). Such was his prestige, he was frequently employed to survey the estates of gentlemen, and he also helped to survey the remnants of London after the great fire of 1666. A prolific and eclectic author, his work The Compleat Surveyor, which was first published in 1653 is regarded as a classic of its kind and (in collaboration with one Vincent Wing) the 1649 volume Urania Practica, was the first book in English devoted to astronomy. MORE IMAGES ATTACHED TO THIS LISTING, ALL ZOOMABLE, FURTHER IMAGES ON REQUEST. POSTAGE AT COST.