La SferaDati, Gregorio, 1362-1436[between 1450 and 1500]itaManuscript on paper (watermarks buried in gutter) of Gregorio (or Leonardo?) Dati, La Sfera. This rhyming treatise (ottava rima) is divided into two parts: 1) a treatise on astronomy; 2) rules for navigation and the determination of the position of the seaIn Italian.Script: Written by one person in neat mercantile script.One 4-line initial, f. lr., gold capital with white-vine foliage against a blue, pink and green ground, connected to a 3/4 white-vine border with brown penwork and gold dots; a coat of arms in wreath at center of lower margin. Two 3-line initials, ff. 7r and 14v, gold, against pink and green grounds with yellow and white filigree. Folios 1r-14v illustrated in margins with astronomical and geographical diagrams, all of them circular, tinted drawings in brown pen with red, yellow, blue and green washes. Folios 15r-24v decorated with unframed maps and illustrations drawn in brown pen, and tinted green, brown and red. Most illustrations unlabeled.Some leaves repaired; the manuscript shows signs of heavy use.Binding: 16th-17th centuries. Resewn on three vegetable fiber supports. Rounded spine. Covered in black/brown sheepskin over wooden boards with corner tongues. Blind-tooled with five line fillets forming diamonds. There are traces of four bosses on each board and two clasp-and-catch fastenings, the catches on the lower board. Fastenings and bosses are wanting. Concentric circles are scratched in the center of the lower board. Rebacked.