PORTO, Emanuel.

RARE JEWISH SCIENCE

PORTO, Emanuel. Porto astronomico

Padova, Sebastiano Sardi, 1636

£5,750.00

FIRST EDITION. 12mo, two parts in one, separate t-ps. Roman letter, woodcut floriated initials and typographical ornaments. T-p with Hebrew quote at head: העמים לעיני חכמתכם ובינתכם (Devarim/Deuteronomy 4:6, “[The Torah’s laws are] your wisdom and intelligence before the eyes of the nations”).  Numerous geometric diagrams, trigonometric tables and one horoscope in second part, occasional contemporary manuscript corrections to the tables. Age yellowing, very faint waterstain to outer blank margin of a couple of initial ll. A very good copy, crisp and clean, in contemporary vellum over boards, upper joint cracked, spine lifting exposing printed fol. from an unfindable edition of ‘Sylloges vindiciarum et animadversionum’ by Johann Georg Dorsche used in binding, vellum holed at head, covers bordered with a double blind rule, a few small ink stains, small hole to lower outer corner of upper cover also exposing fol. from ‘Sylloges’. Ink stamps of the Chateau de Waillet, Marche-en-Famenne (Luxembourg) to blank verso of t-p and rear pastedown, sticker “n. 34 valeur postage Waillet 1954 450 fra(ncs)” to fly.

First edition of this very rare Jewish illustrated treatise on trigonometry applied to astronomy. Emanuel Porto (Rabbi Menahem Zion Porto Kohen Rappa, d. c. 1600) was born at Trieste and held rabbinical office in Padua. An excellent mathematician and astronomer, Porto is the author of a series of highly regarded works on these subjects in Italian, Latin and Hebrew. “Porto astronomico” is the longest and most important; Galileo had a copy of this edition in his personal library.

‘Porto astronomico’ (Astronomical Harbour) was conceived as “a heaven for all those who are wandering in the vast sea of the celestial disciplines”. “Porto” means harbour, but it is also the author’s surname: in the preface, there is a series of letters and poems written by Paduan scholars praising Porto’s treatise with charming wordplays. The work is divided in two books. The first begins introducing the basic principles of trigonometry (how to find sine, tangent and secant of angles), then focuses on spherical trigonometry and its applications to astronomical calculations. In particular, Porto explains how to “represent the celestial sphere”, e.g. he describes how to determine the ‘astronomical hours’ and the position of the celestial poles; he also defines latitude and shows how to locate stars and constellations in the sky. Book 2 contains simple but very clear geometrical diagrams illustrating the theory presented in the first book, accompanied by detailed descriptions, as well as numerous trigonometric tables indicating the values of sine, tangent and secant for angles of different measures. Interestingly, as specified in the ‘errata’ leaf at the end, the contemporary manuscript corrections to numbers in the tables were made in the printer’s workshop.

USTC 4008744; Houzeau and Lancaster 5140; Riccardi p. 313. Not in Brunet, Graesse, Stein Schneider, BM STC It. C17 or Bibliotheca Chemico-Matematica.

Worldcat records four copies in the US (New York Public, Huntington, Jewish Theological Seminary of America, Hebrew Union College).