Abstract
Corsuno’s treatise on the astrolabe (Barcelona, 1378) is extant in only one Hebrew manuscript preserved at the Bayerische Staatsbibliothek in Munich. This text, which is a set of instructions for constructing an astrolabe, is, according to Corsuno’s words, a translation of the Arabic treatise that he devoted to the same topic in Seville in 1376, which is not extant. The text presents original traits in relation to contemporary astrolabe sources and certainly in relation to Hebrew sources on the astrolabe. The article analyses Corsuno’s contribution to the field of astrolabe literature in Hebrew and presents the Hebrew edition and translation of his astrolabe text (the Hebrew edition available in the Hebrew appendices, in the online version of JHA).
Keywords
King Pere IV of Aragon and His Astronomers: Jacob ben Abi Abraham Isaac al-Corsuno
Four fourteenth-century astronomers collaborated in constructing the astronomical tables of Pere IV the Ceremonious, King of Aragon and Count of Barcelona (1336–1387). 1 Two of them were Jewish, Jacob ben David Bonjorn and Jacob ben Abi Abraham Isaac al-Corsuno. José Chabàs has studied Jacob ben David and his tables of true syzygies for 31 years starting in 1361. 2 We know very little about the other Jewish astronomer, Jacob Corsuno, not even his birthplace, but he is the author of the Tables of Barcelona (1381). 3 The other two astronomers of Pere IV were Christian: Pere Gilbert, a native of Barcelona, and Dalmau Ses Planes, a native of Perpignan and disciple of Pere Gilbert. They both appear in various documents in the Archives of the Crown of Aragon connected to astrolabes and texts on astronomy and astrology, in all of which King Pere was interested. They both were the authors of the Taules i Almanac, for which they constructed and used different astronomical instruments to update previous data and to make astronomical observations, between 1360 and 1366, although the Taules i Almanac are probably dated 1373. 4 After Pere Gilbert’s death in 1362, Dalmau continued working on the Taules i Almanac, partially preserved in a unique Catalan manuscript now in Bern (Ms. 227, ff. 40r–43r). 5 Dalmau died in 1383. 6
According to the first colophon of the Hebrew version of his treatise on the astrolabe, Jacob Corsuno was in Barcelona in 1378, and in 1380, he was hired by King Pere to complete the tables, by, principally, translating them into Hebrew and composing canons for them. 7 In June of 1380, Corsuno was designated “translator in the House of the King” and was paid “270 sueldos of Barcelona” for 3 months of work at the Catalan court. 8 Chabàs proposed that Corsuno may have been brought to the project to prepare some tables for the latitude of Barcelona, to transcribe some other tables using pre-existing sources, and to compose the canons, with a prologue by King Pere. 9 For these tasks, Corsuno may have brought astronomical information with him from Seville, very likely a copy of Ibn al-Kammād’s Tables, which would re-introduce the Andalusian tradition of using sideral longitudes. 10 Chabàs and Goldstein suggested that, given the absence of a star table among the Tables of Barcelona, Ibn al-Kammād’s list of stars in his al-Muqtabas might be considered the missing list of stars of the Tables of Barcelona. 11
As Corsuno wrote the Arabic and the Hebrew texts on the astrolabe in 1376 and 1378, respectively, and the Tables of Barcelona were not completed until 1381, he could not use them. He used instead the Tables of King Alphonse X and of Gersonides, the only two astronomical sources that he mentions in his treatise on the astrolabe. Why did he not use the Taules that Gilbert and Ses Planes had compiled between 1360 and 1366? He may well not have had access to them, especially if he was living in Castile. The circulation of scientific texts might have been not as swift as one might have expected, especially tables, which could have enjoyed some sort of “protection” (updated astronomical data also served the purposes of astrology and this played an important role in medieval courts, politics and war). If he did have them, he may not have considered them good enough to use or even complete, for after Corsuno’s participation there was a new set of the Tables of Barcelona and its canons (the latter preserved in Hebrew, Latin and Catalan). 12
Corsuno composed the original Arabic text of the astrolabe in Seville in 1376, according to his testimony on the Hebrew manuscript.
13
In the Hebrew text, Corsuno refers to the year of the composition of the Arabic treatise as the current year (see 5b.7), suggesting that he was translating his Arabic text word-for-word without updating it. The date (and the place) of the Arabic version are also mentioned on the colophon of the manuscript to say immediately after that the Hebrew version was completed in Barcelona in 1378 (9.2–3): 2. It was finished the year 5136 [Julian year 1376] in the sixth millennium according to the counting that we use, in the city of Seville. 3. I translated it from Arabic into Hebrew in the month of Elul, in the city of Barcelona, the year for I give you good doctrine <(Pr 4:2)> [i.e. 5138, Julian year 1378].
In addition to the Tables of Barcelona and the astrolabe text studied here, Corsuno also translated Ibn al-Ṣaffār’s eleventh-century Arabic astrolabe treatise into Hebrew. According to Norman Roth, there are three manuscripts of Corsuno dealing with astrolabes at the Bayerishe Staatsbibliothek in Munich: Hebr. 256.1, Hebr. 261.11, and Hebr. 289.5. 14 Roth thought that the first two were Corsuno’s Hebrew translations into Hebrew of Ibn al-Ṣaffār’s treatise, and the third was Corsuno’s commentary on this translation. 15 However, the first text (Hebr. 256.1) is Jacob ben Maḵir’s translation of Ibn al-Ṣaffār’s treatise on the astrolabe, 16 the second one (Hebr. 261.11) is Corsuno’s original text on the construction of an astrolabe that is the subject of this study, 17 and the third one (Hebr. 289.5) is Corsuno’s Hebrew translation of Ibn al-Ṣaffār’s treatise on the astrolabe. 18
Neither of Corsuno’s two versions (Arabic and Hebrew) on the construction of an astrolabe are quoted in contemporary or later sources, suggesting that they were not very well known.
The Arabic version was written in Seville, a city of the Castilian kingdom, where Castilian was the vernacular, and the Hebrew version was written in Barcelona, a city of the Aragon Crown, where Catalan was the vernacular. The extant Hebrew version retains some traces of the context of its composition. For example, several Judaeo-Arabic words appear for the names of the months, likely holdovers from the original Arabic version. More interesting is the imprint of its composition in Barcelona. First, Corsuno dates his translation using the Hispanic Era (ṣafar Sezar, in 5b.7), a dating system used in Iberia until the fifteenth century, when it was replaced by the Anno Domini system. 19
In addition, a Catalan word (l’ullet) transcribed in Hebrew characters (ha-lullet) appears several times denoting the hole in the throne that holds the ring (5.3 and 8c.1) and by extension the suspensory part of the astrolabe. 20 The standard Latin term for this specific component was armilla fixa. Since the thirteenth-century, in the Iberian Peninsula, vernacular scientific production (astronomy and astronomical instruments included) was starting to take over from the traditional languages of science, Arabic, Latin, and in a lesser degree, Hebrew. 21 While it is unlikely that Corsuno spoke Catalan as David Romano thought, 22 he may well have understood it. His knowledge of Arabic and his stay in Seville might indicate that he was an Andalusian Jew, but this is uncertain. He certainly heard Catalan during his stay in Barcelona (1378–1380) at the court of Pere IV, where he was surrounded by Catalan people, some of whom were astronomers and astrologers, who would have referred to the components of an astrolabe in Catalan. The Hebrew language already had a technical term to denote this part of the astrolabe, which is also in Corsuno’s text (teliyyah). 23
Corsuno appears to have had disciples working in Arabic; someone who presented himself as “a Muslim disciple of Corsuno” copied the Arabic version of Ptolemy’s Almagest in Saragossa in the fourteenth-century. 24 He might also have disciples in Hebrew in the same city of the Crown of Aragon; Yehiel ben Menasheh, who is otherwise unknown, copied Corsuno’s Hebrew version of his astrolabe treatise in Saragossa in November/December of 1467 (according to the colophon in Ms. Hebr. 261, f. 104b of the Bayerische Staatsbibliothek), which is the same manuscript edited in this study and the only extant.
Corsuno’s Treatise and Its Contribution to Medieval Astrolabe Knowledge
Corsuno’s treatise on the astrolabe in the Hebrew version is a monograph on the construction of astrolabes, with no reference to its uses, structured in eight chapters which are explicitly numbered in the manuscript. Corsuno’s text makes many references to diagrams but the only extant manuscript has none; I have added them to the translation in order to illustrate the instructions and to verify the correctness of the construction. Errors in the text have been noted and corrected. There are eight chapters but I have introduced sub-divisions to make the reading easier. Furthermore, the sentences have been numbered. References are thus given in the form x.y where x is the number of the chapter and y is the sentence number.
The text opens with a brief introduction consisting of two parts. The first part (0.1–4) declares the authorship of the text, acknowledges God as the creator and mover of the stars and their cycles, and places men above any other creature because only men realize the greatness of God. 25 The second part of the introduction (0a.1–5) explains Corsuno’s motive for writing a treatise on the astrolabe. He saw that craftmen were using old-fashioned methods to construct astrolabes, he studied how artisans taught this craft to their students and took from them what was most convenient for teaching astrolabe construction easily. The treatise is thus the result of reflection and practice (0a.3) with a pedagogical focus. This pedagogical agenda is apparent in the structure and throughout the text of the treatise.
Corsuno includes an example at the end of three of the chapters, so that after the general explanation of the procedure, the readers can see an example that gives specific values for the parameters and the results. The examples are to be found in chapter two (almucantars, example in 2a.1–14), chapter three (azimuthal lines, example in 3b.1–16), and chapter seven (the pointers of the stars, example in 7.8–18). The particular values that Corsuno uses for the explanation and the example are different in two of the three examples. In the chapter on the almucantar construction, he describes almucantar divisions every 6º, which would make a “sextile” astrolabe, while in the corresponding example, the almucantars are every 2º, which makes a “medial” astrolabe. Again, for the chapter on the azimuthal lines, the explanation gives divisions every 10º, while the example has divisions for every 20º. These changes might have had a pedagogical intention.
The pedagogical intention is apparent not only in the examples, but also in how Corsuno pays attention to the description of minor details of the components, for example, the construction of the pin and horse. The treatise as a whole is very explicit about minor details; it specifies that the tops of the letters must be placed in such and such form with respect to the surrounding scales during the engraving, and how to fashion the small components of the instrument (the pin and horse). With the original diagrams and drawings that may have displayed either the construction or the shape of different parts of the instrument, the original manuscript would have been clear and very enlighting for students (while the extant copy displays a messy and hurried script and looks like the hasty notes of a student).
Corsuno’s treatise offers one novelty and two rare features to the field of medieval astrolabe making. The novelty appears in the first chapter of the treatise, in the explanation of how to project the three standard circles (the tropics of Cancer and Capricorn and the equatorial circle) onto the metal surface of the plate (1.1–12, Diagrams 2 and 3). 26 Corsuno uses the same method that he uses to project the ecliptic of the rete in chapter 6 (Diagrams 25 and 26). This method of projecting the three standard circles is, to the best of my knowledge, completely new in astrolabe sources. This is certainly the only Hebrew treatise on astrolabes that introduces it. Medieval treatises do not use this method; it seems that medieval astrolabists preferred to keep to more traditional methods of projecting. The standard method of projecting these circles was exact, but depended on the value of the ecliptic; the more accurate the value of the ecliptic, the more accurate the result. Corsuno’s method works despite the rounded off value of the ecliptic that he is using (24º), which was also very frequent in Hebrew astrolabe treatises despite that their authors were aware of more precise values.
Corsuno or his source must had been playing with an astrolabe plate and a pair of compasses and found that the diameter of the ecliptic just happens to closely match the 90 degree chord of the circle of Capricorn, i.e., AB is approximately equal to AZ in Diagram 1 (see below). Corsuno’s technique depends on a useful and surprising coincidence that generates a readily realizable approximation in which the value of the obliquity plays a critical role. There is no geometrical or astronomical rationale for it, only that it is a good fit for what is established by the traditional methods of projection, and found on actual instruments. Corsuno is well aware of this, as his enigmatic words (0a.3) clearly suggest at the beginning of the treatise (“even though there is no demonstrative proof for some things”). Given the novelty of this ad hoc method and because Corsuno presents a construction that looks geometrical, I will explain the mathematics that is behind this contingent way of constructing the three standard circles, even if this explanation is not necessary.
Let us call c the radius of the circle of Capricorn (H, HA), a the radius of the circle of Aries or the equator (H, HE), and α the inclination of the ecliptic or obliquity.
Let us start with the circle of the equator.
AHḤ is an isosceles triangle, so that γ = β and 2β + α + 90º = 180º. Hence α = 90º - 2β, and also β = (90º - α)/2 (1).
Tan β = HE/AH = a/c; hence a = c tanβ (2).
The standard value for the inclination of the ecliptic is α = 24º, in which a = c tan (90 – α/2) = 0,65 c (3).
According to Corsuno’s method, AHB is an isosceles and right triangle. U is the midpoint between A and B; one draws the circles (A, AU) and (T, TA) with the same radius, so that the distance AU is equal to AT and also to TE. Let us call this distance/radius u.
AB2 = AH2 + BH2, but BH = AH and AB = 2 AU, so that: 2 c2 = 4 u2, hence u = c/√2 (4).
EHT is a right triangle, so TE2= TH2 + HE2, where TH = AH - AT,
so TE2 = (AH - AT)2 + HE2. If we substitute the terms with their equivalent radii c and a:
u2 = (c - u)2 + a2, and from here u2= c2 + u2 - 2cu + a2 that implies a2 = 2cu - c2.
If we susbtitute u for the value found in (4), we get:
a2 = 2c (c/√2) - c2 = c2(2/√2) - c2, hence a = ±c√(√2–1), that implies a = 0.6436 c. This is practically the same value one gets in formula (3).
Now, the construction of the circle of Cancer:
p is the radius of the circle of Cancer (H, HZ), given that AU = TZ = AT = TE
line E’Z’ is parallel to line AE, so that it subtends the same angles (Thales theorem), and
p = a tan β; applying (2) p = c tan β tan β = c tan2 β (5).
Likewise radius p = HZ = TZ -TH = u - (c + u) = 2u - c if one substitutes here u according to (4), one gets p = 2 (c/√2) – c = c (2–√2)/√2; hence p/c = 0.41. Using formula (5)
p/c = tan2β = 0.41 then tan β = √0.41 = 0.64, which hardly differs in about 0.5% from the ratio previously obtained for the other two circles.
Corsuno’s method gets practically the standard value for the inclination of the ecliptic in astrolabe treatises found in (2) with the standard method. Corsuno’s method according to (1) gives to β the value of arc tan 0.6436 = 32;76°, which means that the value for the inclination of the ecliptic is α = (90–β)/2 = 24;28°. Corsuno’s geometrical method of projecting the three standard circles is simple and reaches a rather good value for the inclination of the ecliptic. 27
The first of the two unusual features of Corsuno’s astrolabe is that it displays not only hour divisions for the seasonal hours measuring time from sunrise to sunset and vice-versa, but it also displays a diagram showing the Babylonian hours (equinoctial hours in which the day starts at sunrise). 28 Usually astrolabes display equinoctial hour divisions on the limb with a 1-to-12 scale that starts at both meridians. 29 As far as I know, this is the only medieval Hebrew astrolabe text that describes how to engrave a diagram of the Babylonian hours on a latitude plate. Other treatises explaining the use of astrolabes in Hebrew do not even allude to this way of telling time. 30 Babylonian hours, as well as equinoctial hours and local seasonal hours, were one of the several ways of telling time with different devices. The most frequent until the fourteenth century was the measure of time in local seasonal hours, but equinoctial hours eventually imposed by the spread of the use of clocks.
The second rare feature of Corsuno’s astrolabe is an alidade that is graduated to tell time according to the shadow projected by one of the pinnules, which was used as a vertical Greek/Roman sundial. 31 As was customary since Antiquity, the measurement with these devices was based on the length of the shadow projected by a vertical gnomon (here the pinnule) onto a surface (here the surface of the alidade and its divisions), independently of the latitude but approximate, i.e. it was universal (time as a function of the solar altitude). A few medieval alidades display this feature, 32 and those I have seen have graduations as Corsuno explains them. 33 In order to understand Corsuno’s construction and its similarities to the methods available in Arabic sources, I have translated the explanations that the Persian astronomer Al-Ṣūfī (903–986) gave to construct these graduations in an alidade. Al-Ṣūfī used a method (Appendix 1) based on numerical values taken from a table, so that he does not work directly with the projection as Corsuno does. Al-Bīrūnī (973–1048) refers to two methods, one similar to Al-Ṣūfī’s method and the other similar to Corsuno’s. 34 I have found Corsuno’s and Al-Bīrūnī’s method to project the hours onto the surface of the alidade in a Hebrew manuscript that the Jewish astronomer and mathematician Mordeḵai ben Abraham Finzi copied in Mantova in the first half of the fifteenth century (Maʿaseh ha-asṭrolab ve-hu le-Batlamius le-šivʿah ʾaqlimim, Accademia Nazionale dei Lincei, Ms. Or. 259, ff. 97a–105a, here f. 105a). 35 This method uses a quarter of circle divided into six equal parts to project these divisions onto the surface of the alidade and determine the hour lines (Appendix 2, and my Hebrew edition in the online version of JHA). I have completed the description of the telling-time alidade with an anonymous explanation of its use that Mordeḵai ben Abraham Finzi copied in Mantova in the first half of the fifteenth century (Biʾur keli ha-aṣṭrolab le-ḥaḵam Baṭalmius, Accademia Nazionale dei Lincei, Ms. Or. 259, f. 92a (Appendix 3, and my Hebrew edition in the online version of JHA).
The construction of the remaining components is standard. In relation to the projection of the almucantars onto the plate, Corsuno provides one method (Ch. 2, Diagrams 4–9) and an example (Diagrams 10–12). His method is standard (although it is not the only available) and can be found in other Hebrew and non-Hebrew treatises, for instance in Comtino’s treatise on constructing an astrolabe. 36 The same applies to the projection of the azimuths, for which Corsuno also provides an explanation (Ch. 3, Diagrams 13–16) and an example (Ch. 3, 3b.1–16, Diagrams 17–18). This is also a standard method (one of the several available for this construction) that relies on the system of projection that draws a line through the centres of the circles that cross the zenith of the latitude plate. 37
For the construction of the rete, Corsuno uses a set of tables prepared specifically for the construction of an astrolabe. He takes into consideration the precession of the fixed stars and recommends using a value of one degree every 70 years for updating available star tables. 38 This is one of the standard values (Al-Ṣūfī’s), which appears also in Abraham ibn Ezra’s texts. 39 The stellar coordinates used for the construction of the star pointers are given in a table at the end of the seventh chapter of Corsuno’s treatise (7.3-12). These stellar coordinates are prepared to be used specifically in the construction of an astrolabe. Two additional tools are needed: two threads placed in a specific way on top of the rete, and the rete (which has to be placed according to some of the coordinates indicated in the table). When these elements have been conveniently placed, the position of the pointer of the star in the rete is determined by the intersection of the two threads. As the calculation is too delicate to be carried out directly on the metal of the rete, it is calculated first on a rete made of paper and the results are then moved to the brass rete. Corsuno seems to perform them directly onto the metal using two threads and possibly ink and wax (the former mentioned once in 5b.4 and the latter not mentioned at all in the manuscript). Chabàs, who did not identify these stellar coordinates, 40 noticed that despite the similarities of Corsuno’s list of stars in his treatise on the astrolabe to the list of stars in the Tables of Barcelona, there is not a clear relationship between them. The stars of the Tables of Barcelona coincide with the list of stars of Ibn al-Kammād in his Al-Zīj al-Muqtabas. As Goldstein and Chabàs noticed, both lists of stars are very similar and belong in the same tradition. 41
The table of correspondences between the first day of the months and the degrees of the zodiac, which is taken from Gersonides, mentioned together with the Tables of King Don Alphonse X (hem ha-yoter meduyyaqim še-beineinu bi-zemanu, in 5b.7), implies that the vernal equinox takes place between the 11th and the 12th of March. 42 This is the same value that Ben Eliezer Comtino (c. 1425–c. 1490) uses for his astrolabe (spring equinox March 11th). 43 Corsuno’s reference to the Alfonsine tables may be of considerable interest, since there are few references to these tables in fourteenth-century Hebrew texts. As Corsuno explains (see 5b.8–9), although Gersonides uses minutes and seconds for the positions of the sun at the beginning of every month, he has simplified and rounded them off to the value of the next degree (e.g., Pisces 20º for 1 March rather than Pisces 19;7,40º). This rounding off to the next degree works in all cases except for October 1st (15;37,8º), November 1st (16;45,45º), and January 1st (19;9,44º) of the first table of Gersonides, and 1 March (18;59,12º), 1 October (15;48,18º), 1 November (16;52,37º), and 1 January (19;7,36º) of the variant table of Gersonides. 44 This rounding up of parameters is not due to carelessness or disregard but to Corsuno’s awareness of the limitations of astronomical instruments, and astrolabes in particular, as regards their graduations. The astronomical section of Gersonides’ Wars of the Lord was an important source for the circle of astronomers working around King Pere; Jacob ben David Bonjorn, the author of a set of astronomical tables, considered Gersonides the “crown of the sages.” 45
When dividing the ecliptic or zodiac, each quarter of the ecliptic of the rete should be divided into three unequal parts, but this is not properly done in this treatise. According to Corsuno’s method, one places the ruler on the centre of the astrolabe and extends a line through each of the 12 equal divisions marked on the border of the plate (i.e. the circle of Capricorn). This gives the division in unequal sections of the ecliptic of the rete, but it is very approximate. There were more accurate methods of doing this. This method, called of “the false right ascensions,” is the same one found in early Latin treatises, such as those of Hermann of Reichenau, Raymond of Marseille, and Rudolph of Bruges. 46 This is also one of the two methods that Mordeḵai ben Eliezer Comtino presents in his treatise; the other is the method “per lineas rectas.” 47 One would have expected in Corsuno’s text a more accurate method for the division of the ecliptic; it remains unexplained why he chose this one.
Translation of Corsuno’s Hebrew Text
Munich, Bayerische Staatsbibliothek Ms. Hebr. 261 ff. 103a–104b 48
<Table of the contents>
<0>. <Introduction>
<1>. First chapter: How to find the beginning<s> of Capricorn, Aries, and Cancer.
<A new method for the construction>
<2>. Second chapter: Finding the almucantars.
<Explanation of the method>
<Example>
<3>. Third chapter: To find the lines of the circles crossing the zenith that are the azimuths.
<Explanation of the method>
<Example>
<4>. Fourth chapter: The knowledge of the seasonal and the equinoctial hours of every latitude.
<Construction of the seasonal hours>
<Construction of the Babylonian hours>
<5>. Fifth chapter: The knowledge of the construction of the front and the back <of the mater> called in Arabic al-ḥuğra (i.e. the limb).
<The mater and the throne>
<The limb>
<The back: the altitude scale>
<The back: the zodiac scale>
<The back: the calendar scale>
<The graduation and engraving of the zodiac scale>
<The graduation and engraving of the altitude scale>
<The graduation of the calendar scale>
<Excursus on calendrical tables to correlate the days of the year and the degrees of the zodiac>
<The back: the shadow square>
<The graduation of the shadow square>
<6>. Sixth chapter: The construction of the rete and the division of the zodiac on it.
<The projection of the ecliptic>
<The division and graduation of the ecliptic>
<Projecting a section of the equatorial ring>
<7>. Seventh chapter: The construction of the pointers of the fixed stars in the rete.
<The almuri or index>
<Explaning how to place the pointers of the stars using coordinates prepared for an astrolabe>
<Example>
<Excursus on how to update the tables according to the precession movement> <Coordinates of twenty-three fixed stars>
<8>. Eighth chapter: The construction of the alidade and drawing the hour divisions on it, and the construction of the suspensory part, the ring, the pin, and the horse.
<The alidade and its sighting vanes or pinnules>
<Graduation of the alidade to tell time in seasonal hours>
<Identifying the hour divisions projected onto the alidade>
<The pin>
<The suspensory part>
<The ring>
<The horse>
<9>. <Colophon of the writer>
<10>. <Colophon of the copyist>
<Introduction>
0 . 1 (f. 103a) Explanation of the construction of an astrolabe
2 Jacob the Israelite, son of his honoured father Abraham Itzhaq ha-Meyassed (i.e. the Founder), called al-Corsuno, the Sephardic, said: 3 Praise be to God, Who is the primal, the eternal, Who has neither beginning nor end, 49 Who moves the planets in their orbs and the concentric spheres with their planets. 50 4 To Him belong praise and thanks for giving to the human species preference and a position higher than all His <other> creatures, so that they recognize His greatness and His highness.
6 I have divided my text into eight chapters.
1 . 1 First chapter: how to find the beginning<s> of Capricorn, Aries, and Cancer
<A new method for the construction>
2 When you want to find the circle of the beginning of Capricorn, draw a circle of any size you want around the centre of the plate, 3 with the condition that it leaves on the border of the plate <about> a little more than a fifth of a finger; this circle is called the circle of the beginning of Capricorn. 4 Then divide the plate into four equal parts around the centre: from A to G <the meridian line> and from B to D <the east-west line> through the central point H.
5 After that draw line AB, such that line AU bisects it at point U; take the amount from A to U and <apply it> to the distance from A to Ṭ. 6 Hence the distance from A to Ṭ is equal to the distance from A to U, and let point Ṭ be the centre <of a new circle>. 7 Put on it one leg of the pair of compasses and move the other leg <making it passing across A>. 8 Mark the place where the pair of compasses intersects line AG; this is point Ḥ. 9 Also, determine the point where the leg of the pair of compasses intersects line DB and mark it point Z.
10 Then place the leg of the compasses on the centre of the plate and move the other leg until it falls on point {Z} [Ḥ]. 11 Draw a circle through it (i.e. Ḥ) and call it the circle of the beginning of Cancer. 12 Keep <the> leg of the compasses on point H, which is the centre of the plate, and move the other leg until it falls on point Z. 13 Draw another circle through it (i.e. Z) and call it the circle of the beginning of Aries and the beginning of Libra. 54
2. 1 Second chapter: finding the almucantars
<Explanation of the method>
2 When you want this, divide one quarter of the circle of Aries into 90 degrees as you prefer, every 5, 6, or 10 <degrees>. 3 Then take from Z to {A} [G] in the circle of Aries as much as the latitude of the place for which you want the construction of the plate. 55 4 Mark on it point I. 5 After that place the rule 56 on point Ṭ of the circle of Aries <where it intersects the horizontal line> and also on point I. 6 Make a straight line from Ṭ through I, and extend it directly to point Ḥ on the circle of Capricorn. 7 Mark the place at which this line intersects line AG, which is point Y. 57 8 This is the point of the horizon, which is the beginning of the almucantars.
{9 Then take as much as the distance between A and Y on a line that extends beyond the plate in a straight line, which is going to be line ṢA, and mark on it point Ṣ.} 58 10 Also draw a line from point {Ḥ} [Ṭ] on the circle of {Capricorn} [the equator] to point {Ṣ} [I’], <until this line crosses the meridian at point Ṣ>, which is <on the line that extends> outside the plate. 11 Divide it <the line between Ṣ and Y> into two equal parts {at point Y} and draw an arc of a circle around it<s middle point> {through points Ṣ and M}. 12 The centre of this circle <draws the first almucantar> {is point Y}.
13 Also divide this arc (i.e. the upper half of the circle of the equator between I and I’) into 30 equal parts <I1, I2, I3, … I’3, I’2, I’1>, if you want the almucantars every 6 <degrees>.
14 Draw line<s> between point Ṭ in the circle of Aries and every point of the divisions in the arc that you drew <I1, I2, I3, … I’3, I’2, I’1>. 15 Find the point <Y1, Y2, Y3 … Ṣ3, Ṣ2, Ṣ1> at which the line that you have drawn intersects the meridian line, which is line {LY} [ṢY].
16 Find the centre of this <first> circle between the {line} [point] that you have drawn on the upper part <Ṣ> and the {line} [point] that you have drawn on the lower part <Y>.
17 Draw either an arc of a circle or, if it is possible, a complete circle. 18 Do the same until completing all the almucantars <with the pairs of points Ṣ1–Y1, Ṣ2–Y2, Ṣ3–Y3, etc.>.
<Example>
5 Then we have drawn a line between point Ṭ and point N and marked the place at which this line intersects the meridian line, which is point G. 6 We have also drawn a line between Ṭ and I<‘>, which intersects the meridian line at point L, and we have found the midpoint between G and L and have got a circle <with this centre>. 7 We have also drawn a line from Ṭ through K and this line also intersects the meridian line at point Š. 8 We have also drawn a line between Ṭ and K<‘>, which intersects the meridian line at point Ṣ<‘>, and have found the midpoint between Ṣ<‘> and Š.
9 We have drawn a circle around it. 10 We have also drawn a line between Ṭ and D, and this line intersects the meridian line at point B. 11 We have drawn again a line between Ṭ and Z, which intersects the meridian line at point T. 12 We have found the centre of <the> circle between B and T and have got a circle. <Et cetera>. 13 We finish all the almucantars with the completion of the <last> circle, and the centre <Ḥ> is the point of the zenith. 14 This is enough as regards this.
3 . 1 Third chapter: to find the lines of the circles <crossing the zenith> that are the azimuths
<Explanation of the method>
2 When you want this, mark the point of the zenith that we explained in the previous chapter, which is point Ḥ. 3 After that find the centre <of a circle> on the line of the lower meridian of the circle, which is centre Ṣ, <and place one leg of the compasses here>. 4 The other leg <of the compasses> passes through point Ḥ and the two points Z and Ṭ. 5 These are the two points that the circle of Aries intersects on the east-west line. 6 Finish the drawing of the circle, and divide it in the centre of the plate with a straight line, line ḤL, <and another line perpendicular to this through Ṣ>. 7 Then you have divided this circle into four equal parts around centre Ṣ. 8 Extend this line beyond the plate to whatever length you prefer. 9 This line is called the line-of-the-centres-of-the-circles-crossing-the-zenith.
10 After that divide half of this circle into nine equal parts, if you want the circles crossing the zenith every {10} [20] degrees, and draw a line from point Ḥ to each of the divisions. 61
11 Mark on the line that is called the line-of-the-centres-of-the-circles-crossing-the-zenith the place at which each line intersects it. 12 Do the same until <completing the> drawing <of> the lines of the divisions of the circle from point Ḥ, <which> you mark on the line-of-the-centres-of-the-circles-crossing-the-zenith.
13 Then place one of the legs (lit. “the centre”) of the compasses on each of the marks of the lines on the line-of-the-centres-of-the-circles-crossing-the-zenith, and the other leg on centre Ḥ. 14 Make an arc through <them> from the beginning of the almucantars to the zenith. 15 Do the same until completing the drawing of all the circles crossing the zenith.
<Example>
6 In the same way, we have drawn a line between point Ḥ and point N. 7 This line intersects the line-of-the-centres-of-the-circles-crossing-the-zenith at point Ṣ. 8 We have placed one of the legs (lit. “the centre”) of the compasses on point Ṣ and the other on point Ḥ and have got an arc of a circle. 9 We also have drawn a line from Ḥ to K and to point Y <and placed> one of the legs (lit. “the centre”) <of the compasses> on the line-of-the-centres-of-the-circles-crossing-the-zenith 62 on point Š <and on point R respectively>. 10 (f. 103b) <We have placed> the other leg <of the compasses> on point Ḥ and have got an arc of a circle <with each of points Š and R>. 11 We have also drawn a line from Ḥ to T<‘>, and to point Š<‘> on the line-of-the-centres-of-the-circles-crossing-the-zenith. 12 We have made Š<‘> the centre <of a circle> and have got a segment of the circle with radius Š<‘>Ḥ. 13 We have also drawn a line from Ḥ to I and to S on the line-of-the-centres-of-the-circles-crossing-the-zenith. 14 We have made S the centre <of another circle> and have got an arc of a circle with radius SḤ. 15 Here, <more than> half of the lines of the circles crossing the zenith are completed. 63 16 You will perform exactly the same on the side that is left and shall find the truth with clarity.
4. 1 Fourth chapter: the knowledge of the arcs of the seasonal and the equinoctial hours of every latitude
<Construction of the seasonal hours>
2 When you want to draw the seasonal hours, divide <half of> the part below the horizon of the circles of Cancer, Aries, and Capricorn into six equal parts, i.e. each one of them. 3 The example is that you divide what is below in the drawing: divide what is between Š and T 64 in the circle of Capricorn into six equal parts and <write> on them A B G D H. 4 The same regarding what is between Ṣ and L in the circle of Aries into six equal parts and <write> on them A B G D H. 5 The same regarding what is between Y {P} and N in the circle of Cancer and <write> on them A B G D H.
6 Also find the centre of the circle whose arcs cross the lines of three <points> A A A. 7 I mean, one leg of the compasses <is placed on the centre and the other leg> crosses all three points A A A and you get an arc of a circle. 8 Find also the centre of the circle on which <one leg of the compasses is on the centre and> the other leg of the compasses crosses all points B B B and you get an arc of a circle. 9 The same regarding all <three> points G G G, D D D, and H H H. 10 Then, the 6 hours since the moment of sunrise until the moment of midday are completed. 65
11 You do the same with the six remaining hours <on the other half below the horizon>. 12 I mean, you divide what is between S and T <in the circle of Capricorn> into six equal parts, what is between L and M <in the circle of Aries> into six equal parts, and what is between N and P <in the circle of Cancer> into six equal parts. 13 You do with the arcs of the<se> six remaining hours as you did with the previous ones. 14 Then the 12 seasonal hours in that horizon are completed.
<Construction of the Babylonian hours>
3 After that find the centre of the circle on which one leg of the compassses <is placed on the centre and the other> crosses the three points previously mentioned, as you did regarding the seasonal hours. 4 You do the same with the following three points, the ones following after them, and with all the remaining. 5 The centre of each of them is in the western part, i.e. in the part of Y {Š Ṣ} [Ṣ Š].
6 There is no doubt that you shall get the hours and the fractions of an hour corresponding to every degree of the zodiac circle for any horizon at that moment. 7 However, be warned that the arcs of an hour do not cross the circle of the horizon at all, only then your work shall be right.
5. 1 Fifth chapter: the knowledge of the construction of the front and the back <of the mater> called in Arabic al-ḥuğra (i.e. the limb)
<The mater and the throne>
2 When you want to make the front <of the mater>, make it as you wish, either with a <scribing?> stick or with a <metal?> stylus. 3 <The mater> shall be cast a little pointed at one side, which is called the throne (lit. “the hook”) and is the place of the suspensory part and the ring. 4 It is joined to the plate that fits to it and is called the mater.
<The limb>
5 You divide this border (i.e. the limb) into 360 equal parts, either right or left. 6 Right is when the number starts from the position of the suspensory part and goes westward. 7 Left is the opposite, i.e., it starts from the position of the suspensory part and goes eastward. 8 You mark and write the number of the degrees above, i.e., on the edge of the limb. 9 You mark the degrees below them and the opposite of this for the other side. 67
<The back: the altitude scale>
10 Draw a circle around the centre of the plate with enough distance between it and the perimeter of the circle to be able to write on it the number of the degrees of the altitude (i.e. the degrees of the altitude scale). 11 Draw also another circle inside it, with enough distance between them to be able to mark on it the degrees of the altitude.
<The zodiac scale>
12 Draw again a <third> circle inside the previous one with enough distance between them to be able to write on it the number of the degrees of the zodiac. 13 Draw a <fourth> circle <inside the previous one> with enough distance between them to be able to mark on it the degrees of the zodiac. 14 Draw a <fifth> circle inside it with enough distance between them to be able to write on it the names of the zodiac signs.
<The calendar scale>
15 Draw a <sixth> circle inside it with enough distance between them to be able to write on it the names of the solar months of the year. 16 Draw a <seventh> circle inside it with enough distance between them to be able to write on it the number of the days of the months. 17 Draw an <eighth> circle inside it with enough distance between them to be able to mark the days of the months. 68
Arabic astrolabe with Kufic script (made in Toledo in 1029–1030) that displays the scales of altitude, the zodiac, and the calendar as Corsuno describes them for the back of his astrolabe. The only difference in this astrolabe with respect to Corsuno’s astrolabe is that the divisions of the single altitude degrees, the single zodiac degrees, and the single divisions of the days of every month are practically absent on this astrolabe (very few divisions of the altitude degrees and the zodiac degrees are sparsely engraved). Photograph of the author by courtesy of the Staatsbibliothek zu Berlin – Preußischer Kulturbesitz (astrolabe accession no. 6567).
<The graduation and engraving of the zodiac scale>
<The graduation and engraving of the altitude scale>
9 Also write the number of the degrees of the altitude on the circle that is the perimeter <of the mater>. 10 This must start from the east point, which is <the first> point of <this> complete part (i.e. this quarter), and <the end> is the position of the suspensory part. 70 11 This is because in this way, the tops of the letters shall be inward from the perimeter of the mater.
Detail of a medieval western astrolabe (made ca. 1300 in Valencia or Catalonia). Notice the starting point of the script of the numbers on the outer circle (altitude scale) from the equinoctial line (horizontal) on the left (point east according to Corsuno’s instruction) moving upwards. Here, the heads of the numbers (it would be letters in the Hebrew and Arabic notation of the numbers) are outward, while in the counting starting also on the left but moving downwards the tops of the numbers are inward. This is to avoid confusion and to separate the two scales of altitude. The remaining interior scales of the zodiac and the calendar have the script and the numbers with the tops pointing inward. On this astrolabe, the zodiac scale and the calendar scale are separated by a strip with a vegetable motif. Photograph of the author by courtesy of the Society of Antiquaries in London (astrolabe accession no. LDSAL55).
Arabic astrolabe made in Cordova in 1054 with later additions in Catalan. Notice the tops of the Arabic numbers (in fact letters denoting numbers) and the top of the script of the names pointing outward on all the scales of the back of this astrolabe. Only the Catalan script added later has the top of the numbers and the letters pointing inward (with the exception of the outer altitude scale). The outer altitude scales starting on the equinox line and progressing upwards and downwards display the letters denoting numbers with the tops inward and outward respectively to separate and distinguish the altitude scales of each quadrant. Photograph of the author by courtesy of the Jagiellonian Museum (Kraków) (astrolabe accession no. 4037).
12 Write the western quarter and start to write from the western point, which is point D, and the counting finishes at the position of the suspensory part. 13 The tops of the letters shall be on the side of the perimeter of the mater (i.e. with the tops inward). 14 Write the second western quarter and start the counting from point D. 15 The counting finishes at point G and the tops of the letters shall be inward from the perimeter of the mater. 16 Write the eastern quarter and start from point B, finishing the counting at point G. 17 The tops of the letters shall be inward from the perimeter of the mater.
<The graduation of the calendar scale>
<Excursus on calendrical tables to correlate the days of the year and the degrees of the zodiac>
7 The present year is 5136 since the Creation of the world, thousand and {776} [376] since the Incarnation (of Jesus, in the Julian calendar), 778 for the Arabs, and thousand and 414 since the Era (ṣafar), called in Latin Caesar’s <era>, 71 according to the tables of the glorious king Don Alphonse, king of Castile, which are the most accurate in our time. 8 This is according to what study testifies. However, according to what the polymath scholar R. Levi ben Gershom of blessed memory <says> in {chapter 28 of} the first part of the fifth book in the {third} 72 book of The Wars of Lord, the first of March the sun shall be at 20 degrees of Pisces, the first of April at 20 degrees of Aries, the first of May at 19 degrees of Taurus, the first of June at 19 degrees of Gemini, the first of July at 17 degrees of Cancer, the first of August at 17 degrees of Leo, the first of September at 17 degrees of Virgo, the first of October (f. 104a) at 17 degrees of Libra, the first of November at 18 degrees of Scorpio, the first of December at 18 degrees of Sagittarius, the first of January at 19 degrees of Capricorn, and the first of February at 21 degrees of Aquarius. 73 9 Although there are some divisions for minutes, and for seconds in a lesser degree or missing entirely, it is not possible to correct the shortcomings of the instruments used in our time.
Medieval Hebrew astrolabe in a private collection. The spring and autumnal equinoxes fall in 11 March and 15 September, respectively (underlined with a black line extended between the dates of the equinox in March and September on the calendar scale and the beginning of Aries and Libra on the zodiac scale). The calendar scale of this astrolabe displays equinoctial and solstitial dates that are very likely identical to the calendar scale described in Corsuno’s treatise (although Corsuno does not say whether his calendar scale is eccentric or concentric with respect to the zodiac scale, we should assume that it is concentric, contrary to the calendar scale on this Hebrew astrolabe). Photograph of the author by courtesy of a private collector.
<The back: the shadow square>
<The graduation of the shadow square>
6 You make the digits as you made the altitude degrees. 7 Divide the side of the square in the western part, i.e., from U to L, into 12 equal divisions and place the rule on the centre of the plate, which is point H, and on each of the 12 divisions. 8 Then mark the digits of the shadow in the distance between the two squares as you did before. 9 You do the same on the second side, which is from L to Z, and you complete the divisions of the digits of the shadow square. 10 Know that the side between U and L is called the inverted shadow, while the shadow between L and Z is called the straight shadow.
Medieval Hebrew astrolabe in a private collection. This astrolabe displays a double shadow square, while Corsuno’s astrolabe only has one on the right side of the astrolabe (“in the western part” in the manuscript). Detail of the shadow square underlined in black: line UL displays the inverted shadow or umbra versa (cotangent), while line ZL displays the right shadow or umbra recta (tangent). The enumeration of the units of the shadow or digits (12 on each of the two sides of the square) starts from the equinoctial and from the solstitial lines respectively. They are indicated with single divisions and with a longer division and a number every group of four digits (4–8–12). The diagonal of the shadow square must cross the centre of the astrolabe and intersect the altitude scale at an angle of 45º to be correctly constructed (as Corsuno explains). Photograph of the author by courtesy of a private collector.
6. 1 Sixth chapter: the construction of the rete and the division of the zodiac on it
<The projection of the ecliptic>
2 When you want this, have in your hand a thick plate the size of which is like the size of the remaining plates of the astrolabe that you want <to construct>. 3 Draw a circle around the centre <H>; the size of <this> circle of Capricorn will be like the size of the plates. 4 Divide the plate into four equal parts; the lines of the division cross the centre of the plate <H>. 5 Draw a line between A and B and divide it into two equal parts at point U. 6 After that, starting from point A on the side of the centre, take on line AG as much as the distance AU, which is point Ṭ. 7 Draw a circle around point Ṭ. 8 Its diameter is A{G} [Ḥ] on the condition that the pair of compasses keeps <the radius of the circumference drawn> above, i.e., the distance between the two legs of the compasses is like distance AU. 9 Draw also another circle inside it so that you can write between it and the first one the names of the zodiac signs. 10 This circle is called the zodiac belt.
<The division and graduation of the ecliptic>
11 Divide again the plate alongside its border into 12 equal parts and start from the <initial> point of any of the quarters. 12 Place the rule on the centre of the plate and on each one of the 12 divisions. 13 Draw the divisions on the zodiac belt and the result of the division is the 12 zodiac signs <of the rete>. 14 Start to write the names of the zodiac signs from point M and its beginning is from Aries. 15 After that place the remaining according to their order.
<Projecting a section of the equatorial ring>
16 Place one leg of the compasses on the centre of the plate and draw <with the other leg> an arc of a circle on the side of the lower meridian. 17 The distance between this arc and the perimeter of the mater is like {the} [its] distance from the zodiac belt. 74
Rete of an Arabic astrolabe with Kufic script (made in Toledo in 1029–1030). Notice the pointers of the stars numbered according to their positions in the ecliptic. The segment of the equator below the ecliptic or zodiac contains the pointers and the names of the stars number 5, 6, 8, 11, and 13. Photograph of the author by courtesy of the Staatsbibliothek zu Berlin – Preußischer Kulturbesitz (astrolabe accession no. 6567). 75
18 This arc is intended for writing on it the names of a few of the fixed stars. 19 Leave between the two extremities of this arc and the east and the west lines distance enough to mark on it two or three stars.
7. 1 Seventh chapter: the construction of the pointers of the fixed stars in the rete
<The almuri or index>
2 When you want this, make a pointer (the almuri or index) in the rete that is a tiny tooth between the end of the zodiac sign Sagittarius and the beginning of the zodiac sign Capricorn.
<Explaining how to place the pointers of the stars using coordinates prepared for an astrolabe>
3 After that place the rete inside the mater and take a thread of silk or thin linen/flax, and place one of its extremities on the point of the <upper> meridian on the limb. 4 This is the place from which the enumeration of the degrees of the limb starts and ends. 5 Also <place> the other extremity <of the thread> on the opposite part, on the lower part of the limb, which is the place at which the point 180 degrees of the degrees of the limb is placed. 5 Also take another thread the length of which is like the diameter of the instrument, a little more, and attach one of its extremities to the point east on the limb. 76 6 The joining of these threads is in al-ʿAzah (the Powerful?) or in Zaphat (the Tarred?) or <stars> similar to them. 7 Introduce the <latitude> plate in it (i.e. the mater) and turn the rete until the indicator <of the beginning of Capricorn> (the almuri) falls on the number corresponding to this star <on the table below>.
<Example>
8 The example: if you want to locate the Eye of Taurus, you see that the degree 149 corresponds to it (i.e. the star) <on the table below>. 9. <Turn the rete 149° westwards from the top and the second degree of Gemini will fall under the first thread, as in the first two numerical columns of the table below>. 10 Move also the second thread that you attached to the point east until it falls on the second number that you find <on the third numerical column of the astronomical tables> corresponding to the star. 11 <For this> example in relation to Aldebaran (the Arabic name for the Eye of Taurus), you find written aligned with it the second number <of the second set of coordinates>, 42 <degrees>. 12 Mark a point on the place at which the two threads intersect, it is the position of the star in the circle of the zodiac in longitude and latitude for our time.
<Excursus on how to update the tables according to the precession movement>
13 Just as you have done regarding the first number, you shall find <the number> corresponding to every star, <but> every 70 years <you should add> one degree. 14 I mean you find that 149 corresponds to Aldebaran, but after 70 years the number corresponding to it will be 150. 15 However, it is not necessary to subtract from the second number <of the stellar coordinates> or to add anything to it. 16 Therefore, it is necessary to add one degree to the position of the culmination of the fixed stars. 77 17 I mean, if Aldebaran is now located at two degrees of Gemini, the culmination shall be <after 70 years> at 3 <degrees> of Gemini. 18 Understand this and you will find the truth.
<Coordinates of twenty-three fixed stars>
{If the days are engraved on the limb. If the names are written on the limb.} 78
8. 1 Eighth chapter: the construction of the alidade and drawing the hour divisions on it, and the construction of the suspensory part, the ring, the pin, and the horse
<The alidade and its sighting vanes or pinnules>
2 Indeed, the making of the alidade consists in taking a piece of brass as long as the diameter of the astrolabe and one finger and a half wide. 3 Divide it longitudinally into two equal parts with a straight line. 4 Engrave a longitudinal line along it (the alidade), but stop at the centre of the two parts. 5 Pierce a hole in the midpoint <of the alidade> and make two small pinnules. 6 Then pierce two holes in them (one in each pinnule) in such a way that they (the two holes) are aligned with each other. 7 Place each of them (the pinnules) at each extremity of the alidade on the condition that you leave about a finger at each extremity of the alidade <with respect to the edge of the alidade>. 80
<Graduation of the alidade to tell time in seasonal hours>
<Identifying the hour divisions projected onto the alidade>
5 Then make perpendicular lines on the wide side of the alidade passing through the point<s> that you marked on it. 6 The distance between the centre of the alidade (i.e. the base of the pinnule) and the first mark is the first and the {twelfth} [eleventh] hours and the second {hour} [division] is the {eleventh} [tenth] and second hours. 7 The third <division> is the third and the {tenth} [ninth] hours, the fourth <one> is <the fourth and> the {ninth} [eighth] <hours>, and the fifth <division> is the fifth and the {eighth} [seventh] <hours>. 83 8 This is their diagram. 84
Detail of the medieval alidade of an Andalusian astrolabe engraved with Kufic script (made in Toledo in 1029–1030), which displays the hour divisions and their numbers on the front of the alidade, just as Corsuno describes them in his treatise: the first division next to the pinnule indicates hours 1 and 11, the second hours 2 and 10, and so on until the last division next to the other pinnule. Some of the divisions and the numbers have disappeared from wear. Photograph of the author by courtesy of the Staatsbibliothek zu Berlin – Preußischer Kulturbesitz (astrolabe accession no. 6567).
<The pin>
Pin and horse of a medieval Catalan astrolabe (made in Barcelona in 1375 by Petrus Raimundi). Detail of the pin (vertical piece) and the horse (transversal piece) of the astrolabe. They are both late replacement pieces as their rough finish reveals. These small pieces were very likely to be lost during the handling of the astrolabe throughout centuries. Photograph of the author by courtesy of the Museum of Fine Arts in Boston (astrolabe accession no. 88.654).
<The suspensory part>
<The ring>
(a) Front and (b) profile. Arabic astrolabe made in Cordova in 1054 with later additions in Catalan. Detail of the suspensory part with the throne, the armilla fixa (the fixed ring), and the armilla reflexa (the mobile ring). Photographs of the author by courtesy of the Jagiellonian Museum (Kraków) (astrolabe accession no. 4037).
<The horse>
9. <Colophon of the author>
1 Here ends the explanation of the construction of an astrolabe, thank God! 2 It was finished the year 5136 (Julian year 1376) in the sixth millennium according to the counting that we use, in the city of Seville. 89 3 I translated it from Arabic into Hebrew in the month of Elul, in the city of Barcelona, the year for I give you good doctrine <(Pr 4:2)> (i.e. 5138, Julian year 1378, month of August/September). 90
10. <Colophon of the copyist>
1 This was written by myself, Yehiel son of Menasheh of blessed memory, in the holy community of Saragosse, in the month of Tevet, year 5228 (i.e. November/December of 1467). 2 Thank God. Amen.
Supplemental Material
Hebrew_edition_and_Hebrew_appendices_J._Rodriguez-Arribas – Supplemental material for A Treatise on the Construction of Astrolabes by Jacob ben Abi Abraham Isaac al-Corsuno (Barcelona, 1378): Edition, Translation and Commentary
Supplemental material, Hebrew_edition_and_Hebrew_appendices_J._Rodriguez-Arribas for A Treatise on the Construction of Astrolabes by Jacob ben Abi Abraham Isaac al-Corsuno (Barcelona, 1378): Edition, Translation and Commentary by Josefina Rodríguez-Arribas in Journal for the History of Astronomy
Footnotes
Appendix 1
Appendix 2
Appendix 3
Acknowledgements
I want to thank the staff of the museums and libraries who assisted me before and during my stays to study and describe the astrolabes mentioned in this article: Marietta Camareri and Abigail Hykin of the Museum of Fine Arts in Boston; Marcin Banas of the Jagiellonian Museum at the University of Kraków; Christoph Rauch of the Staatsbibliothek zu Berlin – PK; Julia Dudkiewicz of the Society of Antiquaries of London; and a private collector in Paris. I deeply appreciate Stephen Johnston, Flora Vafea, Jose Chabàs, Bernard R. Goldstein and Amos Geula for their very valuable comments on different aspects of this article. I also thank Maud Kozodoy and Katelyn Mesler for their reading. Needless to say, I am solely responsible for the contents and for any possible error or mistake.
Funding
Notes on Contributor
Josefina Rodríguez-Arribas has substantial research experience in the fields of the history of medieval science (astronomy, astrology, and scientific instruments) and medieval Hebrew language (the emergence and constitution of technical terminology in medieval Hebrew). Since 2011 her research has focused on the relations of the textual and the material scientific cultures of Jews, notably, the cultural role of astrolabes among Jews in Europe and the Near East between the 12th and 17th centuries. She is currently preparing a commented catalogue of Jewish astrolabes and two books on the literature related to astrolabes written by Jews in the Middle Ages and the Renaissance.
Notes
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
