Samsó, Julio

Suhayl International Journal for the History of the Exact and Natural Sciences in Islamic Civilisation

Revistes Catalanes amb Accés Obert

Suhayl 9 (2009-2010), pp. 229-246 
 
 
 
 
 
 
 
Reviews 
 
 
Arianna Borelli, Aspects of the 
astrolabe, “architectonica ratio” 
in tenth- and eleventh-century 
Europe. Sudhoffs Archiv 57, 
Wissenschaftsgeschichte. Franz 
Steiner Verlag, Stuttgart, 2008, 
270 pp. 
 
Arianna Borelli’s Aspects of the 
astrolabe is an excellent revision, 
with new interpretations, of all 
known aspects of the early 
collection of Latin texts on the 
astrolabe and other astronomical 
instruments compiled in Catalonia 
towards the end of the 10th century, 
which had a clear Arabic origin. It is 
based on a complete, updated 
bibliography (see pp. 246-266) and 
a direct study of the available 
manuscripts: the two lists of 
manuscripts dealing with the 
astrolabe and dated between the 11th 
and the 15th centuries, which appear 
in appendixes 7 and 8 (pp. 226-
237), are extremely useful and a 
good starting point for any future 
research on the subject. 
 The book comprises six chapters 
plus six appendixes, a bibliography 
and indexes of names and subjects. 
Chapters 1 and 2 give a thorough 
explanation of what an astrolabe is 
and a survey of stereographic 
projection which is more or less 
intuitive and avoids the use of 
geometry and trigonometry. In this 
way the author explains how Latin 
scholars of the late 10th and 11th c. 
were able to understand the treatises 
on the construction of the astrolabe. 
The book continues with a brief 
outline of the history of the 
astrolabe until the 11th c. (3.1) 
followed by an analysis of sources: 
both actual astrolabes (3.2) and texts 
including a survey of editions and 
results obtained in previous research 
(3.3 and 3.4). In this chapter Borelli 
also explains something which is 
essential for the first of the two 
main theses she presents in her 
study: the state of the sources makes 
it extremely difficult to prepare a 
critical edition of the corpus, as she 
exemplifies with the different 
attempts made to establish the text 
of J (De utilitatibus astrolabii). In 
the same way she also underlines an 
obvious truth: only two Arabic 
sources have been identified by Paul 
Kunitzsch as texts translated into 
230 Reviews 
 
Latin in the collection (short 
passages of a treatise by al-Khw×-
rizm÷ and of an Arabic translation of 
Ptolemy’s Planisphaerium).  
The first of her two theses is 
formulated in chapter 4 in which she 
states that the astrolabe manuscripts 
of the old collection “are the written 
traces of a process of transmission 
and assimilation of knowledge 
which took place thanks to a 
combination of written and non-
written, verbal and non-verbal 
strategies of communication” (p. 
99). In other words, one should not 
consider that the extant texts of the 
early collection are, all of them, 
translations of Arabic originals or 
revisions of earlier translations, but 
rather notes taken during or after 
(Borelli emphasizes the importance 
of memory) an oral explanation in 
which drawings were used: one of 
the great assets of this book is its 
careful study of illustrations (see 
4.4, pp. 118-129). 
I fully support this theory 
although I believe that one should 
add actual Arabic artefacts to the 
drawings. The author underlines (p. 
110) the insistence of the texts on 
the need to memorize the Arabic 
terms of the parts of the astrolabe 
and this is, in my opinion, extremely 
important. When one reads, for 
example, the Astrolabii sententiae 
or De utilitatibus astrolabii one is 
somewhat puzzled by the use of 
Arabic terms (in some cases even a 
full sentence) which are totally 
unnecessary because they are 
immediately followed by a Latin 
translation. It seems to me that only 
Arabic astrolabes were available at 
an early stage (the case of the 
“Carolingian astrolabe” is unique) 
and that a minimal knowledge of 
Arabic was necessary to read the 
inscriptions (mainly the abjad 
notation, star names etc.) if one had 
to use an astrolabe. A good example 
of the kind of instruments used can 
be found in the bilingual drawings 
of an Arabic astrolabe made by 
Khalaf ibn al-Muþ×dh, extant in ms. 
BnF lat. 7412 and studied by 
Kunitzsch (2004). Here all the 
inscriptions of the instrument are 
copied carefully in Kufic script and 
are perfectly readable in an 11th c. 
manuscript (see 5.6.1, pp. 203-206). 
An evolution of this kind of 
bilingual illustration can be seen in 
a photograph of the (no longer 
extant) 12th c. ms. Chartres 214 fol. 
30r, where we find a clumsy attempt 
to reproduce the Arabic inscriptions 
of the instrument which become 
barely illegible here; a third 
example, which is even worse, can 
be found in the ms. London, British 
Library Old Royal 5 B, fol. 71r, the 
date of which is doubtful; here the 
author of the drawing has made an 
unsuccessful attempt to reproduce 
the Arabic inscriptions but seems to 
have tired of the effort, leaving most 
of the spaces empty. It is obvious 
that the author of the drawings of 
the BnF manuscript knew Arabic, 
but this is not the case of the two 
others and the successive copies of 
Arabic inscriptions by illustrators 
Reviews 231 
 
who did not know the Arabic 
alphabet became progressively more 
corrupt and illegible. Illustrations of 
this kind are referred to in an 
appendix to the Astrolabii senten-
tiae (Millàs, 1931, p. 288) the title 
of which is “Hec est figura 
interpretationis verborum arabico-
rum in latinum que sunt in 
astrolapsu” (see on this topic J. 
Samsó, “Els inicis de la introducció 
de la ciència àrab a Europa a través 
de Catalunya”, in Joan Vernet & 
Ramon Parés (dirs.), La ciència en 
la història dels Països Catalans. I. 
Dels àrabs al Renaixement. Valèn-
cia, 2004, pp. 115-159, especially 
pp. 132-141). 
Within chapter 4 two subchapters 
are particularly interesting: the first 
(4.5, pp. 129-137; see also 6.3.8, pp. 
187-188) emphasizes, quite convin-
cingly, the echoes of the Arabic 
translation of the Planisphaerium in 
several texts and drawings of the old 
collection, with a thorough analysis 
of the construction of the two 
tropics and the ecliptic. It seems 
clear that the short text edited by 
Kunitzsch (1993) is not isolated and 
that the Planisphaerium was read 
and understood by the Latin 
scholars. The second subchapter 
(4.6, pp. 137-157) contains a careful 
study of the procedures used to 
divide the projection of the ecliptic 
into the twelve zodiacal signs both 
in the different texts and in the 
drawings of manuscripts Vat. Reg. 
lat. 598, fol. 120r and BnF lat. 7412 
fol. 19v, as well as in the 
Carolingian astrolabe. In this latter 
instrument it seems that the division 
of the ecliptic into signs 
corresponds to the original date in 
which the astrolabe was built and 
that it agrees with the instructions 
registered in the texts, while the 
subdivisions into smaller parts, as 
well as the inscriptions with the 
name of the zodiacal signs, are 
much later and made incom-
petently. 
Other details related to the 
astrolabe are referred to in chapter 
5. Thus in 5.6, when Borelli 
discusses the perfect drawings of an 
astrolabe in ms. BnF 7412, she 
remarks (p. 204) that “neither 
Western not Eastern Arabic-Islamic 
astrolabe artefacts usually had plates 
for the seven climates”. This may be 
true but one must bear in mind that, 
at least the Astrolabii sententiae and 
the De astrolabii compositione (see 
Millàs, 1931, pp. 279 and 309) seem 
to refer to plates of this kind when 
they state that an astrolabe is 
composed by five rotae: one of 
them should correspond to the rete, 
another to the “mother” (on which 
the plate for one latitude is 
engraved) and the other three are 
three plates, with latitude diagrams 
on both sides. We have, therefore, 
seven possible latitudes in which the 
astrolabe may be used and it is 
logical to assume that these seven 
latitudes correspond to the seven 
climates. Another reference to the 
climates can be found in 5.3.2 and 
5.3.3 in which Borelli collects 
references in the different manu-
scripts of J (De utilitatibus 
astrolabii) to the maximum length 
232 Reviews 
 
of a temporal hour: 18º, 19º and 20º 
are the values quoted, and it is easy 
to see  that a longest hour of 18º 
corresponds to a longest day of (18 
x 12)/ 15 = 14h 24m, an 
approximation to 14 h. and 30 m 
which, in Ptolemy’s division of the 
climates, corresponds to climate IV; 
similarly a longest hour of 19º 
corresponds to a longest day of  15 
h 12m (15 h in climate V) and 20º to 
16 h (climate VI). The values for the 
longest hour used by the manu-
scripts are, perhaps, the result of 
adaptations to the local latitudes of 
the place in which each manuscript 
was copied. Finally, also in 5.6 (p. 
204), when the author refers to the 
calendric scale on the back of the 
astrolabe drawings of ms. BnF 
7412, as well as in the Carolingian 
astrolabe and in several texts of the 
collection, she believes that this 
scale is a result of the influence of 
Latin culture. This is a hypothesis 
with which I was in full agreement 
until David King published (Suhayl 
8, 2008, pp. 93-119) a study of an 
instrument made by NasÐýlus in 
Baghdad ca. 900 in which a diagram 
of this kind appeared. Nowadays 
one cannot be so sure. 
Chapter 5 begins with the second 
main thesis of the book in which 
Borelli investigates why early 
medieval Latin scholars were 
interested in the astrolabe. Accord-
ing to her, the instrument was useful 
as a way to understand and 
rationalise the structure of the 
world. This is absolutely correct and 
there is no doubt that the astrolabe 
has always been considered as a 
practical instrument of particular 
use for an elementary course on 
spherical astronomy. On the other 
hand, it is obvious that the old 
collection of Latin texts omits any 
reference to astrology (cf. pp. 173-
174). It is also clear that the Latin 
astrological collection published by 
David Juste (2007) under the title 
Alchandreana, which seems to have 
the same origin as the astronomical 
one, explains divination techniques 
which are mostly unrelated to 
astronomy and to astrology proper. 
Therefore the astrolabe was of little 
use to the readers of the 
Alchandreana. The Latin texts 
insist, however, on the utility of the 
instrument for time reckoning and 
for other monastic applications. 
Borelli seems somewhat sceptical 
about the ability of the instrument to 
tell the time (pp. 162-163) and 
refers to the famous passage, 
already discussed by Poulle (1980), 
in which Walcher of Malvern states 
that he has used an astrolabe (a 
nocturnal, according to Poulle?) to 
determine the time of a lunar eclipse 
in 1092. She also refers (pp. 184-
187) to the text in which the depth 
of a body of water is established by 
measuring the time needed by a 
loaded sinker to reach the bottom 
and, then, to reappear again after 
discharging its load: according to 
the text an astrolabe is used for this 
purpose. Borelli believes that other 
instruments, like sundials (see 
below), are more reliable for 
timekeeping. She is probably right 
but, perhaps, slightly hypercritical 
in her rejection of the practical 
Reviews 233 
 
applications of the astrolabe: it is 
obvious that establishing the time 
by an observation of the solar 
altitude has practical difficulties, but 
the determination of the altitude of a 
star is perhaps less difficult. On the 
other hand, the use of the diagram 
for the hours, in the lower part of 
each plate, only gives approx-
imations, but a much better result 
can be obtained by measuring the 
rotation of the index of the rete 
between the rise of the star and the 
moment in which it reaches the 
observed altitude. In daytime a 
sundial can be used, although the 
precision in the measurement of 
time is in ordinary sundials rather 
low. During the night, if one does 
not want to use an astrolabe, the 
only possibilities are a nocturnal or 
a clepsydra. A drawing of a 
nocturnal appears in the lower part 
of Fig. 25 (p. 194), from ms, BnF 
7412, fol. 15r: it depicts a polar 
sighting tube with a graduated 
movable disk at the end. Sighting 
tubes were used by Arab 
astronomers but there is no evidence 
of their knowledge of the nocturnal. 
Chapter 5 also contains an 
analysis of the available information 
on sundials in the old corpus (5.1.4 
and 5.1.5, pp. 164-166) and we find 
most interesting data about equa-
torial sundials in 5.5 (pp. 197-203), 
in which I would like to emphasize 
the importance of the drawing 
reproduced also in Fig. 27 (p. 198): 
ms. BnF lat. 7412, fol. 19r, repre-
sents an equatorial sundial with 
curves corresponding to the hours of 
the five monastic prayer throughout 
the solar year. I do not know 
whether such curves are common in 
early medieval Latin texts and 
instruments, but they remind me of 
the curves for the prayers of Þuhr 
and þa½r in Arabic sources. In the 
same chapter we also find in-
formation on other astronomical 
instruments such as the quadrant 
which Millàs called vetustissimus 
(5.4.5, pp. 195-197) and, especially, 
the celestial globe (5.3.5, pp. 181-
183) described in “De horologio 
secundum alkoram id est speram 
rotundam”: I entirely agree with 
Borelli’s interpretation that the 
passage does not deal with a 
spherical astrolabe, but rather with a 
celestial sphere, as was established 
by Richard Lorch in 1980. It is, 
however, more difficult to accept 
Marco Zuccato’s interpretation 
(2005), according to which the Latin 
text would derive from a treatise by 
Dun×sh ibn Tam÷m, active in the 
Fatimid court of Mahdiya (Tunis)  
ca. 925-960, who would have sent a 
treatise on the sphere to the Jewish 
Cordovan physician ©asd×y b. 
Shaprý£. The possible connections 
of ©asd×y with Catalonia are easy 
to justify but the problem is that the 
treatise sent by Dun×sh to ©asd×y 
did not deal with the celestial globe 
but was an introduction to astron-
omy composed of three parts: the 
science of the structure of the 
spheres, mathematical astronomy 
and astrology (see S.M. Stern in the 
Festschrift for Millás-Vallicrosa, 
Barcelona, 1956). If one looks for a 
source of the Latin text, the use of 
an alidade with two sights 
234 Reviews 
 
(foramina) and other details of the 
description make me think of the 
bayÅa described by al-Batt×n÷ in his 
z÷j, a source that was well known by 
Maslama al-Majr÷Ð÷, whose in-
fluence on the old Latin corpus is 
well established. In fact, the 
drawing of ms. BnF 7412 fol. 15r 
(Fig. 25, p. 194) representing a 
sphere with seven sighting tubes 
may correspond to the afore-
mentioned celestial sphere in which 
the illustrator tried to draw seven 
different positions of the alidade 
which is probably fixed to a 
movable ring (circulus horarum) 
which rotates perpendicularly to the 
horizon. 
Chapter 6 (pp. 214-225) contains 
a summary of the whole book and 
an analysis of the success the texts 
of the old collection had, as it was 
copied until the 15th century. The 
most popular were the late 
recension made by Hermann of 
Reichenau on the construction of 
the astrolabe (text h) and the 
Horologia viatorum, as well as text 
J (De utilitatibus). They remained 
the standard works of reference on 
the astrolabe until, in the mid 13th 
century, the two books on the 
construction and use of the astrolabe 
by the pseudo-M×sh×’all×h appear-
ed. 
 
Julio Samsó 
 
 
Massimiliano Lisa, Mario 
Taddei, Edoardo Zanon, The 
Book of Secrets in the Results of 
Ideas. Incredible Machines from 
1000 Years Ago, Ibn Khalaf al-
Mur×d÷. Leonardo3, Milano, 
2008.  
 
This important publication is a 
luxury product which has been able 
to see the light thanks to the 
sponsorship of the emir of QaÐar. It 
contains the first complete edition 
and translation of Ibn Khalaf al-
Mur×d÷’s Kit×b al-asr×r f÷ nat×’ij al-
afk×r, a book which describes five 
mechanical toys (machines 1-5), 18 
clocks moved by water (machines 
6-15, 17-20, 27-30), four war 
machines (machines 21-24), two 
water-lifting devices (machines 25-
26) and a sundial (machine 31, 
followed by four appendixes, on 
which see below). Machine 16 is 
missing in the manuscript.  
The work is presented in the 
form of four fascicles contained in a 
card box. They are not numbered 
but I will give them numbers 
following a logical order: 
1) Facsimile reproduction of the 
Arabic manuscript Florence, Medi-
cea - Laurenziana Library Or 152, 
fols. 1r-48v. This is the only extant 
manuscript of al-Mur×d÷’s work. 
The date on which it was copied 
appears in fol. 48v: the last ten days 
of May of year 1304 of the Hispanic 
era (1266 A.D.) = 21 Shaþb×n 664 H 
(28th May). Dating according both 
to the Hispanic era and the Islamic 
calendar implies, in principle, that 
the manuscript was copied by a 
Muslim (or, perhaps, a Jew) living 
in one of the Christian kingdoms of 
Spain. The year coincides  with the 
reign of King Alfonso X (1252-


Reviews: ARIANNA BORELLI, Aspects of the astrolabe, “architectonica ratio” in tenth- and eleventh-century Europe

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