some medieval reports of venus and mercury transits

To the Elephant, in grateful appreciation

Some Medieval Reports of Venus and Mercury Transits

by BERNARD R. GOLDSTEIN*

Introduction

Medieval reports of transits are generally taken as observations of sunspots because the descriptions, dates, and durations make more sense according to that interpretation. Indeed, I have no quarrel with those scholars who would use these reports as data for sunspot activity, but it must be also recognized that to understand the reports themselves, the medieval astronomical context has to be kept in mind. To be sure the possibility that a medieval report refers to an actual Venus transit cannot be excluded, for such an event, though rare, is visible to the naked eyel.

To confirm this statement, I can refer to a newspaper clipping that was left between the leaves of a copy of a report by Simon Newcomb located in the Yale Astronomy Library.

OBSERVATIONS IN THE HAWAIIAN ISLANDS BY THE BRITISH ASTRONOMICAL PARTY.

From the Honolulu Commercial Advertiser, Dec. 12. [ 18741

The long-expected celestial phenomenon has been most satisfactorily observed at this point; and the success of the eminent astronomers now residing here is a cause for rejoicing in this community. During the day there was a very general demand for broken panes of glass and bottles, which were smoked and held in readiness for looking at the sun at 3:30 o’clock, when the great celestial event was predicted to take place. The natives were as busy with their preparations for astronomical observations as the white foreigners. Little Kanakas were going about the streets with pieces of blackened glass in hand, for the purpose of looking, as they said, at the Hokulaa, the Morning Star,

,

* Yale University, New Haven, Conn. U.S.A. This research was supported by a National Science Foundation Research Grant.

Cencaurur 1969: vol. 14: no. 1: pp. 49-59

4 CENTAUIIUS, VOL. XIV

50 Bernard R. Goldsrein

go through the sun, which they expect will be hereafter burnished with an increased solar splendor.

It was curious to listen to the remarks and speculations of natives whose savage fathers had never suspected this occasional spot on the great light of day. They knew that Lono, or Capt. Cook, the discoverer of these isles, had come to these seas to observe a star in the sun, and it had been predicted in his day that it should be seen again more than a hundred years afterward on this day, with the hour and the minute, and the very second specified. And now there were ten thousands throughout these isles looking upward to prove the truth of this century- old prediction.

At a few minutes past 3, you could see everywhere in the streets faces looking upward toward the sun, with a piece of shaded glass in hand to screen his fierce rays from man’s weak, yet ambitious, searching eyes. A minute or two elapsed, and no change in the dusky red ball above. Another minute gazing upward, and still no spot flecks the face of the sombre rubescent orb. Ha!-“aia la!”-there it is, cries one keen-sighted, close watching Kanaka; and now we begin to see, a little’ to the right of the top or vortex of the sun, a slight dent or notch; and as we gaze on, the dent or spot enlarges, advances within the borders of the disc; and as the clearly-defined dark macula upon the ruddy plane is now distinctly seen by every eye, an enthusiastic native says, “Surely they who behold this were prophets, and Lono was a prophet. . . ”

In ancient and medieval astronomical treatises, the discussion of transits is often introduced in the section on the order of the planets, for if a transit had been observed, the planet involved must be below the sun. In this context, Ptolemy remarked that even if a planet did transit the sun, it might not be visible on account of the brightness of the sun and the small area of it that the planet would cover.2 Despite this difficulty, Ptolemy concluded that the spheres of Mercury and Venus lie below the sun, i.e. that at both inferior and superior conjunction they are closer to the observer than is the sun. We now know that a transit may only occur at inferior conjunction, but Ptolemy’s widely accepted theory allowed for the possibility of transit at superior conjunction as well. Thus it would have been entirely proper for a medieval astronomer, seeking to determine the order of the planets by an astronomical observation,

Some Medieval Reports of Venus and Mercury Transits 51

to compute in advance the latitude of Venus or Mercury at inferior or superior conjunction. If the latitude was close to zero he could then look to see whether a transit occurred. But his procedure for observing a transit would also permit him to see a sunspot if one were visible at the time, and the sunspot, taken to be a planet, would then confirm his transit prediction.3

Transit reports are associated with the names of al-Kindi (ninth century), Avicenna (eleventh century), Averroes (twelfth century), and Ibn Biijja (twelfth century). In addition to these reports, a few transits are mentioned in a non-astronomical context. In this category is the alleged Mercury transit of 807, said to have lasted eight days, that is reported in a chronicle of the life of Charlemagne.4 The author of this chronicle cannot be expected to have known that by any astronomical theory, including those of ancient and medieval astronomers, this duration for a transit is out of the question. Yet we shall find that even among astronomers, transit reports were treated uncritically.

1. The Transit Report of al-Kindi

Ibn al-Qifli (d. 1248) gives this report in Arabic.5 Ghars al-Na‘ma Muhammad b. al-Ra’is Hiliil b. al-Muhassin al-SZbi said in his book: I found in the handwriting of Jayar b. al-Muktafi [d. 98716 . . . that in the year 22s during the caliphate of al-Mu‘tajim there appeared a black spot (nukta) close to the middle of the sun. This took place on Tuesday, 19 Rajab 225 [May 2.7, 8401, and when two days had gone from this date, i.e. after 21 Rajab, events (cala- mities) occurred. Al-Kindi mentioned that this spot lingered on the sun for 91 days and soon thereafter Mu‘tajim died. Before the death of al-Mu‘tasim two comets appeared, as some had before the death of al-Rashid. AI-Kindi mentioned that this spot was due to the oc- culting of the sun by Venus, and their clinging together for this period. . . Up to here this (passage) is taken from the treatise of Ibn al-Muktafi.

In addition to Ibn al-Qifli’s report, another source for this alleged transit is a statement by Averroes (who lived before Ibn al-Qifli). Aver- roes’s account (see Section 3 below) is consistent with that of Ibn al- Q@i but no mention is made of the duration of the transit.

If Ibn al-Qifli’s report is based on an accurate transmission of al-

4.

52 Bernard R. Goldstein

Kindi’s interpretation, namely, that he considered the spot on the sun to be a Venus transit that lasted for 91 days (in fact a transit only lasts several hours), it does not speak well for al-Kindi’s knowledge of astronomy. Moreover, on May 25, 840, Venus was near its greatest elongation from the sun.’

2. The Transit Report of Avicenna

Unlike the other transit reports considered in this paper, Avicenna’s is not at all well known. I first came across Avicenna’s report in looking at authors who mentioned al-BipGji, a twelfth century Spanish philosopher known for his attempt to replace Ptolemy’s astronomical models. * In Yahuda b. Solomon Kohen’s encyclopedia (originally in Arabic, but extant only in a Hebrew version by the author himself) there is a descrip- tion of al-Bitriiji’s theory preceded by a short introduction on the order of the planets.9 Yahuda notes that al-BitrGji put Venus above the sun and Mercury below it, whereas Jgbir b. Aflahlo argued that both Mercury and Venus lie above the sun. But “Avicenna saw Venus appearing like a spot (ketem) in the midst of the sun and thus Venus lies below the sun.”ll The same observation by Avicenna is reported by NaSir al-Din al-Tiisi in his redaction of the Almagest at the beginning of Book IX,1* where he also mentions a report by another author, Salih b. Muhammad, whom I cannot identify.13 The fact that the latter report mentions an interval of 20 years between two Venus transit observations automatically excludes a Venus transit for at least one of them.

I [Nasir al-Din] say: al-Shaikh al-Ra’is abii ‘Ali b. Sind [Avicenna] mentions in (one of) his books that he had seen Venus as a spot (khd aw shiima) on the surface of the sun. Salih b. Muhammad al- Zaynabi [ ?] al-Baghdddi mentioned, in his book which he called The Almagest, that al-Shaikh Abii ‘Umrcin, in Baghdad, and ~ u ~ a ~ ~ a d b. Abii Bakr al-Hakim, in Farsin in the neighborhood of Tiilak [?I, saw the body of Venus on the disk (qurs) of the sun, twice, separated, by about 20 years.

It was my hope that the original passage in Avicenna’s own work would include a date from which one could decide if he had observed a transit, a sunspot at the time of conjunction, or a sunspot at an astro- nomically meaningless time.


I obtained a microfilm of an Arabic text from the Bibliothitque Na- tionale, Paris, identified in the catalogue as Avicenna’s Compendium of the Almagest.14 Avicenna here states (in his comments on the beginning of Book IX concerning the order of the planetary spheres):15 “I say that I saw Venus as a spot on the surface of the sun,” with the very words cited by Nasir al-Din. Unfortunately, no date is given for the observation, nor does he mention the other transits that Nasir al-Din cited. Since Avicenna died in 1037 A.D., the only Venus transit in his lifetime took place on May 24, 1032, and this transit may not have been visible where he lived.16

3. The Transit Report of Averroes

The transit report associated with the name of Averroes is well known because Copernicus took note of it in De RevoZutionibus.~7 In 1893, Steinschneider identified the work of Averroes in which this report oc- curs, preserved in a Hebrew translation of the original Arabic text.18 Averroes reports, in a comment on the arguments for the order of the planets in Ptolemy’s Planetary Hypotheses (Sefer ha-sippiir), that two black spots (ketamim) were seen on the sun at the time of Ibn Mu‘iidh by Ibn Mu‘iidh’s nephew (ben ahot), and that by computation he, Aver- roes, found that Mercury and Venus were in conjunction with the sun at that time. No date is given but Ibn Mu‘Bdh is known to have observed the solar eclipse of July 3, 1079.19 Averroes goes on to mention that he read in “some books” that a similar event was noted at the time of al-Kindi, and when al-Kindi was asked about it, he reasoned that one of the two planets was below the sun (i.e. Mercury or Venus was in our line of sight).

It should be noted that the underlying report does not associate the observation with a transit, but that in the interpretation of the report Venus and Mercury are introduced. Presumably the widely held theory of the incorruptability of the heavens led him to ignore the possibility that the spots were on the body of the sun itself. Averroes implies, by stating that he computed positions, that the original report included a date. Since simultaneous transits of Mercury and Venus did not take place, he either miscomputed, used faulty tables, or ignored the planetary latitudes. It seems to me that the third possibility is most probable, introduces the fewest assumptions, and is consistent with the text. If this

54 Bernard R . Coldstein

is the case, a possible, but by no means unique, date for Averroes’s computation is May 15, 1068, when both Mercury and Venus were very nearly in conjunction with the sun.20 In any event, Averroes has used an extant observation to prove that Mercury and Venus lie below the sun.

Near the end of Levi ben Gerson’s lengthy treatise on astronomy (in Hebrew), he considers the problem of the order of the planets, and in this section be recalls the observation reported by Averroes.21

Averroes (Ibn Rushd) reported that spots (ketamim) were perceived below the sun at the time of its [Venus’s?] conjunction with the sun. If this is the case, it must have been due to objects (iitiit, lit.: signs) in the air that occulted part of the sun by the amount of that spot. Indeed it is improbable that this (spot) observed on the body (of the sun) was due to any of theplanets, for reasons mentioned earlier. Moreover, the shadows of these planets do not reach it, and therefore cannot hide any part of the sun from our sight. On the other hand, i f the object between us and the sun were perceptible by itself, it might be perceived for that reason; but Mercury is not perceived in this place. Yet even if it were perceived, it would not obscure the sun because it (Mercury) is a luminary, and on account of its small size one could not distinguish between the two luminaries. For Venus it is even clearer that it cannot be perceived in the way just described. This report (of Averroes) seems to me not unlike one told by a Master of Opinion (ba‘al ha-sevara) to strengthen and confirm his belief. Thus there is the report by Galen on the basis of which he explains that an animal probably stays alive for a short time without a heart22. . ,

It is clear that this report of Averroes did not affect Levi’s views on the order of the planets. His arguments for rejecting the report, however, are not entirely clear to me. Earlier, in the same chapter, Levi indicates that he prefers the view that the planets are self-luminous rather than that they receive their light from the sun. Moreover, he states that it is more likely that Venus and Mercury lie above the sun than below it. Here, I take it, he first considers the planets as opaque, in which case they would cast a shadow. Since the umbra would not reach us, he concludes that we would not see a transit. If this interpretation is correct, he has simply neglected the penumbra effect. The second argument is


based on the assumption that the planets are self-luminous. Here he notes that the planets are not visible near conjunction with the sun. But even if a planet were visible as it approached the sun, a transit would not be visible because one could not distinguish the body of the planet from that of the sun.

4. The Transit Report of Ibn Biijja

Qutb al-Din al-Shiriizi (d. 1311), a student of Nasir al-Din al-Tiisi, wrote several important astronomical treatises, among them NihZyat al-idrCk.23 In the section on the order of the planets he cites an observation of a Venus transit by the Spanish phiIosopher Ibn Biljja (d. 1139) whose astronomical writings do not survive.24 This passage was quoted by al-Birjandi (early sixteenth century) and ascribed to “the author of Nihaycit al-idriik,”zs and was also quoted by Ali al-Qiishji (d. 1474175) in his commentary on Qutb al-Din’s al-Tuhfa al-ShZhiya.26 This is what Qutb al-Din wroteP

The scholar Abii Bakr b. (SZeigh)2g known as Ibn BZjja29 al-Andalusi mentioned in one of his books, “At sunrise one day I was standing on the roof of my house, and I saw two spots on the surface of the sun. I calculated the positions of Venus and Mercury at that time from the zij, and I found them both near the position of the sun. Therefore I concluded that the two spots were Venus and Mercury.”

In this case the observation could not have been of a Venus transit, for none took place between 1040 and 1153, and Ibn Biijja died in 1139.

Conclusion

It is clear that we do not have a well authenticated medieval report of a transit; the only report for which the observation of a transit cannot be excluded immediately is that of Avicenna, whose report includes too little information.


NOTES

1. Cf. J. Meeus, “The Transits of Venus of Venus 3000 B.C. to A.D. 3000”, I. of the Brit. Astron. Assoc., 68 (1958), 98-108. Meeus writes (p. 991, “As transits of Venus over the Sun are visible with the naked eye, a table of such transits might be of some value to historians of astronomy.” Of possible interest for the subsequent discussion are the four Venus transits between 800 and 1200 A.D.; Nov. 23-24, 910; May 24, 1032; May 22, 1040; and Nov. 23-24, 1153 (Meeus, p. 101).

2. B. Goldstein, “The Arabic Version of Ptolemy’s Planetary Hypotheses,” (Trans. Amer. Phii. SOC. n.s. 57, 1967), p. 6.

3. Kepler once thought he had observed a Mercury transit (using a camera obscura), which he expected on the basis of a computation prior to the event, and published a short treatise in 1609 announcing it (Cf. Kepler. Gesammelte Werke IV (1941). p. 92). However, Kepler later realized that what he had observed was in fact a sunspot and not a transit. For a discussion of this episode, cf. E. Rosen. Kepler’s Conversation with Gulileo’s Sidereal Messenger, New York and London: Johnson Reprint Corp.,

4. Mon. Germ. Hist. Script., I (1826), 194, and Annales Regni Francorum, ed. F . Kurze, Hannover, 1895, p. 123: “A. 807.. . Nam etstella MercuriiXVZ. KaI. Apriiis [March II] visa est in sole quasi parva macula, nigra tamen, paululum superius medio centro eiusdem sideris, quae a nobis octo dies conspicirur. Sed quando primo inrravir vel exivit, nubibus impedientibus minime adnotare potuimus.” GaIiIeo was aware that this report was erroneous and stated that it described the observation of a sunspot (Cf. S . Drake, Discoveries and Opinions of GaZiIeo, New York: Anchor Books. 1957, p. 117). To be sure, there was no Mercury transit at that time. Cf. G. Sarton, “Early observations of sunspots?” Isis 37 (1947). 69-71, for this report and some others.

5. Tu’rikh al-bukarnd, ed. I. Lippert. Leipzig, 1903, p. 156. This passage may also be found in Casiri, Bibliotheca Arabico-Hispana Escurialensis, Madrid, 1760, vol. 1,

6. Cf. H . Suter, Die Mathematiker und Astronomen der Araber (Abhandlungen zur Ge- schichte der marhematischen Wissenschaften, vol. 10, Leipzig, 1900). pp. 64-65, 212.

I. B. Tuckerman, Planetary, Lunar, and Solar Positions A.D. 2 to A.D. 1649 (Memoirs Djfhe Amer. Phil. Soc., vol. 59, 1964). p. 438.

8. The Latin version of al-Bitrfiji’s treatise is published: De motibus celorum, ed. F. J. Carmody, Berkeley and Los Angeles, 1952. I have prepared B critical edition of the original Arabic text with an English translation and notes, which wiii appear, I trust, in the not too distant future.

9. On Yahuda ben Solomon Kohen (thirteenth century, Spain), see M. Steinschneider, Die Hebraeischen Uebersetzungen des Mittelalters, Berlin, 1893, p. 1 ff. I have consulted the copy of this encyclopedia preserved in Ms. Bodleian hebr. Michael 551.

10. On Jttbir b. Aflah (twelfth century, Spain) see H. Suter, op. cit., p. 119; Steinschneider, op. cit . , p. 543; and Delambre, Histoire de I’astronomie du moyen bge, Paris, 1819, pp. 179-85. The Latin version of Jlbir’s astronomical treatise was published by P. Apianus in 1534.

11. Ms. Bodleian hebr. Michael 551, fol. I60a.

1965, pp. 9i-99.

p. 422-23.


12. On Nasir at-Din (thirteenth century, Iran) see E. S . Kennedy, A Survey of Islamic Asfronomical Tables (Trans. of the Amer. Phil. Soc., n.s. 46, 1956), pp. 125, 161-62; A. Sayili, The Observafory in Islam, pp. 189 ff.; and Suter, op. cif., pp. 146-53. For Nasir al-Din’s redaction of the Almagest, I consulted Ms. British Museum arab. Reg. 16A. VIII; book IX begins on a folio numbered in two ways: 131b and 251b. This passage was noted by C. A. Nallino, Scritti V (1944), p. 82.

13. A. Sayili mentions observations of Venus transits by Ibn Sina, Muhammad $Blih ibn Muhammad al-BaghdBdi, and Muhammad ibn Abi Bakr al-Hakim, on the authority of the annotations by ‘Abd al-‘Ali al-Birjandi (early sixteenth century) to QBdizHda’s commentary on the Mulakhkhq of Chaghmini, published in Istanbul 1290 H., pp. 16, 40. Professor Sayili sent me a hand copy of the passage and I checked it with two manuscripts of this text of at-Birjandi: Princeton H. 504, fol. 84a-84b, and Yale A-307, fol. 338. At-Birjandi indicates that he is quoting from Nasir al-Din al-TGsi’s redaction of the Almagest (tubrir al-mujisfi). Cf. A. Sayili, “Islam and the Rise of the Seventeenth Century Science,” Turk Turih Kurumu, Belleten, 22 (1958), 360.

14. Ms. Paris arab. 2484. The copy is dated 673 A.H. [1274/5] on fol. 143b, yet the catalogue (Paris, 1883-95) gives 683 A. H. Suter (up. cit., p. 90) cites another copy of this work in the Bodleian Library on the basis of Uri’s Catalogue of Arabic mss. there (1787, 1, 1012, ms. Marsh 621 dated 671 A.H. [1272/3]), and Brockelmann also accepted this identification (Gesch. urub. Lift., 2nd ed., Leiden, 1943, G 1457, no. 70). This Bodleian text is definitely not the same work as that found in the Paris manuscript and there is no evidence in the manuscript to connect it with Avicenna. The Paris text states that it is Avicenna’s Compendium of the Almagest (fol. lb) and in general it follows the order of books and chapters in the Almagest. On the other hand, the Bodleian text gives neither a title nor an author (after a short invocation it begins: qdla aJ-shaikh gaddasa alhh rtibahu), and it does not follow the order of books and chapters in the Almagest. Avicenna believed that his observation of a Venus transit demonstrated that Venus lies below the sun, but the author of the Bodleian text states that Venus lies above the sun and Mercury below it (fol. 185*). The unusual theory of planetary sizes and distances as well as the many references to Ptolemy’s Planetary Hypotheses make the Bodleian text of considerable interest. Dr. Noel Swerdlow of the University of Chicago is currently working with me on a study of this anonymous manuscript and we plan to publish our results shortly.

15. Ms. Paris, arab. 2484, fol. 978-97b. 16. It is known that Avicenna lived in many different places in Iran and environs (cf.

Suter, op. cit., p. 86-90), but I do not know where he was on May 24, 1032. For this reason I asked Dr. Brian Marsden of the Smithsonian Astrophysical Observatory to consider whether the sun was above the horizon at the time of the transit anywhere in the region between Baghdad and India. His conclusion, communicated to me in a letter dated Nov. 8, 1967, was that on the basis of available modern astronomical data it remains an open question as to whether Avicenna (or anyone else in this region) could have seen the transit or not. Marsden’s reasoning is presented below:

“Using the equation in Meeus’ article [see note I], for the time of sunset in Baghdad on 1032 May 24, I get 16h02mUT. Not having any reliable eclipse data from the 11th century, we cannot be sure what the difference between


ET [Ephemeris Time] and UT [Universal Time] was, but it is my guess that Meeus’ values for the U T time of the transit of Venus are correct to within about 15 minutes. The earliest possible time for the first contact would thus be 15h21m, and the latest possible time for the second contact (Venus fully on the solar disk) would be 16h07m. The longitudes of places where the sun is setting (upper limb of sun on refracted horizon) at these times at various latitudes are given in the following table:

U T 15h21m 16h07m Lat. 30“N 52O.8 E 41O.3 E 32 54.0 42.5 34 55.2 43.7 36 56.5 45.0 38 57.9 46.4 40 59.3 47.8

For a mountain site the longitude would be further east. Something of the transit might have been visible west of the longitudes in the first column (i.e. west of the line from Shiraz to Ashkhabad), and Venus almost definitely could have been seen completely on the disk west of the longitudes in the second column?’

17. Copernicus, De Revolutionibus, I, 10, ed. F. Zeller and C. Zeller, Munich, 1949, p. 23. A note on this passage (p. 440-41) refers us to E. Zinner, Enrstehung und Ausbreitung der coppernicanischen Lehre, Erlangen, 1943, p. 510, where it is argued that Averroes is a mistake for Aven Rodan rA1i b. RidwBn, eleventh century] and that Copernicus had misread the relevant passage in Pic0 della Mirandola. The evidence, however, leads to the conclusion that it is Zinner, and not Copernicus, who misread Pico. As Nallino points out (Scritti, V (1944), 82), Copernicus’s source was probably Pico’s Disputationes in astrologiam X , 4 (Opera omnia. Basel, 1572-73, vol. 1, p. 685): “Averrois in paraphrasi magnae compositionis Ptoiemaei dicit se quondam in Sole duas quasi maculas nigricantes annotasse, cumque numeros digessisset per id tempus, inventum Mercusium Solis radii oppositum.” I consulted the 1495 edition (Bononiae, Benedictus Hectoris), and it agrees exactly with the Basel edition.

18. Steinschneider, op. cit., p. 546 ff. I have consulted Ms. Paris hebr. 696, fol. 82b. 19. A report of his observation is preserved in Ms. Paris hebr. 1036, fol. 1-6. On Ibn

Mu‘ldh, cf. H. Hermelink, “Tabulae Jahen,” Archive for History of Exact Sciences 2 (1964), 108-12, and A. I. Sabra, “The Authorship of the Liber de crepusculis,” Isis

20. Tuckerman, op. cit., p. 552. The longitude of the sun was 60.28”, of Mercury (in retrograde motion) was 59.59”. and of Venus (in direct motion) was 60.03”. The latitude of Mercury was not close to zero at this time. That Venus was in direct motion, i.e. at superior conjunction, and yet considered to lie between us and the sun, conforms to the Ptolemaic view that the sphere of Venus lies entirely below that of the sun.

58 (1967), 77-85.

Some Medieval Repor15 of Venus and Mercury Transits 59

21. On Levi ben Gerson (fourteenth century, southern France), see M. Steinschneider Mathematik bei den Juden, 2nd edition, Hildesheim, 1964, p. 129 ff.; and E. Renan, “Les Ccrivains juifs franCais du XIVe sikcle,” Histoire littiraire de la France, Paris, 1893, vol. 31, p. 586 ff. For this report, I have consulted Ms. Paris hebr. 724, fol. 253O (Milhamdt Adonai, Book V, part 1, ch. 133).

22. I wish to thank Mr. Jerome Bylebyl for identifying the corresponding passage in Galen’s works: Galen, Opera omnia 20 vols., ed. K. G. Kiihn, Leipzig, 1821-33, De pfacitis Hippocratis et Platonis libri novem, lib. 11. cap. iv (vol. 5, p. 238-39):

Accidit hoc sane etiam in muItis sacrificiis, quae sic de more celebrantur, et ap- parent animantia, corde jam aris imposito, non respirare tantum, aut clamare fortiter, sed etiam fugere, usque dum sanguinis profluvio commoriantur. Celerrime autem nimirum ex ipsis sanguis evacuatur, quatuor maximis vasis divulsis: sed quuusque adhuc vivunt, et respirant, et clamant, et currunt.

23. On Qutb al-Din al-Shirazi, see Suter, op. cit., p. 158, and E. S. Kennedy, “Late Medieval Planetary Theory,” h i s 57 (1966), 365-78, especially 371 ff. For NihEyat al-idrrik I have consulted British Museum Ms. Add. 7482.

24. On Ibn Biijja (also known as Avempace) as an astronomer, see Suter, op. cit., pp. 116-17.

25. Cf. A. Sayili, The Observatory in Islam, Ankara, 1960, pp. 184-85. The texts cited in note 13 (above) also refer to the observation of Ibn Bajja.

26. On ‘Ali al-Qfishji, see Suter, op. cit., p. 178. I am indebted to Professor Sayili for bringing this passage to my attention and sending me a copy of it based on Ms. Bursa, Hiiseyin Celebi 750, fol. 70b.

27. British Museum Ms. Add. 7482, fol. 21b. 28. Unclear in the British Museum copy of Nihcyat al-idrak, but quite clear in ‘Ali Qfishji’s

29. In no manuscript is the bci pointed, and in some of them this letter could easily be quotation of this passage.

taken for a mim. Nevertheless, there can be no doubt that Ibn Bajja is meant.

some medieval reports of venus and mercury transits

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