NOTES

Armillary Sphere according to Ptolemy.Fig. 9. Armillary Sphere according to Ptolemy.

Fig. 9. Armillary Sphere according to Ptolemy.

It is expressly stated by Ptolemy that a celestial globe was constructed by Hipparchus, who is reputed to have been the founder of spherical trigonometry,41and Pliny tells us that Hipparchus was the inventor of the astrolabe,42which statement probably means that he greatly improved the simple armillae used at an earlier date as an instrument for astronomical calculations.

Ptolemy, in his ‘Syntaxis,’ or ‘Almagest’ as it was called by the Arabs, devoted a chapter to the method of constructing, and to the use of the astrolabe, which must have closely resembled the armillary sphere, describing therein, in terms not altogether easy of comprehension, its several rings and cylinders, and the method of adjusting the same for purposes of determining the latitude and the longitude of celestial bodies. He tells us also how to construct a representation of the sphere of the fixed stars by means of a solid ball, how to place thereon the several constellations, and how to use the same in the study of astronomical problems. Such a globe, he says, “should be of a dark color, that it might resemble the night and not the day.” His description is detailed as to the proper method of procedure in marking the position of the celestial circles on this globe, in arranging the movable rings of “hard and well polished material,” in graduating the rings and adjusting them to move about an axis which is likewise an axis of the globe proper. In marking the position of the fixed stars, we are told that the proper method is to commence at some constant and invariable point of a certain constellation, and hesuggests that the best starting point is the fixed star in Canis Major, that is, the so-called dog star, or Sirius. “The position of the other fixed stars, as they follow in the list, could easily be determined,” he says, “by making the globe to turn upon the poles of the zodiac, thus bringing the graduated circle to the proper point of each. The stars could be marked with yellow or with such other color as one might choose, having due regard for their brilliancy and magnitude. The outline of each of the constellations should be made as simple as possible, indicating with light strokes, differing but little in color from that of the surface of the globe, the figures which the stars in the several constellations represent, preserving in this manner the chief advantage of such representation, which should be to make the several stars very prominent without destroying, by a variety of color, the resemblance of the object to the truth. It will be easy to make and to retain a proper comparison of the stars if we represent upon the sphere the real appearance or magnitude of the several stars. While neither the equator nor the tropics can be represented on the globe, it will not be difficult to ascertain the proper position of these circles. The first could be thought of as passing through that point on the graduated meridian circle which is 90 degrees from the poles. The points on this meridian circle 23 degrees 51 minutes (sic) each side of the equator will indicate the position of the tropics, that toward the north the summer solstitial circle, that toward the south the winter solstitial circle. With the revolution of the globe from east to west, as each star passes under the graduated meridian circle, we should be able to ascertain readily its distance from the equator or from the tropics.”43

That the Romans especially interested themselves in globes, either celestial or terrestrial, is not at all probable, because of their very practical inclinations. There is evidence, however, that in the time of the emperors celestial globes were constructed, especially in the studios of sculptors, but these were made largely for decorative purposes, having therefore an artistic rather than a scientific value. In the year 1900 there was found in a villa at Boscoreale, not far from Pompeii, an interesting fresco (Fig.10), this being acquired by the Metropolitan Museum of New York in the year 1903. It has been referred to as a sundial, but was clearly intended to represent, in outline, a globe exhibiting the prominent parallels and a certain number of the meridians. It is not at all improbable that such subjects were frequently selected for wall or floor decoration.44It appears that astrologers at times made use of globes in forecasting events.45It may further be noted that on certain early Roman coins there may be found the representation of a globe (Figs.11,12), which perhaps had as its prime significance the representation of universal dominion.46

Bosco Reale Roman Fresco, ca. 50 A. D.Fig. 10. Bosco Reale Roman Fresco, ca. 50 A. D.

Fig. 10. Bosco Reale Roman Fresco, ca. 50 A. D.

Greek and Roman Coins.Fig. 11. Greek and Roman Coins.

Fig. 11. Greek and Roman Coins.

Roman Gems.Fig. 12. Roman Gems.

Fig. 12. Roman Gems.

Not until the day of the Byzantine Emperors do we meet with a real scholar who made a particular study of such astronomical apparatus, apparatus which he describes in a special treatise. Among historical scholars the work of Leontius Mechanicus seems not to have found the recognition which it deserves.47He appears to have been a practical man, very active within the field concerning which he wrote, and from his remarkably detailed description we are able to learn something of the extent to which globe technique was carried in the days of the early Eastern Emperors. We at any rate learn from him that globes were constructed in his workshop, which globes, in all important respects, were like those in use at the present time, being, for example, provided with a meridian circle adjusted to move through notches in a horizon circle. The information given us by Leontius, which here follows, is in free translation or paraphrase of his treatise, the whole being condensed. He appears to have been a student of astronomy, as represented by Aratus, for he tells us that he had endeavored to construct a globe on which the constellations and the circles could be made to conform to the records ofthe ancient poet astronomer. He tells us further that he constructed this globe for Elpidius, an estimable man of letters, and one full of zeal for study; that at the time of its construction, though he had the leisure, he did not prepare a description of the globe, but on the insistence of his friends such description he now proposed to write. This appears to be theraison d’êtrefor his treatise. The importance of adhering closely to the statements of Aratus he insists upon, though admitting that writer’s errors, being convinced that most of the globes of which one had knowledge in his day agreed neither with him nor with Ptolemy. Leontius first directs attention to Aratus’ threefold plan in describing the several constellations, in which description that author speaks first of the relation which part bears to part in each; second, of the position of each constellation relative to the celestial circles, as, for example, to the tropics, and third, its position in the heavens relative to the constellations in the zodiac. He follows this statement with a somewhat lengthy reference to the constellation Ophiuchus, or the Serpent, in explanation of the method of description. After having the surface of the globe portioned out for the representation of the several constellations and the important circles, he then proceeds, as he states, to consider the execution, by which he means representing in proper color and outline the several figures, and the mounting of the globe. Upon a properly constructed support should first be placed the horizon circle, through which a second circle should be made to pass; this second circle will serve as a meridian. These circles, he observes, will enclose the ball, all the points of the surface of which should be equally distant from the inner surface of the horizon and meridian circles, that is, there should be a perfect adjustment of the enclosing rings and the enclosed ball. The surface of the sphere should be painted a dark color, as, for example, azure. He sets forth, with considerable detail, the proper method of procedure in locating the several principalcircles, each of which should be graduated. The zodiac should be divided into twelve parts, and the constellations belonging to each of the several parts should be designated by name, beginning with Cancer, following this with Leo, Virgo, and so on, one after the other. In giving the globe a position which actually conforms to the world, the pole should be set to the north, and the movement of the sky can then be imitated by turning the globe to the left. Leontius, by way of summary and definition, at the conclusion of his treatise, speaks of a sphere as a solid having a surface, from all the points of which, if straight perpendicular lines of equal length be drawn, they will reach a point within called the center. This center in the great sphere of the universe is the earth. The poles of the sphere are the extremities of the axis on which it turns. The horizon cuts the sphere into two hemispheres, the one superior and the other inferior to the earth. The sky, which is continually turning, encircles all, one half of it being above, the other below the earth, which is as far removed from the superior part of the heavens as from the inferior.48

30Cicero’s allusion to Thales, cited p. 16, is probably a reference to a tradition.

31Wolf, R. Geschichte der Astronomie. München, 1877, p. 193; Gassendi, P. Opera Omnia. Leipzig, 1658. Vol. V, p. 375. See statement by Cicero, cited below, p. 17.

32Aratus’ poem bore the title, “Phaenomena.” See, for an excellent edition of this poem, Prince, C. L. Phenomena. A literal translation of the astronomy and meteorology of Aratus. Lewes, 1895. In his “Bibliographical remarks,” the translator refers to one hundred and nineteen editions of this poem, dating from the first printed at Bonn in the year 1474. See also n.48, below.

33Passeri, G. B. Atlas Farnesianus Marmoreus insigne vetustatis monumentum. (In: Gori, A. F. Thesaurus gemmarum antiquarum astriferarum. Firenze, 1750. Vol. III.); Denza, P. F. Globi celesti della Specola Vaticana. (In: Publicazioni della Specola Vaticana. Torino, 1894. pp. xx-xxiii.)

34Cicero. De Republica. Bk. I, chap. xiv. The citation is from the translation by Hardingham, G. G. The Republic. London, 1884.

35Lactantius. Institutiones divinae. Bk. II, chap. v.

36Pappus. Collectionum mathematicarum. Edited by Commandino. Urbino, 1588. Bk. VII. See especially the introduction.

37Hultsch, F. Uber den Himmelsglobus des Archimedes. (In: Zeitschrift für Mathematik und Physik. Leipzig, 1878. Bd. 22. Hist. Litt. Abteilung, p. 106.); Same author. “Archimedes.” (In: Real-encyklopädie der klassischen Alterthumswissenschaft.)

38Wolf, op. cit., pp. 122-124.

39Wolf, op. cit., pp. 160-166.

40Wolf, op. cit., p. 130.

41Ptolemy, C. Syntaxis. (Almagest.) Various editions. Bk. VII, chap. 1. This work was first printed in Venice, 1496; the first Greek text in Basel, 1538. See Hues, Tractatus de Globis, for an analysis of this work.

42Pliny. Historia Naturalis.

43Ptolemy, op. cit., Bk. V, chap. i; Bk. VII, chap. v; Bk. VIII, chap. iii. Ptolemy mentions by name forty-eight constellations, all of which he probably obtained from the earlier Greeks. These constellations, the names being still retained, are:The Zodiac.AriesCancerLibraCapricornusTaurusLeoScorpioAquariusGeminiVirgoSagittariusPiscesThe Northern Hemisphere.AndromedaCoronaLyraUrsa MajorAquilaCygnusOphiuchusUrsa MinorAurigaDelphinusPegasusSagittaBoötesDracoPerseusCassiopeiaEquuleusSerpensCepheusHerculesTriangulumThe Southern Constellations.AraCetusCraterLupusArgo NavisCentaurusEridanusOrionCanis MajorCorona AustralisHydraPiscis AustralisCanis MinorCorvusLepus

The Northern Hemisphere.

The Southern Constellations.

44Visconte, P. E. Nota intorno ad un’ antico globo celeste scolpito in marmo porino. Roma, 1835; Gaedechens, R. Der marmorne Himmelsglobus des fürstlich Waldechschen Antikenkabinettes zu Arolsen. Göttingen, 1862.

45Schanz, M. Geschichte der römischen Litteratur bis zum Gesetzgebungswerk des Kaisers Justinian. München, 1890. See p. 75 for a reference to the astrologer Nigidius Figulus.

46Coins on which there appears a representation of a globe were numerous. Attention may also here be called to the imperial insignia, a part of which was a globe, which the emperor was represented, in the pictures of the day, as holding in his hand. See King, C. W. Antique Gemsand Rings. Vol. II, plates xxvi and xxxviii.

47Weidler, J. F. Historia astronomiae. Vitembergae, 1741. This author is of the opinion that Leontius lived in the eighth century, p. 201; Susemihl. Geschichte der Griechischen Litteratur der alexandriner Zeit. Leipzig, 1891. See Vol. I, p. 294, for a statement of the belief that Leontius lived in the seventh century.

48Halma, N. Les Phenoménes d’Aratus de Soles, et de Germanicus Cesar; avec les Scholies de Théon, les catasterismes d’Eratosthenes et la sphère de Leontius traduit ... par l’Abbé N. Halma. Gr. avec Fr. Paris, 1821. pp. 65-73.

The Egyptian Gnomon. From pen drawing.

Followers of Ptolemy.—Early armillary spheres.—Interest of the Califs in globes and astronomical instruments.—The record of the ‘Fihrist.’—Ibrahim.—Caissar.—Mohammed ben Helal.—Mohammed el Ordhi.—The Paris globes.—Ridhwan Efendi.

INpassing from the period of classical antiquity to the so-called Christian middle ages, attention may first be directed to the activities of the Arabs in the field of astronomy and geography, in so far as their activities had to do with the construction of globes.49The information which we have, concerning their astronomical studies in particular, is more detailed than is that which has come down to us respecting any other peoples who may have been interested in these centuries in the same field of study.

Doubt may be expressed at the outset that the Arabs were interested in the construction of terrestrial globes, since with the matter of descriptive geography they appear to have been very little concerned, a fact which their imperfect cartographical attempts clearly demonstrate.50Although the theory of a globular earth was early accepted by their learned men,51there is scarcely a trustworthy allusion in literature to Arabic terrestrial globes which can be cited. An occasional reference, however, has been made by modern writers to a globe said to have been constructed for King Roger of Sicily. Without citing his authority, Freyheer F. v. Zach states that “the oldest terrestrial globe which isknown was made for King Roger II of Sicily in the twelfth century, and is especially remarkable for the value of the metal which was used in its construction, this being 400 pounds of silver. A knowledge of this globe would not have come down to our day had not Edrisi, a famous geographer of that time, given an especial description of the same, under the title Nothatol mostak (Pleasure of the Soul).”52It is probable that the reference here is to a circular disc made by Edrisi, or an armillary sphere, but not to a terrestrial globe.53

As to Arabic celestial globes, a different situation presents itself. It is well known that the inhabitants of Arabia, long before the time of Islam, were in the habit of observing the stars, many of which, as Dorn has noted, they knew and designated by names taken from pastoral life, and several of which they worshiped as visible gods.54

Calif al-Mansur, who began his reign in 754 A. D., appears to have been the first to show a decided taste for astronomical science, and for many centuries following him this interest is strikingly pronounced among the people of his country.55Scholars were eagerly attracted to the works of Ptolemy, which were many times translated into Arabic, and commentaries were written upon his description of the names and figures of the several constellations. The only alteration they allowed themselves to make in the names of the stars was to translate them into their own language, or to substitute for those they could not understand other names that conveyed an idea to their minds, applicable to the constellation before the eyes. Andromeda they called “The Chained Lady”; Cassiopeia they called “The Lady in the Chair”; Orion received the name “The Giant.” They followed in the construction of their armillary spheres and celestial globes the description laid down in Ptolemy’s ‘Syntaxis,’ modifying these astronomical instruments, from time to time, as their studies directed them.56

The list of califs interested in astronomy is a long one, both of those who remained in the original homeland, andof those who went to the new home in the Iberian Peninsula.57The Mohammedan Hulagu Khan, for example, erected, about 1264, an observatory in his Mongol capital, Maragha, near Tabriz, which long remained a noted center for astronomical studies.58This observatory, however, was but one of a number of similar institutions erected either by the Arabs or by the Persians. We are told that the construction of astronomical instruments was brought to a high degree of perfection by these peoples in the thirteenth century.59The names of many of the Arabic astronomers who were particularly expert as globe makers are recorded, and there were many who wrote on the subject of celestial spheres, armillary spheres, and astrolabes, even before the tenth century.60The author of the ‘Fihrist,’ Ibn Abî Ja’kûb an-Nadîm, tells us that Kurra ben Kamîtâ al-Harrânî constructed a globe which he himself had seen.61This, he says, was made of unbleached material from Dabik, and colored, but that the colors were much faded. Ibn Alnabdi, who was known as a clever mechanic, mentions two globes which he had examined and admired for their excellency of execution, in the public library of Kahira, in the year 1043. One of these globes, he says, was made of brass, by Ptolemy himself; the other, of silver, was constructed by Abul Hassan Alsufi, for the immediate use of the king, Adad Eddoula.62

As a visible evidence of the interest of the Arabs in astronomical science, and of their skill in the construction of astronomical instruments, we have preserved to us, besides numerous astrolabes, no less than seven globes, known to have been constructed prior to the year 1600. The oldest one extant is now in the possession of the R. Istituto di Studi Superiori of Florence, Italy.63This fine example of the skill which was attained by the instrument makers of Valencia, Spain, at one time a flourishing center of Arabic culture, appears to date from the second half of the eleventh century. According to an inscription on the globe, we learn that it was made at Valencia by Ibrahim Ibn Said-as-Sahli,in the year 473 of the Hegira, a date equivalent to 1080 A. D. This date Professor Meucci finds confirmed by a careful study of the position of the stars represented on the globe. He notes, for example, that the star Regulus had been placed at a distance of 16 degrees 40 minutes from the sign of Leo. Ptolemy, in the year 140 A. D., gave this distance as 2 degrees 30 minutes. According to Albaregnius, this star advances about one degree every sixty-six years. Since 140 A.D. the star, therefore, would have moved 14 degrees 10 minutes, which fact would lead astronomers to place this star, about 1080, as it appears on the globe. The globe is of brass, 20 cm. in diameter, having engraved on its surface forty-seven constellations, as given by Ptolemy, omitting only the Cup, with 1042 stars, each with its respective magnitude indicated.

A second Arabic celestial globe, which dates from the year 1225, has been described in detail in a monograph by Assemani, which he issued in the year 1790.64This remarkably interesting object belonged, at the time, to the extensive and celebrated collection of antiquities and curiosities of Cardinal Borgia, in Velletri, but may now be found in the Museo Nazionale of Naples. It is composed of two brass hemispheres, having both horizon and meridian circles, the whole resting upon four supporting feet. A Cufic inscription tells us that it was made by Caissar ben Abul Casem ben Mosafer Alabiaki Alhanefi, in the year of the Hegira 622. Caissar probably was an astronomer at the court of Cairo, and the Mohammedan date as given, translated into Christian reckoning, gives us the year 1225.

In the year 1829 Dorn published a detailed description of an Arabic globe which had been deposited in the museum of the Asiatic Society of London (Fig.13) by Sir John Malcolm.65It is of brass, has a diameter of 24 cm., and is furnished with a substantial mounting. The peculiar features of the figures which represent the several constellationssuggest Persian workmanship. In the vicinity of the south pole is an inscription in Cufic characters, telling us that it was “Made by the most humble in the supreme god, Mohammed ben Helal, the astronomer of Monsul, in the year of the Hegira 674.” This year answers to the year 1275 of the Christian era, that is, it was constructed about the same time as the Borgian globe and that belonging to the Dresden collection, briefly described below. Forty-seven constellations are represented. On the horizon circle, in their respective places, we find engraved the words, “East,” “West,” “South,” “North.”

Northern Hemisphere of Globe by Mohammed ben Helal, 1275.Fig. 13. Northern Hemisphere of Globe by Mohammed ben Helal, 1275.

Fig. 13. Northern Hemisphere of Globe by Mohammed ben Helal, 1275.

The Arabic globe, to be found in the Mathematical Salon of Dresden (Fig.14), has proved to be one of much interest and scientific value to students of astronomy.66Bode, who described it in the year 1808, refers to its remarkably fine execution and to its Cufic inscriptions as being among the finest extant specimens of early Arabic writing. The sphere is of brass, having a diameter of 14 cm., and is composed of two parts, separable on the line of the ecliptic. It has a brass horizon circle, on which is engraved at the east the word “rising,” and at the west the word “setting.” It is not supplied with a movable meridian circle, but within the horizon circle, from north to south, and from east to west, there are two brass half circles, of the same diameter as the horizon circle and so adjusted as to form one piece with it. Through such an arrangement it is made possible to turn the globe in any desired direction, one half of it being at all times above the horizon. In addition to the above arrangement, there are two movable half circles, attached at the zenith point by a pivot. These half circles are graduated, and are movable, making it possible to find, by means of them, the declination and right ascension of any star. The base, which must be comparatively modern, consists of a circular plate, from which rise four turned support columns, attached at their upper extremities to the two half circles of brass, on which rests the horizon circle.

Globe of Mohammed ben Muwajed el Ordhi, 1279.Fig. 14. Globe of Mohammed ben Muwajed el Ordhi, 1279.

Fig. 14. Globe of Mohammed ben Muwajed el Ordhi, 1279.

The date of construction cannot be far from 1279, whichis determinable from the position of the stars engraved thereon, relative, for example, to the equinoctial points. The maker’s name, “Mohammed ben Muwajed el Ordhi,” appears near the constellation Ursa Major, and is inlaid in silver. There appear, very artistically engraved, the lines representing the principal circles, the outlines of the several constellations, with their names, some of these being inlaid with silver, some with gold. The equator and the ecliptic are represented on the surface of the sphere, each by two engraved parallel lines, and are graduated, the graduation in each instance being represented by four short and one long line, alternating thus by fives throughout the entire three hundred and sixty degrees. The equator is inlaid with gold, the other circles with silver. The names of the twelve constellations in the zodiac are alternately inlaid with gold and silver, while all star names, except as indicated, are inlaid with silver. The constellations represented number forty-eight, the human figures all being clad, turning the front and right face toward the observer.

The Bibliothèque Nationale of Paris possesses two ancient Arabic globes, one of which, neither signed nor dated, has been thought to have been constructed in the eleventh century.67This was obtained by Jomard, in Egypt, more than sixty years ago. It has a diameter of about 19 cm., is furnished with a horizon circle, which is upheld by four semicircular arms, these, in turn, resting upon a base composed of four flat and rather inartistic supports. The engraving on the surface of the brass sphere closely resembles that on the Dresden globe. A detailed description of this globe has not been obtainable.

A second Paris Arabic globe,68like the preceding, belongs to the Bibliothèque Nationale (Fig.15). It has a diameter of something less than 15 cm., and was constructed by Diemat Eddin Mohammed, in the year of the Hegira 981, which in the Christian reckoning corresponds to the year 1573.

Globe of Diemat Eddin Mohammed, 1573.Fig. 15. Globe of Diemat Eddin Mohammed, 1573.

Fig. 15. Globe of Diemat Eddin Mohammed, 1573.

The Imperial Library of Petrograd possesses an Arabic globe, constructed in the year 1701.69It is described by Dorn as a fine example of the globe maker’s art, closely resembling, in its general features, the Arabic globe in the collection of the Royal Asiatic Society of London. It has a diameter of about 19 cm., rests upon an ornamental tripod base, and is adjusted to turn within a brass circle, which circle is fitted into a larger one, so marked and graduated as to represent four concentric circles. The first or inner circle, representing the horizon, is divided into thirty-six divisions of ten degrees each; on the second circle the degrees are indicated by letters; on the third circle appear the twelve signs of the zodiac and the four principal directions, east, west, north, south; the fourth circle is divided into thirty-six parts, formed by the extension of the lines which divide the first, or horizon circle, into thirty-six parts. On the last circle the names of one hundred and four cities and countries are given. Not far from the north pole is an inscription which gives us the name of the maker and the date of construction. Therein we read that it was completed in the year 1113 of the flight of the Prophet, or in the year 1701 of Christian reckoning, by Ridhwan, for Maulana Hassan Efendi, who, toward the end of the seventeenth century, was director of the astronomical observatory of Cairo, and gave substantial encouragement to makers of globes and of other instruments employed in astronomical studies. The equator, the ecliptic, and the parallels are represented, the first two by parallel circles which are crossed or joined by lines dividing them into seventy-two principal parts, each part being again subdivided into fifths. The close resemblance of this example to the earlier known Arabic globes suggests that there was little, if any, progress among those peoples in the art of globe construction since the eleventh century.

Anonymous Arabic Globe, 1635.Fig. 15a. Anonymous Arabic Globe, 1635.

Fig. 15a. Anonymous Arabic Globe, 1635.

49Delambre, J. B. J. Histoire de l’Astronomie ancienne. Paris, 1817. See Vol. I, pp. 372, 516, containing references to globes, celestial and terrestrial, constructed in India and in China about the years 450 and 724 A.D.

50Peschel, O. Geschichte der Erdkunde bis auf C. Ritter und A. V. Humboldt. Berlin, 1877. See pp. 145-160, wherein reference is made to their lack of interest in descriptive geography; Beazley. Dawn of Modern Geography. Vol. I, chap. vii.

51Günther, S. Studien zur Geschichte der mathematischen und physikalischen Geographie. Halle, 1877. Heft 2; Ibn Abî Ja’kûb an-Nadîm. Katâb al-Fihrist (Book of Records), ed. by Gustav Flugel. Leipzig, 1871-1872. 2 vols. The greater part of this Arabic work was written about the year 987 A. D. Edrisi states it as “the opinion of philosophers, of illustrious savants, and of skilled observers in the knowledge of celestial bodies, that the earth is round as a sphere.” See Edrisi, Geography, tr. de l’Arabe en français par P. Amédée Jaubert. (In: Receuel de voyages et de mémoires. Paris, 1830. 2 vols.) Vol. I, p. 1.

52Zach, F. v. Monatliche Korrespondenz. Gotha, 1806. Vol. XIII, p. 157; Suter, H. Das Mathematiker-Verzeichniss im Fihrist. (In: Zeitschrift für Mathematik und Physik. Leipzig, 1892.) This work contains many references to distinguished oriental scholars who treated in their writings the doctrine of the sphere, the astrolabe, and the armillary sphere.

53Wittstein, T. Historisch-astronomische Fragmente aus der arabischen Litteratur. (In: Abhandlungen zur Geschichte der Mathematik. Leipzig, 1892. Heft 6, p. 98.) The opinion is here expressed that a terrestrial globe by Edrisi never existed; Hadradauer, C. v. Die Feldzeugmeister Ritter von Hauslabische Kartensammlung. (In: Mitteilungen der K. K. Geographische Gesellschaft zu Wien. Wien, 1886. Neue Folge 19, pp. 387-388.) The opinion is expressed that Edrisi constructed a planisphere and not a globe. Amari, M. Storia dei Musulmani di Sicilia. Firenze, 1868. pp. 453 ff., 669 ff.

54Dorn, B. Description of an Arabic celestial globe. (In: Transactions of the Royal Asiatic Society. London, 1829. Vol. II, pp. 371-392.)

55Dorn, op. cit.

56Dorn, op. cit.

57See the list as given in the Fihrist, referred to in note 4. Naser ben Mohamed Abul Gioush, King of Castile, is referred to as having been much interested in astronomy, in which science he acquired such proficiency as to enable him to construct a number of very useful astronomical instruments.

58Lelewel, J. Géographie du moyen âge. Bruxelles, 1857. Vol. I, p. 116; Jourdain. Mémoire sur l’observatoire de Méragah. Paris, 1810. It is well known that under the direction of Nasr-Eddin, who was called to the charge of this observatory by Hulagu Khan, astronomical instruments were constructed.

59Dorn, op. cit.

60See the Fihrist, also a list as given by Dorn.

61Dorn, op. cit.

62Dorn, op. cit.

63Meucci, F. Il globo celeste arabico del seculo XI esistente nel Gabinetto degli strumenti antichi di Astronomia, Mathematica nel R. Istitutodi Studi Superiori. Firenze, 1878.

64Assemani, S. Globus coelestis cufico-arabicus Veliterani Musei Borgiani. Patavii, 1790.

65Dorn, op. cit.

66Beigel, W. Nachricht von einer Arabischen Himmelskugel mit Kufischer Schrift, welche im kurfürstlichen Mathematischen Salon zu Dresden aufbewahrt wird. (In: Bodes Astronomisches Jahrbuch für das Jahr 1808. Berlin, 1808. pp. 97 ff.); Drechsler, A. Der arabische Himmelsglobus angefertigt 1279 zu Meragha. Dresden, 1873.

67Sedillot, L. A. Mémoire sur les instruments astronomiques des Arabes. Paris, 1841. pp. 117 ff.; same author. Matériaux pour servir à l’histoire comparée des sciences mathématiques chez les grecs et les orientaux. Paris, 1845. Vol. I, pp. 334 ff.; Jomard, M. Monuments de la Géographie. Paris, 1854. It is very doubtful that a date so early should be given to this globe.

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