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Dante and the early astronomers . Fig. 29. The Epicycle.Ptolemys method of accounting for movements such as those shown in Fig. 28,. Fig. 30. Planet retrograding, and in opposition {i.e. in opposition to the sun.) PTOLEMY. 141 two motions neutralize one another, so that it appearsstationary, as Mars did on August 22, 1909. Afterthis, the motion of the epicycle more than counter-balances the motion of the deferent, and the planetseems to reverse its direction until it reaches thepoint on the epicycle marked S. After this the twomotions are once more in the same direction, so theplanet is seen t Stock Photo
RM2AJ70WF–Dante and the early astronomers . Fig. 29. The Epicycle.Ptolemys method of accounting for movements such as those shown in Fig. 28,. Fig. 30. Planet retrograding, and in opposition {i.e. in opposition to the sun.) PTOLEMY. 141 two motions neutralize one another, so that it appearsstationary, as Mars did on August 22, 1909. Afterthis, the motion of the epicycle more than counter-balances the motion of the deferent, and the planetseems to reverse its direction until it reaches thepoint on the epicycle marked S. After this the twomotions are once more in the same direction, so theplanet is seen t
Dante and the early astronomers . e other hemi-sphere consequently is all in darkness, from Ganges(la riva ^) to Morocco. Other spirits have been met and spoken with, andthey are still climbing when evening comes, and Dante,thinking he is to reach the summit of the mountainand see Beatrice that day, entreats Virgil to hasten.**See, he says, how the mountain now casts a shadow^For the sun has travelled round to the west, and thepoets, still on its eastern side, are in deep shadow: thisexplains how, when they meet Sordello, he does notrecognize that Dante is a living man, as all the spiritsuntil Stock Photo
RM2AJ6KYE–Dante and the early astronomers . e other hemi-sphere consequently is all in darkness, from Ganges(la riva ^) to Morocco. Other spirits have been met and spoken with, andthey are still climbing when evening comes, and Dante,thinking he is to reach the summit of the mountainand see Beatrice that day, entreats Virgil to hasten.**See, he says, how the mountain now casts a shadow^For the sun has travelled round to the west, and thepoets, still on its eastern side, are in deep shadow: thisexplains how, when they meet Sordello, he does notrecognize that Dante is a living man, as all the spiritsuntil
Dante and the early astronomers . also the immense sphere of stars beyond,were all sweeping together at the same time in anopposite direction, and at the almost incredible paceof one revolution in a day. The brilliant idea occurredto him : Leave the stars at rest, let the seven planetsrevolve in their seven orbits, the nearer to the centrethe faster, and let earth herself revolve fastest of all,viz. in twenty-four hours, in the same direction. Ifshe keeps one face always turned towards the centre,like the moon, this will account quite as well for theapparent diurnal revolution of all the heave Stock Photo
RM2AJ75NF–Dante and the early astronomers . also the immense sphere of stars beyond,were all sweeping together at the same time in anopposite direction, and at the almost incredible paceof one revolution in a day. The brilliant idea occurredto him : Leave the stars at rest, let the seven planetsrevolve in their seven orbits, the nearer to the centrethe faster, and let earth herself revolve fastest of all,viz. in twenty-four hours, in the same direction. Ifshe keeps one face always turned towards the centre,like the moon, this will account quite as well for theapparent diurnal revolution of all the heave
Dante and the early astronomers . lation in the sky was worthy to be comparedwith it. This, he believed, was the very cross of whichDante had spoken in a prophecy. Even among Dantes most enthusiastic admirers, Isuppose none will be found to-day to support this view;but many think that he must have heard of the Crossfrom travellers. True, these stars are visible during atleast part of the year in all places south of 34° north,and therefore in North Africa, and they had beencatalogued by Ptolemy as part of the Centaur, so thatno astronomer could take them to be a newly-foundconstellation, but mi Stock Photo
RM2AJ6R3K–Dante and the early astronomers . lation in the sky was worthy to be comparedwith it. This, he believed, was the very cross of whichDante had spoken in a prophecy. Even among Dantes most enthusiastic admirers, Isuppose none will be found to-day to support this view;but many think that he must have heard of the Crossfrom travellers. True, these stars are visible during atleast part of the year in all places south of 34° north,and therefore in North Africa, and they had beencatalogued by Ptolemy as part of the Centaur, so thatno astronomer could take them to be a newly-foundconstellation, but mi
Dante and the early astronomers . — When on the first day of the month of Nisan the.asterism Mulmul (the Pleiades) ^ and the Moon are seentogether, the year will be normal. When on the thirdday of Nisan the asterism Mulmul and the Moon aretogether, the year will be full (that is, will contain13 months). Each Babylonian month began when the new moonwas first visible after sunset; if at this moment she ^Sayce and Bosanquet indentifyDilgaii with Capella, nob with partof Aries, and consider that a date of about B.C. 2000 is indicated—{MonthlyNotices xxxix, 454). But in any case the method of calen Stock Photo
RM2AJ78F7–Dante and the early astronomers . — When on the first day of the month of Nisan the.asterism Mulmul (the Pleiades) ^ and the Moon are seentogether, the year will be normal. When on the thirdday of Nisan the asterism Mulmul and the Moon aretogether, the year will be full (that is, will contain13 months). Each Babylonian month began when the new moonwas first visible after sunset; if at this moment she ^Sayce and Bosanquet indentifyDilgaii with Capella, nob with partof Aries, and consider that a date of about B.C. 2000 is indicated—{MonthlyNotices xxxix, 454). But in any case the method of calen
Dante and the early astronomers . geless, changes may occur, and in order that eventhe least of these should not pass unnoticed, he setto work to note the number, brightness, and positionof all he could see. This great catalogue of 1080 stars,copied by Ptolemy in his Almagest, was the basisfor all succeeding catalogues, from Spain to Turkestan,until quite modern times. In it, for the first time,the places of the stars were not merely described 124 HIPPARGHU8. according to their position in the constellation figures,but were noted in degrees on the sphere, as is doneto-day. One day, when compar Stock Photo
RM2AJ729W–Dante and the early astronomers . geless, changes may occur, and in order that eventhe least of these should not pass unnoticed, he setto work to note the number, brightness, and positionof all he could see. This great catalogue of 1080 stars,copied by Ptolemy in his Almagest, was the basisfor all succeeding catalogues, from Spain to Turkestan,until quite modern times. In it, for the first time,the places of the stars were not merely described 124 HIPPARGHU8. according to their position in the constellation figures,but were noted in degrees on the sphere, as is doneto-day. One day, when compar
Dante and the early astronomers . Zsntth. Horizon, Fig. 39. Sun, moon, and zenith.To illustrate Par. xxix. 1-6. {See p. 265). In the first figure the sun and nioon are balanced, as it were, being at equal distancesfrom the zenith : in the second, a few minutes later, by the rising of the sun and thesetting of the moon, the balance is disturbed, and each changes its hemisphere. 268 MOVEMENTS OF THE MOON. sister of the sun,i and with the sun one of the twoEyes of Heaven.^ One exception to this harsh treat-ment is in the beautiful description of reaching theheaven of the moon,^ for there she is t Stock Photo
RM2AJ6RPC–Dante and the early astronomers . Zsntth. Horizon, Fig. 39. Sun, moon, and zenith.To illustrate Par. xxix. 1-6. {See p. 265). In the first figure the sun and nioon are balanced, as it were, being at equal distancesfrom the zenith : in the second, a few minutes later, by the rising of the sun and thesetting of the moon, the balance is disturbed, and each changes its hemisphere. 268 MOVEMENTS OF THE MOON. sister of the sun,i and with the sun one of the twoEyes of Heaven.^ One exception to this harsh treat-ment is in the beautiful description of reaching theheaven of the moon,^ for there she is t
Dante and the early astronomers . s, and the moon is ambiguousonce, but quite explicable. Taking the allusions ina simple popular sense, as he seems to intend us to do,assuming that the signs and the constellations of thezodiac are identical, and that the moon, which at firstis opposite the sun, traverses about 13° in the zodiacdaily, and loses about an hour of time more or less,there is very little difiiculty in following him. It isquite enough to know that the sun is somewhere inAries throughout, and that the moon is therefore inLibra at the beginning. But if we wish to know a little more ac Stock Photo
RM2AJ6JPH–Dante and the early astronomers . s, and the moon is ambiguousonce, but quite explicable. Taking the allusions ina simple popular sense, as he seems to intend us to do,assuming that the signs and the constellations of thezodiac are identical, and that the moon, which at firstis opposite the sun, traverses about 13° in the zodiacdaily, and loses about an hour of time more or less,there is very little difiiculty in following him. It isquite enough to know that the sun is somewhere inAries throughout, and that the moon is therefore inLibra at the beginning. But if we wish to know a little more ac
Dante and the early astronomers . gi,come venne, veloce. ^ The sun has now driven Capri-corn from the mid sky with his bright beams, that is,the stars have become invisible in bright daylight, andfig. 46 shows that when Aries rises over the easternhorizon Capricorn will be overhead. But the sun isstill very low, so swift was the coming of the spirits,for Dantes shadow is not yet visible to them: it is byhis breathing that they perceive he is a living man.It is only after the meeting with Casella, and the dis-persal of the spirits by Cato, that the sun, still red withsunrise tints, makes Dantes Stock Photo
RM2AJ6M72–Dante and the early astronomers . gi,come venne, veloce. ^ The sun has now driven Capri-corn from the mid sky with his bright beams, that is,the stars have become invisible in bright daylight, andfig. 46 shows that when Aries rises over the easternhorizon Capricorn will be overhead. But the sun isstill very low, so swift was the coming of the spirits,for Dantes shadow is not yet visible to them: it is byhis breathing that they perceive he is a living man.It is only after the meeting with Casella, and the dis-persal of the spirits by Cato, that the sun, still red withsunrise tints, makes Dantes
Dante and the early astronomers . Fig. 13, The Universe of Leudppus. rim, to secure its contents, and made it divide the sphereof air into two parts, so that it rested upon air, and airwas also in the sky above. The underside of the discwas not inhabited, no doubt because no one could standupside down. His order of the successive heavens is 64 LATER FLAT-EARTH SYSTEMS. not quite the same as that of Leucippus, as he puts themoon and the Morning Star together, and the rest ofthe planets beyond the sun. This scheme gave the universe a beautifully sym-metrical form, which must have pleased the Gre Stock Photo
RM2AJ765C–Dante and the early astronomers . Fig. 13, The Universe of Leudppus. rim, to secure its contents, and made it divide the sphereof air into two parts, so that it rested upon air, and airwas also in the sky above. The underside of the discwas not inhabited, no doubt because no one could standupside down. His order of the successive heavens is 64 LATER FLAT-EARTH SYSTEMS. not quite the same as that of Leucippus, as he puts themoon and the Morning Star together, and the rest ofthe planets beyond the sun. This scheme gave the universe a beautifully sym-metrical form, which must have pleased the Gre
Dante and the early astronomers . Fig. 10. The Scorpion.From a boundary stone (now in thaBritish Museum) set up in the reign ofNebuchadnezzar I., king of Babylonia,about 1100 B.C.. Fig. 11. The Goat, with Fishes Scales.Froui a Babylonian boundary stone. A Scorpion with immense claws, and a Goat withfishes scales appear several times on monuments atleast as old as 1000 B.C. and it is very probable,although this fact alone would not prove it, that theywere then used as constellation fio;ures. It has beendefinitely proved from inscriptions that before 600 B.C.the name of Scorpion was applied to s Stock Photo
RM2AJ77GY–Dante and the early astronomers . Fig. 10. The Scorpion.From a boundary stone (now in thaBritish Museum) set up in the reign ofNebuchadnezzar I., king of Babylonia,about 1100 B.C.. Fig. 11. The Goat, with Fishes Scales.Froui a Babylonian boundary stone. A Scorpion with immense claws, and a Goat withfishes scales appear several times on monuments atleast as old as 1000 B.C. and it is very probable,although this fact alone would not prove it, that theywere then used as constellation fio;ures. It has beendefinitely proved from inscriptions that before 600 B.C.the name of Scorpion was applied to s
Dante and the early astronomers . ry deep, andunder the mountain is the abode of the dead. It isentered from the west, which surely was suggested bythe setting of the heavenly bodies in the west. Thevaulted sky above the earth has divisions : the rim of thelowest part rests upon the supporting watery deep;above it are the upper waters (the source of rain) ; andabove this again is the dwelling-place of the celestials.The sun issues forth each morning from a door in theupper heaven, or from the mount of sunrise, andenters another heavenly door, or the sunset mountain,at night. The similarity to Stock Photo
RM2AJ77C9–Dante and the early astronomers . ry deep, andunder the mountain is the abode of the dead. It isentered from the west, which surely was suggested bythe setting of the heavenly bodies in the west. Thevaulted sky above the earth has divisions : the rim of thelowest part rests upon the supporting watery deep;above it are the upper waters (the source of rain) ; andabove this again is the dwelling-place of the celestials.The sun issues forth each morning from a door in theupper heaven, or from the mount of sunrise, andenters another heavenly door, or the sunset mountain,at night. The similarity to
Dante and the early astronomers . IMew moon close toReiades^ Fig. 7. First Year, normal. New Moon near the Pleiades aftersunset on the 1st of Nisan. The position of the young moon (which always closely follows the sun) showed thatthe sun was not far west of the Pleiades ; and about 1000 B.C. this proved that it wasnear the vernal equinox. The suns position is given for about half an hour after sun-set, when the Pleiades would first be visible. this case he would also be west of Dilgan, the RamsHead, so those stars would rise after him in themorning, and be hidden in his light: therefore, botht Stock Photo
RM2AJ78CB–Dante and the early astronomers . IMew moon close toReiades^ Fig. 7. First Year, normal. New Moon near the Pleiades aftersunset on the 1st of Nisan. The position of the young moon (which always closely follows the sun) showed thatthe sun was not far west of the Pleiades ; and about 1000 B.C. this proved that it wasnear the vernal equinox. The suns position is given for about half an hour after sun-set, when the Pleiades would first be visible. this case he would also be west of Dilgan, the RamsHead, so those stars would rise after him in themorning, and be hidden in his light: therefore, botht
Dante and the early astronomers . a diurnal motion like thestars, as well as their own proper motions, each sethad to be provided with a sphere which moved exactlylike the great all-enclosing star-sphere. Thiis, the sun had one sphere turning like the star-sphere, and within this was a second, on which thesun was fixed, which turned round in a year, in awest-to-east direction. The sun, carried along by thecombined motion, travelled through the sky with thedaily and yearly motions, as we see them. The planetary spheres were much more difficult toarrange. Eudoxus used four spheres for each, andt Stock Photo
RM2AJ747Y–Dante and the early astronomers . a diurnal motion like thestars, as well as their own proper motions, each sethad to be provided with a sphere which moved exactlylike the great all-enclosing star-sphere. Thiis, the sun had one sphere turning like the star-sphere, and within this was a second, on which thesun was fixed, which turned round in a year, in awest-to-east direction. The sun, carried along by thecombined motion, travelled through the sky with thedaily and yearly motions, as we see them. The planetary spheres were much more difficult toarrange. Eudoxus used four spheres for each, andt
Dante and the early astronomers . ickly, so that she rapidly passes many posts,although all the time she is being carried backwardswith them: she is the moon. Children run backwardsand forwards: they are the planets. Finally, if all 20 APPARENT MOVEMENTS OF these people are also constantly crossing the platfoimslowly from right to left and back again, theirmovements will be oblique to the platform movementand will imitate the north and south movements ofsun, moon, and planets. It is in this fashion that the movements of the skiespresent themselves to careful observers on this seem-ingly statio Stock Photo
RM2AJ795D–Dante and the early astronomers . ickly, so that she rapidly passes many posts,although all the time she is being carried backwardswith them: she is the moon. Children run backwardsand forwards: they are the planets. Finally, if all 20 APPARENT MOVEMENTS OF these people are also constantly crossing the platfoimslowly from right to left and back again, theirmovements will be oblique to the platform movementand will imitate the north and south movements ofsun, moon, and planets. It is in this fashion that the movements of the skiespresent themselves to careful observers on this seem-ingly statio
Dante and the early astronomers . ter observations, made with an astrolabe, weremuch more precise; Ptolemy quotes one from Theon ofSmyrna, which states that Mercury was 3° 50 in advanceof the Heart of the Lion (Regulus), and for his ownobservations he also usually gives the sign, degree, andminute. Sometimes the planets had been observed sonear stars that their positions could be very accuratelydetermined by the aid of Hipparchus star-catalogue.Timocharis, on a certain morning in the 13th year ofPtolemy Philadelphus (B.C. 273), saw Venus beside thelast star in the wing of the Virgin (Beta Virg Stock Photo
RM2AJ703G–Dante and the early astronomers . ter observations, made with an astrolabe, weremuch more precise; Ptolemy quotes one from Theon ofSmyrna, which states that Mercury was 3° 50 in advanceof the Heart of the Lion (Regulus), and for his ownobservations he also usually gives the sign, degree, andminute. Sometimes the planets had been observed sonear stars that their positions could be very accuratelydetermined by the aid of Hipparchus star-catalogue.Timocharis, on a certain morning in the 13th year ofPtolemy Philadelphus (B.C. 273), saw Venus beside thelast star in the wing of the Virgin (Beta Virg
Dante and the early astronomers . circle could be read. This last and the eclipticcircle were both divided into 360 degrees, and asmany fractions of a degree as space and skill wouldallow. The equinoctial astrolabe was similar, but the fixedcircle was in the plane of the equator, instead of theecliptic. One of each of these is seen in the viewof the Pekin Observatory. But how did the old astronomers know how to findthe ecliptic and the equator in the sky, and set theircircles in those planes ? This they did by means ofthe suns motion. The gnomon told them the dayof the equinox (see p. 25), and Stock Photo
RM2AJ7393–Dante and the early astronomers . circle could be read. This last and the eclipticcircle were both divided into 360 degrees, and asmany fractions of a degree as space and skill wouldallow. The equinoctial astrolabe was similar, but the fixedcircle was in the plane of the equator, instead of theecliptic. One of each of these is seen in the viewof the Pekin Observatory. But how did the old astronomers know how to findthe ecliptic and the equator in the sky, and set theircircles in those planes ? This they did by means ofthe suns motion. The gnomon told them the dayof the equinox (see p. 25), and
Dante and the early astronomers . ^NesternXHorr^on. lIew Moon 2EW0f Pleiade Fig. 9. Third Year, •full. New Moon distant from the Pleiadeson the 1st of Nisan. Tne sun is now 2x11 = 22 days march, or about 22% short of his tirst position, andthe young moon consequently about 22° west of the Pleiades, so she will not come upwith them until the 3rd Nisan, after travelling 2x13 = 26°. The year was thereforefull, that is an extra month of 29 days was added, which is more than the 22 daysneeded to enable the sun to reach hi.s first psit on by tlie 1st tif Nisan in tlie fourth ye:ir. It apjjears, the Stock Photo
RM2AJ77N7–Dante and the early astronomers . ^NesternXHorr^on. lIew Moon 2EW0f Pleiade Fig. 9. Third Year, •full. New Moon distant from the Pleiadeson the 1st of Nisan. Tne sun is now 2x11 = 22 days march, or about 22% short of his tirst position, andthe young moon consequently about 22° west of the Pleiades, so she will not come upwith them until the 3rd Nisan, after travelling 2x13 = 26°. The year was thereforefull, that is an extra month of 29 days was added, which is more than the 22 daysneeded to enable the sun to reach hi.s first psit on by tlie 1st tif Nisan in tlie fourth ye:ir. It apjjears, the
Dante and the early astronomers . astronomers in placing Saturn, Jupiter, andMars, beyond the sun, in order of the periods of theirdeferents, which were all longer than a year. Venusand Mercury, however, had periods the same as thesun: on which side of him, then, must they be placed ?Some modern authors, Ptolemy says, thought they werebeyond the sun, but he agrees with the most ancient,and places them between sun and moon. The generaldisposition of the heavenly bodies according to Ptolemyis shown in Fig. 35, with the periods of epicycles anddeferents, and the directions of the several movement Stock Photo
RM2AJ6Y3H–Dante and the early astronomers . astronomers in placing Saturn, Jupiter, andMars, beyond the sun, in order of the periods of theirdeferents, which were all longer than a year. Venusand Mercury, however, had periods the same as thesun: on which side of him, then, must they be placed ?Some modern authors, Ptolemy says, thought they werebeyond the sun, but he agrees with the most ancient,and places them between sun and moon. The generaldisposition of the heavenly bodies according to Ptolemyis shown in Fig. 35, with the periods of epicycles anddeferents, and the directions of the several movement
Dante and the early astronomers . $^ % <? Fig. 48. Dantes first view of Earth from the Stars. Par. xxii. (see p. 397). imagined, the shadow of night sweeping westwardover the globe. The Atlantic Ocean, where Ulyssessailed beyond Gades, is all in daylight, and so is theMediterranean, but the sun is setting over Jerusalem,for he says that its position prevents him from seeingbeyond the coast whence Europa was carried (i.e.Phoenicia or Palestine). It must therefore be middayat Gades, and the sun is on the meridian there; it is a 1 Far. xxiii. 29, 30. 396 PARADTSE. sign and more, or something b Stock Photo
RM2AJ6K8J–Dante and the early astronomers . $^ % <? Fig. 48. Dantes first view of Earth from the Stars. Par. xxii. (see p. 397). imagined, the shadow of night sweeping westwardover the globe. The Atlantic Ocean, where Ulyssessailed beyond Gades, is all in daylight, and so is theMediterranean, but the sun is setting over Jerusalem,for he says that its position prevents him from seeingbeyond the coast whence Europa was carried (i.e.Phoenicia or Palestine). It must therefore be middayat Gades, and the sun is on the meridian there; it is a 1 Far. xxiii. 29, 30. 396 PARADTSE. sign and more, or something b
Dante and the early astronomers . zes of sun and moon, as Earth is nearer or fartherfrom them, but the Pythagoreans were quite readyto believe that all the heavenly bodies are so distantthat this journey of Earth makes no difference to theirapparent size or brightness. The planets were thoughtto be worlds like ours, and inhabited ; and it was evenguessed that plants and animals on the moon mustbe fifteen times as strong as ours, apparently becausethere the average day consists of nearly fifteen of ourdays (of twenty-four hours), and the nights are equallylong. It was the braver of the Pythagor Stock Photo
RM2AJ7500–Dante and the early astronomers . zes of sun and moon, as Earth is nearer or fartherfrom them, but the Pythagoreans were quite readyto believe that all the heavenly bodies are so distantthat this journey of Earth makes no difference to theirapparent size or brightness. The planets were thoughtto be worlds like ours, and inhabited ; and it was evenguessed that plants and animals on the moon mustbe fifteen times as strong as ours, apparently becausethere the average day consists of nearly fifteen of ourdays (of twenty-four hours), and the nights are equallylong. It was the braver of the Pythagor
Dante and the early astronomers . alendar led their inhabitants to observe theskies thousands of years ago ; but their early workwas naturally vague and rude. This star-worship and star-study seems to have beenlearned by the Semitic Babylonians, and their descend-ants and rivals the Assyrians, from a race with whomthey met and mingled in the grey dawn of history,but whose existence was unknown to us before themiddle of last century. sky where it was then too northerly for Aratus, leaving Corvus to thesouth of the line. Much the same may be said about the trojtical circles.Either Aratus was car Stock Photo
RM2AJ78MG–Dante and the early astronomers . alendar led their inhabitants to observe theskies thousands of years ago ; but their early workwas naturally vague and rude. This star-worship and star-study seems to have beenlearned by the Semitic Babylonians, and their descend-ants and rivals the Assyrians, from a race with whomthey met and mingled in the grey dawn of history,but whose existence was unknown to us before themiddle of last century. sky where it was then too northerly for Aratus, leaving Corvus to thesouth of the line. Much the same may be said about the trojtical circles.Either Aratus was car
Dante and the early astronomers . ntinued it for many centuries theywould have found that their year was too long, andthe months were all falling in the wrong seasons.Thishas actually happened with Hindus and Parsis,who now keep their New Year in the middle of ourApril, although when their calendar was fixed, aboutthirteen hundred years ago, the years began at thespring equinox. For the sun is like a runner in acircular race-course who thinks he has completed alap when he returns opposite a group of spectatorsoriginally standing at the starting-point, but afterseveral laps he finds that the sp Stock Photo
RM2AJ7220–Dante and the early astronomers . ntinued it for many centuries theywould have found that their year was too long, andthe months were all falling in the wrong seasons.Thishas actually happened with Hindus and Parsis,who now keep their New Year in the middle of ourApril, although when their calendar was fixed, aboutthirteen hundred years ago, the years began at thespring equinox. For the sun is like a runner in acircular race-course who thinks he has completed alap when he returns opposite a group of spectatorsoriginally standing at the starting-point, but afterseveral laps he finds that the sp
Dante and the early astronomers . orthern signs, and the dayslonger than the nights, but as soon as Night beginsto assert her supremacy, and the nights begin to belonger than the days, the sun enters Libra and thenit is not visible all night. This is the meaning of le Bilance,Che ]e caggion di man quando soverchia.^ When Night becomes dominant, the Scales fall fromher hand, for the sun is in that sign. Applying this idea to the passage quoted above, itwill mean The nights are going southward, for thesun in Aquarius is not far from the point where hecrosses the equator to the north, therefore N Stock Photo
RM2AJ6REA–Dante and the early astronomers . orthern signs, and the dayslonger than the nights, but as soon as Night beginsto assert her supremacy, and the nights begin to belonger than the days, the sun enters Libra and thenit is not visible all night. This is the meaning of le Bilance,Che ]e caggion di man quando soverchia.^ When Night becomes dominant, the Scales fall fromher hand, for the sun is in that sign. Applying this idea to the passage quoted above, itwill mean The nights are going southward, for thesun in Aquarius is not far from the point where hecrosses the equator to the north, therefore N
Dante and the early astronomers . the summer solstice of the year B.C. 281, andthis tells us the date at which he flourished. He wasrenowned for a very ingenious method by which he ^ It is also mentioned in a comiDilation of philosophers opinions,probably made in the fifth century a.d. by Stobaeus, who is very likelyquoting Plutarch. 107 108 ARISTARGHUS. tried to discover how much further from us the sunis than the moon. When the moon is half full theangle sun-moon-earth is a riglit angle, and if the anglesun-earth-moon be measured, by pointing the astrolabefirst to sun and then to moon, the t Stock Photo
RM2AJ7418–Dante and the early astronomers . the summer solstice of the year B.C. 281, andthis tells us the date at which he flourished. He wasrenowned for a very ingenious method by which he ^ It is also mentioned in a comiDilation of philosophers opinions,probably made in the fifth century a.d. by Stobaeus, who is very likelyquoting Plutarch. 107 108 ARISTARGHUS. tried to discover how much further from us the sunis than the moon. When the moon is half full theangle sun-moon-earth is a riglit angle, and if the anglesun-earth-moon be measured, by pointing the astrolabefirst to sun and then to moon, the t
Dante and the early astronomers . , normal. New Moon near the Pleiades aftersunset on the 1st of Nisan. The position of the young moon (which always closely follows the sun) showed thatthe sun was not far west of the Pleiades ; and about 1000 B.C. this proved that it wasnear the vernal equinox. The suns position is given for about half an hour after sun-set, when the Pleiades would first be visible. this case he would also be west of Dilgan, the RamsHead, so those stars would rise after him in themorning, and be hidden in his light: therefore, boththe morning and the evening observation combin Stock Photo
RM2AJ786M–Dante and the early astronomers . , normal. New Moon near the Pleiades aftersunset on the 1st of Nisan. The position of the young moon (which always closely follows the sun) showed thatthe sun was not far west of the Pleiades ; and about 1000 B.C. this proved that it wasnear the vernal equinox. The suns position is given for about half an hour after sun-set, when the Pleiades would first be visible. this case he would also be west of Dilgan, the RamsHead, so those stars would rise after him in themorning, and be hidden in his light: therefore, boththe morning and the evening observation combin
Dante and the early astronomers . nteresting to note that he does notexplain her varying velocity by an eccentric, as withthe sun and the planets. She has an eccentric, butPtojemy needed it for representing his own discovery,the evection, so he gave her an epicycle, using it inquite a different way from the epicycles of the planets.This epicycle also revolved while moving on theeccentric, but in the opposite direction, and there wasso little difference in speed between the two motionsthat it never brought the moon to a stop, nor reversedher direction, but simply increased and retarded hermotio Stock Photo
RM2AJ6YF2–Dante and the early astronomers . nteresting to note that he does notexplain her varying velocity by an eccentric, as withthe sun and the planets. She has an eccentric, butPtojemy needed it for representing his own discovery,the evection, so he gave her an epicycle, using it inquite a different way from the epicycles of the planets.This epicycle also revolved while moving on theeccentric, but in the opposite direction, and there wasso little difference in speed between the two motionsthat it never brought the moon to a stop, nor reversedher direction, but simply increased and retarded hermotio
Dante and the early astronomers . ^ Let PA be a greatrevolving circle upon which Mars is fixed. (In thehands of the Alexandrian mathematicians the spheresalmost disappear, and they deal practically only withcircles.) If the earth were at its centre, as Eudoxusdemanded. Mars must always be at the same distance,but if we make the circle eccentric to Earth, byputting its centre at C while Earth is at E, then the THE SCHOOL OF ALEXANDRIA. 119 distance and consequently the brightness will constantlyvary, and Mars will be brightest when at perigee P(point nearest Earth), and faintest when in apogeeA Stock Photo
RM2AJ72GM–Dante and the early astronomers . ^ Let PA be a greatrevolving circle upon which Mars is fixed. (In thehands of the Alexandrian mathematicians the spheresalmost disappear, and they deal practically only withcircles.) If the earth were at its centre, as Eudoxusdemanded. Mars must always be at the same distance,but if we make the circle eccentric to Earth, byputting its centre at C while Earth is at E, then the THE SCHOOL OF ALEXANDRIA. 119 distance and consequently the brightness will constantlyvary, and Mars will be brightest when at perigee P(point nearest Earth), and faintest when in apogeeA
Dante and the early astronomers . A D 150 ^. Fig. 25. The Sun and the Equinox. and night equal, and from this we count the beginningand ending of our seasons. So our year is countedfrom equinox to equinox, and is twenty minutesshorter than the sidereal, or star year, of theancient Babylonians. Hipparchus, from observationsof equinoxes and solstices, made the year 365 days5 hours and nearly 55 minutes, which is only 6 minuteslonger than the correct value. HIPPARGHUS. 129 After Hipparchus had made his discovery, astronomersagreed upon a somewhat clumsy and very confusingdevice, by which the zodi Stock Photo
RM2AJ71W9–Dante and the early astronomers . A D 150 ^. Fig. 25. The Sun and the Equinox. and night equal, and from this we count the beginningand ending of our seasons. So our year is countedfrom equinox to equinox, and is twenty minutesshorter than the sidereal, or star year, of theancient Babylonians. Hipparchus, from observationsof equinoxes and solstices, made the year 365 days5 hours and nearly 55 minutes, which is only 6 minuteslonger than the correct value. HIPPARGHUS. 129 After Hipparchus had made his discovery, astronomersagreed upon a somewhat clumsy and very confusingdevice, by which the zodi
Dante and the early astronomers . earchamong ancient monuments and writings. Some ofthe old constellations are met with in Isaiah andJob, in Homer, on tablets found at Nineveh, and animmense antiquity is sometimes claimed for them.Dupuis, writing at the end of the eighteenth century,thought he had conclusively proved that the figuresof the zodiac were designed in Egypt 15,000 yearsago ! ^ Miss Plunkett, in her Ancient Calendars andConstellations assigns them to the seventh milleniumbefore Christ. An ingenious theory, suggested independently bySchwartz and Proctor, and developed by Mr. E. W.Mau Stock Photo
RM2AJ78Y7–Dante and the early astronomers . earchamong ancient monuments and writings. Some ofthe old constellations are met with in Isaiah andJob, in Homer, on tablets found at Nineveh, and animmense antiquity is sometimes claimed for them.Dupuis, writing at the end of the eighteenth century,thought he had conclusively proved that the figuresof the zodiac were designed in Egypt 15,000 yearsago ! ^ Miss Plunkett, in her Ancient Calendars andConstellations assigns them to the seventh milleniumbefore Christ. An ingenious theory, suggested independently bySchwartz and Proctor, and developed by Mr. E. W.Mau
Dante and the early astronomers . •5b 2 Si ^ -^ c6 o l-H -p ^^ c3 -n (1) <DO X5 bO 42 OS .^3 3 o oa QQ X! +3 o id ^fl oSi ^ 4)O 0) ce ^ > T3 0) o O o d O ^H O — a> o .-H ^ ^ f^ O Oh 3 o !; 03 S fcJD.S c6 id ri-i d 9^ ^ a i^ 2 « ^ O rd d +3c8 H © ; ^ CO o TO 4^ -p ;=! .a 2 a ft O (* a) © ce d O ^H o ;^ a d - 10 • . X o d (1) d ^ d 0) ifJ-i s o -a?ft 5bo 12 -+3 «> 0 tM ^ ^ 0 -p •+3 s , a St > +3 X! m t4 d00 a g a ?P O) More thourssunris(8 a.m. oo (D S •=* o «^ f rH O rC W 4J += O ^H O TS o oxn a ID09 ft 3 2 o 5> be fl -^ as ft o oo -,, Si a; m a 0 fe. Stock Photo
RM2AJ6MXB–Dante and the early astronomers . •5b 2 Si ^ -^ c6 o l-H -p ^^ c3 -n (1) <DO X5 bO 42 OS .^3 3 o oa QQ X! +3 o id ^fl oSi ^ 4)O 0) ce ^ > T3 0) o O o d O ^H O — a> o .-H ^ ^ f^ O Oh 3 o !; 03 S fcJD.S c6 id ri-i d 9^ ^ a i^ 2 « ^ O rd d +3c8 H © ; ^ CO o TO 4^ -p ;=! .a 2 a ft O (* a) © ce d O ^H o ;^ a d - 10 • . X o d (1) d ^ d 0) ifJ-i s o -a?ft 5bo 12 -+3 «> 0 tM ^ ^ 0 -p •+3 s , a St > +3 X! m t4 d00 a g a ?P O) More thourssunris(8 a.m. oo (D S •=* o «^ f rH O rC W 4J += O ^H O TS o oxn a ID09 ft 3 2 o 5> be fl -^ as ft o oo -,, Si a; m a 0 fe.
Dante and the early astronomers . of moon and planets areslightly and variously inclined to it. Thus the daily path of a star is aff^ected only by thesimple uniform movement of the entire heaven (inreality the rotation of the Earth) but the daily pathof a planet, or of the sun or moon, results from acombination of this general movement with its ownpeculiar movement, which is generally in the oppositedirection. If it is difficult to conceive a body moving simultane-ously in two different directions, an earthly analogywill make it easy. On a great moving platform, such THE HEAVENLY BODIES. 19 as Stock Photo
RM2AJ79GM–Dante and the early astronomers . of moon and planets areslightly and variously inclined to it. Thus the daily path of a star is aff^ected only by thesimple uniform movement of the entire heaven (inreality the rotation of the Earth) but the daily pathof a planet, or of the sun or moon, results from acombination of this general movement with its ownpeculiar movement, which is generally in the oppositedirection. If it is difficult to conceive a body moving simultane-ously in two different directions, an earthly analogywill make it easy. On a great moving platform, such THE HEAVENLY BODIES. 19 as
Dante and the early astronomers . n continued, we shouldsee Spica, for instance, sink slowly lower in thesouthern sky and after ages rise again northwards,but there would be very little preceptible movementeast or west. The movement observed by Hipparchus, then, wasnot a movement of Spica and other stars, but amovement of the equinox. For the celestial equatoris simply a reflection of Earths equator in the skies,and as it keeps changing the direction of its tilt inthe way described, it changes the point at which itcuts the ecliptic. This may best be seen by takingtwo rings or hoops (two large Stock Photo
RM2AJ71HN–Dante and the early astronomers . n continued, we shouldsee Spica, for instance, sink slowly lower in thesouthern sky and after ages rise again northwards,but there would be very little preceptible movementeast or west. The movement observed by Hipparchus, then, wasnot a movement of Spica and other stars, but amovement of the equinox. For the celestial equatoris simply a reflection of Earths equator in the skies,and as it keeps changing the direction of its tilt inthe way described, it changes the point at which itcuts the ecliptic. This may best be seen by takingtwo rings or hoops (two large
Dante and the early astronomers . n centre of gravity enables us to determine the gravitationalforce they exercise on each other, and thus their combined mass ; andtheir spectra give some idea of their density. For instance, the mass ofthe double star Alpha Centauri is nearly twice that of our sun ; and asthe components appear to be about equal to each other, and both show aspectrum resembling that of the sun, we may conclude that AlphaCentauri consists of two stars, each-of which has about the same diameteras our sun. Arcturus has a diameter far greater, some say ten times,some not less than Stock Photo
RM2AJ6X4R–Dante and the early astronomers . n centre of gravity enables us to determine the gravitationalforce they exercise on each other, and thus their combined mass ; andtheir spectra give some idea of their density. For instance, the mass ofthe double star Alpha Centauri is nearly twice that of our sun ; and asthe components appear to be about equal to each other, and both show aspectrum resembling that of the sun, we may conclude that AlphaCentauri consists of two stars, each-of which has about the same diameteras our sun. Arcturus has a diameter far greater, some say ten times,some not less than
Dante and the early astronomers . ectual fervour was the influenceof Arab culture, with which Europe came into contactthrough the crusades, and through the Saracens inSicily, and the Moors in Spain. For this reasonastronomy and astrology took a high rank among thenew studies. To distinguish between the two is quitea modern idea, and in mediaeval times either name wasused indifferently to cover both subjects. In Bolognauniversity in the thirteenth century an important schoolof medicine and arts arose, through Arab influence, andthe Arab doctors of medicine introduced the systemof astronomy whic Stock Photo
RM2AJ6WYA–Dante and the early astronomers . ectual fervour was the influenceof Arab culture, with which Europe came into contactthrough the crusades, and through the Saracens inSicily, and the Moors in Spain. For this reasonastronomy and astrology took a high rank among thenew studies. To distinguish between the two is quitea modern idea, and in mediaeval times either name wasused indifferently to cover both subjects. In Bolognauniversity in the thirteenth century an important schoolof medicine and arts arose, through Arab influence, andthe Arab doctors of medicine introduced the systemof astronomy whic
Dante and the early astronomers . from the Sun. On September 24, when Marswas in the middle of his retrograde arc in Pisces, thesun was exactly opposite, in the constellation of Virgo.This is found to be always the case, not only withMars, but with Saturn and Jupiter too. Wheneverone of these planets has the position 0 on its epicycle,and therefore is retrograding, the sun will be foundto be exactly opposite in the sky. Mars comes intothis position, and is opposite the sun, once in 780 days;this, therefore, Ptolemy called the period of hisepicycle, while a little less than two years was the L Stock Photo
RM2AJ70FW–Dante and the early astronomers . from the Sun. On September 24, when Marswas in the middle of his retrograde arc in Pisces, thesun was exactly opposite, in the constellation of Virgo.This is found to be always the case, not only withMars, but with Saturn and Jupiter too. Wheneverone of these planets has the position 0 on its epicycle,and therefore is retrograding, the sun will be foundto be exactly opposite in the sky. Mars comes intothis position, and is opposite the sun, once in 780 days;this, therefore, Ptolemy called the period of hisepicycle, while a little less than two years was the L
Dante and the early astronomers . Fig. 16. The System of Philolaus : night on earth. Only the side turned away from the centre is inhabited: consequently the CentralFire and Autichthou are invisible.. Fig. 17. Twelve hours later : day on earth. Earth has made half a revolution and her outer side is now lighted by the sun, which has only moved about half a degree forward in its yearly orbit. Antichthon has also made half a revolution, theiefore remains invisible. 74 PYTHAGORAS AND HIS FOLLOWERS. great round ball, a planet among planets, swiftly movingthrough space; the crystal dome that tenderl Stock Photo
RM2AJ74R8–Dante and the early astronomers . Fig. 16. The System of Philolaus : night on earth. Only the side turned away from the centre is inhabited: consequently the CentralFire and Autichthou are invisible.. Fig. 17. Twelve hours later : day on earth. Earth has made half a revolution and her outer side is now lighted by the sun, which has only moved about half a degree forward in its yearly orbit. Antichthon has also made half a revolution, theiefore remains invisible. 74 PYTHAGORAS AND HIS FOLLOWERS. great round ball, a planet among planets, swiftly movingthrough space; the crystal dome that tenderl
Dante and the early astronomers . groundregions, through the night. It was clearly recognizedthat the visible course of each heavenly body was partof a circle, the whole of which we could see if we couldonly travel fast enough and go to the underside ofthe earth. But this was just what never could be done, for out- Leucippus side the schools of the Greeks in Italy c. 450 B.C. (Pythagorean and Eleatic), Earth still had an uninhabitable underside. Distinguished men like Leucippus and Democritus sought to combine the belief LATER FLAT-EARTH SYSTEMS. 63 in an all-surrounding spherical heaven with Stock Photo
RM2AJ76GP–Dante and the early astronomers . groundregions, through the night. It was clearly recognizedthat the visible course of each heavenly body was partof a circle, the whole of which we could see if we couldonly travel fast enough and go to the underside ofthe earth. But this was just what never could be done, for out- Leucippus side the schools of the Greeks in Italy c. 450 B.C. (Pythagorean and Eleatic), Earth still had an uninhabitable underside. Distinguished men like Leucippus and Democritus sought to combine the belief LATER FLAT-EARTH SYSTEMS. 63 in an all-surrounding spherical heaven with
Dante and the early astronomers . ocean which surrounds all the land. At theopposite or western extremity are the Pillars of Her-cules, which two angels appear to be guarding. Inthe centre, but not so exactly or conspicuously centralas in some other maps, we find Hierusalem. Alongthe south is the long narrow continent of Africa, withthe Atlas and Ethiopian mountains; and the Nile,rising far in the south-west, after mysterious sub-mergences and reappearances, finally flows into theMediterranean, past the pictured Pyramids, herestrangely called (according to Dark-Age myth) theBarns of Joseph. In Stock Photo
RM2AJ6P35–Dante and the early astronomers . ocean which surrounds all the land. At theopposite or western extremity are the Pillars of Her-cules, which two angels appear to be guarding. Inthe centre, but not so exactly or conspicuously centralas in some other maps, we find Hierusalem. Alongthe south is the long narrow continent of Africa, withthe Atlas and Ethiopian mountains; and the Nile,rising far in the south-west, after mysterious sub-mergences and reappearances, finally flows into theMediterranean, past the pictured Pyramids, herestrangely called (according to Dark-Age myth) theBarns of Joseph. In
Dante and the early astronomers . ^d -^ !i ?d Si ^°^ d ;=! «^ > § eg r^ =; d . bO 5 ^ eg d a>k^ d -^^•-^ o Si ^r t) ^|a d ^ rd eg O o 9 d Sbo 2 Si •^ bo oj a^ ^ 2 >? >i d a o CO bO CO 3 u,« CQ 03 d oQ oO rd dO i dO d eg °.6 >. .-kj fl ^ d a> !3 S-, >-:w o o p. Id do CIS J-, ^ CO d d^ 2 c6 a P, Si) ©do . . P «2 S bD O d ^ o ^^ i eg -1-3 eg>? r-i T3^ eg g a oj ^ m 02 O 60 dd Si o Sieg COCO o I—I w t S 2 ^ . f-< . to m ft w S^:] fe «2 W hJ o fci < o < <1 o Ts . ^ ^ -^ a 2 ma M g OB fl ^?.^ ill si lii ^-^^^i ^ ^ IJ -111 1^§^ II ?^.^ l£^?§ -^ -« -S- S ^^^ ^S-o S^ Stock Photo
RM2AJ6MJH–Dante and the early astronomers . ^d -^ !i ?d Si ^°^ d ;=! «^ > § eg r^ =; d . bO 5 ^ eg d a>k^ d -^^•-^ o Si ^r t) ^|a d ^ rd eg O o 9 d Sbo 2 Si •^ bo oj a^ ^ 2 >? >i d a o CO bO CO 3 u,« CQ 03 d oQ oO rd dO i dO d eg °.6 >. .-kj fl ^ d a> !3 S-, >-:w o o p. Id do CIS J-, ^ CO d d^ 2 c6 a P, Si) ©do . . P «2 S bD O d ^ o ^^ i eg -1-3 eg>? r-i T3^ eg g a oj ^ m 02 O 60 dd Si o Sieg COCO o I—I w t S 2 ^ . f-< . to m ft w S^:] fe «2 W hJ o fci < o < <1 o Ts . ^ ^ -^ a 2 ma M g OB fl ^?.^ ill si lii ^-^^^i ^ ^ IJ -111 1^§^ II ?^.^ l£^?§ -^ -« -S- S ^^^ ^S-o S^
Dante and the early astronomers . rs point ofview. Fig. 21 gives a general view of the PekinObservatory, and Fig. 22 one of their astrolabes datingfrom the 13th century a.d. At first glance there seems to be here absolutelynothing like our modern observatories. Ancient andmediaeval astronomers had indeed no telescopes, being-ignorant of the properties of lenses: therefore theywere unable to study the features of any heavenlybody except the moon, and they had no way of findingout anything about their physical constitution; butthey had many v/ays of measuring their distances andmotions, and even Stock Photo
RM2AJ73MF–Dante and the early astronomers . rs point ofview. Fig. 21 gives a general view of the PekinObservatory, and Fig. 22 one of their astrolabes datingfrom the 13th century a.d. At first glance there seems to be here absolutelynothing like our modern observatories. Ancient andmediaeval astronomers had indeed no telescopes, being-ignorant of the properties of lenses: therefore theywere unable to study the features of any heavenlybody except the moon, and they had no way of findingout anything about their physical constitution; butthey had many v/ays of measuring their distances andmotions, and even
Dante and the early astronomers . lled backwards against thesigns until October 26th, when it stopped again,reversed its direction once more, and during the restof the year moved rapidly forward. Fig. 29 shows the principle on which Ptolemy wouldhave explained this curious track. Each planet wassupposed to be fixed on a small circle, the epicycle,and this was fixed upon a large circle, or deferent, uponwhich it travels in the direction shown by the arrow,at a uniform speed, returning to the same place inthe sidereal period of the planet. Thus Mars, as seenfrom Earth, which is near C the centre Stock Photo
RM2AJ714E–Dante and the early astronomers . lled backwards against thesigns until October 26th, when it stopped again,reversed its direction once more, and during the restof the year moved rapidly forward. Fig. 29 shows the principle on which Ptolemy wouldhave explained this curious track. Each planet wassupposed to be fixed on a small circle, the epicycle,and this was fixed upon a large circle, or deferent, uponwhich it travels in the direction shown by the arrow,at a uniform speed, returning to the same place inthe sidereal period of the planet. Thus Mars, as seenfrom Earth, which is near C the centre
Dante and the early astronomers . they alsoexplain the movements of the skies. For the figuresof the zodiac face west (those that have faces), andthis is why the diurnal movement of the whole heavenis towards the west, so that the constellations maymove straightforward, in the natural way. On theother hand, the planets move in the opposite directionbecause it would not be seemly for them to pass eachfigure of the zodiac arriving first at the back andmoving on to the head. This is the true reason ofthe contrary direction of the two principal celestialmovements. Ristoro does not approve of the s Stock Photo
RM2AJ6TGE–Dante and the early astronomers . they alsoexplain the movements of the skies. For the figuresof the zodiac face west (those that have faces), andthis is why the diurnal movement of the whole heavenis towards the west, so that the constellations maymove straightforward, in the natural way. On theother hand, the planets move in the opposite directionbecause it would not be seemly for them to pass eachfigure of the zodiac arriving first at the back andmoving on to the head. This is the true reason ofthe contrary direction of the two principal celestialmovements. Ristoro does not approve of the s
Dante and the early astronomers . ighbours,Mercury, Venus, and Mars; just as Jupiter is largestamong the giant planets—Saturn and the more recentlydiscovered Uranus and Neptune. In the gap betweenthese two groups modern astronomers have discoveredhundreds of tiny planets, to which Earth is a monster,for many are only a few miles in diameter. Themeteorites which shoot across our view, startlingquiet eyes, we still regard as a kind of conflagrationin our upper atmosphere, but instead of vapours risingfrom Earths surface we recognise them as visitantsfrom inter-planetary space, caught by Earths g Stock Photo
RM2AJ6JBC–Dante and the early astronomers . ighbours,Mercury, Venus, and Mars; just as Jupiter is largestamong the giant planets—Saturn and the more recentlydiscovered Uranus and Neptune. In the gap betweenthese two groups modern astronomers have discoveredhundreds of tiny planets, to which Earth is a monster,for many are only a few miles in diameter. Themeteorites which shoot across our view, startlingquiet eyes, we still regard as a kind of conflagrationin our upper atmosphere, but instead of vapours risingfrom Earths surface we recognise them as visitantsfrom inter-planetary space, caught by Earths g
Dante and the early astronomers . ancients. It was a pity that Ptolemy did not take more painsto verify the worK of Hipparchus on the sun, for thesuns apogee, or point of greatest distance from Earth,has an extremely slow motion among the stars whichought to have been quite perceptible in nearly threecenturies; ^ but here again he seems to have thoughtthat where Hipparchus had given so much attention hemight pass on to something else, and so missed aninteresting discovery. Instead, he worked very hard at the moon, and addedanother periodical irregularity to those already known.Perhaps his feel Stock Photo
RM2AJ6YYN–Dante and the early astronomers . ancients. It was a pity that Ptolemy did not take more painsto verify the worK of Hipparchus on the sun, for thesuns apogee, or point of greatest distance from Earth,has an extremely slow motion among the stars whichought to have been quite perceptible in nearly threecenturies; ^ but here again he seems to have thoughtthat where Hipparchus had given so much attention hemight pass on to something else, and so missed aninteresting discovery. Instead, he worked very hard at the moon, and addedanother periodical irregularity to those already known.Perhaps his feel
Dante and the early astronomers . e there is some beautyin the description of the aurora which preceded moon-rise ^ on the first night in Purgatory, but Dante givesit an ugly name, and the waning moon when seen onthe following night, four days after full, is oddly com-pared to a bucket in shape. Dante did not admire thisgibbous form, for he instances the outline of the moonwhen not quite full as an ignoble curve, contrasting itwith the beauty of a perfect circle.^ Hardly ever does he find a beautiful epithet for her:she is ruler of Hell,^ Cain and the Thorns ^ (in refer-ence to the legend whic Stock Photo
RM2AJ6T46–Dante and the early astronomers . e there is some beautyin the description of the aurora which preceded moon-rise ^ on the first night in Purgatory, but Dante givesit an ugly name, and the waning moon when seen onthe following night, four days after full, is oddly com-pared to a bucket in shape. Dante did not admire thisgibbous form, for he instances the outline of the moonwhen not quite full as an ignoble curve, contrasting itwith the beauty of a perfect circle.^ Hardly ever does he find a beautiful epithet for her:she is ruler of Hell,^ Cain and the Thorns ^ (in refer-ence to the legend whic
Dante and the early astronomers . ution combined, the eclipse becomes visible successively from different parts of the earth. Dante realized this when he quoted the argument of some theologians that the miraculous three-hours darkness described in the Gospels could338 CELESTIAL PHENOMENA AND TIME. 339 not have been caused by an eclipse of the sun, asAquinas and others had suggested, because it wasvisible all over the earth at the same absolute time,that is, during the Crucifixion.^ Some said, he tells us,that the moon went back and placed herself betweenus and the sun (for the moon at Passover Stock Photo
RM2AJ6PCD–Dante and the early astronomers . ution combined, the eclipse becomes visible successively from different parts of the earth. Dante realized this when he quoted the argument of some theologians that the miraculous three-hours darkness described in the Gospels could338 CELESTIAL PHENOMENA AND TIME. 339 not have been caused by an eclipse of the sun, asAquinas and others had suggested, because it wasvisible all over the earth at the same absolute time,that is, during the Crucifixion.^ Some said, he tells us,that the moon went back and placed herself betweenus and the sun (for the moon at Passover
Dante and the early astronomers . sun is nota mere lagging behind the stars, for his west to eastmotion is combined with a north and south motion.If we note the star-groups which are just behind himwhen he sets (or just before him when he rises), weshall find that they form a great circle round the globe,half of which lies north and half south of the celestialequator. The Greeks named this circle the Zodiac, orPath of the Animals, because the star-groups formingit were mostly called by the names of animals (theRam, Lion, Fishes, etc.). When the sun is in the mostnortherly part of the zodiac it Stock Photo
RM2AJ7A22–Dante and the early astronomers . sun is nota mere lagging behind the stars, for his west to eastmotion is combined with a north and south motion.If we note the star-groups which are just behind himwhen he sets (or just before him when he rises), weshall find that they form a great circle round the globe,half of which lies north and half south of the celestialequator. The Greeks named this circle the Zodiac, orPath of the Animals, because the star-groups formingit were mostly called by the names of animals (theRam, Lion, Fishes, etc.). When the sun is in the mostnortherly part of the zodiac it
Dante and the early astronomers . Fig. 8. Second Year, normal. New Moon not far from Pleiadeson the 1st of Nisan. It takes the sun 365 days to return to the same place among the stars, but theBabylonian year of 12 lunar months (each of 29 or 30 days) was 11 dajs short of this :therefore on the 1st of Nisan in this year the sun had still 11 days march before himere he returned to the position of Fig. J . This is equal to about 11, so the youngmoon was also about 11° west of her former position, near the Pleiades. But as shetravels about 13 eastward every day, she would be near the Pleiades on t Stock Photo
RM2AJ7817–Dante and the early astronomers . Fig. 8. Second Year, normal. New Moon not far from Pleiadeson the 1st of Nisan. It takes the sun 365 days to return to the same place among the stars, but theBabylonian year of 12 lunar months (each of 29 or 30 days) was 11 dajs short of this :therefore on the 1st of Nisan in this year the sun had still 11 days march before himere he returned to the position of Fig. J . This is equal to about 11, so the youngmoon was also about 11° west of her former position, near the Pleiades. But as shetravels about 13 eastward every day, she would be near the Pleiades on t
Dante and the early astronomers . s which surround Beatrice and himselfto a double rainbow, and to two garlands of immortal 1 If the barbarians coming from some region That every day by Hoi ice is covered,Revolving with her son whom she delights in.Beholding Rome and all her noble works Were wonder-struck. .. Par. xxxi. 31-35. {Longfellow). 2 Those under the sway of the seven cold oxen. THE STARS. 299 roses. In the next canto he finds a new simile : inimagination he takes some of the biightest and mostfamiliar stars from our sky, and makes of them two newconstellations in the form of two crown Stock Photo
RM2AJ6PTG–Dante and the early astronomers . s which surround Beatrice and himselfto a double rainbow, and to two garlands of immortal 1 If the barbarians coming from some region That every day by Hoi ice is covered,Revolving with her son whom she delights in.Beholding Rome and all her noble works Were wonder-struck. .. Par. xxxi. 31-35. {Longfellow). 2 Those under the sway of the seven cold oxen. THE STARS. 299 roses. In the next canto he finds a new simile : inimagination he takes some of the biightest and mostfamiliar stars from our sky, and makes of them two newconstellations in the form of two crown
Dante and the early astronomers . idian ofJerusalem, which is obviously impossible while one isin Aries and the other in Gemini; and as he refersback to the first passage from the second he cannothave forgotten this.^ 1 Compare Purg. xv. 1-5, where the course the sun still has to runbetween vespers and sunset is described as equal to the space betweenthe third hour and sunrise. 2 The threshing-floor that maketh us so proud, To me revolving with the eternal Twins,Was all apparent made from hill to harbour. Far. xxii. 151-3. {Longfellow). ^ Delia Valle boldly assumes that they were over the same Stock Photo
RM2AJ6K1C–Dante and the early astronomers . idian ofJerusalem, which is obviously impossible while one isin Aries and the other in Gemini; and as he refersback to the first passage from the second he cannothave forgotten this.^ 1 Compare Purg. xv. 1-5, where the course the sun still has to runbetween vespers and sunset is described as equal to the space betweenthe third hour and sunrise. 2 The threshing-floor that maketh us so proud, To me revolving with the eternal Twins,Was all apparent made from hill to harbour. Far. xxii. 151-3. {Longfellow). ^ Delia Valle boldly assumes that they were over the same
Dante and the early astronomers . 1° in a century, according to Ptolemy, sothat it completes a revolution in 36,000 years. Coming now^ to the fixed stars, their number, andbrightness, Alfraganus does not copy Ptolemys greatcatalogue, but informs us that learned men (sapientes)did number all the fixed stars as far south as theycould see in the 3rd climate, and divided them accord-ing to magnitude into six classes. To the first classthey assigned the bright and shining stars such asCanis (Sirius) and Procyon, Vultur Cadens (Vega) andCor Leonis (Regulus). Stars a little less bright theycalled sec Stock Photo
RM2AJ6XKJ–Dante and the early astronomers . 1° in a century, according to Ptolemy, sothat it completes a revolution in 36,000 years. Coming now^ to the fixed stars, their number, andbrightness, Alfraganus does not copy Ptolemys greatcatalogue, but informs us that learned men (sapientes)did number all the fixed stars as far south as theycould see in the 3rd climate, and divided them accord-ing to magnitude into six classes. To the first classthey assigned the bright and shining stars such asCanis (Sirius) and Procyon, Vultur Cadens (Vega) andCor Leonis (Regulus). Stars a little less bright theycalled sec
Dante and the early astronomers . aremuch more easily observed than those of the sun,since we can see the stars at the same time, and herrevolution is much more rapid. She also is apparentlycarried round with the daily east to west movement,and she also has a west to east motion of her own, butso fast that it takes her round the star-sphere in onemonth, instead of one year. This revolution also takesplace in the zodiac. She is first visible as a finecrescent, just following the sun, in the west, after he ^ Greek gnomon, an interpreter. A pole set up in order to show thelength of shadow thrown Stock Photo
RM2AJ79RA–Dante and the early astronomers . aremuch more easily observed than those of the sun,since we can see the stars at the same time, and herrevolution is much more rapid. She also is apparentlycarried round with the daily east to west movement,and she also has a west to east motion of her own, butso fast that it takes her round the star-sphere in onemonth, instead of one year. This revolution also takesplace in the zodiac. She is first visible as a finecrescent, just following the sun, in the west, after he ^ Greek gnomon, an interpreter. A pole set up in order to show thelength of shadow thrown
Dante and the early astronomers . this is the highest position inwhich the inhabitants of Maria can ever see it]. If a man stood upright in Maria, and kept turninghis face to the sun, he would see it move to his right[as we do]. After reaching his greatest height in the sky, thesun would begin to descend again, in the same spiralway like a screw turning, for another ninety revolutionsor so, until once more he was circling down on thehorizon, only half his body visible. ^ Adopting the reading of Dr. Moore : nella raezza terra, alia mezzaierza, that is, at the equator at middle tierce. See Studi Stock Photo
RM2AJ6PJ1–Dante and the early astronomers . this is the highest position inwhich the inhabitants of Maria can ever see it]. If a man stood upright in Maria, and kept turninghis face to the sun, he would see it move to his right[as we do]. After reaching his greatest height in the sky, thesun would begin to descend again, in the same spiralway like a screw turning, for another ninety revolutionsor so, until once more he was circling down on thehorizon, only half his body visible. ^ Adopting the reading of Dr. Moore : nella raezza terra, alia mezzaierza, that is, at the equator at middle tierce. See Studi
Dante and the early astronomers . uctory to the wholeCoTnmedia, he mentions the time at which he assumesthat his vision began. It was nel mezzo del cammindi nostra vita,* which may mean simply that he wasmiddle-aged, or comparing it with the passage in theConvivio quoted earlier (see p. 347), we may suppose itto mean that he was exactly in his 35th year. Theseason was spring—la dolce stagione,^ and whennight was over the sun rose among those stars whichwere with him at the Creation, which was believed tohave taken place at the vernal equinox some sixty-fivecenturies before. 11 Sol montava su c Stock Photo
RM2AJ6NE8–Dante and the early astronomers . uctory to the wholeCoTnmedia, he mentions the time at which he assumesthat his vision began. It was nel mezzo del cammindi nostra vita,* which may mean simply that he wasmiddle-aged, or comparing it with the passage in theConvivio quoted earlier (see p. 347), we may suppose itto mean that he was exactly in his 35th year. Theseason was spring—la dolce stagione,^ and whennight was over the sun rose among those stars whichwere with him at the Creation, which was believed tohave taken place at the vernal equinox some sixty-fivecenturies before. 11 Sol montava su c
Dante and the early astronomers . ts, includ-ing : -30 Star Charts (13|x9i inches), embracing the whole Star Sphere, on thelarge scale of about 5 degrees to the inch, and showing positions for epoch1900 ; two charts by means of which the positions of stars in Right Ascensioiiand Declination may be found for any required epoch, past or future, in amoment; large Map of the Mood, &c., &c. I ^amn ^^^^^^ ixX*xi^ ( PQ 4401 .06 1913 IMS,Evershed, M. A. (Orr) •Dante and the earlyastronomers OF mediaeval: studieb f9 QUEENS PARKiCO^JTO ^ CANADA v»«» ^ rniJ^. DANTE STUDYING. From a fresco by Luca Signer Stock Photo
RM2AJ7ADX–Dante and the early astronomers . ts, includ-ing : -30 Star Charts (13|x9i inches), embracing the whole Star Sphere, on thelarge scale of about 5 degrees to the inch, and showing positions for epoch1900 ; two charts by means of which the positions of stars in Right Ascensioiiand Declination may be found for any required epoch, past or future, in amoment; large Map of the Mood, &c., &c. I ^amn ^^^^^^ ixX*xi^ ( PQ 4401 .06 1913 IMS,Evershed, M. A. (Orr) •Dante and the earlyastronomers OF mediaeval: studieb f9 QUEENS PARKiCO^JTO ^ CANADA v»«» ^ rniJ^. DANTE STUDYING. From a fresco by Luca Signer
Dante and the early astronomers . in vain to find a suo-aestion of this kind. Yet an explanation and a source of this statementis not far to seek, and instead of proving ignorance itindicates that the author of the Qucestio knew hisAlfraganus well. The passage is evidently slightlycorrupt, but the clue to its meaning lies in the wordeccentricity. In two other places of the Qucestiothe moons eccentric orbis is alluded to,^ but if wetranslate tliis as orbit we shall be introducingmodern ideas which meant nothing to Dante or his ^ Nearest Elarth. ^ Qu. vii. 4, 6, and xxiii. 52. { THE SPHERES AND Stock Photo
RM2AJ6JF8–Dante and the early astronomers . in vain to find a suo-aestion of this kind. Yet an explanation and a source of this statementis not far to seek, and instead of proving ignorance itindicates that the author of the Qucestio knew hisAlfraganus well. The passage is evidently slightlycorrupt, but the clue to its meaning lies in the wordeccentricity. In two other places of the Qucestiothe moons eccentric orbis is alluded to,^ but if wetranslate tliis as orbit we shall be introducingmodern ideas which meant nothing to Dante or his ^ Nearest Elarth. ^ Qu. vii. 4, 6, and xxiii. 52. { THE SPHERES AND
Dante and the early astronomers . and Jews.Cecco dAscoli was not so fortunate. This learnedItalian received the high and honoured post of pro-fessor of astrology in Bologna, where he lectured andcast horoscopes for his students. He was well versedin natural science, but the shady side of astrology hada fatal attraction for him: he fell under suspicion as asorcerer, was condemned, and burned at the stake inFlorence in 1327 (six years after Dantes death). The reputations achieved by these and otherthirteenth-century astrologers in Italy, belonging tosuch different ranks of life, show what an imm Stock Photo
RM2AJ6W89–Dante and the early astronomers . and Jews.Cecco dAscoli was not so fortunate. This learnedItalian received the high and honoured post of pro-fessor of astrology in Bologna, where he lectured andcast horoscopes for his students. He was well versedin natural science, but the shady side of astrology hada fatal attraction for him: he fell under suspicion as asorcerer, was condemned, and burned at the stake inFlorence in 1327 (six years after Dantes death). The reputations achieved by these and otherthirteenth-century astrologers in Italy, belonging tosuch different ranks of life, show what an imm
Dante and the early astronomers . Fig. 17. Twelve hours later : day on earth. Earth has made half a revolution and her outer side is now lighted by the sun, which has only moved about half a degree forward in its yearly orbit. Antichthon has also made half a revolution, theiefore remains invisible. 74 PYTHAGORAS AND HIS FOLLOWERS. great round ball, a planet among planets, swiftly movingthrough space; the crystal dome that tenderly coveredit like a bell-glass over some fragile flower, has lifted,and the vast sphere is seen, infinitely distant, andstudded with enormous stars. Man himself is now Stock Photo
RM2AJ74FM–Dante and the early astronomers . Fig. 17. Twelve hours later : day on earth. Earth has made half a revolution and her outer side is now lighted by the sun, which has only moved about half a degree forward in its yearly orbit. Antichthon has also made half a revolution, theiefore remains invisible. 74 PYTHAGORAS AND HIS FOLLOWERS. great round ball, a planet among planets, swiftly movingthrough space; the crystal dome that tenderly coveredit like a bell-glass over some fragile flower, has lifted,and the vast sphere is seen, infinitely distant, andstudded with enormous stars. Man himself is now
Dante and the early astronomers . ^ them inside theirrespective heavens, which doubtless was clear tohimself, though unfortunately it is not at all clear tous. Some writers have maintained that these heavenswere spheres, but for several reasons it is diflficult tobelieve this, and probably the sky was still to A De Coelo, I. 3, and 11. 1. THALE8 AND ANAXIMANDEK 59 Anaximander, as to the Homeric Greeks, a slightlyflattened hemisphere,^ only divided into these layers,and instead of ending at the horizon it continued alittle below, to allow of the passage of the heavenlybodies between setting and Stock Photo
RM2AJ76RY–Dante and the early astronomers . ^ them inside theirrespective heavens, which doubtless was clear tohimself, though unfortunately it is not at all clear tous. Some writers have maintained that these heavenswere spheres, but for several reasons it is diflficult tobelieve this, and probably the sky was still to A De Coelo, I. 3, and 11. 1. THALE8 AND ANAXIMANDEK 59 Anaximander, as to the Homeric Greeks, a slightlyflattened hemisphere,^ only divided into these layers,and instead of ending at the horizon it continued alittle below, to allow of the passage of the heavenlybodies between setting and
Dante and the early astronomers . tlife, in the north. The constellations are upside downfor the south, so they can have no effect there, there-fore, there are no animals there (since every race ofanimals is under the protection of a constellation);therefore no plants, since they exist for animals, andtherefore, Ristoro concludes his chain of argumenttriumphantly, there are no men, and no lands, for landwithout life would be useless. Ristoro reproduces Alfraganus description of the USED BY DANTE. 247 suns movements as seen in different latitudes, quoteshim as saying that the equatoral regions Stock Photo
RM2AJ6TPE–Dante and the early astronomers . tlife, in the north. The constellations are upside downfor the south, so they can have no effect there, there-fore, there are no animals there (since every race ofanimals is under the protection of a constellation);therefore no plants, since they exist for animals, andtherefore, Ristoro concludes his chain of argumenttriumphantly, there are no men, and no lands, for landwithout life would be useless. Ristoro reproduces Alfraganus description of the USED BY DANTE. 247 suns movements as seen in different latitudes, quoteshim as saying that the equatoral regions

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