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Easton is of opinion that the annular hypothesis of the Milky Way is inconsistent with our present knowledge of the galactic phenomena, and he suggests that its actual constitution resembles more that of a spiral nebula.471 On this hypothesis the increase in the number of stars in the regions above referred to may be due to our seeing one branch of the supposed “two-branched spiral” projected on another branch of the same spiral. This seems supported by Sir John Herschel’s observations in the southern hemisphere, where he found in some places “a tissue as it were of large stars spread over another of very small ones, the immediate magnitudes being wanting.” Again, portions of the spiral branches may be richer than others, as photographs of spiral nebulæ seem to indicate. Celoria, rejecting the hypothesis of a single ring, suggests the existence of two galactic rings inclined to each other at an angle of about 20°, one of these including the brighter stars, and the other the fainter. But this seems to be a more artificial arrangement then the hypothesis of a spiral. Further, the complicated structure of the Milky Way cannot be well explained by Celoria’s hypothesis of two distinct rings one inside the other. From analogy the spiral hypothesis seems much more probable.
Considering the Milky Way to represent a colossal spiral nebula viewed from a point not far removed from the centre of the spiral branches, Easton suggests that the bright region between β and γ Cygni, which is very rich in comparatively bright stars, may possibly represent the “central accumulations of the Milky Way,” that is, the portion corresponding to the nucleus of a spiral nebula. If this be so, this portion of the Milky Way should be nearer to us than others. Easton also thinks that the so-called “solar cluster” of Gould, Kapteyn, and Schiaparelli may perhaps be “the expression of the central condensation of the galactic system itself, composed of the most part of suns comparable with our own, and which would thus embrace most of the bright stars to the 9th or 10th magnitude. The distance of the galactic streams and convolutions would thus be comparable with the distances of these stars.” He thinks that the sun lies within a gigantic spiral, “in a comparatively sparse region between the central nucleus and Orion.”
Scheiner thinks that “the irregularities of the Milky Way, especially in streams, can be quite well accounted for, as Easton has attempted to do, if they are regarded as a system of spirals, and not as a ring system.”
Evidence in favour of the spiral hypothesis of the Milky Way, as advocated by Easton and Scheiner, may be found in Kapteyn’s researches on the proper motions of the stars. This eminent astronomer finds that stars with measurable proper motions – and therefore in all probability relatively near the earth – have mostly spectra of the solar type, and seem to cluster round “a point adjacent to the sun, in total disregard to the position of the Milky Way,” and that stars with little or no proper motion collect round the galactic plain. He is also of opinion that the Milky Way resembles the Andromeda nebula, “the globular nucleus representing the solar cluster, and the far spreading wings or whorls the compressed layer of stars enclosed by the rings of the remote Galaxy.”
With reference to the plurality of inhabited worlds, it has been well said by the ancient writer Metrodorus (third century B.C.), “The idea that there is but a single world in all infinitude would be as absurd as to suppose that a vast field had been formed to produce a single blade of wheat.”472 With this opinion the present writer fully concurs.
The achievements of Hipparchus in astronomy were very remarkable, considering the age in which he lived. He found the amount of the apparent motion of the stars due to the precession of the equinoxes (of which he was the discoverer) to be 59″ per annum. The correct amount is about 50″. He measured the length of the year to within 9 minutes of its true value. He found the inclination of the ecliptic to the plane of the equator to be 23° 51′. It was then 23° 46′ – as we now know by modern calculations – so that Hipparchus’ estimation was a wonderfully close approximation to the truth. He computed the moon’s parallax to be 57′, which is about its correct value. He found the eccentricity of the sun’s apparent orbit round the earth to be one twenty-fourth, the real value being then about one-thirteenth. He determined other motions connected with the earth and moon; and formed a catalogue of 1080 stars. All this work has earned for him the well-merited title of “The Father of Astronomy.”473
The following is a translation of a Greek passage ascribed to Ptolemy: “I know that I am mortal and the creature of a day, but when I search out the many rolling circles of the stars, my feet touch the earth no longer, but with Zeus himself I take my fill of ambrosia, the food of the gods.”474 This was inscribed (in Greek) on a silver loving cup presented to the late Professor C. A. Young, the famous American astronomer.475
Some curious and interesting phenomena are recorded in the old Chinese Annals, which go back to a great antiquity. In 687 B.C. “a night” is mentioned “without clouds and without stars” (!) This may perhaps refer to a total eclipse of the sun; but if so, the eclipse is not mentioned in the Chinese list of eclipses. In the year 141 B.C., it is stated that the sun and moon appeared of a deep red colour during 5 days, a phenomenon which caused great terror among the people. In 74 B.C., it is related that a star as large as the moon appeared, and was followed in its motion by several stars of ordinary size. This probably refers to an unusually large “bolide” or “fireball.” In 38 B.C., a fall of meteoric stones is recorded “of the size of a walnut.” In A.D. 88, another fall of stones is mentioned. In A.D. 321, sun-spots were visible to the naked eye.
Homer speaks of a curious darkness which occurred during one of the great battles in the last year of the Trojan war. Mr. Stockwell identifies this with an eclipse of the sun which took place on August 28, 1184 B.C. An eclipse referred to by Thucydides as having occurred during the first year of the Peloponnesian War, when the darkness was so great that some stars were seen, is identified by Stockwell with a total eclipse of the sun, which took place on August 2, 430 B.C.
A great eclipse of the sun is supposed to have occurred in the year 43 or 44 B.C., soon after the death of Julius Cæsar. Baron de Zach and Arago mention it as the first annular eclipse on record. But calculations show that no solar eclipse whatever, visible in Italy, occurred in either of these years. The phenomenon referred to must therefore have been of atmospherical origin, and indeed this is suggested by a passage in Suetonius, one of the authors quoted on the subject.
M. Guillaume thinks that the ninth Egyptian plague, the thick “darkness” (Exodus x. 21-23), may perhaps be explained by a total eclipse of the sun which occurred in 1332 B.C. It is true that the account states that the darkness lasted “three days,” but this, M. Guillaume thinks, may be due to an error in the translation.476 This explanation, however, seems very improbable.
According to Hind, the moon was eclipsed on the generally received date of the Crucifixion, A.D. 33, April 3. He says, “I find she had emerged from the earth’s dark shadow a quarter of an hour before she rose at Jerusalem (6h 36m p.m.); but the penumbra continued upon her disc for an hour afterwards.” An eclipse could not have had anything to do with the “darkness over all the land” during the Crucifixion. For this lasted for three hours, and the totality of a solar eclipse can only last a few minutes at the most. As a matter of fact the “eclipse of Phlegon,” a partial one (A.D. 29, November 24) was “the only solar eclipse that could have been visible in Jerusalem during the period usually fixed for the ministry of Christ.”
It is mentioned in the Anglo-Saxon Chronicle that a total eclipse of the sun took place in the year after King Alfred’s great battle with the Danes. Now, calculation shows that this eclipse occurred on October 29, 878 A.D. King Alfred’s victory over the Danes must, therefore, have taken place in 877 A.D., and his death probably occurred in 899 A.D. This solar eclipse is also mentioned in the Annals of Ulster. From this it will be seen that in some cases the dates of historical events can be accurately fixed by astronomical phenomena.
It is stated by some historians that an eclipse of the sun took place on the morning of the battle of Crecy, August 26, 1346. But calculation shows that there was no eclipse of the sun visible in England in that year. At the time of the famous battle the moon had just entered on her first quarter, and she was partially eclipsed six days afterwards – that is on the 1st of September. The mistake seems to have arisen from a mistranslation of the old French word esclistre, which means lightning. This was mistaken for esclipse. The account seems to indicate that there was a heavy thunderstorm on the morning of the battle.
A dark shade was seen on the waning moon by Messrs. Hirst and J. C. Russell on October 21, 1878, “as dark as the shadow during an eclipse of the moon.”477 If this observation is correct, it is certainly most difficult to explain. Another curious observation is recorded by Mr. E. Stone Wiggins, who says that a partial eclipse of the sun by a dark body was observed in the State of Michigan (U.S.A.) on May 16, 1884, at 7 p.m. The “moon at that moment was 12 degrees south of the equator and the sun as many degrees north of it.” The existence of a dark satellite of the earth has been suggested, but this seems highly improbable.
The sun’s corona seems to have been first noticed in the total eclipse of the sun which occurred at the death of the Roman emperor Domitian, A.D. 95. Philostratus in his Life of Apollonius says, with reference to this eclipse, “In the heavens there appeared a prodigy of this nature: a certain corona resembling the Iris surrounded the orb of the sun, and obscured its light.”478 In more modern times the corona seems to have been first noticed by Clavius during the total eclipse of April 9, 1567.479 Kepler proved that this eclipse was total, not annular, so that the ring seen by Clavius must have been the corona.
With reference to the visibility of planets and stars during total eclipses of the sun; in the eclipse of May 12, 1706, Venus, Mercury, and Aldebaran, and several other stars were seen. During the totality of the eclipse of May 3, 1715, about twenty stars were seen with the naked eye.480 At the eclipse of May 22, 1724, Venus and Mercury, and a few fixed stars were seen.481 The corona was also noticed. At the eclipse of May 2, 1733, Jupiter, the stars of the “Plough,” Capella, and other stars were visible to the naked eye; and the corona was again seen.[483]
During the total eclipses of February 9, 1766, June 24, 1778, and June 16, 1806, the corona was again noticed. But its true character was then unknown.
At the eclipse of July 8, 1842, it was noticed by observers at Lipesk that the stars Aldebaran and Betelgeuse (α Orionis), which are usually red, “appeared quite white.”482
There will be seven eclipses in the years 1917, 1935, and 1985. In the year 1935 there will be five eclipses of the sun, a rare event; and in 1985 there will be three total eclipses of the moon, a most unusual occurrence.483
Among the ancient Hindoos, the common people believed that eclipses were caused by the interposition of a monstrous demon called Raha. This absurd idea, and others equally ridiculous, were based on declarations in their sacred books, and no pious Hindoo would think of denying it.
The following cases of darkenings of the sun are given by Humboldt: —
According to Plutarch the sun remained pale for a whole year at the death of Julius Cæsar, and gave less than its usual heat.484
A sun-darkening lasting for two hours is recorded on August 22, 358 A.D., before the great earthquake of Nicomedia.
In 360 A.D. there was a sun-darkening from early morn till noon. The description given by the historians of the time corresponds to an eclipse of the sun, but the duration of the obscurity is inexplicable.
In 409 A.D., when Alaric lay siege to Rome, “there was so great a darkness that the stars were seen by day.”
In 536 A.D. the sun is said to have been darkened for a year and two months!
In 626 A.D., according to Abul Farag, half the sun’s disc was darkened for eight months!
In 934 A.D. the sun lost its brightness for two months in Portugal.
In 1090 A.D. the sun was darkened for three hours.
In 1096, sun-spots were seen with the naked eye on March 3.
In 1206 A.D. on the last day of February, “there was complete darkness for six hours, turning the day into night.” This seems to have occurred in Spain.
In 1241 the sun was so darkened that stars could be seen at 3 p.m. on Michaelmas day. This happened in Vienna.485
The sun is said to have been so darkened in the year 1547 A.D. for three days that stars were visible at midday. This occurred about the time of the battle of Mühlbergh.486
Some of these darkenings may possibly have been due to an enormous development of sun-spots; but in some cases the darkness is supposed by Chladni and Schnurrer to have been caused by “the passage of meteoric masses before the sun’s disc.”
The first observer of a transit of Venus was Jeremiah Horrocks, who observed the transit of November 24 (O.S.), 1639. He had previously corrected Kepler’s predicted time of the transit from 8h 8m a.m. at Manchester to 5h 57m p.m. At the end of 1875 a marble scroll was placed on the pedestal of the monument of John Conduitt (nephew of Sir Isaac Newton, and who adopted Horrocks’ theory of lunar motions) at the west end of the nave of Westminster Abbey, bearing this inscription from the pen of Dean Stanley —
The transit of Venus which occurred in 1761 was observed on board ship(!) by the famous but unfortunate French astronomer Le Gentil. The ship was the frigate Sylphide, sent to the help of Pondicherry (India) which was then being besieged by the English. Owing to unfavourable winds the Sylphide was tossed about from March 25, 1761, to May 24 of the same year. When, on the later date, off the coast of Malabar, the captain of the frigate learned that Pondicherry had been captured by the English, the vessel returned to the Isle of France, where it arrived on June 23, after touching at Point de Galle on May 30. It was between these two places that Le Gentil made his observations of the transit of Venus under such unfavourable conditions. He had an object-glass of 15 feet (French) focus, and this he mounted in a tube formed of “four pine planks.” This rough instrument was fixed to a small mast set up on the quarter-deck and worked by ropes. The observations made under such curious conditions, were not, as may be imagined, very satisfactory. As another transit was to take place on June 3, 1769, Le Gentil made the heroic resolution of remaining in the southern hemisphere to observe it! This determination was duly carried out, but his devotion to astronomy was not rewarded; for on the day of the long waited for transit the sky at Pondicherry (where he had gone to observe it) was clouded over during the whole phenomenon, “although for many days previous the sky had been cloudless.” To add to his feeling of disappointment he heard that at Manilla, where he had been staying some time previously, the sky was quite clear, and two of his friends there had seen the transit without any difficulty.488 Truly the unfortunate Le Gentil was a martyr to science.
The famous German astronomer Bessel once said “that a practical astronomer could make observations of value if he had only a cart-wheel and a gun barrel”; and Watson said that “the most important part of the instrument is the person at the small end.”489
With reference to Father Hell’s supposed forgery of his observations of the transit of Venus in 1769, and Littrow’s criticism of some of the entries in Hell’s manuscript being corrected with a different coloured ink, Professor Newcomb ascertained from Weiss that Littrow was colour blind, and could not distinguish between the colour of Aldebaran and the whitest star. Newcomb adds, “For half a century the astronomical world had based an impression on the innocent but mistaken evidence of a colour-blind man respecting the tint of ink in a manuscript.”
It is recorded that on February 26, B.C. 2012, the moon, Mercury, Venus, Jupiter, and Saturn, were in the same constellation, and within 14 degrees of each other. On September 14, 1186 A.D., the sun, moon, and all the planets then known, are said to have been situated in Libra.490
In the Sanscrit epic poem, “The Ramaya,” it is stated that at the birth of Rama, the moon was in Cancer, the sun in Aries, Mercury in Taurus, Venus in Pisces, Mars in Capricornus, Jupiter in Cancer, and Saturn in Libra. From these data, Mr. Walter R. Old has computed that Rama was born on February 10, 1761 B.C.491
A close conjunction of Mars and Saturn was observed by Denning on September 29, 1889, the bright star Regulus (α Leonis) being at the time only 47′ distant from the planets.492
An occultation of the Pleiades by the moon was observed by Timocharis at Alexandria on January 29, 282 B.C. Calculations by Schjellerup show that Alcyone (η Tauri) was occulted; but the exact time of the day recorded by Timocharis differs very considerably from that computed by Schjellerup.493 Another occultation of the Pleiades is recorded by Agrippa in the reign of Domitian. According to Schjellerup the phenomenon occurred on November 29, A.D. 92.
“Kepler states that on the 9th of January, 1591, Mæstlin and himself witnessed an occultation of Jupiter by Mars. The red colour of the latter on that occasion plainly indicated that it was the inferior planet.”494 That is, that Mars was nearer to the sun than Jupiter. But as the telescope had not then been invented, this may have been merely a near approach of the two planets.
According to Kepler, Mæstlin saw an occultation of Mars by Venus on October 3, 1590. But this may also have been merely a near approach.[496]
A curious paradox is that one can discover an object without seeing it, and see an object without discovering it! The planet Neptune was discovered by Adams and Leverrier by calculation before it was seen in the telescope by Galle; and it was actually seen by Lalande on May 8 and 10, 1795, but he took it for a star and thus missed the discovery. In fact, he saw the planet, but did not discover it. It actually appears as a star of the 8th magnitude in Harding’s Atlas (1822). The great “new star” of February, 1901, known as Nova Persei, was probably seen by some people before its discovery was announced; and it was actually noticed by a well-known American astronomer, who thought it was some bright star with which he was not familiar! But this did not amount to a discovery. Any one absolutely ignorant of astronomy might have made the same observation. An object must be identified as a new object before a discovery can be claimed. Some years ago a well-known Irish naturalist discovered a spider new to science, and after its discovery he found that it was common in nearly every house in Dublin! But this fact did not detract in the least from the merit of its scientific discovery.
There is a story of an eminent astronomer who had been on several eclipse expeditions, and yet was heard to remark that he had never seen a total eclipse of the sun. “But your observations of several eclipses are on record,” it was objected. “Certainly, I have on several occasions made observations, but I have always been too busy to look at the eclipse.” He was probably in a dark tent taking photographs or using a spectroscope during the totality. This was observing an eclipse without seeing it!
Humboldt gives the credit of the invention of the telescope to Hans Lippershey, a native of Wesel and a spectacle-maker at Middleburgh; to Jacob Adreaansz, surnamed Metius, who is also said to have made burning-glasses of ice; and to Zachariah Jansen.495
With reference to the parabolic figure of the large mirrors of reflecting telescopes, Dr. Robinson remarked at the meeting of the British Association at Cork in 1843, “between the spherical and parabolic figures the extreme difference is so slight, even in the telescope of 6-feet aperture [Lord Rosse’s] that if the two surfaces touched at their vertex, the distance at the edge would not amount to the 1⁄10000 of an inch, a space which few can measure, and none without a microscope.”496
In the year 1758, Roger Long, Lowndean Professor of Astronomy at Cambridge, constructed an “orrery” on a novel principle. It was a hollow metal sphere of about 18 feet in diameter with its fixed axis parallel to the earth’s axis. It was rotated, by means of a winch and rackwork. It held about thirty persons in its interior, where astronomical lectures were delivered. The constellations were painted on the interior surface; and holes pierced through the shell and illuminated from the outside represented the stars according to their different magnitudes. This ingenious machine was much neglected for many years, but was still in existence in Admiral Smyth’s time, 1844.497
A “temporary star” is said to have been seen by Hepidanus in the constellation Aries in either 1006 or 1012 A.D. The late M. Schönfeld, a great authority on variable stars, found from an Arabic and Syrian chronicle that 1012 is the correct year (396 of the Hegira), but that the word translated Aries would by a probable emendation mean Scorpio. The word in the Syrian record is not the word for Aries.498
Mr. Heber D. Curtis finds that the faintest stars mentioned in Ptolemy’s Catalogue are about 5·38 magnitude on the scale of the Harvard Photometric Durchmustering.499 Heis and Houzeau saw stars of 6-7 magnitude (about 6·4 on Harvard scale). The present writer found that he could see most of Heis’ faintest stars in the west of Ireland (Co. Sligo) without optical aid (except short-sighted spectacles).
With reference to the apparent changes in the stellar heavens produced by the precession of the equinoxes, Humboldt says —
“Canopus was fully 1° 20′ below the horizon of Toledo (39° 54′ north latitude) in the time of Columbus; and now the same star is almost as much above the horizon of Cadiz. While at Berlin, and in northern latitudes, the stars of the Southern Cross, as well as α and β Centauri, are receding more and more from view, the Magellanic Clouds are slowly approaching our latitudes. Canopus was at its greatest northern approximation during last century [eighteenth], and is now moving nearer and nearer to the south, although very slowly, owing to its vicinity to the south pole of the ecliptic. The Southern Cross began to become invisible in 52° 30′ north latitude 2900 years before our era, since, according to Galle, this constellation might previously have reached an altitude of more than 10°. When it had disappeared from the horizon of the countries of the Baltic, the great pyramid of Cheops had already been erected more than five hundred years. The pastoral tribe of the Hyksos made their incursion seven hundred years earlier. The past seems to be visibly nearer to us when we connect its measurement with great and memorable events.”500
With reference to the great Grecian philosopher and scientist Eratosthenes of Cyrene, keeper of the Alexandrian Library under Ptolemy Euergetes, Carl Snyder says, “Above all the Alexanders, Cæsars, Tadema-Napoleons, I set the brain which first spanned the earth, over whose little patches these fought through their empty bootless lives. Why should we have no poet to celebrate so great a deed?”501 And with reference to Aristarchus he says, “If grandeur of conceptions be a measure of the brain, or ingenuity of its powers, then we must rank Aristarchus as one of the three or four most acute intellects of the ancient world.”502
Lagrange, who often asserted Newton to be the greatest genius that ever existed, used to remark also – “and the most fortunate; we do not find more than once a system of the world to establish.”503
Grant says —
“Lagrange deserves to be ranked among the greatest mathematical geniuses of ancient or modern times. In this respect he is worthy of a place with Archimedes or Newton, although he was far from possessing the sagacity in physical enquiries which distinguished these illustrious sages. From the very outset of his career he assumed a commanding position among the mathematicians of the age, and during the course of nearly half a century previous to his death, he continued to divide with Laplace the homage due to pre-eminence in the exact sciences. His great rival survived him fourteen years, during which he reigned alone as the prince of mathematicians and theoretical astronomers.”504
A writer in Nature (May 25, 1871) relates the following anecdote with reference to Sir John Herschel: “Some time after the death of Laplace, the writer of this notice, while travelling on the continent in company with the celebrated French savant Biot, ventured to put to him the question, not altogether a wise one, ‘And whom of all the philosophers of Europe do you regard as the most worthy successor of Laplace?’ Probably no man was better able than Biot to form a correct conclusion, and the reply was more judicious than the question. It was this, ‘If I did not love him so much I should unhesitatingly say, Sir John Herschel.’” Dr. Gill (now Sir David Gill), in an address at the Cape of Good Hope in June, 1898, spoke of Sir John Herschel as “the prose poet of science; his popular scientific works are models of clearness, and his presidential addresses teem with passages of surpassing beauty. His life was a pure and blameless one from first to last, full of the noblest effort and the noblest aim from the time when as a young Cambridge graduate he registered a vow ‘to try to leave the world wiser than he found it’ – a vow that his life amply fulfilled.”505
Prof. Newcomb said of Adams, the co-discoverer of Neptune with Leverrier, “Adams’ intellect was one of the keenest I ever knew. The most difficult problem of mathematical astronomy and the most recondite principles that underlie the theory of the celestial motions were to him but child’s play.” Airy he regarded as “the most commanding figure in the astronomy of our time.”506 He spoke of Delaunay, the great French astronomer, as a most kindly and attractive man, and says, “His investigations of the moon’s motion is one of the most extraordinary pieces of mathematical work ever turned out by a single person. It fills two quarto volumes, and the reader who attempts to go through any part of the calculations will wonder how one man could do the work in a lifetime.”507
Sir George B. Airy and Prof. J. C. Adams died in the same month. The former on January 2, 1892, and the latter on January 22 of the same year.
It is known from the parish register of Burstow in Surrey that Flamsteed (Rev. John Flamsteed), the first Astronomer Royal at Greenwich, was buried in the church at that place on January 12, 1720; but a search for his grave made by Mr. J. Carpenter in 1866 and by Mr. Lynn in 1880 led to no result. In Mrs. Flamsteed’s will a sum of twenty-five pounds was left for the purpose of erecting a monument to the memory of the great astronomer in Burstow Church; but it does not appear that any monument was ever erected. Flamsteed was Rector of the Parish of Burstow.508 He was succeeded in 1720 by the Rev. James Pound, another well-known astronomer. Pound died in 1724.509
Evelyn says in his Diary, 1676, September 10, “Dined with Mr. Flamsteed, the learned astrologer and mathematician, whom his Majesty had established in the new Observatory in Greenwich Park furnished with the choicest instruments. An honest sincere man.”510 This shows that in those days the term “astrologer” was synonymous with “astronomer.”
In an article on “Our Debt to Astronomy,” by Prof. Russell Tracy Crawford (Berkeley Astronomical Department, California, U.S.A.), the following remarks occur: —
“Behind the artisan is a chemist, behind the chemist is a physicist, behind the physicist is a mathematician, and behind the mathematician is an astronomer.” “Were it not for the data furnished by astronomers, commerce by sea would practically stop. The sailing-master on the high seas could not determine his position, nor in what direction to head his ship in order to reach a desired harbour. Think what this means in dollars and cents, and estimate it if you can. For this one service alone the science of astronomy is worth more in dollars and cents to the world in one week than has been expended upon it since the beginning of civilization. Do you think that Great Britain, for instance, would take in exchange an amount equal to its national debt for what astronomy gives it? I answer for you most emphatically, ‘No.’”
In his interesting book, Reminiscences of an Astronomer, Prof. Simon Newcomb says with reference to the calculations for the Nautical Almanac (referred to in the above extract) —