« PreviousContinue »
shilling in another way with no great difficully. The Greeks themselves were never so ungrateful as the French historian of astronomy is on their behalf. They speak constantly of their having been primitively indebted to foreigners for all the elements of their improvement. Herodotus
that Greece received from Chaldæa the gnomon and the pole, and the division of the day into twelve parts. The old historian's brevity has left this information rather obscure as to what was meant by the gnomon and the pole. The most of translators have thought that the gnomon and the pole means, in Herodotus, only two parts of one and the same instrument, namely, the dial-plate and the shadow-caster in its centre. Larcher, the French translator, had a different idea, and thought that the pólos, or pole, implied an instrument constructed with a knowledge of the altitude of the earth's pole. For this far-fetched idea Ideler compliments him by saying, that it shows his utter ignorance respecting the dials of the ancients. I shall scarcely be able however to do justice to Ideler's ideas of ancient gnomonics without quoting them in his own words: “ During the day,” he says, “ men made their first calculations of time from the position of the
sun in regard to terrestrial objects, and from the length and di“ rection of the shadow. It was soon observed that at noon the “ shadow was shortest, and had constantly the same direction : in “ order to obtain exactly this important section of the day, and also “ the hours before and after noon, at least in a rough way, it is “probable that they very early succeeded in discovering the use of “ the gnomon. From this simple device, which consisted chiefly in “ the tracing of a meridian line on a horizontal plane, and the putting
upon it an erect staff or obelisk, the Greeks invented gradually the « sun-dial, ωρολόγια ηλιακά, or σκιοθηρικά, for the hand of their dial “stood generally vertical; whereas the same lies with us in the direc“ tion of the axis of the earth, our dials pot showing a variation of the
hours, but an equal division of the time. Our gnomonics are there“ fore quite different from those of the ancients.” Herodotus,” Ideler continues, “ says that the Greeks, together with the division “ of the day, borrowed the dial from the Babylonians: Scaliger, in
commenting on this passage of Herodotus, suggested the strik
ingly probable idea that rólos was the earlier name among the “ Greeks for the word 'Noodóylov. But Larcher asks, if Herodotus “ meant the dial by rólos, why does he add the word yvúuwv “ to it? To this it may be answered, that Herodotus might as “ well put the two words tólos and yvúuwy together as Suidas “puts wpolóylov and yvóuwy together, when he asserts that Ana“ ximander introduced them into Greece. To Larcher it seemed “ natural that Herodotus, in mentioning the sun-dial, thought of the
pole of the earth; but Larcher knew nothing of the dials of the “ ancients when he thought of their constructing them parallel to " the earth's axis.” The gnomon (Ideler remarks) was used also without the index for hours ; not to discover the hours, but the seasons, the solstices, and the equinoxes. “ It is exceedingly probable,” he adds, “ that it was Anaximander, who lived about one hundred
years before Herodotus, who first acquainted his countrymen with " this invention of the Orientals ; for, according to Pliny, he was the * first' of the Greeks who discovered, or rather measured, the obliquity “ of the ecliptic, for which he had no other means than the obser“ vation of the meridional shadow on the gnomon. We cannot assert “ with certainty that he had already made use of a sun-dial, as Sui“ das and Diogenes Laertius assure us, or whether it was his pupil, “ Anaximenes, who first erected a horologion sciothericon. Be “ this as it may, we must always regard those first attempts in “ scientific instrument making) as exceedingly raw. Centuries elapsed “ before gnomonics reached the perfection to which they attained " among the ancients. This did not take place before the institution “ of the museum of Alexandria, when practical astronomy, which “ then began to be cultivated, made the want of an exact measure“ ment of time be sensibly felt.”
This quotation from Ideler may well save me from saying much about the famous Chaldæan philosopher Berosus, whose solar quadrant was the most ingenious production of the Chaldæan school. Whether this Berosus lived in the time of Alexander, according to Salmasius, or in the time of Hippocrates, according to Vitruvius, he was at least antecedent to the Alexandrian school. Now Ideler shows that it was even late in the day of the Alexandrian school ; that is, not earlier than Hipparchus' time, that the gnomonic science of the Greeks grew to a state beyond that of absolute rudeness ; so that he cannot seem to contradict Delambre, when the latter astronomer expresses himself thus of Berosus' hollow sphere, that it “supposes no knowledge more than that of the form and spherical movement of the heavens.
The greatest difference which I find on the subject of ancient astronomy, between Delambre and Ideler, is in their estimation of the correctness of Chaldæan astronomy. “ Their very mode of computing the appearance of the stars,” says Delambre, “must have produced, on account of refraction, an error of half a degree as to every star.” Some of these Chaldæan observations have been brought into Greece. Ptolemy has preserved to us six of their eclipses; of which, after the example of Hipparchus, he has made use in order to determine the movements of the moon. Now,” says Delambre, “ if the Chaldæans could have themselves determined “ those movements of the moon, why were the determinations not “ also brought into Greece along with the observations from which “ they had been deduced ? or why has Ptolemy left us no mention “ of them? Besides in what consisted those observations ? On such “ a day, two hours before midnight, or an hour after sunset, the moon “ was eclipsed to the north, or to the south, by a half or a quarter of “ its diameter. The time is never expressed but in hours: the quantity “ of the eclipse is never reduced to a smaller fraction than a fourth “ of the diameter of the body eclipsed. For such observations it “ was only necessary to have eyes and a little attention.”
“ The same Chaldæans,” Delambre adds, “ according to the ac“ count of Diodorus Siculus, assiduously observed the rising and “ setting of the stars and planets from the tower of the temple of “ Belus, one face of which looked to the east, another to the west. “ This account has nothing improbable. These observations may “ have given to the Chaldæans the first perception of the length " of the year, the first notion of the obliquity of the sun's annual
" route, with 'regard to the equator, and, may have conducted them " to a division of the equator. They had not, however, according “ to all appearance, any distinct idea of the ecliptic. It was not “ the circle of the heavens which they divided. We are told that
they determined the portions of the equator which passed through “ the horizon in a given time. The number of these portions is “ always proportional to the time that passes ; but the same is “ not the case with the arcs of the ecliptic, which rise within the “same given time. The operation which equally divided the equator could but very unequally divide the ecliptic.” Ideler's idea of Chaldæan astronomy is more favorable. The Chaldæans, he says, (Technische Chronologie, Vol. I. p. 206.) “were acquainted with "several lunar periods. Among others worthy of attention, was that “ of 223 changes of the moon.” From Geminus, an ancient Greek astronomer, Dr. Ideler shows, that in the formation of this period, the calculations of the medial daily movement of the moon, made by the Chaldæans, corresponded exactly with those of the Greek tables; and respecting their calculations, he says, “ their ex“ actness must excite our astonishment. They discovered the syno“ dical month, or period of the moon's return to the sun, only with
an error of 44 seconds ; and the periodic month, or the time of the “ moon's return to the same point in the sun's path, only with an
error of a second too much."
We have here proofs of Chaldæan accuracy in sidereal observations, that must have required not a little, but a great deal of attention. But still with all this attention, experience, and accuracy, it does not appear that they could predict eclipses of the sun. Diodorus Siculus confesses that they could not; and to speak generally of their astronomy, the state of their dialling, which Ideler describes, shows that it must have been still a crude and imperfect science.
Whilst the sciences that were to perfect Geography were thus slowly advancing, and centuries before they reached their highest ancient cultivation by the Alexandrian Greeks, Herodotus, by his historic work, practically enlarged geographical knowledge to a valuable extent. Even before his time voyages had been performed, and prose works had appeared, which had tended to the same effect. Hecatæus and the other logographers of Ionia, who described places and antiquities, were eclipsed in reputation by Herodotus; but still they were useful pioneers in the march of historic literature. Still more useful to Geography were the voyagers ; among whom the most distinguished was Hanno, the Carthaginian admiral, who, between five and six hundred years before our era, was sent with a fleet to visit the western coasts of Africa, with a view to colonise them, and to extend the boundaries of commerce. This commission he fortunately fulfilled, and reached as far as the isle of Cerné, which in the opinion of Monsieur Gossellin is the modern isle of Fedal. To this point, about the latitude of Cape Non, Monsieur Gossellin limits the periplus of Hanno. Monsieur Malte-Brun, though he does not imagine Hanno's navigation to have gone quite so far southward as some theorists have pushed it, seeins to me not over-reasonable in suspecting that Hanno went farther south than Gossellin allows. He contends that if the Phænicians and Carthaginians could sail to Britain, and even to Jutland, which was a much greater distance to
the north than Cerné was to the south, they must have sailed farther southward in Africa. To this it may be answered, that admitting Himilco, another Carthaginian voyager, to have gone later in the same age to a greater distance than Hanno went in a different direction, the cause may have been, that the seas and shores of the north had been much longer frequented by navigators than those of the south, and their navigation northward would therefore be easier. · On his return to Carthage, Hanno deposited an official Report of his voyage in the public archives. The senate caused an extract from that Report to be made out in the form of an inscription, which was placed in the temple of Saturn. A Greek copy of it has been preserved to us, and a full and amusing commentary upon it is to be found in the works of Gossellin.
Another navigator of antiquity was Scylax of Caryanda. Three persons of this name figure in ancient Geography, but my business at present is only with the oldest Scylax, who is mentioned by Herodotus, and who must have therefore preceded him. Herodotus says, " that by the orders of Darius Hystaspes, he brought a fleet round “ the capes of Arabia to the most northerly part of the Red Sea.” Here we have another story from the father of history, which it would require all his own credulity to digest: “A fleet of Persians accom“ plishing a voyage which the Greeks under Alexander the Great “ tried and failed to accomplish.” Arrian must have read this passage in Herodotus, and must have smiled at it; but he thought so little of its importance that he has not deigned to notice it. He gives such distinct proofs, however, of the difficulty of doubling the Arabian Capes, to navigators in those days, that we must conclude Herodotus to have mistaken some rumour of Scylax's land journey from India for this imaginary periplus.
However immature Astronomy may have been, in (and even after) the days of Herodotus, it is nevertheless evident from his own account, that more correct ideas about the shape of the earth than be himself entertained had begun to circulate. Without believing for a moment that the Pythagoreans had scientific means to discover that system of the plurality of worlds and of the earth's motion round the sun, at which they merely guessed, it is difficult to imagine men thinking at all, from age to age, upon the subject, and failing to have an idea of the earth's rotundity. The roundness of the moon was a hint to them that the earth might have the same shape, and, whatever the vulgar might think, philosophers in the very infancy of astronomy were aware that the sun and moon were large bodies. If these floated in space, it was evident that the earth could float also. That this truth was surmised in Herodotus's time we collect from the old historian himself, whom some of the illuminati appear to have tormented with doubts about the earth's flatness. Herodotus is, in fact, not a fair representative of the physical philosophy of his age. _He was not imbued with any portion even of its scanty science. Far be it from me, though I speak thus freely of the venerable man, to undervalue all the due respect and gratitude that we owe to his memory. His principal object was history and not geography ; yet so much did he extend geographical-information, that the proportion of space on the globe, known to Ptolemy centuries later, scarcely exceeded that which the map of Herodotus comprehended. The reason was that he knew
more of Africa than Ptolemy, and vastly more than Strabo ; so that the ground gained in Geography for many ages after Herodotus scarcely equalled the ground that was lost.
As a writer he is pre-eminent for clearness and suavity-for benignant moral feeling, and for wielding with graceful ease vast historical materials. Veracious as to all that he saw, he is credulous as to what he heard, only from an honest excess of faith in human testimony. The pleasure which we receive from Herodotus, unless I am deceived by accidental associations, amounts to poetical enjoyment. How can this be, it may be asked, when there is neither figure nor color of fancy in his limpid diction, nor impassioned eloquence in his placid morality. No; but his topographic description has a romantic expanse of scenery, opening vistas to the imagination, from the steppes of Scythia to the gates of Babylon and the pyramids of Egypt. The mind is carried over his historic horizon of almost all the world unfatigued and unperplexed ; and, when he crowns his narrative by bringing all the nations he has described into contact with invaded Greece, he gives history an interest resembling epic grandeur. The genius of prose literature appears in his writings as if she had gone abroad indeed over the world in quest of truth, but yet as if she had so freshly parted from the bowers of poetry that their odours still remained upon her robes.
Yet in some instance this great writer is a sort of prototype of parson Adams for simplicity: his naivété is absolutely amusing. Of Those who hinted at the roundness of the earth, he speaks with even less than his usual good nature--calling them presumptuous persons.
It is highly probable that he was annoyed by men of more physical research than himself with arguments against his opinion of the earth being flat. Let us hope, for the credit of his age,
that there were persons “presumptuous” enough to smile at his doctrine respecting the diversity of climates. According to him the cause of all such diversity lies not in the northern or southern latitude of a country, but a country has its peculiar climate raw or genial, like its richness or poverty of soil, according to the winds by which it is most frequently visited. This idea, however, was not peculiar to Herodotus, for the Greeks before him had placed an island of the blest with its eternal spring to the north of Scythia, as if they thought by getting north of Boreas they eluded his icy breath.
For this mistake the Greeks have some apology in the circumstance, that the winds in their region of the world have extraordinary powers to make places alike in latitude exceedingly different in climate, But still Herodotus exceeds all the allowance that can be made for the prejudices of his age, when he says that in winter, when the cold winds rule in the north, they force the sun to turn away from them to the warmer winds of the south. His accounting for the coldness of the nights in India by the far western distance of the sun, is another proof of his crude notions of meteorology.
But having now detained you longer, I fear, than I have been able to sustain your interest in the subject, I must conclude my remarks ; and I must defer to another opportunity availing myself of the eventual permission, which you may give me, to offer a few farther speculations on the same subject.