The honour of first cultivating astronomy has been ascribed to the Chaldeans, the Egyptians, the Arabians, and likewise to the Chinese;[[A1]] amongst whom, it is pretended, astronomical observations are to be found of almost as early a date as the flood. But little credit is given to these reports of the Jesuits, who it is thought were imposed on by the natives; or else perhaps from motives of vanity, they have departed a little from truth, in their accounts of a country and people among whom they were the chief European travellers.
Not to mention the prodigious number of years in which it is said the Chaldeans observed the heavens, I pass on to what carries the appearance of more probability;[[A2]] the report that when Alexander took Babylon, astronomical observations for one thousand nine hundred years before that time were found there, and sent from thence to Aristotle. But we cannot suppose those observations to have been of much value; for we do not find that any use was ever after made of them.[[A3]]
The Egyptians too, we are told, had observations of the stars for one thousand five hundred years before the Christian era. What they were, is not known; but probably the astronomy of those ages consisted in little more than remarks on the rising and setting of the fixed stars, as they were found to correspond with the seasons of the year;[[A4]] and, perhaps, forming them into constellations. That this was done early, appears from the book of Job, which has by some been attributed to Moses, who is said to have been learned in the sciences of Egypt.[[A5]] “Canst thou bind the sweet influences of Pleiades, or loose the bands of Orion? Canst thou bring forth Mazzaroth in his season, or canst thou guide Arcturus with his sons?” Perhaps too, some account might be kept of eclipses of the sun and moon, as they happened, without pretending to predict them for the future. These eclipses are thought by some to have been foretold by the Jewish prophets in a supernatural way.
As to the Arabians, though some have supposed them the first inventors of astronomy, encouraged to contemplate the heavens by the happy temperature of their climate, and the serenity of their skies, which their manner of life must likewise have contributed to render more particularly the object of their attention; yet it is said, nothing of certainty can now be found to induce us to think they had any knowledge of this science amongst them before they learned it from the writings of Ptolemy, who flourished one hundred and forty years after the birth of Christ.
But notwithstanding the pretensions of other nations, since it was the Greeks who improved geometry, probably from its first rudiments, into a noble and most useful science; and since we cannot conceive that astronomy should make any considerable progress without geometry, it is to them we appear indebted for the foundations of a science, that (to speak without a metaphor) has in latter ages reached the astonishingly distant heavens.
Amongst the Greeks, Hipparchus[[A6]] deserves particular notice; by an improvement of whose labours Ptolemy formed that system of astronomy which appears to have been the only one studied for ages after, and particularly (as was said before) by the Arabians; who made some improvements of their own, and, if not the inventors, were at least the preservers of astronomy. For with them it took refuge, during those ages of ignorance which involved Europe, after an inundation of northern people had swallowed up the Roman empire; where the universally prevailing corruption of manners, and false taste, were become as unfavourable to the cause of science, as the ravages of the Barbarians themselves.
From this time, we meet with little account of astronomical learning in Europe[[A7]] until Regiomontanus,[[A8]] and some others, revived it in the fifteenth century; and soon afterwards appeared the celebrated Copernicus,[[A9]] whose vast genius, assisted by such lights as the remains of antiquity afforded him, explained the true system of the universe, as at present understood. To the objection of the Aristotelians, that the sun could not be the centre of the world, because all bodies tended to the earth, Copernicus replied, that probably there was nothing peculiar to the earth in this respect; that the parts of the sun, moon and stars, likewise tended to each other, and that their spherical figure was preserved amidst their various motions, by this power; an answer that will at this day be allowed to contain sound philosophy. And when it was further objected to him, that, according to his system, Venus and[and] Mercury ought to appear horned like the moon, in particular situations; he answered as if inspired by the spirit of prophecy, and long before the invention of telescopes, by which alone his prediction could be verified, “That so they would one day be found to appear.”
Next follows the noble Tycho,[[A10]] who with great labour and perseverance, brought the art of observing the heavens to a degree of accuracy unknown to the ancients; though in theory he mangled the beautiful system of Copernicus. The whimsical Kepler, too, (whose fondness for analogies frequently led him astray, yet sometimes happily conducted him to important truths) did notable services to astronomy: and from his time down to the present, so many great men have appeared amongst the several nations of Europe, rivalling each other in the improvement of astronomy, that I should trespass on your patience were I to enumerate them. I shall therefore proceed to what I proposed in the second place, and take notice of some of the most important discoveries in this science.
Astronomy, like the Christian religion, if you will allow me the comparison, has a much greater influence on our knowledge in general, and perhaps on our manners too, than is commonly imagined. Though but few men are its particular votaries, yet the light it affords is universally diffused amongst us; and it is difficult for us to divest ourselves of its influence so far, as to frame any competent idea of what would be our situation without it.[[A11]] Utterly ignorant of the heavens, our curiosity would be confined solely to the earth, which we should naturally suppose a vast extended plain; but whether of infinite extent or bounded, and if bounded, in what manner, would be questions admitting of a thousand conjectures, and none of them at all satisfactory.
The first discovery then, which paved the way for others more curious, seems to have been the circular figure of the earth, inferred from observing the meridian altitudes of the sun and stars to be different in distant places. This conclusion would probably not be immediately drawn, but the appearance accounted for, by the rectilinear motion of the traveller; and then a change in the apparent situations of the heavenly bodies would only argue their nearness to the earth: and thus would the observation contribute to establish error, instead of promoting truth, which has been the misfortune of many an experiment. It would require some skill in geometry, as well as practice in observing angles, to demonstrate the spherical figure of the earth from such observations.[[A12]]