It was supposed that we were already pretty ac- curately acquainted with the distance of the moon from the earth, it being so much nearer to us, by observing its parallax, or the difference of its place in the heavens, as seen from the surface of the earth, from that in which it would appear if seen from its centre ^. But the parallax of the sun is so exceedingly small, as scarcely to afford the basis of a mathematical calculation ^ The parallax of Venus is however almost four times as great as that of the sun; and there must therefore be a very sensible difference between the times in which Venus may be seen passing over the sun from different parts of the earth* It was on this account apprehended, that the parallax of the sun, by means of observa- tions taken from different places at the time of the transit of Venus in 1761 and 1769, might be ascer- tained with a great degree of precision"*.
But the imperfectness of our instruments and ^ Bonnycastle, Astronomy, 7th edition, p. 262, et seqq, i.
XXI.] OF ASTRONOMY. 401 means of observation have no small tendei^cy to baffle the ambition of man in these curious investi- gations* " The true quantity of the moon's parallax," says Bonnycastle, *^ cannot be accurately determined by the methods ordinarily resorted to, on account of the varying declination of the moon, and the incon- stancy of the horizontal refractions, which are per- petually changing according to the state the atmo- * sphere is in at the time. For the moon continues but for a short time in the equinoctial, and the refraction at a mean rate elevates her apparent place near the horizon, half as much as her parallax depresses it°."
^^ It is well known that the parallax of the sun can never exceed nine secon4^, or the four-hundredth part of a degree **." "Observations," says Halley, ^^made upon the vibrations of a pendulum, to de- termine these exceedingly small angles, are not sufficiently accurate to be depended upon; for by this method of ascertaining the parallax, it will sometimes come out to be nothing, or even nega- tive; that is, the distance will either be infinite, or greater than infinite, which is absurd. And, to con- fess the truth, it is hardly possible for a person to distinguish seconds with certainty by any instru- ments, however skilfully they maybe made; and therefore it is not to be wondered at, that the ex- cessive nicety of this matter should have eluded the 2 D 402 OF ASTRONOMY. [ESSAY many ingenious endeavours of the most able ope- rators P.
Such are the difficulties that beset the subject on every side. It is for the impartial and dispassionate observers who have mastered all the subtleties of the science, if such can be found, to determine whether the remedies that have been resorted to to obviate the above inaccuracies and their causes, have fulfilled their end, and are not exposed to similar errors. But it would be vain to expect the persons, who have ^^ scorned deUghts, and lived lar borious days'' to possess themselves of the mysteries of astronomy, should be impartial and dispassionate, or be disposed to confess, even to their own minds, that their researches were useless, and their labours ended in nothing.
It is further worthy of our attention, that the in-^ struments with which we measure the distance of the earth from the sun and the planets, are the very instruments which have been pronounced upon as incompetent in measuring the heights of moua^ taips^. In the latter case therefore we have sub- stituted a different mode for arriving at the truth, which is supposed to be attended with greater pi«- cision: but we have no substitute to which we can resort, to correct the mistakes into which we n^y fall respecting the heavenly bodies.
The result of the imcertainty which adheres to p Phil. Transactions, Vol. XXIX, p. 456. «» Sec above, p. 392.
XXI.] OF ASTRONOMY. 403 all astronomical observations is such as might have been expected. Common readers are only informed of the latest adjustment of the question^ and are therefore unavoidably led to believe that the di- stwce of the sun from the earth, ever since astro* nomy became entitled to the name of a science, has by universal consent been recognised as ninety-five millions of miles, or, as near as may be, twenty-four thousand semi-diameters of the earth. But how does the case really stand? Copernicus and Tycho Brahe held the distance to be twelve hundred semi- diameters; Kepler, who is received to have been perhaps the greatest astronomer that any age has produced, puts it down as three thousand five hun- dred semi-diameters; since his time, Riccioli as seven thousand; Hevelius as five thousand two huiidred and fifty'; some later astronomers, mei|-> tioned by Halley, as fourteen thousand; and Halley himself as sixteen thousand five hundred^.
Tl^e doctrine of fluxions is likewise called in by the astronomers in their attempts to ascertain the distance and magnitude of the difierent celestial bodies which compose the solar system; and in this way their conclusions become subject to all the difficulties which Berkeley has alleged against that doctrine.
Kepler has also supplied us with another mode ' Tbey were about thirty and forty years younger than Kepler respectively.
' Halley, apud Philosophical Transactions^ Vol. XXIX^ p.455« 2 d2 404 OF ASTRONOMY. [esSAY of arriving at the distance and size of the sun and the planets: he has hazarded a conjecture^ that the squares of the times of the revolution of the earth and the other planets are in proportion to the cubes of their distances from the sun, their common centre; and, as by observation we can arrive with tolerable certainty at a knowledge of the times of their revolutions, we may from hence proceed to the other matters we are desirous to ascertain. And that which Kepler seemed, as by a divine inspiration^ to hazard in the way of conjecture, Newton professes to have demonstratively established. But the de- monstration of Newton has not been considered as satisfactory by all men of science since his time.
Thus far however we proceed as we may, respect- ing our propositions on the subject of the solar system. But, beyond this, all science, real or pre- tended, deserts us. We have no method for mea- suring angles, which can be applied to the fixed stars; and we know nothing of any revolutions they perform. All here therefore seems gratuitous: we reason from certain alleged analogies; and we can do no more.
Huygens endeavoured to ascertain something on the subject, by making the aperture of a telescope so small, that the sun should appear through it no larger than Sirius, which he found to be only in the proportion of 1 to 27,664 times his diameter, as seen by the naked eye. Hence, supposing Sirius to be a globe of the same magnitude as the sun, it XXI.]. OF ASTRONOMY. 405 must be 27,664 times as distant from us as the sun, in other words, at s\t distance so considerable as to equal 345 million diameters of the earths Every one must feel on how slender a thread this conclu- sion is suspended.
And yet, from this small postulate, the astro- nomers proceed to deduce the most astounding conclusions. They tell us, that the distance of the nearest fixed star from the earth is at least 7,600,000,000,000 miles, and of another they name, not less than 38 millions of millions of miles. A cannon-ball therefore, proceeding at the rate of about twenty miles in a minute would be 760,000 years in passing from us to the nearest fixed star, and 3,800,000 in passing to the second star of which we speak. Huygens accordingly concluded, that it was not impossible, that there might be stars at such inconceivable distances from us, that their light has not yet reached the earth since its crea- tion ".
The received system of the universe, founded upon these so called discoveries, is that each of the stars is a sun, having planets and comets revolving round it, as our sun has the earth and other planets revolving round him. It has been found also by the successive observations of astronomers, that a star now and then is totally lost, and that a new star makes its appearance which had never been remarked before: and this they explain into the ' Encyclopaedia Londinensis, Vol. II, p. 407. " Ibid, p. 408.
406 OF ASTRONjOMY. [esSAY creation of a new system from time to time by the Almighty author of the universe, and the destruc- tion of an old system worn out with age'^. We must also remember the power of attraction every where diffused through infinite space, by means of which, as Herschel assures us, in great le>h of time a nebula, or cluster of stars, may be formed, while the projectile force they received in the beginning may prevent them from all coming together, at least for millions of ages. Some of these nebulae, he adds, cannot well be supposed to be at a less di- stance from us than six or eight thousand times' the distance of Sirius^. Kepler however denies that each star, of those which distinctly present them- selves to our sight, can have its system of planets as our sun has, and considers them as all fixed in the same surface or sphere; since, if one of them were twice or thrice as remote as another, it would, supposing their real magnitudes to be equal, appear to be twice or thrice as small, whereas there is not in their apparent magnitudes the slightest differenced Certainly the astronomers are a very fortunate and privileged race of men, who talk to us in this oracular way of " the unseen things of God from the creation of the world," hanging up their con- clusions upon invisible hooks, while the rest of man- kind sit listening gravely to their responses, and un- reservedly " acknowledging that their science is the XXl.] OF ASTRONOMY. 407 most sublime^ the most interesting, and the most useful of all the sciences cultivated by man^."
We have a sensation, which we call the sensation of distance. It comes to us from our sight and our other senses. It does not come immediately by the organ of sight. It has been proved^ that the objects we see, previously to the comparison and correction of the reports of the organ of sight with those of the other senses, do not suggest to us the idea of distance, but that on the contrary whatever we see seems to touch the eye, even as the objects of the sense of feeling touch the skin.
But, in proportion as we compare the impressions made upon our organs of sight with the impressions made on the other senses, we come gradually to connect with the objects we see the idea of distance. I put out my hand, and find at first that an object of my sense of sight is not within the reach of my hand. I put out my hand farther, or by walking advance my body in the direction of the object, and I am enabled to reach it. From smaller experiments 1 proceed to greater. I walk towards a tree or a building, the figure of which presents itself to my eye, but which I find upon trial to have been far from me. I travel towards a place that I cannot see, but which I am told lies in a certain direction. I arrive at the place. It is thus, that by repeated experiments I acquire the idea of remote distances.
To confine ourselves however to the question of » Ferguson, Astronomy, §!.
408 OF ASTRONOMY. [eSSAY objects^ which without change of place I can dis- cover by the sense of sight. I can see a town^ a tower^ a mountain at a considerable distance. Let us suppose that the limit of my sight, so far as re- lates to objects on the earth, is one hundred miles. I can travel towards such an object, and thus ascer- tain by means of my other senses what is its real distance. I can also employ certain instruments, invented by man, to measure heights, suppose of a tower, and, by experiments made in ways indepen- dent of these instruments, verify or otherwise the report of these instruments.
The height of the Monument of London is some- thing more than two hundred feet. Other eleva- tions, the produce of human labour, are consider- ably higher. It is in the nature of the mind, that we conclude from the observation that we have verified^ to the accuracy of another, bearing a striking analogy to the former, that we have not verified. But analogy has its limits. Is it of irre- sistible certainty, or is it in fact to be. considered as approaching to certainty, because we have verified an observation extending to several hundred feet, that an observation extending to ninety-five millions of miles, or to the incredible distances of which Herschel so familiarly talks, is to be treated as a fact, or laid down as a principle in science? Is it reasonable to consider two propositions as analo- gous, when the thing affirmed in the one is in di- mension many million times as great as the thing XXI.] OF ASTRONOMV. 409 affirmed in the other? The experience we have had as to the truth of the smaller, does it authorise us to consider the larger as -unquestionable? That which I see with a bay of the sea or a wide river between, though it may appear very like something with which I am familiar at home, do I imme- diately affirm it to be of the same species and nature, or do I not regard it with a certain degree of scepticism, especially if, along with the re- semblance in some points^ it differs essentially, as for example in magnitude^ in other points? We have a sensation, and we enquire into its cause. This is always a question of some uncertainty. Is its cause something of absolute and substantive ex- istence without me, or is it not? Is its cause some-r thing of the very same nature, as the thing that gave me a similar sensation in a matter of compa- ratively a pigmy and diminutive extension?
All these questions an untrained and inquisitive mind will ask itself in the propositions of astro- nomy. We must believe or not, as we think proper or reasonable. We have no way of verifying the propositions by the trial of our senses. There they lie, to be received by us in the construction that first suggests itself to us, or not. They are some- thing like an agreeable imagination or fiction: and a sober observer, in cold blood, will be disposed de- liberately to weigh both sides of the question, and to judge whether the probability lies in favour of the actual affirmation of the millions of millions of 410 OF A8TR0N0MV. [ESSAY niiles^ and the other incredible propositions of the travelling of lights and the rest, which even the most cautious and sceptical of the retainers of modem astronomy, find themselves compelled to receive.
But I shall be told, that the results of our obser- vations of the distances of the heavenly bodies are unvaried. We have measured the distances and other phenomena of the sun, the moon. Mercury, Venus, Mars, Jupiter, Saturn, and their satellitesi and they all fall into a grand system, so as to con- vey to every unprejudiced mind the conviction that this system is the truth itself. If we look at them day after day, and year after year, we see them for ever the same, and performing the same divine har- mony. Successive astronomers in different ages and countries have observed the celestial orbs, and swept t^e heavens, and for ever bring us back the same story of the number, the dimensions^ the di- stances, and the arrangement of the heavenly bodies which form the subject of astronomical science.
This we have seen indeed not to be exactly the case. But, if it were, it would go a very little way towards proving the point it was brought to prove. It would shew that, the sensations and results being similar, the causes of those results must be similar to each other, but it would not shew that the causes were similar to the sensations produced. Thus, in the sensations which belong to taste, smell, sound, colour, and to those of heat and cold, there is all XXI.] OF ASTRONOMY. 411 the uniformity which would arise, when the real external causes bore the most exact similitude to the perceptions they generate; and yet it is now universally confessed that tastes^ scents, sounds^ colours^ and heat and cold, do not exist out of our^ selves. All that we are entitled therefore to conclude as to the magnitudes and distances of the heavenly bodies, is^ that the causes of our sensations and per- ceptions^ whatever they are, are not less uniform than the sensations and perceptions themselves.
It is further alleged, that we calculate eclipses, and register the various phenomena of the heavenly bodies. Thales predicted an eclipse df the sun, which took place nearly six hundred years before the Christian era. The Babylonians, the Persians, the Hindoos, and the Chinese early turned their attention to astronomy. Many of their observations were accurately recorded; and their tables extend to a period of three thousand years before the birth of Christ. Does not all this strongly argue the solidity of the science to which they belong? Who, after this, will have the presumption to question, that the men who profess astronomy proceed on real grounds, and have a profound knowledge of ^ these things, which at first sight might appear to be set at a distance so far removed from our ken?
The answer to this is easy. I believe in all the astronomy that was believed by Thales. I do not question the statements relative to the heavenly bodies that were delivered by the wise men of the 412 OF ASTRONOMY. [ESSAY East. But the supposed discoveries that were made in the eighteenth, and even in the latter part of the seventeenth century, purporting to ascertain the pre- cise distance of the sun, the planets, and even of the fixed stars, are matters entirely distinct from this. , Among the earliest astronomers of Greece were Thales, Anaximander, Anaximenes and Anaxagoras. Thales^ we are told, held that the earth is a sphere or glohe; Anaximenes that it is like a round, flat table; Anaximander that the sun is like a chariot- wheel^ and is twenty-eight times larger than the earth. Anaxagoras was put in prison for affirming that the sun was by many degrees larger than the whole Peloponnesus*. Kepler is of opinion that all the stars are at an equal distance from us, and are fixed in the same surface or sphere.
In reality the observations and the facts of astro- nomy do not depend either upon the magnitudes or the distances of the heavenly bodies. They proceed in the first place upon what may be seen with the naked eye. They require an accurate and perse- vering attention. They may be assisted by tele- scopes. But they relate only to the sun and the planets. We are bound to ascertain, as nearly as possible^ the orbits described by the different bodies in the solar system: but this has still nothing to do, strictly speaking, with their magnitudes or di- stances. It is required that we should know them in their relations to each other; but it is no pre- ^ Plutarch^ De Placitis Philosophorum. Diogenes Laertiii$.
XXI.] OF ASTRONOMY. 413 liminary of just, of practical, it might almost be said, of liberal science, that we should know any thing of them absolutely.
The unlimited ambition of the nature of man has discovered itself in nothing more than this, the amazing superstructure which the votaries of con- templation within the last two hundred years have built upon the simple astronomy of the ancients. Having begun to compute the distances of miles by millions, it appears clearly that nothing can arrest the more than eagle-flight of the human mind. The distance of the nearest fixed star from the earthy we are informed, is at least 7^600,000,000,000 miles, and of another which the astronomers name, not less than 38 millions of millions of miles. The .particles of light are said to travel 193,940 miles in every second; which is above a million tunes swifter than the progress of a cannon-ball^. And Herschel has concluded, that the light issuing from the faintest nebulae he has discovered, must have been at this rate two millions of years in reaching the earth ^.
SECTION IIL The next process of the modern astronomer is to affirm the innumerable orbs around us, disco- vered with the naked eye, or with which we are •> Ferguson, §.216. " Light moves," says Brewster, Optics, p, 2, ''from one pole of the earth to the other in the 24th part of a second: a velocity which surpasses all comprehension."
414 OF ASTRONOMY. [ESSAY made acquainted by the aid of telescopes, to be all stocked with rational inhabitants. The argument for this is, that an all-wise and omnipotent creator could never have produced such immense bodies, 4ispersed through infinite space, for any meaner purpose, than that of peopling them with ^ intelli^ gent beings, formed for endless progression in per«- fectipn and felicity*'."
Now it appears to me, that, in these assertions, the modern astronomers are taking upon them- «elve9 somewhat too boldly, to expound the coun*- sels of that mysterious power, to which the universe is indebted for its arrangement and order.
We know nothing of God but from his works. Certain speculative men have adventured to reason upon the source of all the system and the wonders that we behold, h priori^ and, having found that the creator is all powerful, all wise, and of infinite good-^* ness, according to their ideas of power, wisdom and goodness, have from thence proceeded to draw their inferences^ and to shew us in what manner the work« of his hands are arranged and conducted by him. This no doubt they have done with the purest in- tentions in the world; but it is not certain, that their discretion has equalled the boldness of their undertaking.
The world that we inhabit, this little globe of earth, is to us an infinite mystery. Human imagi- nation is unable to conceive any thing more con- XXI.] OF ASTRONOMY. 415 summate than the great outline of things below. The trees and the skies, the mountains and the seas, the rivers and the springs, appear as if the de^ sign had been to realise the idea of paradise. The freshness of the air, the silvery light of day, the magnificence of the clouds, the gorgeous and sooth«» ing colouring of the world, the profusion and ex-^ quisiteness of the fruits and flowers of the earth, are as if nothing but joy and delicious sensations had been intended for us. When we ascend to the animal creation, the scene is still more admirable and transporting. The birds and the beasts, the insects that skim the air, and the fishes that live in the great deep, are a magazipe of wonders, that we may study for ever, without fear of arriving at the end of their excellence. Last of all, comes the crown of the creation, man, formed with Iqoks erect, to commerce with the skies. What a master- piece of workmanship is his form^ while the beauty and intelligence of Gods seems to manifest itself in his countenance! Look at that most consummate of all implements, the human hand; think of his understanding, how composed and penetrating; of the wealth of his imagination; of the resplendent virtues he is qualified to display! ^^ How wonderful are thy works. Oh God; in wisdom hast thou created them all!"
. But there are other parts of the system in which we live, which do not seem to correspond with those already enumerated. Before we proceed ta 416 OF ASTRONOMY. [«SSAY people infinite space, it would be as well, if we sur- veyed the surface of the earth we inhabit. What vast deserts do we find in it; what immense tracks of burning sands! One half of the globe is perhaps irreclaimable to the use of man. Then let us think of earthquakes and tempests, of wasting hurricanes^ and the number of vessels, freighted with human beings^ that are yearly buried in the caverns of the ocean. Let us call to mind in man^ the prime orna- ment of the creation, all the diseases to which his frame is subject^ Convulsions^ epilepsies^ fierce catarrhs^ Intestine stone and ulcer^ colic pangs^ Demoniac frenzy^ moping melancholy^ And moon-struck madness, pining atrophy. Marasmus, and wide-waaCing pestilence, Dropsies, and asthmas, and joint-racking rheums.
The very idea of our killings and subsisting upon the flesh of animals, surely somewhat jars with our conceptions of infinite benevolence.
But^ when we look at the political history of man, the case is infinitely worse. This too often seems one tissue of misery and vice. War, con- quest, oppression, tyranny, slavery, insurrections, massacres, cruel punishments, degrading corporal infliction, and the extinction of life under the forms of law, are to be found in almost every page. It is^ as if an evil demon were let loose upon us, and whole nations, from one decad of years to another, were struck with the most pernicious madness. Cer- XXI.] OF ASTRONOMV. 41?
tain reasoners tell us that this is owing to the free- dom of will, without which man could not exist. But here we are presented with an alternative, from which it is impossible for human understanding to escape. Either God, according to our ideas of be- nevolence, would remove evil out of the world, and cannot; or he can, and will not. If he has the will and not the power, this argues weakness; if he has the power and not the will, this seems to be male- volence.
Let us descend from the great stage of the na- tions, and look into the obscurities of private misery. Which of us is happy? What bitter springs of misery overflow the human heart, and are borne by us in silence! What cruel disappointments beset us! To what struggles are we doomed, while we struggle often in vain! The human heart seems framed, as if to be the capacious receptacle of all imaginable sorrows. The human frame seems con- structed, as if all its fibres were prepared to sustain varieties of torment. " In the sweat of thy brow shalt thou eat bread, till thou return to the earth.*^ But how often does that sweat prove ineflective! There are men of whom sorrow seems to be the destiny, from which they can never escape. There are hearts, into which by their constitution it ap- pears as if serenity and content could never enter^ but which are given up to all the furious passions, or are fpr ever the prey of repining and depression.
2 £ 418 OF ASTRONOMY. [esSAY Ah, little think the gay, licentious proad. Whom pleasure, power and affluence surround. How many pine in want! How many shrink Into the sordid hut, how many drink The cup of grief, and eat the bitter bread Of misery!
And, which aggcavates the evil^ almost all the worst vices, the most unprincipled acts, and the darkest passions of the human mind, are bred out of po- verty and distress. Satan, in the Book of Job, says to the Almighty, ^^Thou hast blessed the work of thy servant, and his substance is increased in the land. But put forth thy hand now, and take away all that he hath; and he will curse thee to thy face.'* The prayer of Agar runs, " Feed me with food con- venient for me; lest I be poor, and steal, and take the name of my God in vain."
It is with a deep knowledge of the scenes of life, liiat the prophet pronounces, ^'My thoughts are not your thoughts; neither are your ways my ways, saith the Lord."
An reflecting persons, who have surveyed the state of the world in which we live, have been struck with the contrarieties of sublunary things; and many hypotheses have been invented to solve the enigma. Some have maintained the doctrine of two principles, Oromasdes and Arimanius, the ge- nius of good and of evil, who are perpetually con- tending with each other which shall have the greatest i^way in the fortunes of the world, and each alternately acquiring the upper hand. Others have XXI.] OF ASTRONOMY. 419 inculcated the theory of the fall of man^ that Qod at first made all things beautiful and good^ but that man has incurred his displeasure, and been turned out of the paradise for which he was destined. Hence, they say, has arisen the corn^tion of our nature. " There is none that doth good, no, not one. That every mouth may be stopped, and all the world become guilty before God.** But th€ solution that has been most generally adopted^ par-*- ticularly in later days, is that of a future state of retribution, in which all the inequalities of our pre* sent condition shall be removed, the tears of the unfortunate and the sufferer shall be wiped from their eyes, and their agonies and miseries compen* sated. This, in other words, independently of the light of revelation, is to infer infinite wisdom and benevolence from what we see, and then, finding the actual phenomena not to correspond with our theories, to invent something of which we have no knowledge, to supply the deficiency.
The astronomer however proceeds from what we see of the globe of earth, to fashion other worlds of which we have no direct knowledge. Finding that there is no part of the soil of the earth into which our wanderings can penetrate, that is not turned to the account of rational and happy beings, creatures capable of knowing and adoring their creator, that nature does nothing in vain, and that the world is full of the evidences of his unmingled beneficence^ according to our narrow and imperfect ideas of he^ 2 E 2 420 OF ASTRONOMY. [ESSAY neficence^ (for such ought to be our premises) we proceed to construct millions of worlds upon the plan we have imagined. The earth is a globe^ the planets are globes, and several of them larger than our earth: the earth has a moon; several of the planets have satellites: the globe we dwell in moves in an orbit round the sun; so do the planets: upon these premises, and no more, we hold ourselves au- thorised to affirm that they contain ^^ myriads of intelligent beings, formed for endless progression in perfection and feUcity.** Having gone thus far, we next find that the fixed stars bear a certain re- semblance to the sun; and, as the sun has a num- ber of planets attendant on him, so, we say, has each of the fixed stars, composing all together '^ten thousand times ten thousand" habitable worlds.