2. Astronomy.
The omniscience and prescience of the human intellect have been largely glorified by some Infidel lecturers, upon the strength of the accuracy with which it is possible to calculate and predict eclipses, and to the disparagement of Bible predictions. And this glorification has been amazingly swollen by Le Verrier's prediction in 1846 of the discovery of the planet Neptune. But the prediction of some unknown motion would form a more correct basis for a comparison of the prophecies of science with those of Scripture; such, for instance, as Immanuel Kant's prediction of the period of Saturn's rotation at six hours twenty-three minutes fifty-three seconds; "which mathematical calculation of an unknown motion of a heavenly body," he says, "is the only prediction of that kind in pure Natural Philosophy, and awaits confirmation at a future period." It is a pity that this unique scientific prediction should not have had better luck, for the encouragement of other guessers; but after waiting long and vainly, for the expected confirmation, it was finally falsified by Herschel's discovery of spots on the surface of the planet, and observation of the true time, ten hours sixteen minutes forty-four seconds.[330] This, however, was not his only astronomical prediction. He predicted that immense bodies in a transition state between planets and comets, and of very eccentric orbits, would be found beyond the orbit of Saturn, and intersecting it, but no such bodies have been discovered. Uranus and Neptune have no cometary character whatever, their orbits are less eccentric than others and do not intersect, nor approach within millions of miles of Saturn's orbit. The verification of Le Verrier's prediction affords even a more satisfactory proof of the necessarily conjectural character of astronomical computations of unknown quantities and distances. The planet Neptune has not one-half the mass which he had calculated; his orbit, which was calculated as very elliptical, is nearly circular; and the error of the calculation of his distance is three hundred millions of miles![331]
"Let us then be candid," says Loomis, "and claim no more for astronomy than is reasonably due. When in 1846 Le Verrier announced the existence of a planet hitherto unseen, and when he assigned it its exact position in the heavens, and declared that it shone like a star of the eighth magnitude, and with a perceptible disc, not an astronomer of France, and scarce an astronomer in Europe, had sufficient faith in the prediction to prompt him to point his telescope to the heavens. But when it was announced that the planet had been seen at Berlin, that it was found within one degree of the computed place, that it was indeed a star of the eighth magnitude, and had a sensible disc—then the enthusiasm not only of the public generally, but of astronomers also, was even more wonderful than their former apathy. The sagacity of Le Verrier was felt to be almost superhuman. Language could scarce be found strong enough to express the general admiration. The praise then lavished upon Le Verrier was somewhat extravagant. The singularly close agreement between the observed and computed places of the planet was accidental. So exact a coincidence could not reasonably have been anticipated. If the planet had been found even ten degrees from what Le Verrier assigned as its probable place, this discrepancy would have surprised no astronomer. The discovery would still have been one of the most remarkable events in the history of astronomy, and Le Verrier would have merited the title of First Astronomer of the age."[332]
Nevertheless, astronomy from the comparative simplicity of the bodies and forces with which it has to deal, and the approximate regularity of the paths of the heavenly bodies, may be regarded as the science in which the greatest possible certainty is attainable. It opens at once the widest field to the imagination, and the noblest range to the reason; it has attracted the most exalted intellects to its pursuit, and has rewarded their toils with the grandest discoveries. These discoveries have been grossly abused by inferior minds, ascribing to the discoverers of the laws of the universe the glory due to their Creator; and boasting of the power of the human mind, as if it were capable of exploring the infinite in space, and of calculating the movements of the stars through eternity. Persons who could not calculate an eclipse to save their souls, have risked them upon the notion that, because astronomers can do so with considerable accuracy, farmers ought to reject the Bible, unless its predictions can be calculated by algebra. It may do such persons good, or at least prevent them from doing others harm, to take a cursory view of the errors of astronomers; errors necessary as well as accidental.
Sir John Herschel, than whom none has a better right to speak on this subject, and whose devotion to that noble science precludes all supposition of prejudice against it, devotes a chapter to The Errors of Astronomy,[333] which he classifies and enumerates:
"I. External causes of error, comprehending such as depend on external uncontrollable circumstances; such as fluctuations of weather, which disturb the amount of refraction from its tabulated value, and being reducible to no fixed laws, induce uncertainty to the amount of their own possible magnitude.
"II. Errors of observation; such as arise for instance from inexpertness, defective vision, slowness in seizing the exact instant of the occurrence of a phenomenon, or precipitancy in anticipating it; from atmospheric indistinctness, insufficient optical power in the instrument, and the like.
"III. The third, and by far the most numerous class of errors, arise from causes which may be deemed instrumental, and which may be divided into two classes.
"The first arises from an instrument not being what it professes to be, which is error of workmanship. Thus if an axis or pivot, instead of being as it ought, exactly cylindrical, be slightly flattened or elliptical—if it be not exactly concentric with the circle which it carries—if this circle so called be in reality not exactly circular—or not in one plane—if its divisions, intended to be precisely equidistant, shall be in reality at unequal intervals—and a hundred other things of the same sort.
"The other subdivision of instrumental errors comprehends such as arise from an instrument not being placed in the position it ought to have; and from those of its parts which are made purposely movable not being properly disposed, inter se. These are errors of adjustment. Some are unavoidable, as they arise from a general unsteadiness of the soil or building in which the instruments are placed.[334] Others again are consequences of imperfect workmanship; as when an instrument, once well adjusted, will not remain so. But the most important of this class of errors arise from the non-existence of natural indications other than those afforded by astronomical observations themselves, whether an instrument has, or has not, the exact position with respect to the horizon, and the cardinal points, etc., which it ought to have, properly to fulfill its object.