PRESENTIMENTS.

REASON Seems to deny the existence of any faculty in the mind capable of anticipating future events. The impenetrable veil which shrouds from mortal vision to-morrow's fate, and conceals from many an unsuspecting victim the dark scenes of his existence, appears to be woven by the hand of mercy in pity to wanderers through this chequered vale of joy and grief. Yet there are times when the veil, raised by some secret and mysterious power, exhibits a faint glimpse of the future, indistinct it is true, but yet apparently intended to warn a departing spirit of its doom. The experience of almost every one who has lived long in the world will furnish him with well authenticated instances of such prophetic forebodings. Whether such are to be ranked only amongst singular coincidences concurring in a world of chance; or whether the unseen principle which rules and upholds the universe, occasionally manifests its mysterious influences to prove the reality of a spiritual world, is, and will, perhaps, for ever rest

unknown.

The following interesting fact, communicated by an officer who had served in Spain and Portugal the greater part of the Peninsular war, presents us with a remarkable instance of presentiment verified.

"During the night preceding the battle of Salamanca,” said he, "I was on duty with my company under arms-the tramp of feet indicated a body of men in motion. It proved to be Major at the head of a storming party.

it you?' cried I.

Ah, Major! is

'What now, what's in the wind?' M

my boy!' he replied, I'm going to knock my head against stone wallswe are ordered to carry yon fort.' • Well, Major, good luck to ye,' was my answer. 'M-,' said he, with emotion, give me your hand, we shall never meet again.' Nonsense, Major! you an old soldier, and give way to such bugbears as those!' Nothing, however, could remove the impression. We had no time for many words. The fort was attempted, the assailants defeated, and the Major slain. I could see, as the morning dawned, by the aid of my glass, the lifeless corpse of the Major stretched on the ramparts, distinguishable only

by his dark whiskers; for the enemy had stripped and plundered the body. My own company was soon after ordered to the attack of the fort, and we happily succeeded."

It may be imagined, that it was no extraordinary circumstance for a man on so perilous an enterprize,. to forebode a fatal termination of his efforts; and it will readily be granted, that, in a young soldier, and a first battle, such might be the case, and might serve to explain the fact. But the Major was neither a young nor a timid soldier; he had been the foremost in many a well-fought fight, and, in the words of his friend, "knew not what fear was." A similar instance is recorded in the memoirs of the immortal Nelson; and surely no one will charge him with cowardly forebodings. He left England with a strong impression that he should never return alive; and when he had attained the object of his earnest wishes-the certainty of being able to force the enemy to action-his letters to his brother-officers breathe more strongly still this presentiment.

It would be fruitless to endeavour to explain such coincidences. It would be apathy not to notice, nor be struck by them. Their cause, if cause they have, is deeply hidden in the mysterious operations of the mind. How far it may be prudent to heed such monitions may admit of a question, and whether or not a cherished apprehension may not have a tendency to secure. its own fulfilment, deserves consideration. Perhaps the safest and most rational solution of all such cases is, that there is nothing preternatural belonging to them. The feelings which such extraordinary circumstances of peril superinduce must originate in minds the most fearless reflexions on the probabilities of a fatal issue, and these probabilities may so predominate as to amount almost to a certainty, which apparent certainty may itself precipitate the event, and indispose the mind for taking those very precautions which might avert the catastrophe. That thus it was in Nelson's case scarcely admits of a doubt. He felt that he should fall in the contest, and he resolved to fall with all his honours upon him. This very impression, therefore, inducing him to wear on that lamented occasion all the insignia of his rank, rendered him a most conspicuous mark for the enemy's rifles, and, upon such unequal terms, it would have been almost a folly to expect his safety. It was, in fact, like setting up a target for the trial of skilful marksmen.

Whether in every case it can be as clearly shewn that the issue has been the offspring of the presentiment is uncertain; but it is sufficiently evident, that in many instances, such may be the result; and if in any, why not in all?

Y.

WHAT ARE COMETS? No. III.

But

MATHEMATICAL demonstration has generally been considered as furnishing the surest and most conclusive of all evidence; so severe are the tests which it applies, and so cautious are the steps by which it advances, that it seems to "make assurance doubly sure," and to give additional confirmation even to the perceptions of sense, as well as to the clearest deductions of reason. all its calculations must set out from certain data; and it is only where these data are so thoroughly understood and positively settled, as to leave no room for change or doubt, that we can regard as indisputable the conclusions to which they lead. When these, on the contrary, are in the least degree hypothetical or uncertain, the results obtained from them can be no more than matter of conjecture, however just the principles and accurate the process by which they are traced.1 The whole history of practical astronomy bears ample testimony to this truth, in the continual series which it presents, of observation correcting observation, and tables supplanting tables, before the science could be brought to that wonderful degree of perfection to which it has attained. So infinite is the space, and so remote the points, where human genius has discovered the means of carrying on those measurements, on which its calculations are founded, that no reproach can possibly attach to the failure of its first efforts; in such a case success can only be expected from repeated trials, each in its turn improving or confirming previous observations; and the correctness of the final result can only be established by its accordance with those visible operations which it is designed to explain. In no instance has a single observation, or even a

1 Qui speculationum suarum fundamentum desumunt ab hypothesibus, etiamsi deinde secundum leges mechanicas accuratissimé procedant; fabulam quidem, elegantem forté et venustam, fabulam tamen concinnare dicendi sunt.- Ex Cotesii præfatione in secundam Principiorum Editionem.

single revolution, been found sufficient to determine, with precision, the orbit of any planetary body: this has never been definitively ascertained till after years of unremitting and minute investigation, and many opportunities of watching its return to those points which are the most favourable for marking its progress.

Nearly a century elapsed from the death of Copernicus before Kepler discovered that the planets revolve in ellipses and not in circles and within the next century even his observations proved to have been defective; for the Rudolphine tables, which were for the most part drawn up by him, and published under his inspection, were found by Cassini to contain various errors; in particular that of two degrees in fixing the aphelion of Jupiter. 2 Cassini also pointed out that the first satellite of Saturn, at the end of twenty years, was fifteen degrees behind the point which it ought to have reached at that time, according to the calculations of Huygens.3 The error in computing the period in which even our earth completes its passage round the sun, or the precise length of our year, is well known to have caused the alteration of the stile, by which it was remedied in 1752. Even in our days the most eminent astronomers have been materially deceived in the data from which they deduced the elements of the new planets, and have drawn conclusions, which the event has not only not justified, but has shewn to be exceedingly erroneous. Thus Sir Wm. Herschel himself 4 stated the inclination of the orbit of Ceres to be 15° at least, which has since been found to be only 10° 37′; and Mons. Burckhardt5 calculated the annual period of the same planet to be 4 years 1 month and a half, which is actually 4 years 7 months and 10 days. Every page in the annals of astronomy presents so many instances similar to these, that it is unnecessary to select more of them in support of my argument; but I cannot refrain from citing upon this point the authority of a distinguished modern mathematician. "No calculations," says Mr. Bailey, 6 "can have much weight at the present day formed from tables, which the subsequent improvements in astronomy have shewn to be exceedingly defective and Even the mean motions of the sun and moon are not

incorrect.

2 Phil. Trans. abridged to 1700, p. 410.

3 Phil. Trans. abridged to 1700, p. 370. 5 Moniteur, 4 Pluviose, An. 10, No. 24.

4 Phil. Trans. for 1803, p. 340.

6 Phil. Trans. for 1811, p. 228.

given with a sufficient degree of accuracy, either in the Rudolphine or Halleian tables, to enable us to determine, with any tolerable correctness, their true mean place of conjunction at any remote period."

Nor is it in such cases only as these that mathematical calculations, proceeding upon insufficient data, have led to wrong conclusions; for even in determining by celestial observations the situation of many points on the surface of our globe-a process that seems to be attended with every facility for discovering and correcting errors-there have been the same false reckonings and the same slow progress in ascertaining with accuracy the desired result. In 1770, the latitude of Dresden was nearly 3' false;7 and even so late as 1806 that of Berlin was uncertain for 25′′; in 1790, the position of Mannheim was false by 1′ 21′′; and before the observations of M. Monnier the true latitude even of Paris itself was not known by 15". M. Humboldt, from whom these particulars are quoted, relates also a remarkable instance of the effect produced by the false position so long assigned to Mexico. The almanacs of that country, calculating on this wrong supposition, had announced the eclipse of the sun, Feb. 21st, 1803, as scarcely visible there; but to the great consternation of the people, it proved to be total, and set even the philosophers in commotion to discover the cause of the error into which they had fallen. 8

"In every physical inquiry," says an eminent mathematical writer, 9 "the fundamental conditions should be such as are supplied by observation. Were it possible to observe this rule in every case, theory would always comprehend in its determinations a true account of the phenomena of nature.” But from the foregoing brief review of facts, it is sufficiently evident, that with respect to the system of the heavens, even these "fundamental conditions" can lead to no certain conclusions, until they have been corrected and confirmed by a long series of repeated observations. Nor can the accuracy of the data themselves be at all satisfactorily proved, except by some actual operation of the

7 Humboldt's Political Essay on New Spain. Introduction, p. 8, note. See also Bruce's Travels, vol. 1, p. 15, for the errors of astronomers in settling the latitude of Alexandria.

8 Political Essay on New Spain, p. 30.

9 Mr. Ivory's Remarks on the Mechanique Celesti, in the Phil. Trans. for 1812, page 1.