of each succeeding impulse lies-it is obvious that the line of direction verges on the utmost limits of the influence of gravity, and that in such a situation the least inaccuracy in estimating any one point must propagate an error, that, as it advances, will depart more and more widely from the real truth, and finally sanction the most mistaken views of the operations which it professes to explain. 7 Halley, in his Synopsis Astronomia Cometica, acknowledges, that if the motions of comets be exactly parabolic, they will "acquire such a velocity, as that they may again fly off into the remotest parts of the universe, moving upwards with a perpetual tendency, so as never to return again to the sun." The passage just quoted from Mr. Ivory's paper admits, also, that the nicest observations do not enable us to distinguish the real orbit (of comets) from the parabola, with which it intimately coincides." Mr. Woodhouse likewise gives the following testimony on this point: "Comets are said to differ from planets, because they move in orbits so eccentric. The eccentricities of those that have been observed are so great, that it has been found parabolas would nearly represent them."8 To these authorities must be added that of the most eminent natural philosopher of the present day, who, with his father's patient industry and fearless research, combines talents of the highest order and unrivalled attainments in science. Sir J. F. W. Herschel, in his recent admirable Treatise on Astronomy, says, "Should the orbit of a comet be of the hyperbolic character, when once it had passed its perihelion, it could never more return within the sphere of our observation, but must run off to visit other systems, or be lost in the immensity of space. A very few comets have been ascertained to move in hyperbolas, but many more in ellipses." 9 It 7 "The effect of every little error of observation, or want of absolute precision in calculation, though insensible on a short interval, must go on increasing, when observations made at distant times are compared with the results of the former computation."-Sir H. Englefield on the Orbits of Comets, p. 125. "A small error in the observations will materially affect the elements of the orbit."-Woodhouse's Elementary Treatise, p. 387. 8 Woodhouse's Elementary Treatise, p. 386. 9 Lardner's Cabinet Cyclopædia, vol. 43, p. 307. The following concise expla nation, which precedes the above-quoted passage, will make it intelligible to general readers :-" The parabola is that conic section which is the limit between the ellipse on one hand, which returns into itself, and the hyperbola on the other, which runs out into infinity." The whole treatise will afford instruction and delight to those who take any interest in the study of astronomy. It particularly brings into notice the late Sir Wm. Herschel's discoveries of Nebula and double stars, the importance of which has never yet been duly appreciated. is evident, therefore, that the slightest error of observation may turn the scale in favour of any one of these courses, and be made to support a false theory-that a mistake, amounting to no more than a fractional part of a second, in computing a comet's situation at any one point, may give an entirely false direction to its unseen progress-may make it appear that a body, whose flight extends beyond the range of our sun's attraction, is periodically revolving round him, and assign the elements of an elliptical orbit to a velocity of motion, that is not actually susceptible of such control. It is true, that most of the numerous observations which have been made upon the paths of comets, agree in representing them as moving in such directions as, according to mathematical calculation, will bring them back again to the same points. But we may perceive a remarkable, although slow, advance towards a different conclusion. For a long time the universal result was, that all those bodies are revolving in ellipses. It was then found, that "parabolas would nearly represent" their courses; and, finally, it has of late been discovered, that some of them do actually "move in hyperbolas;" so that they "must run off to visit other systems." Some of the earlier observations must, therefore, have been defective; and if some-why not all? Where the line, which separates truth from error, is so imperceptible, (as it confessedly is in this case,) and the mind of the observer is biassed by a preconceived notion as to the result of his investigation, it is impossible that this previous impression should not exercise an insensible influence over his judgment, in deciding any doubtful points. Astronomers who have watched the motions of comets for the purpose of computing their orbits, have generally set about their observations fully prepossessed with the idea of their periodic return. If, therefore, they have fallen into errors -and to suppose that they have not fallen into many would be contrary to nature, to reason, and to experience—their errors cannot but have been conformed to the previous bias of their minds; and as no opportunities for correcting them can possibly have been afforded, the difficulties of the subject, and the experience of all analogous cases, authorize us to suspect, that, without any intentional or conscious deception, false data have still been very frequently assumed, and given temporary importance to an unsubstantial and illusive theory. But this suspicion must amount almost to certain conviction, when we find that the most distinguished mathematicians and philosophers have not only been bewildered in their endeavours to demonstrate the question from the data thus obtained, but have been betrayed into the most palpable and fatal errors. The solution proposed by Newton himself failed entirely; and the Abbé Boscovick asserts, that its want of success arose from its illustrious author having altogether overlooked, in his calculations, the connection between the motion of the earth and that of the comet. 1 Even Halley, whose opinion has been generally considered as decisive on all points relating to a subject which he had studied with so much attention, has given no explanation of the method by which he determined the orbits of comets. As he most probably adopted that of his great contemporary and friend, the result of his enquiries must necessarily be involved in the same uncertainty that has been shewn to attach to the system on which we must suppose them to have been conducted. Nor has any greater success attended the efforts that have been made since that period, to establish this theory on clear and satisfactory principles; for, to borrow again the words of the writer2 from whom I before quoted, "all the resources of modern mathematics have been directed to overcome the peculiar difficulties of this intricate investigation. Yet it must be confessed, that practical astronomy has not reaped so much benefit as might justly have been expected from the labours of so many eminent men." These repeated failures surely indicate some fundamental error in the principle, which thus resists every attempt at applying it to these operations. If the immortal genius, who traced the planets through their widest courses, and weighed the sun as in a balance, failed in the method which he prescribed for determining the orbits of comets—if the most refined combinations of that universal arithmetic, which he carried to such high perfection, have been vainly adapted to the same object by the followers of his steps and the inheritors of his views-surely the theory on which 1 I quote this fact on the authority of Mr. Ivory. (Phil. Trans. for 1814, pp. 128 and 131.) That Newton did not entirely leave out of his consideration the motion of the earth will be evident to any one who refers to Prop. 41 of the 3rd book of his Principia. I cannot, therefore, help suspecting, that his acknowledged failure in this instance is to be attributed, less to his having overlooked any material subordinate point, than to his having been altogether misled by erroneous observations and mistaken ideas of the motions of comets. 2 Mr. Ivory. Phil. Trans. for 1814, p. 127. they have proceeded ought to be considered anew, and reconstructed on other principles. At the least, we may safely assert, that mathematically it has not been proved, and thus it must be left to rest wholly upon the authority of fact. THE SPIRIT OF SONG. Parodied from "The Spirit of Song," by T. H. Bailey. O! why hast thou left me, sweet Spirit of Song? O! how blue were the hours-how beaming the sky, And when light left the earth on its glorious wings, That o'er the deep darkness a mild lustre flung; And the Moon walk'd in beauty, the queen of the throng, And when, far away in the mountain-land, Yes! thou mad'st the lovely seem lovelier to me; And thou didst a charm to earth's rich scenes impart, But the stern hand of Destiny solv'd that sweet spell, Then, Hope, shall I feed on thy sweet fare no more? RECOLLECTIONS OF A CAMPAIGN (OF A DAY) IN DEMERARY. EARLY one morning in the month of June or July, in 1805, when the French fleet, so nobly pursued by our Norfolk hero, with an inferior force, had appeared in the seas of the West Indian Archipelago, the peaceable inhabitants of Stabraeh and its suburbs were disturbed from their just and natural sleep by the discharge of three guns from Fort William Frederic, which was in a short time followed by the sounding of the bugles of the rifle corps, the trumpets of the Demerary cavalry, and the drums of the militia, calling to arms. I immediately rose, and dressing myself in the costume of the rifle corps, of which I was a member, desired my servant to follow me with my rifle to the muster ground. In my progress thither, the reports I encountered were various: the town, however, had already ring appearance. The members of the different corps wending their way to their respective places of rendezvous, the clattering of the cavalry, the solemn roll of the drum, the lively bugle, and |