Imágenes de páginas
PDF
EPUB

Yorkshire to Dunnose in the Isle of Wight, a remarkable anomaly appeared, for which it was very difficult to account ;-the degrees, instead of increasing with the latitude, seemed, if the measurement could be trusted, to decrease. Thus, for latitude 51° 2' 54", a degree in fathoms, as given by Colonel Mudge (Phil. Trans. 1803), was 60884; for lat. 52° 2' 20" it was 60820; and for lat. 52° 50' 30" it was 60766. Hence we should be led to suppose that the Earth, instead of being flattened at the Poles, is more elevated there than at the Equator, contrary to the received notions of its figure. The apparent variance between these results and the results obtained by the National Institute, led Don J. Rodriguez to examine the matter, in order to reconcile the difference and to detect the error which he concluded must exist in the English observations; and, without adverting more particularly to his measurements and calculations, we may state that he ascribes the appearance of progressive augmentation in the degrees, to error in Colonel Mudge's observed latitudes. (Phil. Trans. for 1812, p. 336.) Bearing this in mind, Captain Kater prepared to ascertain the latitudes at the stations in question with all the exactness possible. The corrections for precession, &c. were those used at Greenwich Observatory; and the mean polar distance of the Pole Star, was taken from the latest observations of the Astronomer Royal. The mean of five series of observations, made between the 3d and 12th of October, gave the latitude of Clifton Beacon 53° 27' 29".89. The observed arc between Greenwich and Clifton Beacon, as given by Colonel Mudge, was 1° 58' 51".59. Add this to the latitude of Greenwich, 519 28' 38".01, and we have for the latitude of Clifton Beacon, 53° 27' 29".6, differing only by 0".29 in defect from that obtained by the repeating circle. Again, at Arbury Hill, the mean of three series of observations, made on the 18th, 22d, and 26th of October, gave the latitude equal to 52° 13' 25'.72. The observed arc between Greenwich and Arbury Hill was 0° 44' 48".19, which therefore gives 52 13' 26".20 for the latitude by the Trigonometrical Survey; differing only 0".48 in excess from the latitude obtained by the repeating circle. Lastly, the latitude of Dunnose was found by the repeating circle to be 50° 37' 5".27, and by the zenith sector, 50° 37' 6".61; the difference being 1".34 in excess. It is very probable that this difference, small as it is, arose from Captain Kater being compelled, by the nature of the ground, to take a station at some distance from that used in the Survey. He chose Shanklin Farm instead of Dunnose; and the ground was so unfavourable for measuring a base, that there was great difficulty in connecting the two points. We are the better en

titled to ascribe the discrepancy in this case to the circumstance now mentioned, because the difference was so very minute in the other stations where the points of observation coincided. That these latitudes, then, are as correct as observed latitudes can be, we may safely assume; but it is possible that they may differ from the true latitudes of the several stations. If this difference can be accounted for, the anomaly above alluded to will be satisfactorily explained. . ..

The diminution of the force of gravitation from the Poles to the Equator, may be found by the difference of the lengths of pendulums oscillating in equal times at the Poles and at the Equator; or by the ratio of the squares of the number of vibrations in 24 hours, observed in different latitudes, with the same pendulum. The diminution indicated by the decrease observed to take place in the number of vibrations between any two given latitudes, must be the same, from whatever portions of the me ridian it is computed, unless it be affected by some irregular attraction. But it is found from observations at Unst, and each of the other stations in succession, that the diminution deduced from the arc between Unst and Portsoy, is less than that obtained from the arc between Unst and Leith; the number expressing the diminution being .0053639 in the former case, and .005480 in the latter. When Unst and Clifton are the two latitudes, the diminution is .0056340; Unst and Arbury Hill give .0054282, denoting an increase of gravitation; Unst and London give .0055510 ; and a still further decrease appears from comparing the observations at Unst and Dunnose, the diminution thus obtained being .0055262. Again, Portsoy and Dunnose give .0055920, being a greater diminution than the last mentioned. Clifton and Dunnose make it only .0052616, which is smaller ; while Arbury Hill and Dunnose give.0060212, which is greater than any of the preceding.

From these statements we gather, that in advancing towards the Equator, the decrease of gravity is greater than it ought to be by the theory; and also, that at some of the stations, the action of a disturbing force, proceeding probably from the greater density of the materials in the neighbourhood, has produced an irregularity in the diminution of gravity. The sudden increase perceptible at Arbury Hill deserves particular attention. It should also be observed, that the action of this disturbing force does not extend far; for, by the experiments at London and Dunnose, the number expressing diminution is reduced to .0052837. We may thence infer, that there exists very near Arbury Hill a mass of matter of considerable density. Captain Kater conjectures that this mass is Mount Sorrel, which consists of gra

nite; and other rocks of primitive formation are situated in its vicinity. Be this as it may, the disturbance must arise from some such inasses; and they must be situated to the north of Arbury Hill, because we have seen that, at a very small distance in a southerly direction, the force ceases to act. Another effect of these disturbing forces will be to attract the plumb-line northward : in which case the observed latitude will be less than the true ; consequently the length of the degree computed from the arc between Arbury Hill" and Dunnose will exceed, and that deduced from the arc between Clifton and Arbury Hill, will fall short of the true latitudes. This difference between the real and apparent latitudes, sufficiently accounts for the variance which seemed to exist between the lengths of the degrees and the latitudes, in the statements of the Trigonometrical Survey.

We have extended this account of Captain Kater's paper so far, that we have left no room for any additional remarks. The Appendix to his Report contains all the observations from which the results were derived which we have now analyzed. These observations are arranged in distinct Tables, according to the different places of observation. To persons who may be engaged in similar inquiries, they cannot fail to be of the greatest use; while they are the best vouchers of that extreme accuracy which gives to the author's own conclusions the whole value that belongs to such investigations. This is not to be attained, indeed, without the greatest labour and perseverance : But we should be infinitely mistaken in supposing that very great ingenuity is not also required, both in planning the operations, and conducting their details.

ART. IV. Poems. By BERNARD BARTON. 8vo. pp. 280.

London, 1820.

Though there is much that is pleasing in this little volume,

the thing that has pleased us most about it, is to learn that it is the work of a Quaker ;and that, not merely because a Quaker poet is a natural curiosity, but because it is gratifying to find that the most tolerant and philanthropic and blameless of all our sectaries, are beginning to recommend themselves by the graces of elegant literature, and to think it lawful to be distinguished for their successful cultivation of letters as well as of Science. The interdiction of all light and frivolous amusements, and of all those pastimes which merely dissipate the mind, and distract the affections, ought never to have been construed as extending to that pursuit which not only implies the most vigorous exercise of the intellectual faculties, but may be truly defined to be the art of recommending moral truth, and making virtue attractive. Poetry has been commonly supposed, indeed, to aim more at the gratification than the instruction of its votaries, and to have for its end rather delight than improvement; but it has not, we think, been sufficiently considered, that its power of delighting is founded chiefly on its moral energies, and that the highest interest it excites has always rested on the representation of noble sentiments and amiable affections, or on deterring pictures of the agonies arising from ungoverned passions. The gifts of imagination may no doubt be abused and misapplied, like other gifts; but their legitimate application is not, for this, less laudable or blameless ;--and much of the finest poetry in our language may unquestionably be read by the most rigid moralist, not only with safety, but advantage.

Toa Quaker poet, it is perhaps true that the principles or prejudices of his sect would oppose some restraints, from which other adventurers are free; and that the whole range of Parnassus conld not be considered as quite open to his excursions--some of its loftiest, as well as some of its gayest recesses, being interdicted to his muse. The sober-mindedness which it is the great distinction and aim of the Society to inculcate and maintain, will scarcely permit him to deal very freely with the stronger passions: and the mere play of lively and sportive imagination, the whole department of witty and comic invention, would, we suspect, be looked upon as equally heterodox and suspicious. They have no reason, however, to complain of the scantiness of what remains at their disposal ;--all the solemnity, warmth, and sublimity of devotion-all the weight and sanctity of moral precept--all that is tender in sorrow—all that is gentle in affection--all that is elegant and touching in description, is as open to them as to poets of any other persuasion; and may certainly afford scope for the most varied as well as the most exalted Song. When employed upon such themes, and consecrated to such objects, it is impossible, we should think, for the most austere sectary, to consider poetry as a vain or unprofitable occupation, or to deem amiss of an attempt to recommend the purest sentiments, and enforce the noblest practice, by all the beauty of diction, and all the attractions of style. The Society was for a good while confined to the lower classes; and when it first became numerous and respectable, the revolting corruptions of poetry which took place after the Restoration, afforded but too good an apology for the prejudices which were conceived against it; and as the Quakers are peculiarly tenacious of all the maxims that have been handed down from the patriarchal times of their institution, it is easy to understand how this prejudice should have outlived the causes that produced it. It should not however be forgotten, that W. Penn amused himself with verses, and that Elwood the Quaker is remembered as the friend and admirer of Milton, and the man to whose suggestion the world is indebted for the Paradise Regained. In later times, we only remember Mr · Scott of Aimwell as a poetical writer of the Society.

[graphic]

The volume before us has all the purity, the piety and gentleness, of the Sect to which its author belongs-- with something too much perhaps of their sobriety. The style is rather diffuse and wordy, though generally graceful, flowing, and easy; and though it cannot be said to contain many bright thoughts or original images, it is recommended throughout by a truth of feeling and an unstudied earnestness of manner, that wins both upon the heart and the attention. In these qualities, as well as in the copiousness of the diction and the facility of the versification, it frequently reminds us of the smaller pieces of Cowper,-the author, like that eminent and most amiable writer, never disdaining ordinary words and sentiments when they come in his way, and combining, with his most solemn and contemplative strains, a certain air of homeliness and simplicity, which seems to show that the matter was more in his thoughts than the manner, and that the glory of fine writing was less considered than the clear and complete expression of the sentiments, for the sake of which alone he was induced to become a writer. Though the volume contains sixty or seventy different pieces, and almost every variety of versification, there is something of uniformity in the strain and tenor of the poetry. There is no story, and of course no incident, nor any characters shown in action. The staple of the whole is description and meditation description of quiet, home scenery, sweetly and feelingly wrought out-and meditation overshaded with tenderness, and exalted by devotion-but all terminating in soothing and even cheerful views of the condition and prospects of mortality. The book, in short, is evidently the work of a man of a fine and cultivated, rather than of a bold and original mind-of a man who prefers following out the suggestions of his own mild and contemplative spirit, to counterfeiting the raptures of more vehement natures, and thinks it better to work up the genuine though less splendid materials of his actual experience and observation, than to distract himself and his readers with more ambitious and less manageable imaginations. His thoughts and reflections, according's, have not only the merit of truth and consistency, but bear

« AnteriorContinuar »