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but be always libelled before service, The average expense of raising and
cause the warrants to arrest, poind, (says he, App. p. 148.,) to blank &c. would be contained in, and apwrits, or writs of style, shewing inere- pended to the original decree. ly the nature of the demand. Let If, again, these extracts and the the pleadings in Court begin with a copy for the record were allowed, as declaration, or claim by the pursuer, in the Jury Court, to be prepared by stating his case."
the agents themselves, one extractor 2. Hornings, Captions, fc.
· might sign all the extracts of the
Court of Session, and thus the whole When a decree is obtained, the ex- expense of the absurd establishment tract should have appended, in a of so many extractors might be saved. printed form, warrant to charge, ar- The only objection to the econorest, inhibit, poind, and imprison ; mical plan proposed, is the vested and no separate letters of horning and interest of the Writers to the Signet. poinding, arrestment, and inhibition It would not be difficult to show and caption, which are quite super- that all the compensation which they fluous and unnecessary, should be could fairly claim would be very permitted. The unnecessary and ex- trifling. But their claims of compensive forms of letters of suspension pensation should be no obstacle to and advocation, which are abolished such a national benefit. Let the Bain maritime causes, but are carelessly rons of Exchequer be empowered to intended by the new bill to be con. examine these claims, and to sustain tinued, should in all cases be abo. them in so far as may be just. lished.
Loch-na-bo. How sweet a little spot is here !
O, from loath'd scenes of selfish strife, Who'd think, 'mid shapeless bills so drear, Where dulness chills the springs of life, To meet with such a scene?
How gladly I'd retreat
To this embow'ring solitude,
The tranquil mind to fret!
All day, among the willows green, Reflecting the soft Summer sky,
I'd muse upon the varied scene
In soothing reverie ;
The wild drake on his webb’d oars lie,
Not timorous of me.
Slow soaring took his fight;
I'd cross the blue lake in my skiff, The wild fowl and the dappled deer To the lone cot beside the cliff, Make the lone spot their own.
And dream of bliss all night! C.
ON THE FIGURE OF THE EARTH. A SPECTATOR, placed on any part the sun, and the meridian altitudes of the earth's surface, sees around of all the other heavenly bodies, him a certain limited portion of its when seen from different parts of its surface, and this portion is called the surface, or in different latitudes; and risible horizon of that place. If the this variation, when accurately obspectator advances twenty or thirty served at two places, whose distance miles from his first position, in any is known, or which we can measure, direction, either east, west, north, enables us to determine, with great or south, he will have an entirely accuracy, the diameter of the earth. new visible horizon, which will not It is difficult, however, when meacontain any one of the objects which suring the meridional distance bewere seen in his first position. By tween two places, to keep always advancing still farther, he will have exactly in that meridian ; we may another visible horizon, filled again deviate a little to the one side or to with fresh objects, and bounded by the other, in consequence of which, a different portion of the earth. If our measured distance between the the earth were perfectly globular, two places will be greater than the the boundaries of all these visible true distance. We can place upright horizons would, in every position, poles, or other objects, in the meribe circles ; but as the figure of the dian which lies between the two earth is that of an oblate spheroid, places, in the following manner: the boundaries of all the visible ho- Let a transit instrument, at one of rizons, except when the spectator is the places, be placed in the meridian, at either of the poles, will be ellipses. by the help of circumpolar stars, or Now the perpetual change of objects otherwise; direct the telescope toin the visible horizon cannot pose wards a distant object, some part of sibly arise from the inequalities of which is in the meridian. Upon this the earth's surface, considered as a object make a mark, exactly in the plane of indefinite extent; for even direction of the vertical wire in the from the highest mountains in one of middle of the telescope ; this point the horizons, we cannot see the obe will be in the meridian: the same jects contained in the other. . It fol- kind of operation may be made at lows, then, that the surface of the the second station which was made earth is not plane, but convex; and at the first; and, in this manner, since this change in the visible hori. the meridian line may be continued zon takes place equally, as to obser- as far as we please. When the disa vation, in every part of the earth tance between the two places is which has been visited, we are en- measured, and the difference betitled to conclude that the earth is tween the zenith distances of a star round. When the visible horizon is situated on the same meridian, corcomposed wholly of sea, we have oc- responding with the measured dise cular proof of the earth's convexity: tance, is ascertained; this is what As a ship comes in sight, the top of astronomers call the measure of a dethe mast first appears, while the gree of the meridian. The measurehull and the sails, at least the lower ment of two degrees, in the direcparts of them, are invisible. We tion of the meridian, in two different next perceive more of the rigging, latitudes, is sufficient to determine and, as she approaches, the whole of the two axes of the generating elthe vessel rises, as it were, above the lipse, and, consequently, the figure horison, or above the convexity of of the earth, supposing it to be ellipthe sea ;-and the surface of the tical. Several degrees have been earth is nothing more than the con- measured, in different latitudes, and tinuation of the surface of the sea, in the result of these measurements is, all directions, and raised a little far- that the mean diameter of the earth ther from the earthi’s centre. The is about 7912 miles ;—that a degree globular form of the earth is still of the meridian is longer at the poles more satisfactorily proved by the va. than at the equator; and, therefore, riation in the mid-day altitudes of that the earth' is an oblate spheroid, VOL. xv.
a solid generated by the revolution of the gratuitous suppositions which an ellipse about its shorter axis, and Newton had adopted, that if a plathat the proportion of the less axis is net, supposed to be fluid and homoto the greater as 300 to 301. The geneous, be composed of particles difference, however, in the results which attract in the ratio of their which have been obtained by ma- masses, and inversely as the square king use of various degrees measured of their distances, at the same time in different parts of the earth, by col. that it revolves round an axis in a lating them in pairs, was sufficient given time, it will remain in equilito induce Laplace to suspect that the brium if it have the form of an elearth is really not a solid of revolu- liptic spheroid, whatever may be the tion, but that the terrestrial meri- ratio of the axis. Maclaurin has only dian is a curve of double curvature. employed in his demonstrations the That illustrious philosopher was led synthetic geometry of the ancients ; to this erroneous conclusion, partly but we regard his method as a masby making use of the incorrect de ter-piece, superior to any thing which gree of the meridian measured by Archimedes or Apollonius has left Maupertius and his associates in Lap- us.” Maclaurin divided the prize land, and some similar wrong results given by the Academy of Sciences at given by La Caille, deduced from Paris with Euler and Daniel Bernoumeasurements and experiments made illi. Now, although it was thus de. at the Cape of Good Hope, and partly monstrated that the parts of a homoby an error in his own calculations, geneous fluid, (on which the figure which affected his results. From of the earth, just described, was any subsequent experiments, however, how induced,) would be in equilibrio, more accurately conducted, it is now yet it was not shown inversely, that extremely probable that the earth is whenever an equilibrium takes place a solid of revolution, and that both in such a fluid mass, the figure of hemispheres are exactly similar. The the mass must be the oblate sphedegree in Lapland has been re-mea. roid in question. D'Alembert, indeed, sured, and an error detected in the showed that there are more spheroids old measurement of about 200 fa- than one, in which the state of equithoms. Professor Playfair ascribed librium may be maintained, and this the small discrepancies, which arise result, though it was not observed by from making use of measured degrees Maclaurin, might easily, however, in different places, to the unequal have been inferred from his solution. density of the materials of which Legendre afterwards proved that the the carth may be composed at those solids of equilibrium must always places near its surface, by means of be elliptic spheroids; and that, in which the direction of gravity may general, there are two spheroids that be disturbed.
will satisfy the specified conditions. A homogeneous fluid, of the mean In the case of a homogeneous mass density of the earth, and revolving on of the mean density of the earth, reits axis in 23 hours, 56 minutes, 4 volving in the space of 23 hours, 56 seconds, of solar time, would be in minutes, 4 seconds, one of the spheequilibrio if it had the figure of an roids is that above mentioned, the oblate spheroid, of which the axis is other is one in which the equatorial to the equatorial diameter as 229 to diameter is to the polar as 681 to 1. 230. This is the figure which New- Laplace has added the following liton ascribed to the earth; his inves- mitations. A fuid and homogeneous tigation of its figure, however, though mass cannot be in equilibrium with extremely ingenious, involved as- an elliptic figure, if the time of its sumptions which prevented it from rotation be less than 2 hours, 25 being quite satisfactory. A very ac- minutes, 17 seconds. If the time of curate and elegant demonstration was revolution be greater than this, there not long after given by Maclaurin, will always be two elliptic figures, or which was afterwards improved, and spheroids, and not more, in which rendered more analytical, by Clairaut. an equilibrium may be maintained. Respecting Maclaurin's solution, jf'the earth be not homogeneous, Bossut makes the following remark: but composed of strata that increase “ He demonstrated, without any of in density as they approach the cen
tre, it will still be an elliptic sphe- another about 2.75, and some of the roid, but of less oblateness than if it rocks as high as 3, and even 3.2. On weré homogeneous. This was de- the whole, then, it appears not un. monstrated by Clairaut. Newton reasonable to suppose the mean specifell into a mistake, by supposing the fic gravity of the mountain to be from contrary to be the case. The greater 2.7, to 2.75, or 27. Now, } x 2, density of the earth, towards the gives té, or almost 5 ; that is, under centre, is in itself probable; but it these circumstances, the medium has been placed beyond the possi- density, or specific gravity of the bility of doubt, by very accurate ex- whole mass of the earth, in proporperiments made on different sides of tion to that of water, is nearly as 5 the mountain Schehallien, in Perth- to 1, or that it is about five times shire, by the late Dr Maskelyne.
the weight of water."-Hutton's By observations of the zenith dis- Tracts, p. 64. Vol. II.
Newton tances of stars, the difference of the thought it probable that the mean latitude of two stations on the north density of the earth might be five or and south sides of the mountain was six times as great as the density of determined. A trigonometrical sur- water, and it has now been detervey of the mountain (executed, we mined to be five times as great. have been informed, by the late Reu- Since, therefore, the common mata ben Burrow) ascertained the distance ter of our earth on the surface therebetween the two stations; and thence, of is about twice as heavy as water, from the known length of a degree and a little lower, in mines, is found of the meridian under that parallel, about three or four, or even five the difference of the latitudes of the times more heavy, it is probable that two stations was inferred, and was the quantity of the whole matter of found less by 11.6" than by astro- the earth may be five or six times nomical observations. The zeniths, greater than if it consisted all of then, of the stations, had been se- water, especially as I have showed parated from each other by more before that the earth is about four than the usual proportion of the me- times more dense than Jupiter."ridian distance, and this could only Principia, Book III. p. 230. arise from the plummet on each side Notwithstanding the irregularities being attracted towards the body of above-mentioned, the figure of the the mountain. From the quantity earth is so near to the spheroid of of this change, in direction of the equilibrium, as to indicate either the plummet, the ratio of the attraction
original fluidity of the whole mass, of the mountain to the attraction of or the gradual acquisition of a sphethe whole earth, or to the force of roidal figure, in consequence of the gravity, was calculated by Dr C. repeated waste and reconsolidation of Hutton, and found to be as 1 to the parts near the surface. If the 17,804. The bulk and figure of the whole mass of the earth was ever in mountain also being given, from an a fluid state, it must have been so actual survey, its mean density was from the action of heat. The insofound to be, to the mean density of lubility of the greatest part of rocks the earth, nearly as 5 to 9. The and minerals in water, and the immean density of the earth, then, is
mense quantity of that fluid which nearly double the density of the would be required for dissolving even rocks which compose Schehallien; those that are soluble, are insuperawhich appears, again, to be consi- ble objections to the hypothesis of derably more dense than the mean of aqueous formation. The igneous for. those which form the general exte- mation is not subject to either of rior crust of the earth. From a sur- these difficulties. vey of the mountain, made after- The spheroidal figure may have wards by Mr Playfair, its density been gradually acquired, without was ascertained to be greater than supposing the original fluidity of the Dr Hutton had supposed it to be. whole mass. In a terraqueous body, " By what Mr Playfair could con- however irregular its primitive form, jecture, the mean specific gravity of the prominent parts are subject to the whole would be about 2.7 or be worn down; and having been thus 2.8, one stratum being about 2.4, detached, will be carried to the lower parts, occupied by water, where they having taken place at Schehallien. will acquire a horizontal stratifica. These latter observations ought to tion, and, by certain mineral opera. be repeated on different mountains, tions, be afterwards consolidated into the interior construction of which can stone; such a body, in the course be ascertained; but the most eligible of ages, must acquire a surface every method which has ever yet been sugwhere at right-angles to the direction gested, is that of making observaof gravity, and consequently more or tions on the large Pyramid of Ghizeh, less approximating to a spheroid of in Egypt, the materials of which, equilibrium. The natural history of as well as its exact figure, being the earth gives considerable coun- known, would render observations tenance to these suppositions, and made on it particularly desirable ; seems to furnish us with a very raespecially as they would afford certain tional explanation of the ellipticity data, and reduce the calculations, or spheroidal form belonging to the which are now extremely complicated, earth, and to the planets which are to almost nothing. This method was known to revolve about an axis. The recommended by Dr C. Hutton, in distribution of the solid materials in his last paper published in the Phithe interior of the earth will very losophical Transactions of London ; much affect the nature of this solid; when that veteran declared, that if and the manner in which the figure ill health and old age did not prevent is acquired must probably prevent him, he would make a journey to the approximation from ever being Egypt, entirely, for that purpose entirely complete. The distribution, “Ön the whole, the facts known however, of the materials, at any from observation agree in general considerable distance below the sur. with the theory ; but there are, in face, must remain to us for ever un- the expression of that theory, so known; we have no means of ex- many quantities which are yet inde. amination, except by the measure- terminate, that a perfect coincidence ment of degrees, the experiments on of the two cannot be strictly affirmpendulums, or from observations ed; in fact, the business is not yet made on the deviation of the plumb- completed; something further still line from the perpendicular similar remains for future philosophers to to what has just been described as accomplish.”
First in her battles; he has rear'd her fanes,
Restor'd her laws, struck off her galling chains,
By yonder lifeless form, and on his check
Mark the big tear in silent language speak,
Him on whose sunny face he lov'd to gaze,
H. G. B.
As our military and naval officers are many of them quite competent to the undertaking, and as Great Britain always affords facilities for such experiments, may we not entertain hopes, that, before long, some gentleman, finding himself near the spot, will make the necessary observations, and immortalize his name by determining the deviation of the plumb-line, caused by the Great Pyramid ; for, together with this, its dimensions and figure, and the specific gravity of the materials of which it is con. structed, would afford sufficient data for the solution of the intricate but very useful problem.