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but be always libelled before service, or using arrestment or inhibition. The arrestment or inhibition should fall to the ground, unless the summons were lodged with the Clerk of Court, on expiry of the inducia. A copy of the summons and executions, as an inhibition recorded in the record of inhibitions, like a copy of a petition for sequestration, should be a sufficient inhibition. Mr Forsyth, Advocate, who has perhaps had more practice, and is better skilled in Scots forms than any other counsel now at the Bar, concurs substantially in approving of this plan. "Return (says he, App. p. 148.,) to blank writs, or writs of style, shewing merely the nature of the demand. Let the pleadings in Court begin with a declaration, or claim by the pursuer, stating his case."

2. Hornings, Captions, &c.

When a decree is obtained, the extract should have appended, in a printed form, warrant to charge, arrest, inhibit, poind, and imprison ;and no separate letters of horning and poinding, arrestment, and inhibition and caption, which are quite superfluous and unnecessary, should be permitted. The unnecessary and expensive forms of letters of suspension and advocation, which are abolished in maritime causes, but are carelessly intended by the new bill to be continued, should in all cases be abolished.

How sweet a little spot is here!
Who'd think, 'mid shapeless hills so drear,
To meet with such a scene?
It seems some fairy solitude,
Where elves resort in lightsome mood,
To sport 'mong copses green.

The average expense of raising and executing signet-letters, viz. summons, arrestment, inhibitions, suspensions, horning and poinding, and caption, may be stated from £.10 to £.25 upon each debt, although, perhaps, not exceeding £.5 or £.10 in

Loch-na-bo.

How calm the little lake doth lie,
Reflecting the soft Summer sky,

One sheet of azure hue!
And, raising their round heads, are seen
The wooded isles of softest green,
Amid the waters blue.

Dark woods hemm'd round on every side,
And tow'ring hills extended wide,

Shut out the world unknown;
No human footstep presses here;
The wild fowl and the dappled deer
Make the lone spot their own.

amount.

By the new plan proposed, the blank warrant of citation, arrestment, and inhibition, should cost about seven shillings, and all the other expenses of letters of horning, arrestment, &c. would be saved, except a trifle for recording an inhibition or charge, because the warrants to arrest, poind, &c. would be contained in, and appended to the original decree.

If, again, these extracts and the copy for the record were allowed, as in the Jury Court, to be prepared by the agents themselves, one extractor might sign all the extracts of the Court of Session, and thus the whole expense of the absurd establishment of so many extractors might be saved.

The only objection to the economical plan proposed, is the vested interest of the Writers to the Signet. It would not be difficult to show that all the compensation which they could fairly claim would be very trifling. But their claims of compensation should be no obstacle to such a national benefit. Let the Barons of Exchequer be empowered to examine these claims, and to sustain them in so far as may be just.

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ON THE FIGURE OF THE EARTH.

A SPECTATOR, placed on any part of the earth's surface, sees around him a certain limited portion of its surface, and this portion is called the visible horizon of that place. If the spectator advances twenty or thirty miles from his first position, in any direction, either east, west, north, or south, he will have an entirely new visible horizon, which will not contain any one of the objects which were seen in his first position. By advancing still farther, he will have another visible horizon, filled again with fresh objects, and bounded by a different portion of the earth. If the earth were perfectly globular, the boundaries of all these visible horizons would, in every position, be circles; but as the figure of the earth is that of an oblate spheroid, the boundaries of all the visible horizons, except when the spectator is at either of the poles, will be ellipses. Now the perpetual change of objects in the visible horizon cannot possibly arise from the inequalities of the earth's surface, considered as a plane of indefinite extent; for even from the highest mountains in one of the horizons, we cannot see the objects contained in the other. It follows, then, that the surface of the earth is not plane, but convex; and since this change in the visible horizon takes place equally, as to observation, in every part of the earth which has been visited, we are entitled to conclude that the earth is round. When the visible horizon is composed wholly of sea, we have occular proof of the earth's convexity. As a ship comes in sight, the top of the mast first appears, while the hull and the sails, at least the lower parts of them, are invisible. We next perceive more of the rigging, and, as she approaches, the whole of the vessel rises, as it were, above the horizon, or above the convexity of the sea;-and the surface of the earth is nothing more than the continuation of the surface of the sea, in all directions, and raised a little farther from the earth's centre. The globular form of the earth is still more satisfactorily proved by the variation in the mid-day altitudes of

VOL. XV.

the sun, and the meridian altitudes of all the other heavenly bodies, when seen from different parts of its surface, or in different latitudes; and this variation, when accurately observed at two places, whose distance is known, or which we can measure, enables us to determine, with great accuracy, the diameter of the earth. It is difficult, however, when measuring the meridional distance between two places, to keep always exactly in that meridian; we may deviate a little to the one side or to the other, in consequence of which, our measured distance between the two places will be greater than the true distance. We can place upright poles, or other objects, in the meridian which lies between the two places, in the following manner: Let a transit instrument, at one of the places, be placed in the meridian, by the help of circumpolar stars, or otherwise; direct the telescope towards a distant object, some part of which is in the meridian. Upon this object make a mark, exactly in the direction of the vertical wire in the middle of the telescope; this point will be in the meridian: the same kind of operation may be made at the second station which was made at the first; and, in this manner, the meridian line may be continued as far as we please. When the distance between the two places is measured, and the difference between the zenith distances of a star situated on the same meridian, corresponding with the measured distance, is ascertained; this is what astronomers call the measure of a degree of the meridian. The measurement of two degrees, in the direction of the meridian, in two different latitudes, is sufficient to determine the two axes of the generating ellipse, and, consequently, the figure of the earth, supposing it to be elliptical. Several degrees have been measured, in different latitudes, and the result of these measurements is, that the mean diameter of the earth is about 7912 miles ;-that a degree of the meridian is longer at the poles than at the equator; and, therefore, that the earth is an oblate spheroid, D

a solid generated by the revolution of an ellipse about its shorter axis, and that the proportion of the less axis is to the greater as 300 to 301. The difference, however, in the results which have been obtained by making use of various degrees measured in different parts of the earth, by col lating them in pairs, was sufficient to induce Laplace to suspect that the earth is really not a solid of revolution, but that the terrestrial meridian is a curve of double curvature. That illustrious philosopher was led to this erroneous conclusion, partly by making use of the incorrect de gree of the meridian measured by Maupertius and his associates in Lapland, and some similar wrong results given by La Caille, deduced from measurements and experiments made at the Cape of Good Hope, and partly by an error in his own calculations, which affected his results. From subsequent experiments, however, more accurately conducted, it is now extremely probable that the earth is a solid of revolution, and that both hemispheres are exactly similar. The degree in Lapland has been re-measured, and an error detected in the old measurement of about 200 fathoms. Professor Playfair ascribed the small discrepancies, which arise from making use of measured degrees in different places, to the unequal density of the materials of which the carth may be composed at those places near its surface, by means of which the direction of gravity may be disturbed.

the gratuitous suppositions which Newton had adopted, that if a planet, supposed to be fluid and homogeneous, be composed of particles which attract in the ratio of their masses, and inversely as the square of their distances, at the same time that it revolves round an axis in a given time, it will remain in equilibrium if it have the form of an elliptic spheroid, whatever may be the ratio of the axis. Maclaurin has only employed in his demonstrations the synthetic geometry of the ancients; but we regard his method as a master-piece, superior to any thing which Archimedes or Apollonius has left us." Maclaurin divided the prize given by the Academy of Sciences at Paris with Euler and Daniel Bernouilli. Now, although it was thus demonstrated that the parts of a homogeneous fluid, (on which the figure of the earth, just described, was any how induced,) would be in equilibrio, yet it was not shown inversely, that whenever an equilibrium takes place in such a fluid mass, the figure of the mass must be the oblate spheroid in question. D'Alembert, indeed, showed that there are more spheroids than one, in which the state of equilibrium may be maintained, and this result, though it was not observed by Maclaurin, might easily, however, have been inferred from his solution. Legendre afterwards proved that the solids of equilibrium must always be elliptic spheroids; and that, in general, there are two spheroids that will satisfy the specified conditions. In the case of a homogeneous mass of the mean density of the earth, revolving in the space of 23 hours, 56 minutes, 4 seconds, one of the spheroids is that above mentioned, the other is one in which the equatorial diameter is to the polar as 681 to 1. Laplace has added the following limitations. A fluid and homogeneous mass cannot be in equilibrium with an elliptic figure, if the time of its rotation be less than 2 hours, 25 minutes, 17 seconds. If the time of revolution be greater than this, there will always be two elliptic figures, or spheroids, and not more, in which an equilibrium may be maintained.

If the earth be not homogeneous, but composed of strata that increase in density as they approach the` cen

A homogeneous fluid, of the mean density of the earth, and revolving on its axis in 23 hours, 56 minutes, 4 seconds, of solar time, would be in equilibrio if it had the figure of an oblate spheroid, of which the axis is to the equatorial diameter as 229 to 230. This is the figure which New ton ascribed to the earth; his investigation of its figure, however, though extremely ingenious, involved assumptions which prevented it from being quite satisfactory. A very accurate and elegant demonstration was not long after given by Maclaurin, which was afterwards improved, and rendered more analytical, by Clairaut. Respecting Maclaurin's solution, Bossut makes the following remark: "He demonstrated, without any of

tre, it will still be an elliptic sphe roid, but of less oblateness than if it were homogeneous. This was demonstrated by Clairaut. Newton fell into a mistake, by supposing the contrary to be the case. The greater density of the earth, towards the centre, is in itself probable; but it has been placed beyond the possibility of doubt, by very accurate experiments made on different sides of the mountain Schehallien, in Perthshire, by the late Dr Maskelyne.

By observations of the zenith distances of stars, the difference of the latitude of two stations on the north and south sides of the mountain was determined. A trigonometrical survey of the mountain (executed, we have been informed, by the late Reuben Burrow) ascertained the distance between the two stations; and thence, from the known length of a degree of the meridian under that parallel, the difference of the latitudes of the two stations was inferred, and was found less by 11.6" than by astronomical observations. The zeniths, then, of the stations, had been separated from each other by more than the usual proportion of the meridian distance; and this could only arise from the plummet on each side being attracted towards the body of the mountain. From the quantity of this change, in direction of the plummet, the ratio of the attraction of the mountain to the attraction of the whole earth, or to the force of gravity, was calculated by Dr C. Hutton, and found to be as 1 to 17,804. The bulk and figure of the mountain also being given, from an actual survey, its mean density was found to be, to the mean density of the earth, nearly as 5 to 9. The mean density of the earth, then, is nearly double the density of the rocks which compose Schehallien; which appears, again, to be considerably more dense than the mean of those which form the general exterior crust of the earth. From a survey of the mountain, made afterwards by Mr Playfair, its density was ascertained to be greater than Dr Hutton had supposed it to be.

66

By what Mr Playfair could conjecture, the mean specific gravity of the whole would be about 2.7 or 2.8, one stratum being about 2.4,

another about 2.75, and some of the rocks as high as 3, and even 3.2. On the whole, then, it appears not un reasonable to suppose the mean specific gravity of the mountain to be from 2.7, to 2.75, or 2. Now, × 24, gives, or almost 5; that is, under these circumstances, the medium density, or specific gravity of the whole mass of the earth, in proportion to that of water, is nearly as 5 to 1, or that it is about five times the weight of water."-Hutton's Tracts, p. 64. Vol. II. Newton thought it probable that the mean density of the earth might be five or six times as great as the density of water, and it has now been determined to be five times as great. "Since, therefore, the common matter of our earth on the surface thereof is about twice as heavy as water, and a little lower, in mines, is found about three or four, or even five times more heavy, it is probable that the quantity of the whole matter of the earth may be five or six times greater than if it consisted all of water, especially as I have showed before that the earth is about four times more dense than Jupiter."Principia, Book III. p. 230.

Notwithstanding the irregularities above-mentioned, the figure of the earth is so near to the spheroid of equilibrium, as to indicate either the original fluidity of the whole mass, or the gradual acquisition of a spheroidal figure, in consequence of the repeated waste and reconsolidation of the parts near the surface. If the whole mass of the earth was ever in a fluid state, it must have been so from the action of heat. The insolubility of the greatest part of rocks and minerals in water, and the immense quantity of that fluid which would be required for dissolving even those that are soluble, are insuperable objections to the hypothesis of aqueous formation. The igneous formation is not subject to either of these difficulties.

The spheroidal figure may have been gradually acquired, without supposing the original fluidity of the whole mass. In a terraqueous body, however irregular its primitive form, the prominent parts are subject to be worn down; and having been thus detached, will be carried to the lower

parts, occupied by water, where they will acquire a horizontal stratification, and, by certain mineral operations, be afterwards consolidated into stone; such a body, in the course of ages, must acquire a surface every where at right-angles to the direction of gravity, and consequently more or less approximating to a spheroid of equilibrium. The natural history of the earth gives considerable countenance to these suppositions, and seems to furnish us with a very rational explanation of the ellipticity or spheroidal form belonging to the earth, and to the planets which are known to revolve about an axis. The distribution of the solid materials in the interior of the earth will very much affect the nature of this solid; and the manner in which the figure is acquired must probably prevent the approximation from ever being entirely complete. The distribution, however, of the materials, at any considerable distance below the surface, must remain to us for ever unknown; we have no means of examination, except by the measurement of degrees, the experiments on pendulums, or from observations made on the deviation of the plumbline from the perpendicular similar to what has just been described as

having taken place at Schehallien. These latter observations ought to be repeated on different mountains, the interior construction of which can be ascertained; but the most eligible method which has ever yet been suggested, is that of making observations on the large Pyramid of Ghizeh, in Egypt, the materials of which, as well as its exact figure, being known, would render observations made on it particularly desirable; especially as they would afford certain data, and reduce the calculations, which are now extremely complicated, to almost nothing. This method was recommended by Dr C. Hutton, in his last paper published in the Philosophical Transactions of London; when that veteran declared, that if ill health and old age did not prevent him, he would make a journey to Egypt, entirely for that purpose "On the whole, the facts known from observation agree in general with the theory; but there are, in the expression of that theory, so many quantities which are yet indeterminate, that a perfect coincidence of the two cannot be strictly affirmed; in fact, the business is not yet completed; something further still remains for future philosophers to accomplish."

Pericles.-A Sonnet.

He is the pride of Athens! he has fought
First in her battles; he has rear'd her fanes,
Restor❜d her laws, struck off her galling chains,
And gain'd the glory his ambition sought.
Yet say not he is happy; see him stand

By yonder lifeless form, and on his check
Mark the big tear in silent language speak,
As the gay flowers drop sadly from his hand.
They fall upon his last-his youngest child,—

Him on whose sunny face he lov'd to gaze,
Watching how merrily his youthful days
Were dancing on whilst all around him smil'd ;-
But he has died ;-look on the warrior's brow,
In the fond father's heart there is no Athens now! 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 inmortalize 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 constructed, would afford sufficient data for the solution of the intricate but very useful problem.

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