of the place and its elevation above the mean level of the sea, are not the only, nor even the chief, circumstances, that affect the length of the pendulum; and consequently, that the measurement in any one place, even supposing it to be correctly made, and reduced to the level of the sea, by an amount which should not be arbitrarily assumed, does not determine the pendulum of the latitude, because the nature and density of the substances, that compose the upper crust of the earth at the place of observation, have a most important bearing, and which cannot be neglected. The clock and the experimental pendulum were found to be liable to variations of not less than ten seconds per day in the same law titude, according to the nature of the materials upon which they rested; and, as all the observations were necessarily made upon the land, it is inferred that an equal variation in an opposite di rection, might be considered as likely to occur if the experiments could be performed at different points on the surface of the ocean; the whole difference, then, that might arise from the ac tion of the different substances that are found on the surface of the globe may, in the same latitude, amount to no less than twenty: seconds; and the difference in the length of the pendulum at stations differing in local circumstances, but still under the same parallel, might be equal to 0.01 of an inch; or nearly one-tenth of the whole difference of the intensities of gravity at the pole and the equator, or tooth part of the absolute attraction of the earth. It would thus appear, that before the mean force of gravity, in any parallel of latitude, can be inferred with certainty, numerous observations, indeed an almost indefinite number, ought to be made in or near that parallel, to produce by their combination, a near result.

With respect also to the allowance to be applied to the length of a pendulum measured at an height above the sea, to reduce it to what it would have been if measured at the level, it is shewn that the correction which has been recently proposed, for the error arising from the figure of the surface, by which the regular decrease of gravity in proportion to the squares of the distances from the centre is affected, may be safely neglected; but that a far greater uncertainty than from external conformation, and fort which it would be far more difficult to assign a specific correction, is involved by the variable density of the materials, on which the pendulum is raised above the surface of the sea, From these 5 considerations, Captain Sabine concludes that the pendulum of act particular latitude cannot become a standard of reference, because t its length is not practically determinable; that the pendulum offe a particular city, London for example, (whereby it is implied that a length measured in one part of the city should be recoverables d by a measurement made in some other part of the city,) is open b to the same objections, though in a less degree; but that the more

simple standard, and which is of determinate and determinable magnitude, is the pendulum of a particular spot; it being understood that all future repetitions, designed to produce identical results, should be made identically at the same place.

We consider, that Captain Sabine has gone far towards proving that, in this view, the pendulum is applicable to the proposed object; that with proper precautions, and by adopting the method of experimenting which he has pointed out, different observers, using different instruments, may arrive with certainty at identical conclusions: at least so nearly identical as not to differ in the fourth place of decimals of a British inch. But he has also shewn (pages 213 to 233,) that the method which was previously adopted, and employed in the experiments which are considered by the act of parliament to have determined the length of the seconds pendulum in the latitude of London, does by no means ensure identity on repetition within the limits declared in the act; because the method is not independent of individual peculiarity, or of accidental circumstance. The conviction is thus forced upon us, of how essential the experiment itself of repetition is; and that it is expedient to prove that a method will produce identical results in other hands than the original experimenter, before it is officially bequeathed for such purpose to posterity.

The selection of a spot, the pendulum of which is to supply an invariable length in perpetuity, and which will require to be referred to, not less by foreign nations of the present day, who may desire to compare their standards with that of Great Britain, than by those of more distant ages who may seek the recovery of the British measures, is by no means an indifferent consideration It has happened accidentally that the original experiments were made in a private house in London: a circumstance which in itself, must sooner or later have obliged their repetition elsewhere. But if the length of the pendulum is affected by natural local circumstances, to the amount we have stated, (and we think the fact too clearly made out by Captain Sabine to be questioned,) may not even artificial changes in the character of the place of experi ment produce a similar result, although in a less degree? we be assured that the vibrations of a pendulum, in Mr. Browne's house in Portland Place, are the same now, as when, not more than two centuries ago, its site was nearly a mile without the limits of the city? Nor are either of these times identical with that which would be found, were the future observer compelled to seek for the spot amongst masses of rubbish. Nor is this last view of the subject, however improbable or distant, one that is to be entirely neglected. The language, the arts, and the sciences, which are the boast of Great Britain at the present day, are founded upon a basis more secure than that of empire, and will exercise an intellectual supremacy over future ages, should even the fate that

Can

has attended the former "glories of the world," overwhelm, at some remote period, her proud metropolis. It must ever be remembered, that on the transmission of her scale, will depend the value to posterity of every attainment which she either has made, or may make, in which linear measure is concerned; and that consequently her fame and her usefulness in those distant times may materially be influenced by the provision which she may now make for its exact transmission.

For these, and for other reasons which we have not space to state, we should consider it highly expedient that, whenever Kater's original experiments shall be repeated, for the final verification of the British scale, the proceedings should take place in a public building, and at such a distance from any probable extension of dense population, as may secure a close resemblance to its present state for centuries; and that, when the pendulum of that spot shall be considered as fully and satisfactorily determined, other nations, which may be disposed to adopt a similar proceeding, should be invited to a direct comparison of the standards and measurements of the respective countries, not only for the more perfect assurance of accuracy, but in order that the places may be multiplied on the globe, at which the British measures may be hereafter reproducible.

We perceive that we have already attained our limits in the examination of the subjects contained in little more than half the work before us: the remainder consists of geographical, hydrographical, and magnetic notices of great interest, particularly the latter: the subjects however are distinct, and require in fact to be treated of separately; we shall not, therefore, however worthy they may be of notice, trespass further on the patience of our readers; but shall conclude with recommending its perusal to all persons who take an interest in such investigations, as one of the ablest works with which we are acquainted,

III. Remarks on Professor SPOHN'S ESSAY De LINGUA et LITERIS VETERUM EGYPTIORUM, edited by Professor Seyffarth, 4to. Leipzig, 1825. In a Letter to Baron WILLIAM von HUMBOLDT.

MY DEAR SIR,

I HAVE to thank you for the favour of your letter sent me by Mr. Struve: I have delayed making this acknowledgment, until I could return you some answer on the subject of Mr. Spohn, whose posthumous work you mention as having engaged your attention. We might suppose it to be almost impossible that a man possessed of any talents should spend some years of his life in a field of lite

rature not wholly barren, without obtaining some few fruits of his labour, which had escaped the researches of others but I have looked in vain for any one addition to what even Mr. Akerblad had made out, more than thirty years ago, that can justify the pomp and ceremony with which Professor Seyffarth's Prodromus is issued into the world.

The most satisfactory evidence on this subject is that of the papyrus of Casati, which I discovered to be the original of Mr. Grey's Greek antigraph, a little after I had printed, and distributed among a few friends, my attempt to translate some parts of the original, which appeared in the Philosophical Journal for January, 1823. You will find in it Nebonenchus as a proper name, twice over; Apollonius, Antimachus, and Antigenes: the three last having been read nearly in the same manner by Champollion. There is also a phrase, et liberis ejus, hominibus ejus, frequently repeated.

Of these, Professor Spohn has made out the letters nebonen, and etplonies, without marking them as proper names; and he has put down Antimaus and Antigenes as a part of his translation: but he has not attempted any explanation of the phrase, which is repeatedly rendered in the antigraph, with his children and all his family, nor has he rightly translated a single word besides, after the preamble, which is not in the Greek.

With respect to his mode of reading the words, by an alphabet, which, the newspapers tell us, is like the Armenian, this manuscript affords an undeniable criterion of its accuracy, as it consists almost entirely of proper names, originally Egyptian, not one of which has been read by Professor Spohn in any way at all approaching to the truth. For example, instead of Maesis Mirsios, he gives us Eumolme Nnelleme; for Peteutemis Arsiesios, Ischre pepo eepô nenee; and for Petearpocrates Hori, Nearschneoe hne. If his Egyptian dedication to the King of Saxony is equally happy with these specimens, it may happen to pass current in the other world for an address to Sesostris or to Osiris himself, or for a confession of faith in all the gods and goddesses of Ombos and of Tentyra; and thus to have procured him admission into the blessed communion of those deified Egyptian kings, who are occasionally represented, according to Mr. Bankes's drawings, as offering sacrifices to themselves.

London, 22 Sept. 1825.

97&ART. XVI. MISCELLANEOUS INTELLIGENCE. belówi AM to go mich

ods iseng mas ar I. MECHANICAL SCIENCE..100 som f torbor. Black's 1. Dr. Black's Sensible Balance. The following description of 64a very delicate and, to many it may be, very useful balance, is taken from a letter written by Dr. Black, to James Smithson, Esq., and inserted in the Annals of Philosophy, N. S. x. 52, "The apparatus I use for weighing small globules of metals, or the like, is as follows: A thin piece of fir-wood, not thicker than a shilling, and a foot long, 3-10ths of an inch broad at the middle, and 14 tenths at each end, is divided by transverse lin lines into 20 parts, i. e. ten parts on each side of the middle. These are the Vis Principal divisions, and each of them is subdivided into halves and quarters. Across the middle is fixed one of the smallest needles I could procure, to serve as an axis, and it is fixed, in its place by means of a little sealing-wax. The numerations of the divisions is from the middle to each end of the beam. The fulcrum is a bit of plate-brass, the middle of which lies flat on my table when I use the balance, and the two ends are bent up to a 19right angle, so as to stand upright. These two ends are ground

esd

at the same time on a flat hone, that the extreme surfaces of them be in the same plane; and their distance is such that the needle, when laid across them, rests on them at a small distance from the sides of the beam. They rise above the surface of the table only one and a half or two-tenths of an inch, so that the beam is very limited in its play.

"The weights I use are one globule of gold, which weighs one grain, and two or three others which weigh one-tenth of a grain each; and also a number of small rings of fine brass wire, made in the manner first mentioned by Mr. Lewis, by appending a weight to the wire, and coiling it with the tension of that weight round a thicker brass wire in a close spiral, after which the extremity of the spiral being tied hard with waxed thread, I put the covered wire in a vice, and applying a sharp knife, which is struck with a hammer, I cut through a great number of the coils at one stroke, and find them as exactly equal to one another as can be desired. Those I use happen to be the one-thirtieth part of a grain each, or 300 of them weigh ten grains; but I have others much lighter.

"You will perceive that by means of these weights, placed on differents parts of the beam, I can learn the weight of any little mass, from one grain, or a little more, to the Too of a grain. For if the thing to be weighed weighs one grain, it will, when placed on one extremity of the beam, counterpoise the large gold weight at the other extremity. If it weighs half a grain, it will counterpuise the heavy gold weight at five; if it weighs 6-10ths of a VOL. XX.

M