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LAMBRE to scrutinize the latitudes of all the above places with the utmost care; but he could find nothing sufficient to account for the irregularities. (see Base Metrique, tom. III. p.84.) The observation of the latitude at Montjouy appeared exact; yet, when compared with at Barcelona, very near to Montjouy, an error of 3".24 was discovered ; and DE LAMBRE, apparently with much reason, considers this difference as a certain proof of the irregularities of the earth. To the same cause he ascribes the rest; and indeed, from the very progress which they hold, some local affection seems necessarily suggested.
The consequence of all this is, that for the whole of the arch in France, the degrees are best represented by supposing a compression of to, or ag; while, by taking in a greater range, and comparing the degrees in France with those in distant countries, the compression comes out less than the half of this, vize io, or jóg,
To reconcile the measures actually made with a compression of io, it will be necessary to make the following corrections on the latitudes—For Paris, O; Montjouy, + 35.6; Carcassonne, + 0.88; Dunkirk, + 3".06; and for Evaux, + 55.83. These are wholly improbable as errors of observation, and must be attributed to local attractions, which act
irregularly on the plumb line.—Base Metrique, ib. p. 92.
The same thing may be said of the arc measured in England by Colonel Mudge: the whole arc, taken together, agrees very well with the measures in France, and with that in Lapland, as lately ascertained by the Swedish academy. * But if the parts of this arc be compared, an irregularity is found, and
We have compared together the five arches of the meridian, which from their extent, and all other circumstances, seem the best entitled to confidence, viz. that in Peru, by Bouguer and Conda. mine ; in Hindostan, by Major Lambton; in France and England, comprehending the whole extent, from the parallel of Greenwich, to that of Formentera, by Delambre and Mechain, and in part by General Roy; that in England afterwards, by Colonel 'Mudge; and, lastly, that in Lapland, by M. Swanberg; and the results which we have found, are extremely consistent, and give, for the compression at the poles gta5 When this compression is adopted, there does not appear an error of more than 9 fathoms in the measure of any of the above degrees. The French, from their own measures in France and Peru, bring out a compression of zó nearly. Thus the results are consistent with the supposition that the earth is an el. liptic spheroid, when the arches compared are large and distant from one another: when they are small, and near to one another, they do not agree with that hypothesis, nor indeed with any other single hypothesis that can be laid down. This is what might be expected, and does not invalidate the general conclusion.
the degrees appear to increase on going from the north to the south. In giving an account of Colonel Mudge's measurement in a former Number of this Journal, we ascribed the fact just mentioned, to local irregularities in the direction of gravity, and we still consider this as by far the most probable supposition. A paper, however, written with great knowledge of the subject, and full of sound mathematical reasoning, has been published by Don RODRIGUEZ in the Philosophical Transactions for 1812, which is quite on the opposite side, and ascribes the irregularities in the arc to errors of observation. Don RODRIGUEZ, if we mistake not, is one of two Spanish gentlemen who accompanied MM. Biot and ARRAGO, and assisted in the operations by which the meridian that had been traced through France was tended to the southermost of the Balearic isles.
He seems perfectly acquainted with the methods of calculation, and all the most recent improvements which respect the problem of the figure of the earth. We do not think that he has proved that the irregularities in this measurement arise from errors of observation; and we are of opinion, though the amount of these irregularities may now be more exactly estimated than before, that with regard to their cause, the question rests precisely where it did. But though we are not convinced by Don RODRIGUEZ, we must do him the justice to say, that his argument is fairly conducted, and that he has displayed great knowledge of the subject, and perfect familiarity with the best methods hitherto employed in the solution of this difficult problem. We have therefore observed with regret,
that this ingenious foreigner has been attacked in some of the English Journals, with a violence and asperity which the subject did not call for, and which his
paper certainly did not authorise.
When there are unlooked for results in any system of riments or observations, the errors into which the observer may have fallen, naturally come to be considered as affording one solution of the difficulty. We are not to suppose, that any man engaged in experimental investigations, can be exempted from such an inquiry; nor, when such inquiry is instituted, are we to suppose that he is subjected to a personal attack. The principle on which Don Rodriguez proceeds, though it may be ereroneous, seems to be general; it is applied equally to the French and the English mathematicians; and the anomaly of more than 3" in the latitude of Montjouy, is ascribed by him, not to local irregularity, but to the mistake of MECHAIN, a man eminently skilled in the art of astronomical observation. The calm and dispassionate memoir of the Spanish mathematician, VOL. XXI. NO. 42.
does not therefore give any ground for supposing it to be meant as a personal attack, and still less as a national one.
We observe, with pleasure, however, that the true resolution of the difficulty is most probably at hand. The continuation of a meridional arch must afford the best means of discovering from what cause the irregularities observed in it arise. If they arise from physical irregularities in the structure of the globe, or in the direction of gravity, a compensation in the course of a great arch may be expected to take place. If a body of heavy matter, at any point, make the plummets on each side of it converge more than they ought to do, the zeniths will be carried too far off from one another; the amplitude of the celestial arch will be increased; and the length of the terrestrial degree, will, of course, be diminished. But as the zenith on one side of this point was carried too far to the south, and on the opposite too far to the north, the degrees on either side will be rendered too great, the amplitudes of the celestial arches being made too small. Thus an opposite error will take place, and what is added to one degree will probably be taken from the next. This is not likely to happen if the errors arise from inaccuracy of observation: these errors will not be as any function of the distance, but, depending on accident, must be quite irregular in their distribution. It is with pleasure, therefore, that we see a meridian which has been extended from the shores of the British .channel along the west side of England, viz. the meridian of Delamere now produced into Scotland, where it falls on the east side of the island, and is about to be continued till it intersect the shores of the Murray Firth, or the Northern Ocean. The combined arches in France and England will then extend nearly to 20 degrees; and in a few years we shall perhaps see the distance between the parallels of the Balearic and the Orkney Islands, ascertained by actual mensuration. We believe that this important operation could not easily be in better hands than those in which it is actually placed ; and, when it shall be completed, the British army-in General Roy and have succeeded him in the conduct of the English survey—and in Major LAMBTON whose works we have been now treating of, will have the glory of doing more for the advancement of general science, than has ever been performed by any other body of military men.
Art. IV. Photii Lexicon. E duobus Apographis edidit Godofredus Hermannus. Accedit Jo. Albertii Index, suppletus et auctus. Lipsiæ, 1808. pp. 518.
filled the high offices of master of the horse, captain of the imperial guards, ambassador to Assyria, and first secretary of state, and having thus exhausted the whole range of civil preferment, was, on a sudden, elevated to the Patriarchate of the West; having been consecrated, on six successive days, monk, anagnostes, subdeacon, deacon, priest, and patriarch. Excommunicated by Pope Nicholas the First, he excommunicated Pope Nicholas in return; and after being several times ejected from his episcopal chair, and as often reseated, he was at last sent prisoner to an Armenian convent, where he died in the year 891. He seems to have been very learned, and very wicked—a great scholar, and a consummate hypocrite—not only neglecting the occasions of doing good which presented themselves, but perverting the finest talents to the worst purposes.
We have remaining of his works, besides some Letters and a collection of Canons, his Bibliotheca, or Myriobiblon, being an account of the books which were read to him during his embassy to Assyria, and his opinion of their respective merits. The ambassador, it would seem, must have had but little to do in his diplomatic capacity, since he assures us, that these books amounted to about three hundred; a number, we conceive, much greater than most of our ambassadors or public functionaries can boast of having read, in the course of much longer negotiations. It is pleasing to observe in what proper and energetic terms the good and pious Patriarch rails at the disturbers of the Church. The Novatians and Nestorians rarely come off with any gentler appellation than that of dog,' or impious wretch. Our younger readers, however, who take the Myriobiblon in hand, are not to suppose that the book, which at present goes under that name, is really the production of Photius ; we believe that not more than half of it can safely be attributed to that learned and turbulent bishop; and we think it would not be very
difficult to discriminate between the genuine and supposititious parts , of that voluminous production. But our present busines, is with another work of Photius, his celebrated and valuable Lexicon, which, imperfect and mutilated as it is, is more valuable to the critical scholar, than ten Myriobibla.
It is well known to the learned, that the various MSS. of this Lexicon, in different libraries on the Continent, are mere transcripts from each other, and originally from one, venerable for its antiquity, which was formerly in the possession of the celebrated Thomas Gale, and which is now deposited in the library of Trinity College, Cambridge. This manuscript, which is on parchment, bears such evident marks of great antiquity, that it may not unreasonably be supposed to have been a transcript from the author's copy. * It is written in various hands. The compendia, which are used in some parts of it, are extremely difficult to decipher; though, on the whole, they are less so than the contractions which occur in many manuscripts, and particularly those in the library of Saint Germain. The names of authors cited, it is frequently not easy to make out; and the characters of
B, ph, of ra & th, of a&t, of a & «, of a & M, of a & st, of *. & ph, of ax & ples, and many others, are so nearly alike, that an ignorant copyist would be sure to blunder. Ånd, accordingly, we find the various transcripts from this ancient MS. are miserably faulty and corrupt. + It was natural, therefore, that those scholars, who wished for the publication of this Lexicon, should be desirous of seeing it printed from the Galean MS., in preference to any other.
«Non eram ne• scius,' says Mr Hermann, fore, qui neque aliter quam ex
ipso Codice Galeano, edi debuisse censerent.'. We apprehend that this inuendo is levelled at the late Professor Porson, who, it is well known, had transcribed and corrected this valuable Lexicon for the press; and when, unfortunately, his copy had been consumed by the same destructive element which devoured the Alexandrian library, and Parson Adams's Æschylus, the Professor, with incredible industry and patience, began the task afresh, and completed another transcript in his own exquisite handwriting.
* It seems that a copy of this Lexicon, at Florence, was transcribed, about the end of the 16th century, by Richard Thomson, of Oxford; who probably intended to publish it. We find the fol. lowing passage, in a letter from Joseph Scaliger to Richard Thomson, which we extract, as we believe it is not commonly known, and as every thing which fell from that extraordinary man, even in nagoda, deserves to be read. • Remitto tibi nunc Photium tuum,
optimum sane librum, & quem edi e re literaria est ; quanquam
omnia, quæ in illo sunt, hodie in aliis, unde ipse hausit, exstant. • Quia tamen laborem legentium levare possit, quod in eo omnia . congesta sunt, quæ sparsim in aliis relegere labor est, non exiguam • a studiosis gratiam iniveris, si tam utilem librum in publicum exire * patiaris.' Scaliger Epist. p. 503. See also p. 171.
+ Alberti, in his notes on Hesychius, cites the Lexicon of Photíus repeatedly, but with almost as many inaccuracies as citations. This is partly attributable to his having used a very faulty apograph belonging to J. C. Wolf, and partly to his own negligence.