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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, 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 Delambre 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 the officers who 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.