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inquiry now abroad, and which bids fair to place our country among the first where such studies have been successfully cultivated. While we thus bestow praise where it is due, we cannot refrain from tendering our mite to the Geological Society of London, which has done so much towards elucidating the internal structure of England. Sincerely must it be wished, by every true lover of science, that these two societies may cordially co-operate in their common objects. Let this be the case, and we shall anxiously apply to them the spirit of the dying address of Father Paul to his country—"Estote perpetuæ."

COMMUNICATION FROM COL. MUDGE.

(Addressed to the Publisher.)

Edinburgh, 17th June 1817.

SIR,

M. Biot and myself are extremely obliged to you, and thank you for your politeness.

In compliance with your wish to be made acquainted with the business which has brought us to this place, I have the honour to inform you, that in consequence of the trigonometrical survey, carried on under my direction, having been brought on so far into the north as to admit of the description or the longest meridional line passing through Great Britain, M. Biot, under the authority of both the French and English Governments, is arrived in England for the purpose of doing, in the several parts of our arc, the same series of experiments that had been formerly done by himself and the Commission of the Board of Longitude, at Formentera, one of the Balearic islands in the Mediterranean, and other stations, on the French meridian, proceeding from thence to Dunkirk.

The object of these experiments is, to ascertain the force of gravity at certain parts of our meridian, as connected with that of France and Spain. The pendulum is now erecting in Leith Fort, where every convenience offers itself for the experiment, and every wish has been anticipated by the chief engineer,Sir Howard Elphinstone. When the operations shall be completed, we propose to proceed to Kirkwall in the Orkneys, and near that place, or some more convenient situation, if any such can be found, we shall again set up the pendulum, and the ordnance zenith sector, the workmanship of the late celebrated Mr Ramsden. Thus, while the experiments are carrying on to ascertain the force of gravity in that quarter, the observations will be made on proper stars near to the zenith, hereafter to be also observed, in finding the amplitude of the whole meridional arc. The base, now nearly completed in its measurement by Captain Thomas Colby of the Royal Engineers, in the vicinity of Aberdeen, will verify the sides of the triangles towards the northern part of our arc, connecting the Orkney Islands with the main land. It is probable that M. Biot and myself will leave this quarter for Inverness (where the ordnance sector is now deposited) about the end of this month, and we think it likely, if the weather should be fair, that our operations in the Orkneys will be finished early in August. When these observations shall be completed, we shall proceed to Yarmouth, on the coast of Norfolk, which lies nearly on the meridian of Formentera produced, and there we hope to be joined by M. Arago, member of the Institute of France, and one of the Commissioners of the Board of Longitude. By this co-operation, having accurately ascertained the latitude of this place, a notable addition will be made to the arc, running south from Formentera to Dunkirk, independent of the great one running north to the Orkneys; for we hope that the difference of longitude (being only a few degrees) will not have sufficient influence to interfere with the importance of this last connexion. We will repeat the experiments of the pendulum at Yarmouth, and afterwards proceed to Blackdown, near Weymouth, to the meridional limit of the English arc, where, having again observed the pendulum, and made observations with the zenith sector on the same stars as are to be observed in the Orkneys, our united operations will close with Messrs Biot and Arago erecting their clock at the Royal Observatory at Greenwich. It was to be always expected, that whenever peace should arrive, the science of France and England would affiliate, and by the united operations, in this particular, determine the magnitude and figure of the earth, by experiments carried on on a greater scale than could be done in-