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CAPTAIN SABINE TO DAVIES GILBERT, M.P. VICE PRESIDENT OF THE ROYAL SOCIETY.

MY DEAR SIR,

Portland Place, Feb. 8, 1826.

I beg to trouble you with a few remarks on the project of measuring an arc of the meridian at Spitzbergen, previous to its discussion at the Council of the Royal Society.

It is not necessary that I should at this time enter on the reasons which have induced, for more than a century past, measurements to be made of portions of the meridian, for the purpose of determining the figure of the earth. The question now is, rather, shall all that has been effected hitherto in this method, with so much labour and expense, remain in its present incomplete and inconclusive state? or, shall the method be pursued until the result which it is capable of giving be attained?

There have been two arcs measured in the vicinity of the Equator; the Indian one, in particular, deserving of the highest consideration from its extent, and from the care bestowed on its details. To give to these arcs their full value in the proposed determination, there

is wanting a corresponding measurement, or measurements at the Polar extremity of the meridian, with which they may be combined.

Several stations have been named for this purpose besides Spitzbergen; viz., the North Cape, Greenland, and Iceland. From personal knowledge of all these countries (except Iceland, to which, however, the remark equally applies), I can venture to give a practical opinion, that there can be no question as to the superior eligibility of Spitzbergen; a water communication along the whole line of operations, constitutes the superiority; and to those who have thought much on the details of such proceedings, it will not be necessary to explain that this is a point of the very first importance; a view of the chart of Spitzbergen will best show its remarkable fitness in this respect.

An arc, falling a little short of 40, is comprised between Hope Island and Seven Islands, being the northern and southern extremities of the group which passes under the general name of Spitzbergen, and which may be seen by the chart to be so connected by intermediate land as to admit of their being united trigonometrically.

The value of an arc of 44° in the latitude of Spitzbergen towards the deducing the pro

portion of the polar and equatorial diameters by its combination with an arc near the equator, is equivalent to one of 9° in the mean latitude of France, and of 7° in the mean latitude of Britain; its value, therefore, in the ultimate determination, may be estimated by the known importance which is attached to the national arcs of Great Britain and France. It may be further noticed, that it is equivalent to an arc in Lapland, of nearly six times the extent of the arc measured by the French Academicians; the importance of which at this day is such, in the view of the first geometrician of the age, that M. Laplace has recently proposed, that a fresh commission should be sent to re-determine the latitudes of the extremities.

The expediency, then, of undertaking such a measurement at Spitzbergen, is principally to be considered in reference to the natural difficulties which may impede its execution. And on this point, having myself actually resided some weeks on shore at Spitzbergen, having conducted operations of a similar nature, having personal knowledge of the general character of the country to be traversed, the difficulties it presents to persons carrying astronomical instruments, and the modes and facilities of overcoming those difficulties, and having made observations of much deli

cacy, continued through many successive hours, and for successive days, at the summit of one of the hills of principal elevation, such as would probably form the greater part of the trigonometrical stations, I may venture to hazard the opinion which that varied experience warrants. The subject was in my mind when on the spot, and I have since reflected continually, in reference to it, and have heard, I believe, most of the objections which from time to time have been suggested in conversation, against its practical accomplishment. I still, however, entertain the opinion formed on the spot, viz., that there is no reason to anticipate any difficulties, either of climate or country, but such as may be surmounted by the patience and exertion requisite in such operations, or which, being surmounted, would in the slightest degree interfere with the accuracy of the result. I may observe, that I am speaking of difficulties which I think it not improbable I may be called on myself to meet; and that I am not likely, under such circumstances, either lightly or inconsiderately to underrate them.

It is very satisfactory to me to be enabled to add, that the inferences I had drawn from my own personal experience at Spitzbergen, have been greatly strengthened by the highly interesting and important information, as regards this

question, which Mr. Crowe, his Majesty's ViceConsul at Hammerfast, the establisher and proprietor of a British settlement at Spitzbergen, has obtained in the last summer. The following extracts are from a communication which Mr. Crowe has made to Lord Melville:

"It having been mentioned to me by Captain Sabine, in a conservation I had with him previously to my leaving England last summer, that the Admiralty might have it in contemplation to send a vessel in the direction of Spitzbergen, for certain scientific objects, and that any information would be acceptable which might tend to facilitate the progress of such a vessel, I directed the master of a small cutter of forty tons, who was to sail from Hammerfast, to the settlement at Ice Sound, to penetrate up Wyde Jansz Water, an arm of the sea which intersects Spitzbergen in a north and south direction, respecting the free navigation of which Captain Sabine had expressed a wish to be informed. The vessel accordingly did ascend to the parallel of Ice Sound (78°), and the master reports it to have been perfectly free from ice. He next went round the west coast as far as Walden's Island, adjoining the Seven Islands, without meeting with any impediment; and although many shoals of ice were visible from thence, there were many open channels through which he