The Indians discovered by Captain Ross, on the coast of Baffin's bay, in the summer of 1818, in latitude seventy-five degrees fifty-five minutes north, when interrogated from whence they came, pointed to the north, where, according to their account, there were "plenty of people;"[24] that it was a warmer country; and that there was much water there. And when Captain Ross informed them that he came from the contrary direction, pointing to the south, they replied, "that could not be, because there was nothing but ice in that direction:"[25] Consequently these people must live in a country not composed of ice; for it appears they deem such an one uninhabitable. Hence we must infer, if the relation given by Captain Ross be correct, that, north of where they then were, the climate becomes more mild, and is habitable; a change, the cause of which is not easily accounted for on the old philosophic principles.
In high northern latitudes, owing to refraction, or some other peculiar circumstance, which hitherto has not, to my knowledge, been attempted to be accounted for, the extent of vision appears to be greatly increased; so that objects, much further than the ordinary distance, are distinctly seen; frequently appearing elevated above the sea, or their real situation; and their image sometimes pictured in the sky. The real objects, themselves, are sometimes seen with the naked eye one hundred and forty or one hundred and fifty miles,[26] and sometimes at the astonishing distance of two hundred miles. These facts are well attested by Captain Ross and other navigators. How this can be accounted for, on the formation maintained by the old theory, I cannot conjecture. I believe it is admitted that the deck of a vessel at sea, any where between the equator and latitude fifty or sixty degrees, cannot be discovered, even by the best telescope, at a greater distance than twelve or fifteen miles.[27] Nay, were there no end to vision, and could the eye penetrate two hundred miles through our atmosphere with sufficient clearness, it would require an observer to be elevated about five miles, before he could discover an object on the surface of the earth two hundred miles distant. But, on the edge of the verge of the polar opening, if the atmosphere were clear, and the power of vision strong enough, an observer might discover objects situated on the verge at any point all round the sphere; as they would be on an exact plane with the observer. And on the contrary, travelling across the verge from the convexity to the concavity of the sphere, a very few miles make objects disappear.
All northern navigators and travellers agree, that high north the sun becomes less bright, and the sky darker, than in more southern latitudes. Is not this owing to the rays of the sun being refracted round the verge of the polar opening? Another circumstance, observed by navigators, who have visited high latitudes is, that the latitude and longitude, as found by celestial observation, frequently differ very materially, sometimes as much as one half, from that given by the log-line.[28] It has also been observed that the mercury in the barometer is less fluctuating in northern regions, than it is further south.
Those appearances observed in the southern hemisphere, which are termed Magellanic clouds, by navigators, have not, so far as I know, been accounted for. They are three in number, of an irregular shape, and observed by night in the South Atlantic, and the south-east parts of the Pacific oceans, (reversed from New-Holland and New-Zealand,) but never visible in the eastern parts of the Indian ocean: their colour is like that of far distant mountains, on which the sun is shining. In the one sea they appear due south, and in the other to the left. They are stationary, appearing perpetually fixed at a certain height, and in a particular situation, as viewed from any given place. The stars and the heavens, in their diurnal revolutions, sweep by them, and they remain the same. To the navigator, who proceeds to the east or west, they appear to be more or less to the right or left of the meridian, in proportion as he changes his longitude; and as he sails south, they increase in height, until they reach the zenith, and finally become north, when seen by an observer south of the straits of Magellan, which is in latitude fifty-two degrees south. Captain Symmes accounts for the appearance of these clouds by the great refractive power of the atmosphere about the polar openings; causing the opposite side of the verge to appear pictured in the sky, as navigators inform us objects do sometimes appear, in the arctic regions; and in the manner Scoresby's ship appeared in the sky, with every particular about her so accurately represented, as to be at once identified by the observers, though the vessel, at that time, was at such a distance as to render it rather incredible how she could be seen at all. As proof of this position, Captain Symmes alleges, that the relative position, shape, and proportions of these clouds, agree in their general outlines with the southern part of New-Zealand, the southeast part of New-Holland, and the whole of Van-Dieman's land, which are situated on, and near to the verge of the sphere, opposite to where the clouds are visible. These clouds are only seen in the night when the atmosphere is clear, at which time the sun is shining on the islands in question. Hence it is alleged, that from these facts, their relative appearance is deducible. As we are never sensible that the rays of light are refracted by the medium through which they pass before they reach our visual organs; we frequently imagine objects to be situated where they really are not; and such is believed to be the case as respects Van-Dieman's and the circumjacent land, as before described.
Franklin, in his journey far north, on the continent of America, discovered a cloud, which appeared to remain always in the same position, and which the Indians informed him was permanent. Not having the book at hand, I cannot now advert particularly to what he says on the subject: but, from memory only, recollect that he states something to that effect. If such an appearance exist there, may it not be accounted for in the same manner as the Magellanic clouds?
Navigators, who have sailed far north, admit the variation of the needle to be excessive. Captain Ross found it in Baffin's Bay, to be as much as one hundred and ten degrees; and Parry, during his voyage in 1822, found it so changed, that the needle pointed within about fourteen degrees of south. All, I believe, concur, that this is a phenomenon which universally occurs in high northern latitudes; but it has hitherto remained unexplained. I believe, according to the old theory, the needle is imagined to be attracted by something at or near the pole: were this supposition correct, the needle would uniformly maintain its polarity on proceeding north, on any given meridian, until you arrived at the very pole itself. The possibility of a moving magnetic cause is difficult, if not impossible, to be reconciled with a solid globe; yet that the magnetic needle does vary on the same meridian, and to a most extraordinary degree, in high northern latitudes, is confirmed beyond all doubt. Why not then urge the variableness of the magnetic cause against the possibility of a solid globe?
According to the doctrine of hollow spheres, this whole mystery, of the variation of the compass, can be satisfactorily explained. The magnetic needle, it is believed, regards the centre of the polar opening, and not the pole or axis of the earth. It will be recollected, that the axis of the earth, being at an angle of twelve or fifteen degrees from the plane of the polar openings, causes one part of the verge to extend farther north than the other, the highest part of which is nearly on a meridian running through Spitzbergen, in about latitude sixty-eight degrees, and the lowermost side in about the fiftieth degree. Now in proceeding north on the first meridian, running near Spitzbergen, there ought to be no variation of the needle until you arrive at the apparent verge, when the needle would cease to traverse; and by proceeding onwards, would turn and point south. Should you proceed north, on a meridian west of this, when you approached the apparent verge, the needle would seem to turn west, but in reality, it would be the meridian turning to the right along the verge to its highest or most northerly point; the needle keeping at a right angle with the verge. And, in like manner, pursuing a course north, on a meridian east of Spitzbergen, on your approach to the apparent verge, the needle would still direct its course at a right angle into the polar opening, (governed, most probably, by some principle of electricity, or other property contained in matter, and kept in one position, subject to the shape of the earth, which may not even yet be exactly known,) the meridian would here wind to the left, and conduct you to the highest point of the apparent verge, north of Spitzbergen. Hence the variation of the needle would be east in Asia, and west in America, which I am told is the fact. From an examination of the variation of the compass, as ascertained in different degrees of latitude and longitude, it increases as you proceed north, and west; which would be exactly the case in accordance with the theory of concentric spheres.[29]
Admitting the earth to be a solid globe, and the cause of magnetism to be some attractive power at the pole, how could the needle vary differently on the same meridian, in different latitudes, at the same period of time, or vary at the same place, at different periods of time? But, admit the doctrine contended for, by the advocates of concentric spheres, and it can be satisfactorily explained. The observations of modern astronomers, have ascertained, that the poles, or axis of the earth, are not always directed to the same fixed star; and, of consequence, that the axis does not always remain parallel to itself. This variation is discovered to be about fifty-one minutes annually; which would make a degree in about seventy-one years: hence the needle always pointing to the polar opening, would vary in about that proportion, at the same place, in the same period of time.[30]