be the case, by the following communication from Lieut. Burlton :*-The width is rather considerable, it is true, but not sufficient to authorize the idea that the stream has travelled some six or seven hundred miles. "Lieut. Burlton's letter is dated' on the River Burrampooter, N. lat. 27° 54′, E. long. 95° 24', March 31st, 1825.' He reports that he had that day got as high up the river as it was navigable: the bed of the river was a complete mass of rocks, with only a depth of three or four feet of water in the deepest part; the rapidity of the current was also so great that no boat could track against it, putting the danger of striking on the rocks out of the question. He considers it as about the size of the Kullung River (150 yards across), and the extreme banks as being not more than 600 yards apart. Lieut. Burlton regrets that he could not proceed farther either by land or water. It was represented to be at least ten days' journey to the Brahma Koond, and he had but a few days' provisions left. What he had learned respecting the course of the river above was, 'that it runs easterly till it reaches the lowest range of mountains (Lieutenant Burlton could see this range, and supposed it to be about fifty miles distant), where it falls from a perpendicular height of about 120 feet, and forms a large bottomless bay, which is called the Brahma Koond.' Above the low range are some high mountains, which are covered with snow; and, from the narrowness of the water, he imagined that the source of the Burrampooter must be there, as it seemed very improbable such a sinall body of water could run the distance it is represented or supposed to do. "From what the natives said respecting the Seeree Serhit, or Irrawuddy, Lieutenant Burlton was inclined to think that that river rises at the same place." The same paper, of June 30, contains the ensuing additional particulars :— "By means of some Khangtis, originally from the Bor Khangti country, Lieut. Neufville† has been able to give some more intelligence respecting the rivers. The Bor Khangti territory lies on the other side of the high snowy hills of the Brahma Koond. These ranges he now finds extend back to a far greater depth than he had at first supposed, and, he is assured, to a far higher altitude than any of those now visible. The Burrampooter, of Luhit, accessible only as far as the reservoir of the Brahma Koond (unless, perhaps, to the hill Meeshmees), takes its original rise very considerably to the eastward, issuing from the snow at one of the loftiest of the ranges; thence it falls, a mere mountain rivulet, to the basin of the Brahma Koond, which receives also the tribute of three streams from the Meeshmee hills, called Juhjung, Tisseek, and Digaroo. From the opposite side of the same mountains, which give the primal rise to the Burrampooter, the Khangtis state that the Irrawuddy takes its source, running south, intersecting their country, and flowing to the Ava empire. This theory of the sources of the streams is thought by far the most probable; and it agrees more with the general accounts and the geographical features of the country. "A little to the northward of east (the opening of the Brahma Koond) is another less defined dip in the lofty line of the Meeshmee hills, through which Lieut. Neufville has received a route, accessible to mountaineers, of twenty days to the country of the Lama. "There is said also to exist a passage somewhere through the Abor hills to Nipal; but he could find no one able to give him satisfactory intelligence on that head." This officer has been employed upon a survey of this river in Assam.-Ed. Also employed to survey.-Ed. man. MAGNETIC VARIATION. To the Editor of the Asiatic Journal. SIR: An event of material importance to science is now in progress, and calls for the aid of your excellent publication, with a view of promoting a requisite co-operation in India. The celebrated Professor Hansteen, under royal patronage, proceeds to Siberia, in confident expectation of discovering there a north-east magnetic pole.* He is to be accompanied by an eminent French philosopher, Monsieur Coupter. This cannot be the magnetic pole imagined by Dr. Halley, who situated his north-east pole at the intersection of the meridian of 38° east longitude, by the parallel of 76° 30′ north latitude. Halley situated his north-west pole in Baffin's Bay. Three other writers, as stated in Encyclopædiæ, placed their poles in both hemispheres, where recent observations cannot sanction either their position or existence. As formerly stated, by three series of approximations deduced from the observations of Captains Parry and Francklin, and by taking one-third part of the amount of three approximations to the latitude and longitude of the north-west magnetic pole, we cannot be far from the truth in placing it at the intersection of the meridian of 100° west longitude, and the parallel of 70° north atitude. According to the theory of variation which I have been establishing, there can be no variation of the magnetic needle, in the northern hemisphere, in all places under the meridian of the north-west pole, with a small modification to be adverted to. From the time when the variation was nothing in London, till in 1817, the west began to decrease, 160 years passed; and therefore the time of a revolution must be 720 years, and not 1096, according to ChurchObservations do not admit of assigning fractions of time. The pole appears to be moving eastward, at the rate of half a degree of reduced longitude annually; and this occasions the variation on the surface of the earth; and it will be increasing or diminishing according as the moving pole is advancing to, or receding from, the meridian of any place. At present, accordingly, the variation is diminishing. In 200 years from 1817, there will be no variation at London, because the magnetic pole will be under its meridian. An east-variation will go on during 160 years, when again there will be a decreasing variation, because the moving pole will be advancing to the meridian of London, on the other side of the north pole of the earth, which has no magnetic attraction whatever, but is a requisite point from which the reckoning is made for nautical purposes. After that, a west-variation will commence, as in 1657; to cease, as lately, when the pole has attained its maximum of westing. The different cases are applicable, cæteris paribus, to all places in our hemisphere; and, vice versâ, in the southern, where the south-east pole moves in a contrary direction, or westward. It is now generally admitted, on scriptural and philosophical grounds, that the earth is not solid, but “void ;” and that it moves in its orbit in the ether of Sir Isaac Newton, on a similar principle to that by which a balloon floats in the atmosphere. Infinite Power gave the orbicular motion, and that round the axis necessarily followed. The physical cause of the movement of the two magnetic poles within the earth is unknown. These poles are manifestly possessed of the contrary polarity, and, consequently, they must, on known magnetic principles, have a strong mutual attraction: *We learn that the journey of Professor Hansteen has been postponed. He is in the meantime providing himself with every instrument requisite for his purposes.-Ed. attraction; while it may be rationally supposed, that the Deity, for wise purposes, gave them an orbicular motion. The dipping-needle will stand perpendicular on the oblate spheroid of the globe, where the two magnetic poles are situated. If the line of the needle on each pole is supposed to be produced to an intersection of the earth's axis, probably not more than a third part of that axis will remain intercepted between the points of intersection; and a compressed gaseous fluid may prevent a nearer approach, in addition to the action of the orbicular force. Be this as it may, evidently these poles move in contrary directions within the earth, and obviously cause the variation, increasing and decreasing, as stated. The irregularity in the progress of the variation may be naturally accounted for, by the action of magnetic masses found in various places in the shell of the earth. It is manifest, that where such strata lie in the variation-line, some degree of irregular movement must arise till the greater power of the moving pole draws the needle away from such temporary influence. Having necessarily premised thus much, I may presume to think, that the two profound philosophers mentioned will not find a magnetic pole in Siberia. This matter cannot be mistaken, as a pole will throw the dipping-needle into a perpendicular attitude. The dip at Tobolsk will be found nearly similar to what it is in London; and when the investigating men of science proceed as far east as the meridian of 80°, they will find themselves on the north-east line of no variation. In moving north on this line, the dip of the needle will increase, though not, probably, to more than 75°, as far north as the land will carry them. It will be of great service, however, to lay off a meridian on the line of no variation, in order, at a future period, to find how much, annually, a commencing west-variation, on such line, may amount to; for it is by observing such increase and decrease, in various places, by means of true meridians, that the true rate of movement of the pole, and the occasional irregularities, will be nearly ascertained. I come now, sir, to the wished-for co-operation in India. If a line, passing through the north-west and south-east magnetic poles, be drawn all round the earth, the needle, on any part of that line, will point to both poles; but in every other situation, the nearest extremity of the needle will be attracted by the pole of the same name, in the inverse ratio of the square of the distance; and experiments with magnets tend to confirm this. On whatever meridian a little to the east of 80° east longitude the two philosophers find the north-east line of no variation, to ascertain it truly, a proportional allowance must be made for the attraction eastward of the south end of the needle, and this will be more, on the same meridian, near Nagpore and Madras, than in the north of Russia. A comparison of the increasing west-variation on such meridian, for a series of years, will prove the fact; and with this view, it is hoped that, in those places in India under the meridian of the line of no variation to the east of Tobolsk, meridians will be truly laid off in India, in order to compare the quantum of variation in different places under it, and at different periods, in time to come. There is a passage through Behring's Straits, for tides, currents, and fish; but for commercial purposes it would be useless, because it could not be reached without extreme danger, were even a passage to these straits discovered. The discovery of the precise site of the north-west pole becomes, however, an object of the utmost importance to navigation and commerce; and now the completion of it can be effected with safety and facility. The approximated position of the pole, in 70° north latitude, and 100° west longi tude tude, is contiguous to Coppermine River, and can be ascertained from thence. Capt. Parry will next year, probably, pass through Regent's Channel, in which case the position of the pole will be directly in his course. If he should not find an open sea in this channel, he will attempt to pass into the Polar Basin, where he may find an open sea, and be enabled to lay down the geography of these unknown regions. If we cannot say in what line or curve the pole moves, we certainly can indicate that in which it does not revolve. It was laid down by Churchman, that it moved under a parallel of latitude. The gentlemen in habits of observing the variation at Somerset House and Greenwich, differed as to the fact of the commencing decrease of the west-variation. All agree now as to the decrease from 1817; and, from my inquiries, the observers at Paris confirm the case. Now, if the pole moved under a parallel of latitude, the angle of variation would continue to increase for above seventy years more, or till the pole arrived at the part of the parallel of 70° touched by a tangent drawn from London; but, instead of this, the angle is decidedly diminishing. The pole cannot be moving in the plane of any certain meridian, as, in that case, we should have what is not fact, that is, no variation under such meridian in our hemisphere. Again, it is not moving under any line not immediately under the pole of the earth, as all places under such line would always have the same variation, excepting when the pole was directly under any place on the line. This case, however, has never occurred. The question, then, is narrowed to the movement in some eccentric elliptical curve, or in some other irregular curve, whose conjugate diameter is nearly under the meridian of London, and must be short, while the transverse must lie between 100° west and 80° east longitude. For above half a century to come, the site of the pole may be visited from the hyperborean coast of America ; and thus, the latitude and longitude of many polar sites being made out, a line drawn through them will furnish a near approximation to the nature of the polar tract: and here, at present, a question must rest, that cannot be solved by any calculation. By a concentration of several variations taken by Capt. Cook, the southeast magnetic pole must be not far from 75° south latitude; and probably under the meridian of 117° east, if it has moved at the rate of the other pole from its line of no variation, situated above fifty years ago, according to the same able navigator, nearly under the meridian of 144° east longitude. As we do not know the place of the present south-east line of no variation, no calculation of the time of a revolution can be made. An enterprizing naval commander has lately found a clear, open sea, not far from this pole, and this may induce the Admiralty to send out ships to make a discovery, which foreign nations will otherwise accomplish, as their ships are now constantly out, making useful researches. For instance, two of them lately have confirmed my observations of the diurnal variation at Bencoolen and St. Helena, as published in the Philosophical Transactions of 1796 and 1797. This description of variation I ascribe to the action of solar heat and light on the needle, and of the former on the nearest pole. It moves in a contrary direction to that observed in London, and is much less. If, however, it had been observed as far south, as London is north, from the magnetic equator, I have reason to think that little or no difference in quantum would have been found. My idea of the much-disputed subject of a magnetic equator is, that if a line can be supposed drawn round the earth, through all the points where the magnetic needle needle would rest horizontal, because acted on equally by both poles, such line must be the magnetic equator, which is constantly shifting, because both poles are perpetually moving. It must always be recollected, that the magnetic needle, excepting on one circumference mentioned, cannot, in general, point exactly to either of the magnetic poles. To elucidate this, let it be supposed that there is no southeast pole, and that a needle is situated on the present north-west line of no variation, under nearly the meridian of the city of Mexico, where there would be no variation. Suppose, in this state of things, that the south-east pole were suddenly replaced, by a fiat of the Almighty, this pole, according to its present situation, would be above a hundred degrees to the west of the meridian of Mexico, and the consequence would be, what it actually is, that the south end of the needle would be drawn westward, occasioning an inclination of its north end eastward into an east-variation. From the same cause, there is a great west-variation under the meridian of 80° east in the southern hemisphere, though the exploring foreign philosophers will, in the northern hemisphere, find a line of no variation nearly under this meridian. It is on this account, also, that the west-variation increases so rapidly between the Straits of Sunda and the Cape of Good Hope: for as the south-east line of no variation is departed from, the south extremity of the needle is strongly attracted eastward by the nearest pole, which inclines the north end into a great westvariation, aided by the attraction of the north-west pole in the same direction, both poles acting in the inverse ratio of the square of relative distance. It may be remarked here, that the south-east pole cannot be situated as given by four eminent encyclopædists of olden times, because Capt. Cook, and other navigators, in visiting the ascribed sites nearly, found no symptoms of the existence of the imagined poles. An officer on board the Hecla was furnished with my calculations of the movement of the north-west pole in the course of five years, in case there might be an opportunity of trying the supposed fact in former situations, if by chance repaired to. These calculations, though not so exact as could be wished, would shew whether or not the magnetic dip increased on the east, and diminished on the west, side of the pole. I also adverted to a relative difference which would arise in the variation, on the supposition of the polar movement. I have not heard that any opportunity of verifying these suppositions occurred. One or both of these facts would go far to prove the actuality of the movement of the north-west pole in an eastern direction. Summerlands, Nov. 4, 1825. Yours, &c. JOHN MACDONALD. THE BEE INCLOSED IN AMBER. From MARTIAL, Lib. II, Ep. 53. BURIED yet seen within this lucid tomb, The insect could desire no brighter doom, Than (since nor bees nor men death's flood can stem) Asiatic Journ. VOL. XXI. No. 121. I MAUSOLEUM |