Theosophy and Magnetism

 

Contents

  1. Introduction
  2. Modern science
  3. The Mahatma Letters
  4. G. de Purucker
  5. Benjamin G. Jenkins
  6. Halley and Hansteen
  7. Discussion


1. Introduction


Section 2 outlines the modern scientific understanding of the earth's magnetic field. Sections 3 and 4 present comments on magnetism by one of the theosophical adepts and by G. de Purucker. Sections 5 and 6 provide background information. Finally, section 7 discusses some of the issues raised.


2. Modern science


The earth's north and south magnetic dip poles are the two points on the earth's surface where a compass needle points directly downward or upward. They do not coincide with the north and south geographic poles: one of them is located in the Canadian Arctic (82.3°N, 113.4°W), and the other off the coast of Antarctica, south of Australia (64.7°S, 138.0°E). A line joining the two dip poles does not pass through the earth's centre, and they therefore do not lie diametrically opposite one another.

    Since unlike poles attract and like poles repel, and since the north pole of the compass points northward, the magnetic pole in the northern hemisphere is considered to be a south magnetic pole, while the southern magnetic pole is considered to be a north magnetic pole. Studies of the fossil magnetism of rocks of various ages suggest that the magnetic polarity of the northern and southern magnetic poles has reversed completely and repeatedly through geologic time, at intervals ranging from less than 100,000 years to tens of millions of years.
Figure 2.1 The directions of the magnetic lines of force at the earth's surface and in space around the earth are consistent with the presence of an imaginary bar magnet within the earth.   


    Up to 90% of the geomagnetic field – known as the 'main field' – is equivalent to the field that would be produced by a hypothetical dipole magnet located at the centre of the earth, but with its axis offset from the earth's rotation axis by about 11°. The two ends of this magnet are the north and south geomagnetic poles, these being theoretical magnetic poles. A better dipole approximation of the earth's magnetic field can be obtained by moving the inclined dipole away from the centre of the earth by about 530 km; the ends of this magnet are known as the eccentric poles. If the contribution from a centred dipole is subtracted from the observed, highly irregular and complex geomagnetic field, the residual is called the nondipole field, or regional geomagnetic anomaly.


Figure 2.2


    The geomagnetic field is defined at each point on the earth's surface by its strength and direction. The two terms needed to describe its direction are:
- magnetic declination or variation: the angle between magnetic north (the direction in which a compass needle points) and true north (the direction of the north geographic pole);
- magnetic dip or inclination: the angle between a compass needle and the horizontal plane at any particular location. At the north magnetic pole a magnetized needle (if able to move freely) points straight down, near the equator it stays horizontal, at the south magnetic pole it points straight up, and in between it dips to intermediate angles.

    The declination of a compass is rarely such that the needle points directly to the nearest magnetic pole. For instance, to travel direct to the magnetic pole, a person setting out from southern Europe will need to head 8° west of north, whereas the compass points almost 3° east of north. The compass needle will eventually lead the traveller to the north magnetic pole, but not by the most direct route.


Figure 2.3 Map showing isogonic lines (lines of equal magnetic declination).


    The dip poles wander daily around their average position; they may be displaced by up to 80 km, depending on geomagnetic disturbances in the ionosphere and magnetosphere, attributed to bombardment by charged particles emitted by the sun. In addition to short-term fluctuations, the strength and direction of the earth's magnetic field undergo long-term, or secular, variations. The dipole field is currently moving westward around the geographic poles at a rate of about 0.08° per year, whereas the nondipole field is moving at a faster average rate of 0.18° per year. Also, the dipole field is currently weakening by 5% per century.

    The geomagnetic field is said to be generated mainly in the earth's interior, by electrical currents in the earth's fluid outer core, caused by the earth's rotation. Other sources of the overall magnetic field include electrical currents flowing in the ionized upper atmosphere, currents flowing in the earth's crust, and magnetized crustal rocks. At very high altitudes, the magnetic field departs significantly from an ideal dipolar configuration. The solar wind creates a comet-shaped magnetosphere around the earth, compressed to about 10 earth radii on the side toward the sun, and extending tail-like on the side away from the sun to more than 100 earth radii.


Figure 2.4


Sources


3. The Mahatma Letters

[The Mahatma Letters to A.P. Sinnett, Theosophical University Press, 2nd ed., 1926, Letters 23a + b, Oct. 1882]

A.P. Sinnett:
    Could any clue be given to the causes of magnetic variations, – the daily changes at given places, and the apparently capricious curvature of the isogonic lines which show equal declinations? For example – why is there a region in Eastern Asia where the needle shows no variation from the true north, though variations are recorded all round that space? (Have your Lordships anything to do with this peculiar condition of things?) [p. 146]

KH:
    None can ever be given by your men of Science, whose 'bumptiousness' makes them declare that only to those for whom the word magnetism is a mysterious agent the supposition that the Sun is a huge magnet can account for the production by that body of light, heat and the causes of magnetic variations as perceived on our earth. They are determined to ignore and thus reject the theory suggested to them by Jenkins of the R.A.S. of the existence of strong magnetic poles above the surface of the earth. But the theory, is the correct one nevertheless, and one of these poles revolves around the north pole in a periodical cycle of several hundred years. Halley and Handsteen [Hansteen] – besides Jenkins – were the only scientific men that ever suspected it. Your question is again answered by reminding you of another exploded supposition. Jenkins did his best some three years ago to prove that it is the north end of the compass needle that is the true north pole, and not the reverse as the current scientific theory maintains. He was informed that the locality in Boothia where Sir James Ross located the earth's north magnetic pole, was purely imaginary: it is not there. If he (and we) are wrong, then the magnetic theory that like poles repel and unlike poles attract, must also be declared a fallacy; since if the north end of the dipping needle is a south pole then its pointing to the ground in Boothia – as you call it – must be due to attraction? And if there is anything there to attract it, why is it that the needle in London is attracted neither to the ground in Boothia nor to the earth's centre? As very correctly argued, if the north pole of the needle pointed almost perpendicularly to the ground in Boothia, it is simply because it was repelled by the true north magnetic pole when Sir J. Ross was there about half a century ago.
    No; our 'Lordships' have nothing to do with the inertia of the needle. It is due to the presence of certain metals in fusion in that locality. Increase of temperature diminishes magnetic attraction, and a sufficiently high temperature destroys it often altogether. The temperature I am speaking of is, in the present case rather an aura, an emanation than anything science knows of. Of course, this explanation will never hold water with the present knowledge of science. But we can wait and see. Study magnetism with the help of occult doctrines, and then that which now will appear incomprehensible, absurd in the light of physical science, will become all clear. [pp. 168-9]

    We know of no phenomenon in nature entirely unconnected with either magnetism or electricity – since, where there are motion, heat, friction, light, there magnetism and its alter ego (according to our humble opinion) – electricity will always appear, as either cause or effect – or rather both if we but fathom the manifestation to its origin. All the phenomena of earth currents, terrestrial magnetism and atmospheric electricity, are due to the fact that the earth is an electrified conductor, whose potential is ever changing owing to its rotation and its annual orbital motion, the successive cooling and heating of the air, the formation of clouds and rain, storms and winds, etc. This you may perhaps, find in some text book. But then Science would be unwilling to admit that all these changes are due to akasic magnetism incessantly generating electric currents which tend to restore the disturbed equilibrium. [p. 160]

 

4. G. de Purucker


The earth's magnetic poles

[The Theosophical Forum, January 1943, pp. 18-21; this posthumous article was never edited by G. de Purucker]

I do not blame anyone for feeling confused about the apparently paradoxical comments of the Masters regarding magnetism and the poles of the earth. For as has been pointed out by all the speakers tonight, the subject is thorny, thorny mainly because of erroneous scientific teaching of the past and present – and by that I mean teaching erroneous in deductions. As long as the scientists stick to the facts of nature we have no quarrel with them but look upon them as our best friends. As soon as they begin to theorize, their theories are just the ideas of each theorizer and no more; and you can accept them or reject them just as you please. And if you do reject the scientific theorizers' views, the circumstances of the future may show that you may have been right and the scientific 'sharps' wrong.
    I would like to point out this: Don't confuse the two magnetisms in the poles of a magnet with the earth's magnetism; although the earth is likewise a magnet. Its north polar magnetism we call the north polar magnet because that magnetism has its fountain at the north pole, or close to it. Similarly so with the south polar magnetism diametrically opposite. Therefore when we Theosophists say that the type of magnetism of a magnetic instrument, of a compass for instance – when we say that the north pole of that compass is the end which points to the north, we mean just that. In other words, the north pole of the compass is the north pole of the compass. Its south pole is its south pole. Now if you pause and think a moment, you will realize that the compass needle does not point as through a magnetic vacuum to the north pole of the earth; but that the north point of the needle has to work towards the north pole through all the thousands of miles of intermediary magnets naturally. Do you see what I am trying to say?
    Thus, the north pole of the needle being the actual positive pole, as scientific convention calls it, this 'north' pole, when it is taken up to Boothia, where the north magnetic pole of the earth is, points downwards; but if the earth at that place were the actual north magnetic pole, it would not point downwards but would point upwards, the two like poles repelling each other. What does this mean? It means that that point in the earth to which the true north point of the needle attracts itself is, in that small locality, a south pole. Above the earth is the true north pole of the earth. These like poles repelling each other, repel the genuine north pole of the needle to the earth which is likewise attracted at the south pole of that point on the earth. This is simple enough.
    And now we will speak in a very, very scientific way, allowing the scientific imagination full and free play, that scientific imagination which the scientists like Huxley and Tyndall and others say scientists must use. Quite so, but let them use it in accordance with the facts of nature, not to establish theories. Suppose we had twenty magnetic needles and we set them all in a row, every magnet with its north point of the needle point[ing] to the north. Then the south pole of each magnet, would be pointing to the north pole of the magnet just following it. They would attract each other. Do you get it? North pole, south pole; north pole, south pole; and so on. Now instead of twenty such magnets, such magnetic needles, imagine an uninterrupted series of such, from the magnetic needle I am holding in the laboratory up to the north pole. You see now why the actual north pole of the needle points to the north: because it is attracted by the south pole of the magnet immediately to the north of it; and so on, as I have just pointed out with the illustration of the twenty magnetized needles. It must be so. Therefore that end of the magnetic needle which points to the north is the true north pole of that particular magnetic needle. And this is what Jenkins taught: a very intuitive man by the way, of whom we never hear much because he was too intuitive for his time. He was just ignored and sat upon.
    Thus the true magnetic pole of the earth is not actually in the rocks of the earth but above the earth. And I think it was Professor Ryan who said that this true magnetic pole is believed to make a circle around the geographical north pole in about 600 years. That is close enough; and of course the south magnetic pole makes a similar turn, being just the other end of the magnet. Now I think that covers the point of magnetism.

    [Note by H.T. Edge: A brief summary of the point contended for in this article may facilitate its understanding by the reader. Scientists contend that what is called the north pole of a magnet is really a south pole, inasmuch as this so-called north pole is attracted, and not repelled, by the north pole of the earth. Some actually call it a south pole, others call it the north-seeking pole. But this article, following the statements in The Mahatma Letters, declares that the earth's north pole is situated in space above the earth, and not in the ground below the surface. Scientific support for this view is adduced from Fleeming Jenkins,* Halley, and Christopher Hansteen.** In accordance with this view, the so-called north pole of a magnet is actually a north pole, and the reason why it points downwards at Boothia Felix is that its south pole points upwards towards the real north pole of the earth in the space above. Until such facts as the irregularity of the isogonic lines of dip, and the continual fluctuation of the angle of dip, have been explained, science has no sufficient ground for rejecting the views set forth in this article.]

*Edge is in error here. The Jenkins referred to by KH and De Purucker is Benjamin George Jenkins, and not Henry Charles Fleeming Jenkin (without an s); see section 5.

**In the extract from the Mahatma Letters (2nd edition) quoted in section 3, KH writes 'Handsteen' instead of 'Hansteen'. Curiously, the book's index contains the entry: 'Handsteen [Flamsteed, John]'. The 3rd edition and the chronological edition of the Mahatma Letters (Theosophical Publishing House, 1962 and 1993 respectively) even replace 'Handsteen' in the main text with 'Flamsteed'. However, as Edge indicates, the person KH is referring to is certainly Christopher Hansteen – and not the astronomer John Flamsteed (1646-1719). When KH wrote his comments on magnetism he apparently had before his mind's eye an article by B.G. Jenkins, which refers to the four-pole theories of Halley and Hansteen; see sections 5 and 6.


Sleep and magnetism

[The Dialogues of G. de Purucker, Theosophical University Press, 1948, 3:6-9]

    Student – ... We have been told that it is best while sleeping to have the head turned towards the north. ... It seems rather remarkable to me, because according to our teaching, I understand that the head [has] similar polarity to the north pole, in which case they should repel each other. So if magnetic conditions reign over such things, one ought to sleep less well ...

    G. de P. – [W]hen you put two magnets together, it is the north pole of one magnet which must be presented to the south pole of the other magnet in order that the two shall hang together or cohere. ... Therefore the two north ends are pointing in the same direction, and thus do not repel each other. Just so is it with the human body sleeping in bed with the head to the north. The man's positive pole, his north pole, his head, is then pointing to the north pole of the Earth, and thus it receives the magnetism coming from the south pole of all objects immediately contiguous to or touching his head. ...
    That is the reason why the 'north pole,' so called, should be pointed to the north. It is also the reason why a man should have his north pole, his head, also directed to the north. It is because the influence, the magnetism, coming into his north pole, his head, comes from the south pole of the magnet, whatever it may be, visible or invisible, with which his head is in immediate connection. The distance between north pole and head of sleeping man may be small or may be long. But this distance is composed of matter or material things between the north pole and the human head, and thus is like a series of magnets one pendant from the other, in a shorter or longer chain of magnets. In all cases the north poles all point in the same direction to the north pole of the Earth. ...
    [T]he ideal way to sleep ... is the head to the north or northeast – but best of all is to the north – and the body somewhat curved in bed, with the knees more or less drawn up, not uncomfortably so, and with the feet pointing to the south. ... [This] is also said to be the position of the unborn child in its antenatal sleep. [T]he theory is – and it is a fact – that all electro-magnetic energies move in spirals or circles. That is their perfect way; and the body lying in the bed thus curved with the head pointing preferably to the north, and with the knees more or less drawn up and the feet pointing south, offers every opportunity for the natural magnetic circulations of the Earth to have freest passage through the body, without undergoing an unnecessary resistance.


Solar and terrestrial magnetism

[G. de Purucker, Fountain-Source of Occultism, Theosophical University Press, 1974, pp. 305-8]
    The two poles are said to be the store-houses, the receptacles and liberators, at the same time, of Cosmic and terrestrial Vitality (Electricity); from the surplus of which the Earth, had it not been for these two natural 'safety-valves,' would have been rent to pieces long ago.  – The Secret Doctrine, I, 205

    ... The eleven-year sunspot cycle affects each of the planets of the solar family through their north and south poles. The magnetism which reaches us from the sun – physical, astral, as well as mental – enters the earth through the north pole; it then follows certain circulations within and around the earth, and leaves it at the other pole. All these magnetic circulations pass around the equator a certain number of times, whether they be brief or of longer duration. ...
    Terrestrial magnetism is of course connected with the nature and characteristics of the aurora borealis at the north pole as well as the aurora australis at the south pole – both the geographic and the magnetic poles at either end of the earth being involved. The aurorae are manifestations of the psychomagnetic vitality of the earth, and are most intimately linked with the sun, and particularly with the sunspots and, in a somewhat less close relationship, with the seven sacred planetary chains. They are psychomagnetic phenomena, and therefore we must never regard them as merely electric and magnetic displays or outbursts. ...
    The earth as a magnet is infilled with the solar energies streaming continuously from our daystar through the entire solar system. This solar magnetism is septenary and enters the earth in the region of the north pole. Certain elements of this magnetism pass directly from pole to pole through the center of the earth, while other parts sweep around or over its surface, but always from north to south.* Furthermore, there are crosscurrents which this solar magnetism follows in its circulations in and around the earth, and these crosscurrents, although flowing from the north pole, take a slanting or oblique direction, always from the northeast to southwest, pursuing their course around the earth and swinging back again to the north pole.

*... At night ... the body is much more subject to the solar electromagnetic currents of energy. That is why it is best to sleep with the head towards the north or northeast, so that the body may be in corresponding polarity of circulation with the magnetism of the earth as it passes from pole to pole. The head is the positive pole and the feet form the negative pole, just as the north pole of the earth is positive and the south pole negative.

    If we could see these lines of magnetic force, they would appear to us as streaming in from outer space, impacting the earth at its north pole, rebounding thence and sweeping around all the surface of the globe, towards the south pole – where a portion is sucked in and returns to the north pole, again to be sent forth. Thus the circulation continues. But not all the magnetism is sucked in at the south pole; a portion of it streams outwards, cone-like, into space, and ultimately returns to the sun from which it came.


5. Benjamin G. Jenkins


Writing in October 1882, KH says that scientists 'are determined to ignore and thus reject the theory suggested to them by Jenkins of the R.A.S. [Royal Astronomical Society] of the existence of strong magnetic poles above the surface of the earth', and that 'Jenkins did his best some three years ago to prove that it is the north end of the compass needle that is the true north pole'. KH is referring here to the following article by Benjamin G. Jenkins:

'Terrestrial magnetism. No. 1. – On the secular variation of the magnetic needle at London since the year 1580. No. 2. – On the dip of the magnetic needle at London since 1576.' Journal of the American Geographical Society, 10, 1878, pp. 267-75; Reale Accademia dei Lincei Trans., Rome, 3, 1879, pp. 103-8.

The article appeared in both the publications mentioned, with both parts appearing together in the same issue.

    Jenkins begins the first part of his article as follows:

From an examination of the movement of the compass-needle producing declination at London, I find that the various vicissitudes the needle has undergone during the last 300 years, can be explained by supposing that its movements have been governed chiefly by those of a strong magnetic pole revolving round the pole of the earth in about 500 years. I may here state that, in order satisfactorily to explain all magnetic phenomena, four magnetic poles appear to be necessary.


Figure 5.1


    Figure 1 from Jenkins' article is reproduced above. M represents London, at 51.5° north latitude. O is the north geographic pole. The declination of a magnetic compass needle in London in 1541, 1580, 1816, and 1877 was 7°E, 11°17'E, 24°17'W, and 18°57'W respectively. Jenkins assumes that the compass needle in these years pointed directly to the magnetic pole, and argues that the observations can be explained if the north magnetic pole revolves clockwise around the geographic pole, the centre of the circle traced by the magnetic pole being located at V, slightly offset from the geographic pole. According to Jenkins, points K, D, N, C, and H marked around the circumference of this circle indicate the position of the north magnetic pole in 1541, 1580, 1660, 1816, and 1877 respectively.

    In 1831 James Ross discovered the north magnetic dip pole at 70°05'N, 96°46'W. The peninsula in northern Canada where the pole was located was named Boothia Felix after the expedition's sponsor, the gin distiller Felix Booth. This location corresponds to point x on the magnetic polar circle in the above figure.

    Jenkins begins the second part of his article as follows:

Having shown that the declination-needle in its secular movement, as observed for the last 300 years, is always directed to a magnetic pole which appears to revolve round the north pole of the earth in about 500 years, I purpose strengthening this conclusion by adducing the evidence afforded by the dip. This evidence will besides show, in the clearest manner possible, that the north end of the needle is, contrary to the belief and teaching of the last 300 years, a north pole, not a south pole.


Figure 5.2


    Figure 2 from the article is reproduced above. It shows a plane through the earth, passing through V ('the centre of the magnetic polar curve', which coincides with x), M (London), and e (the centre of the earth). In figure 5.1, the positions of the magnetic pole in 1576, the early 1700s, 1831, and 1866 are marked u, y, x, and s on the magnetic polar circle. In figure 5.2, these four positions are projected onto z-V-M; in other words, a straight line drawn from M through the earth to u (or y, x, or s) is swivelled about M so that it lies in the vertical plane shown in the figure. The same applies to the north geographic pole (N).

    In 1831 the magnetic pole (at x) was about 40° from London. If the compass needle at London had pointed directly through the earth at the pole it would need to have dipped 20° (half of 40°)* below the horizontal (represented by the line ho drawn tangent to M). However, the actual dip or inclination (in 1833) was about 70° (line Mb in the figure). Jenkins points out that 70° + 20° equals 90°, and this, he says, 'is an important clue to the solution of the matter'. When the pole was at u, around 1576, the dip ought to have been 18°10', but it was actually 71°50' (line Mv). When the pole was near position y, at the beginning of the 18th century, the dip ought to have been 15°, but it was actually 75° (line Ma). And when, in 1866, the pole was at s, the dip ought to have been 22°, but it was actually 68° (line Mt). In each case, the expected dip is the complement of the real dip; i.e. when added together, they equal 90°.

*Another illustration of the same principle: If you are standing on the equator and told to point directly at the north geographic pole, i.e. in the direction of the north pole not over the surface of the earth but in a straight line through the earth, you would need to hold your arm 45° below the horizontal, i.e. half the angle (90°) separating you from the pole, and in the plane of the meridian (circle of longitude) passing through your location on the equator and the north pole.

    Jenkins proceeds to draw some radical conclusions:

The needle being a dipping-needle, and the universal belief being that its north end is attracted by the north magnetic pole of the earth, it ought certainly to be drawn to point to the north end of the earth; but so far from this being the case, it seems to be repelled from it, and repelled it is, I hold.
    There comes, then, this very natural inquiry: Have we, for hundreds of years, been maintaining that the end of the needle which is directed to the north is the south pole of the needle, and upholding that which is the very opposite of fact? Every unprejudiced mind will admit that it must indeed be so. Indeed, the facts, when properly understood, are found to be in full accord with the great magnetic truth that like poles repel, unlike attract.
    If the dipping-needle be taken to the arctic regions, it will be found in one locality to point to the ground, to be nearly perpendicular. It should be borne in mind that Sir James Ross never found it truly perpendicular, which itself would tend to show that the magnetic power was not in the earth. If the dipping-needle is repelled from the pole at London, much more will it be repelled in Boothia, and it is repelled as much as it possibly can be. The north end of the needle is repelled from the pole which is in the atmosphere, and the south end of the needle is as much attracted by the same pole; and this is as it should be – the north pole of one magnet (the terrestrial) attracting the south pole of another.
    If the north end of the needle is a south pole, as it points to the ground, this should be because it is attracted. If it is attracted, it is attracted by something in the crust or at the centre of the globe. If there is something in the crust which attracts the needle in Boothia, it ought to attract the needle in London; but the needle at London is attracted neither to the crust at Boothia nor to the centre. The magnetic pole, then, appears to be in the atmosphere.
    The fact that the declination-needle points constantly to the magnetic pole does certainly seem to indicate that it is attracted; but it is impossible to believe this, when the same needle and the same end, dipping, is manifestly repelled. The true explanation of the apparent attraction is, I believe, this: the needle places itself in the magnetic meridian as in a position of equilibrium, which the moving magnetic pole is constantly disturbing. ...
    As the declination-needle was known long before the dipping-needle, such a universal belief got abroad that the north end of the needle was attracted by the north magnetic pole because it pointed to it, and that therefore that end of the needle must be a south or austral pole; that, when the dipping-needle was invented, it never occurred to the acutest minds that the same end in the dipping-needle was proclaiming in the most distinct manner that it was not attracted, but repelled – that it was not an austral pole, but a boreal one.
    In conclusion, I would remark that it is admitted that the phenomena of terrestrial magnetism are most satisfactorily explained by four poles – two in the northern and two in the southern hemisphere, as maintained by Halley and Hansteen. I hope to show, hereafter, that the two magnets, as it were, having these poles, are not in the earth, but in the atmosphere; that instead of two rigid magnets in the earth, whose extremities come to the surface near the poles, there are two broad atmospheric magnetic belts extending from the neighborhood of the north pole to the equator, and two similar belts coming up from the south pole to meet them – the austral magnetism of the northern belts uniting with the boreal magnetism of the southern belts along the magnetic equator; the magnetic poles in each case being the free extremities of the magnetic bands. These bands revolve, at slow and unequal rates, round the poles of the earth, producing the secular variation.

    In the last paragraph quoted, Jenkins mentions his intention to write more about the four postulated magnetic poles in a future article. No entry for such an article appears in the Royal Society Catalogue of Scientific Papers, covering the period 1800-1900. The latest article by Jenkins that it mentions appeared in 1881.

    An evaluation of Jenkins' model is presented in section 7.

 

6. Halley and Hansteen


KH says that Jenkins' theory of strong magnetic poles above the surface of the earth is correct, and that 'one of these poles revolves around the north pole in a periodical cycle of several hundred years'. He adds that the only other scientists who suspected this were Halley and Hansteen (who are referred to in Jenkins' article). Neither Halley nor Hansteen spoke of magnetic poles above the earth's surface, but both proposed that there were two magnetic poles in each hemisphere, though their theories were otherwise very different. Mercator had come up with the same idea over a hundred years before Halley. The following brief survey charts the rise and fall of multiple magnetic poles.

    In the early 13th century it was widely believed that since the compass needle points north, toward the polestar, it received its 'virtue' from that star. Another idea was that the compass needle was attracted to a mountain of magnetic rock (lodestone) located at the north pole. In second half of 13th century Petrus Peregrinus challenged this theory since lodestone deposits occurred in many parts of the world, and there was no reason why the polar ones should have preference. On the basis of experiments with spherical pieces of lodestone, he discovered the dipolar nature of the magnet, that the magnetic force is strongest and vertical at the poles, and he became the first (in modern times) to formulate the law that like poles repel and unlike poles attract.

    The compass came into common use as a navigation instrument in the 14th century, and was believed to point to true north. In the following century it became clear that there was a slight deviation from true north (declination). Gerardus Mercator attempted to locate the magnetic pole by determining the intersection point of great circles derived from values of magnetic declination at different locations. He first tried this in 1546 but soon found that his great circles did not intersect at a single point. He solved the problem by invoking two north magnetic poles separated by 500 km. Magnetic inclination – the fact that a compass needle points obliquely into the ground if allowed to rotate around a horizontal axis – was discovered in 1576.

    In 1600, in his book De Magnete, William Gilbert postulated that the earth itself was a giant magnet, and that its magnetic field had its origin in permanent magnetization (lodestone) at the centre of the earth. He defined the magnetic poles as the two places on the earth's surface where a magnetized needle would stand vertically. He believed that the magnetic poles were located at the geographic poles and that declination was caused by large-scale crustal anomalies.

    The idea of a single pair of poles came under increasing criticism because it did not account for observed declinations. The British astronomer Sir Edmond Halley (1656-1742), who published the first magnetic declination chart of the Atlantic Ocean in 1702, postulated that there were two north magnetic poles and two south magnetic poles. He placed two of these poles on the earth's surface and the other two on an inner sphere about 800 km below the surface. The direction of the compass was governed by the balance of the attractions of the two north or south magnetic poles. To explain the long-term variation of declination, he suggested that the inner and outer spheres rotated at slightly different speeds.

    Halley was actually proposing a version of the hollow earth theory. He held that the earth had an outer crust, 800 km thick, and a hollow interior containing three smaller spheres, one within the other, approximately the size of Venus, Mars, and Mercury, each sphere being separated from the next by 800 km of atmosphere. The smallest sphere was thought to form a hot, solid core. Halley speculated that the inner spheres might be inhabited.

    Halley's four magnetic poles did not fare well in the 18th century. Mathematician Leonhard Euler, for instance, proposed that the earth's magnetism was best represented by a single dipole but offset from the centre of the earth so that the two magnetic poles were not antipodal.

    In the early 19th century, the four-pole theory was promoted by Christopher Hansteen (1784-1875). In his Magnetismus der Erde (1819), he noted that the noncircular shape of the magnetic equator (the path along which the magnetic inclination or dip is zero) and the fact that the magnetic force did not increase from the magnetic equator toward the poles as a function of inclination could not be explained by a single magnetic axis. Instead he proposed that there were two magnetic axes, each with two poles.

    Hansteen's definition of what constituted a magnetic pole differs from the definition we use today. He did not regard a magnetic pole as a point where the magnetic field is vertical, or as a point towards which a compass needle points, but rather as a place of maximum magnetic intensity. Then, as now, there was one such region in the Canadian Arctic and another in Siberia (figure 6.1). He believed there was only one point in the northern hemisphere where the needle stands vertically, but did not regard it as the north magnetic pole. He recognized a number of open questions, such as whether the two magnetic axes are electrochemical effects within the earth or are caused from without by the sun or moon.


Figure 6.1 Magnetic field strength (in nanoteslas).


    In 1833 Peter Barlow declared against the four-pole theory. He tried to find the magnetic poles by a detailed examination of the data but found that the calculated poles were located over a very wide area. He concluded that there was no pole to which all needles point, but that every place on earth has its own particular pole and polar revolution (secular magnetic variation). John Herschel agreed, saying that this was equivalent to abandoning the idea of magnetic poles and axes.

    In 1839 Carl Friedrich Gauss produced a new mathematical representation of the geomagnetic field based on spherical harmonic analysis. Making no assumptions about magnetic poles or axes, he predicted the existence of two poles, which he defined as regions on the earth's surface where the horizontal intensity is zero and inclination is plus or minus 90°. He calculated where the centres of maximum force should be, without tackling the meanings attributed to them: one in northern Canada and one in Siberia, but only one for the southern hemisphere. His method made it possible to locate the relative contributions of various causes of the magnetic field; he concluded that the main field is generated inside the earth.

    Gauss's theory did not immediately sweep away previous theories; traditions of research built on theories like Hansteen's continued well into the late 19th century (e.g. Benjamin Jenkins). Some researchers did not trust Gauss' analysis because it was 'embarrassed and complicated' and based on insufficient data. Today Gauss's method of spherical harmonic analysis is universal. In Gauss' model the two additional poles of Hansteen are replaced by significant irregularities in the bipolar field. Using multiple dipoles to model the magnetic field remains a valid procedure, but analyses carried out in the 1960s showed that up to 35 radial dipoles are necessary to model the field with acceptable accuracy.


Sources

 

7. Discussion


Assumptions and predictions

    The rather sparse data that Benjamin Jenkins presents in his article are consistent with his theory that a strong magnetic pole revolves around the geographic pole in a period of about 500 years (figure 5.1). A fundamental assumption underlying his theory is that the compass needle at London (and at several other places he mentions) always points directly at the magnetic pole. But this is manifestly false!

    It is well known that a compass needle anywhere on earth rarely points straight towards the north or south magnetic pole. In other words, the angle of declination (the angle between the compass direction and true north) is usually not the same as the angle between the direction of the magnetic pole and true north. As already mentioned, Mercator discovered this fact in the 16th century, and his response was to introduce an additional north magnetic pole.

    Jenkins too introduces an extra magnetic pole in both the northern and southern hemispheres on the grounds that this is the most satisfactory way of explaining all magnetic observations. But in the article under consideration he gives no indication of the role these extra poles play or where they are located (except that they are above the earth's surface). The north magnetic pole mentioned in his article is clearly the dip pole. But it is not clear whether his additional poles are dip poles, poles of maximum intensity, or something else.

    The current (2004) magnetic declinations at London, Paris, and Moscow illustrate that a compass tends not to point directly at the magnetic pole.1 The declination at London is 2.6°W (i.e. the compass needle points 2.6° to the west of the north geographic pole), whereas the bearing of the north magnetic pole from London is 10.6°W. At Paris, the declination is 3.0°W, whereas the bearing of the magnetic pole is 9.9°W. At Moscow, the declination is 9.4°E, whereas the bearing of the magnetic pole is 5.6°W – a difference of 15°.

    Jenkins predicted that around 1990 the north magnetic pole would be located at 75°N, 180°E (point G in figure 5.1). In reality, the dip pole was located at 79.6°N, 104.8°E – an error of over 75° in longitude. At its average rate of movement over the past 100 years or so, the north magnetic dip pole would take about 2000 years to make a complete circuit of the north geographic pole – rather than 500 years, as Jenkins believed. However, the speed varies widely, and earlier estimates, based on changes in declination, put the period at 960 years. Halley's estimate was about 700 years.


Figure 7.1 Between 1576 and 1823 the declination at London changed from its presumed maximum easterly value to its maximum westerly value. Assuming that declination gave a direct indication of the position of the magnetic pole, Jenkins simply doubled the length of this period to arrive at his figure of about 500 years for a complete circuit of the geographic poles.


    During the 20th century the north magnetic pole moved 1100 km, and since 1970 it has accelerated from 9 km/yr to 41 km/yr. If it maintains its present speed and direction it will reach Siberia in about 50 years, but it is expected to veer from its present course and slow down. The path of the north magnetic pole is not a simple circle, as Jenkins assumed. In fact, theoretical calculations suggest that between 1760 and 1860 the pole may have moved about 860 km southeast – in the opposite direction to its present motion.


   Figure 7.2 Path of the north magnetic pole from its discovery in 1831 to its observed position in 2001.

    Jenkins' predictions for declinations in London tend to be correct to within a few degrees. This is to be expected since his theory is based mainly on the periodicity displayed by declination at that location. He predicted that the declination at London would become 0° in 1990. The actual declination was 4.5°W. He predicted that in 1950 the declination would be 6°W and the dip 65°. The actual values were 4.5°W and 66.5° respectively. Since London is 42.1° from the current north magnetic dip pole, the compass needle would need to have a dip angle of about 21° in order to point directly through the earth at the magnetic pole. According to Jenkins' theory, the actual angle of dip should therefore be 90 - 21 = 69°. In reality, it is 66.5°. Paris is 44.9° from the magnetic pole, and the inclination at Paris is 64.2°, compared with the figure of 67.6° expected on the basis of Jenkins' theory. The inclination at Moscow is 71.1°, close to the figure of 69.4° required by Jenkins' theory.

    If Jenkins had confined himself to saying that, over a period of several hundred years, the declination at London varies in a manner which is consistent with the existence of a magnetic pole that moves in the manner he describes, there would be little to object to. But he is clearly mistaken in identifying this (imaginary) magnetic pole with the dip pole discovered by Ross in 1831. By analyzing declination measurements at other places he might have concluded that the observations at each place could be explained by other magnetic poles in different locations, each periodically circling the geographic pole. This would not mean that there are literally multiple magnetic poles, but would merely imply that the factors causing magnetic declination are subject to cyclic influences.


North and south

    Benjamin Jenkins took issue with the scientific view that the north-seeking end of the magnet was actually a south magnetic pole, which was attracted to the north magnetic pole in the Arctic. Modern science agrees with Jenkins that the north-seeking end of the compass is a genuine north pole, but disagrees with him in its conclusion that the Arctic magnetic pole is a south magnetic pole, while the southern magnetic pole is a north magnetic pole.

    The modern scientific view also existed in Jenkins' time, as shown by the following quotation from a book by Fleeming Jenkin (1876):

Every magnet, if free to turn, takes up a definite position relatively to the earth, which is itself a magnet. The pole, which in each magnet turns to the north, will by us be called the north pole of the magnet. The other pole will be called the south pole. The two north poles of any two magnets repel one another; so do the two south poles; but any north pole attracts any south pole. Hence, the north pole of a magnet is similar in character to the south end of the earth. The pole which is similar to the south end of the earth is sometimes called the positive pole; the other, which we call the south pole of the magnet, is the negative pole.2

    The current theory is the same: the north-pointing end of the compass is a north (positive) pole, and the magnetic pole in the Arctic is a south (negative) pole. The direction of the magnetic field is taken to be the direction in which the north pole of a magnetic compass points.

Field lines start near one end of the magnet and enter near the other end, forming an arc in between. By convention, the end at which the magnetic field is directed outward is termed the 'north' pole of the magnet; the end at which the magnetic field is directed inward is termed the 'south' pole of the magnet. ...
    The magnetic field is directed downward in the northern hemisphere and upward in the southern hemisphere. This implies that the magnetic pole in the Canadian Arctic is really a 'south pole'. However, by long custom and because of its geographical location it is called the North Magnetic Pole.3

    Jenkins argued that if the north end of the compass was a south pole, its attraction to the ground at the dip pole on the Boothia Peninsula must mean that there is something within the earth to attract it (whether near the surface or near the centre), but since in London the compass needle is attracted neither to the crust in Boothia nor to the earth's centre, the magnetic pole must be in the atmosphere.

    KH repeats this argument in his letter to Sinnett:

If he [Jenkins] (and we) are wrong, then the magnetic theory that like poles repel and unlike poles attract, must also be declared a fallacy; since if the north end of the dipping needle is a south pole then its pointing to the ground in Boothia ... must be due to attraction? And if there is anything there to attract it, why is it that the needle in London is attracted neither to the ground in Boothia nor to the earth's centre? As very correctly argued, if the north pole of the needle pointed almost perpendicularly to the ground in Boothia, it is simply because it was repelled by the true north magnetic pole when Sir J. Ross was there about half a century ago.

    Jenkins and KH are referring here to the inclination of the compass needle in London: it points neither straight down to the centre of the earth nor through the earth towards the dip pole, then located in Boothia. As an argument for the existence of a north magnetic pole in the atmosphere, this is not very convincing. In the early 19th century the idea that the compass was attracted to magnetite (lodestone) deposits near the north pole or near the centre of the earth was beginning to be superseded by the theory that geomagnetism was caused by electric currents flowing in the crust and atmosphere. The idea that the primary magnetic field is an induced electromagnetic field rather than that of a permanent magnet became universally accepted in the early 20th century.

    According to modern science, it is wrong, strictly speaking, to think of the northern magnetic pole as 'attracting' a compass needle toward it:

In reality, the magnetic field felt by a compass needle is essentially uniform over the length of a compass needle and as a result the net force on the needle is zero. This means that the needle is not 'pulled' towards either Magnetic Pole. However, because the compass needle is a small dipole with opposite polarity at either end, the northward directed magnetic field of the earth will cause the needle to rotate until it is aligned in the local direction of the magnetic field.4

In other words, the compass needle tries to align itself with the local magnetic field lines, which form part of closed loops of magnetic flux (figure 7.3). From this standpoint, no 'repulsion' by an atmospheric magnetic pole is required to explain magnetic inclination.


Figure 7.3 The right-hand diagrams illustrate the lines of magnetic force as they would be measured by a person standing on the earth's surface at points n, e, and s.


    Jenkins fails to explain why the north pole of a compass points northward in the first place, if that is where the real north magnetic pole is situated. He writes: 'The true explanation of the apparent attraction is, I believe, this: the needle places itself in the magnetic meridian as in a position of equilibrium, which the moving magnetic pole is constantly disturbing.' But if, as he says, the atmospheric north pole in the Arctic repels the north pole of the compass and attracts its south pole, we might still ask why it is not the south pole of the compass that points north.

    In tackling this question, G. de Purucker presents the picture of a continuous chain of magnetic needles ('magnets') extending over the earth's surface up to the north magnetic dip pole, with the north pole of one 'magnet' being attracted to the south pole of the one in front. He concludes that the ground in the locality of the northern magnetic pole is of south-magnetic polarity – something not mentioned by KH, and almost certainly not part of Jenkins' own theory.

    This seems to endorse the modern scientific viewpoint that the northern magnetic pole is really a south magnetic pole. However, De Purucker also says that the north pole of a compass needle is not only attracted to the south-magnetic polarity in the ground in the Arctic but is also repelled by the 'true north pole' above the earth's surface. He says that the dip pole in the southern hemisphere is 'the other end of the magnet', implying that it is a north magnetic pole, but presumably with a 'true south pole' located in the atmosphere above it. The question is how these atmospheric 'poles' are to be interpreted.


Fields and flux

    Modern science does not offer a concrete, causal model of what a magnetic field or magnetic field lines or magnetic polarity really are and how they work – it offers only a mathematical description.

    In earlier centuries, the curved lines formed by iron filings around a bar magnet were believed to represent the paths of magnetic fluids or ethers, and the alignment of the compass needle was explained as due to a flow of magnetic fluid through its length. (Even Gauss thought of his theory as calculating the varying density of magnetic fluid, though he did not think this physical hypothesis was necessary.) Although science officially abandoned the ether in the early 20th century and replaced it with mathematical abstractions, it is absolutely essential if a realistic understanding of physical matter and force is ever to be developed, and many nonmainstream scientists are continuing to explore this approach.

    We can picture the geomagnetic field as comprising ether fluxes circling into and out of the earth along 'field lines', and curving far above the earth's surface. The dip poles are simply the locations where vertically ascending or descending magnetic fluxes intersect the earth's surface. Note that the surveyed dip poles are not really single points but areas where many 'poles' exist, and compasses behave very erratically in the vicinity. As shown by the arrows in figure 2.4, the column of vertically directed magnetic flux extends for some distance above the polar regions, and the notion of atmospheric magnetic 'poles' is therefore quite plausible, though it might be difficult to decide exactly where such poles are located.

    It is logical to suppose that the end of the compass needle that points north must have the opposite polarity to that of the northern magnetic pole. Whether it is the north end of the compass or the north end of the earth that should be called a genuine north magnetic pole is a matter of convention. As already noted, science regards the direction in which the north end of a compass points as indicating the direction of the magnetic field. It also defines north-magnetic polarity as an outwardly-directed magnetic flux, which means that the Arctic magnetic pole is a south pole since the north end of the compass points downward into the earth at that location.

    Following present conventions, we can picture flows of magnetic force entering the earth at the northern pole, exiting at the southern pole, then arcing back to the northern pole. A compass needle will align itself with this flow, such that the pole with outwardly directed magnetism is pointing to the pole of the earth where the magnetic flux is inward; in other words, the magnetic force flows through the compass needle from south to north.

    Again, if, as De Purucker says, lying with our head to the north offers the least resistance to the 'magnetic' energies flowing over the earth, and if energy exits the body via the head, then earth energies must flow out of the earth in Antarctica, through the body from feet to head, and enter the earth in the Arctic. And if the outward flow from the head indicates that it is the body's north pole, then the inward flow at the Arctic pole implies that it must be of south-magnetic polarity – as De Purucker seems to accept on the basis of his chain-of-magnets analogy.

    If, as other remarks by KH and De Purucker could be taken to imply, there is a genuine north magnetic pole above the south-magnetic dip pole in the Arctic, then, bearing in mind that magnetism is always bipolar, there are two possible scenarios: 1) the Arctic and Antarctic atmospheric poles are each paired with the crustal poles below them, so that instead of picturing the earth's magnetic field as being produced by a single (imaginary) magnet located at the earth's centre, there would be two separate magnets in the Arctic and Antarctic, each having one end somewhere below the earth's surface and the other end somewhere above it; or 2) the northern and southern dip poles are the two ends of the same magnet (as De Purucker implies), in which case each atmospheric pole would have to be paired with another magnetic pole of opposite polarity even higher above the earth's surface.

   It is difficult to see how the earth's rotation could produce either of these two configurations, and neither of them could possibly produce the known direction of magnetic force at the earth's surface and in the atmosphere, as observed by satellites. This can clearly be seen by studying figures 2.4 and 7.3.


Another interpretation

    If we adopt the scientific definitions of a north and south magnetic pole, then the northern magnetic pole of the earth must certainly be of opposite polarity to the north pole of the compass. However, De Purucker's warning against confusing the two poles of a magnet with the earth's magnetism indicates that other conventions may be adopted. He says that the northern magnetic pole can be called a north pole simply because it lies in the north – this being in fact the normal, everyday usage. (We could also regard it as a genuine north magnetic pole if we define an inward magnetic flux as indicating north-magnetic polarity in the case of the earth but south-magnetic polarity in the case of a bar magnet or magnetized needle.)

    As already pointed out, magnetic 'poles' are usually understood to be the places where vertically directed magnetic flux enters or exits a permanent magnet, the earth's crust, etc. The column of vertical flux begins far above the Arctic, continues through the earth, and extends for some distance above the Antarctic. De Purucker does not explicitly state that the atmospheric pole in the Arctic has the opposite polarity to the dip pole on the ground; he may call the atmospheric pole the genuine north magnetic pole simply on account of its geographic location – this being the normal, everyday convention. He does however seem to imply that the two poles have opposite polarities when he says that the north pole of the compass is attracted by the dip pole in the Arctic and repelled by the pole in the atmosphere above it. The compass certainly behaves as if this were the case. But if we picture the compass needle as simply aligning itself with the direction of magnetic flux, which at the Arctic magnetic pole is vertically downward, this need not literally be the case.

    On the other hand, if we apply the chain-of-magnets analogy to a flow of magnetic force exiting the earth at the southern magnetic pole, arcing round to the northern magnetic pole, and returning through the earth to the southern magnetic pole, then we can think of successive points along the flow as being of opposite polarity – just as the Arctic and Antarctic magnetic dip poles are regarded as having opposite polarities, even though the magnetic force flows in the same direction all the way through the earth, and just as, if we cut a bar magnet into pieces, each piece will always have a north and south magnetic pole (i.e. a pole of outward and inward flux respectively). So in this sense we can think of the magnetism above the earth as being of opposite polarity to that on the ground.

    In short, depending on the conventions, definitions, and point of view we wish to adopt, we can accept or reject the notion of atmospheric magnetic poles, we can assign them north or south magnetic polarity, and regard their polarity as the same as or different from the corresponding magnetic poles on the earth's surface.

    KH says to Sinnett: ‘Study magnetism with the help of occult doctrines, and then that which now will appear incomprehensible, absurd in the light of physical science, will become all clear.' However, we might be excused for thinking that the comments to be found on this subject in theosophical literature are calculated to have the opposite effect! We should bear in mind that KH says that many things in the letters to Sinnett were 'purposely made obscure' and that they were not written for publication.5 The masters wanted Sinnett to think for himself, to probe and question further, and not blindly accept whatever he was told as gospel truth.

    KH's references to Benjamin Jenkins certainly do not mean that he endorsed every aspect of Jenkins' model. His remarks drew attention to important disagreements about magnetism among scientists, and emphasized that the geomagnetic field extends well beyond the earth's surface. He also pointed to the fact that behind the physical phenomenon of magnetism lie etheric, astral, and akashic processes.

    It is worth repeating that the fundamental nature of magnetism remains unexplained by official science. Picturing magnetic field lines as fluxes of ether may be a step in the right direction, but things are unlikely to be that simple. For instance, instead of one-way flows of magnetic flux from 'north' to 'south', magnetic energies may flow in both directions simultaneously, spiralling clockwise or anticlockwise according to their polarity. Furthermore, a 'flow' of magnetic energy need not involve a displacement of ether from one end of the earth to the other – just as the transmission of acoustic energy (e.g. sound waves) does not involve particles travelling from source to receiver, but rather vibrating successively along the direction of propagation. What is really happening at the etheric level to produce the magnetic force is likely to be more complicated still. Since everything is part of interacting systems within systems, of infinitely varying grades of energy-substance, extending to the infinitely small in one direction and to the infinitely large in the other direction, no 'explanatory' model can ever be more than an approximate description.


Ether spin

    Modern science claims that 80 to 90% of the earth's magnetic field is produced by currents of electrically conducting material in the earth's hypothetical liquid outer core. This theory, however, faces major problems.6

    KH says that magnetism is closely associated with the fact that the earth is a rotating electrified conductor. Noteworthy in this regard is the detailed model of ether physics developed by Harold Aspden, who argues that the earth's magnetic field is generated mainly by ether spin.7 More specifically, it arises from radial charge displacement caused by the spinning ether sphere located within the earth and extending about 100 km above its surface, in conjunction with a balancing charge displacement in the body of the earth. Aspden explains that, with a distributed core charge of one polarity and a compensating surface charge of opposite polarity, the earth's rotation would produce a magnetic field that matches the observed 'main field'. Other factors contributing to the irregular and varying nature of the overall geomagnetic field include electric currents in the ionosphere and magnetosphere, magnetized crustal rocks, and subterranean electric currents (telluric currents).8

    According to this theory, the reason the magnetic poles are offset from the geographic poles is because the ether sphere spins about an axis that is tilted with respect to the earth's spin axis. And the reason the magnetic poles move around the geographic poles is because the ether spin axis precesses around the earth's spin axis in the manner of a gyroscope, due to the turning couple set up by the interaction of the two spinning electric charge systems. Precession is illustrated by the behaviour of a spinning top: as it loses energy, its axis begins slowly rotating or precessing in a slow, smooth circle that is in the opposite direction to its normal spinning motion (figure 7.4). Similarly, the magnetic poles revolve clockwise around the geographic poles, whereas the earth rotates anticlockwise on its axis. The slow gyration of the earth's axis that gives rise to the precession of the equinoxes is likewise a clockwise motion.9


Figure 7.4


References

  1. www.ngdc.noaa.gov/seg/geomag/jsp/struts/calcPointIGRF.
  2. Fleeming Jenkin, Electricity and Magnetism, London: Longmans, Green, and Co., 3rd ed., 1876, pp. 109-10.
  3. www.geolab.nrcan.gc.ca/geomag/what_nmp_e.shtml.
  4. www.geolab.nrcan.gc.ca/geomag/arctics2._e.shtml.
  5. The Mahatma Letters to A.P. Sinnett, Theosophical University Press, 2nd ed., 1926, p. 357.
  6. See Mysteries of the inner earth, part 1, section 6, davidpratt.info.
  7. Harold Aspden, The Physics of Creation, 2003, www.aspden.org/books/2edpoc/2edpoccontents.htm, ch. 8, pp. 150-63.
  8. See Mysteries of the inner earth, part 2, section 4.
  9. See Poleshifts: theosophy and science contrasted, part 1, section 3, davidpratt.info.



David Pratt. August 2004.


Mysteries of the inner earth

Poleshifts: theosophy and science contrasted

Sunken continents versus continental drift

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