Core (magnetism)

“ If the magnetic power is determined exclusively by length, it is to be expected that it will manifest no force, where the piece of iron is of such a shape that no one dimension predominates. Bring a cube of iron near the magnetic needle and it will not exert the slightest degree of power beyond what belongs to it as mere iron. By the perfect equality of the dimensions, the magnetism of the earth appears, as it were, perplexed and doubtful. ”

“ Therefore, iron or steel objects, such as posts, columns, etc., are permeated by the earth's lines of force, which in the United States enter at the top of these objects and leave at the bottom. The lines of force passing through these bodies arrange their molecules in line or magnetize the bodies. The inductive effect of the earth's magnetism indicates how lodestones or natural magnets acquire their magnetized condition. So far as is known, magnetism produces no effect upon the human body. ”

“ When the poker is so placed, it will be seen that it has actually become magnetized by the magnetism of the earth, and it is itself able to attract iron filings or small needles. These lines of force of the earth are closer together nearest to the earth's surface than further away in space, and congregate around the North and South magnetic poles, where they are greatest in number in a given area, and there the magnetic intensity is the greatest. ”

“ If the wire consists of a ferromagnetic metal, it will become “circularly” magnetized by the field, the lines of magnetization being, like the lines of force, concentric circles. So long as the wire (supposed isotropic) is free from torsional stress, there will be no external evidence of magnetism.
Magnetic Shielding.—The action of a hollow magnetized shell on a point inside it is always opposed to that of the external magnetizing force, [14] the resultant interior field being therefore weaker than the field outside. ”

“ Therein he shows, as the result of his customary careful experimental explorations that the magnetism of every known substance (even tissues of the human frame) is manifested in one of two ways. Either the body is, like iron, attracted by the magnet, taking a position coincident with the magnetic forces which he calls paramagnetic (para beside or near, magnetes, magnes, magnet) or bodies—like bismuth, for instance—are repelled by the poles and should therefore be called diamagnetic (dia, across) for they set themselves across, equatorially, or at right angles to the magnetic lines. ”

“ The properties of magnetic force and of 266 iron or steel are purely physical, and it might even be within the bounds of possibility that somewhere in the universe a mass of natural loadstone may have been so balanced as to swing in harmony with the earth’s magnetism. ”

“ On approaching the magnetic poles, compasses become sluggish, for the horizontal deflecting force falls off rapidly. The force, acting in a vertical direction, tending to make the needle dip, correspondingly increases, but is of no value for navigation purposes. However, in the scientific discussion of terrestrial magnetism, both the horizontal and vertical components as well as the absolute value of the total force are important, and the determination of these "elements" is the work of the magnetician. ”

“ If that same bar magnet were held in the field of the electromagnet with its north pole pointed toward the magnet and then, by the action of some outside force of sufficient power, its polarity were reversed, the bar would be repelled. If the magnetism were neutralized and held exactly neutral, it would be neither repelled nor attracted, but would act only as the force of gravity impelled it. ”

“ The magnetic nature is proper to the earth and is implanted in all its real parts ... there is in the earth a magnetic strength or energy (vigour) of its own ... thus we have to treat of the earth, which is a magnetic body, a loadstone. An iron rod held in the hand is magnetized in the end where it is grasped and the magnetic force travels to the other extremity, not along the surface only but through the inside, through the middle.... Iron instantly receives from the loadstone verticity and natural conformity to it, being absolutely metamorphosed into a perfect magnet. ”

“ We can produce a more perfect and shorter circle of attractions by the superposition of magnetism, as at B, Fig. 1. If we magnetize a piece of steel or iron in a given direction with a strong magnetic directing power, the magnetism penetrates to a certain depth. If we slightly diminish the magnetizing power, and magnetize the rod in a contrary direction, we may reduce it to zero, by the superposition of an exterior magnetism upon one of a contrary name existing at a greater depth ”

“ The pulley is turned into such a position that the pull of the suspension skein brings the magnet approximately at right angles to the magnetic meridian. The magnet is in equilibrium under the action of three forces: gravity, the pull of the threads, and the horizontal component of the earth's magnetism. The first two forces being constant, the equilibrium is not destroyed save by a variation in the intensity of the third force. The changes in the direction of that force are never sufficiently great to appreciably alter the position of this magnet. ”

“ As in the case of electricity there have been many theories regarding magnetism. One philosopher in the old days accounts for the variation of the compass-needle on the theory that there are two globes, one revolving within the other, and that any derangement of their normal movements in relation to each other affects the needle. Evidently there were cranks in those days as well as now. Another theory of magnetism was that there were two fluids—a boreal and an austral—one developing north polarity and the other south polarity. ”

“ The magnetism acquired by soft iron while it is in a magnetic field. Soft iron will lose its induced magnetism when it is removed from a magnetic field. The strength and polarity of the induced magnetism will alter immediately as its magnetic latitude, or its orientation in a magnetic field, is changed. The induced magnetism has an immediate effect upon the magnetic compass as the magnetic latitude or heading of a craft changes. ”

“ These bodies are thought to possess poles of mutual repulsion among themselves, and which are equally repelled by the magnetic points of convergence. Confining our ideas to single particles in one condition or the other, we shall, to a certain extent, comprehend the manifold results which must arise from the exercise of these two modes of force. At present, our knowledge of the laws of magnetism is too limited to allow of our making any general deductions relative to the disposition of the molecules of matter ”

“ Directing Couple acting on an Elongated Body.—In a non-uniform field every volume-element of the body tends to move towards regions of greater or less force according as the substance is paramagnetic or diamagnetic, and the behaviour of the whole mass will be determined chiefly by the tendency of its constituent elements. For this reason a thin bar suspended at its centre of gravity between a pair of magnetic poles will, if paramagnetic, set itself along the line joining the poles, where the field is strongest, and if diamagnetic, transversely to the line. ”

“ Magnetism, in one or other of its forms, is now proved to be universal, and to its power we are disposed to refer the structural conditions of all material bodies, both organic and inorganic. This view has scarcely yet been recognised by philosophers; but as we find a certain law of polarity prevailing through every atom of created matter, in whatever state it may be presented to our senses, it is evident that every particle must have a polar and directing influence upon the mass, and every coherent mass becomes thus only a larger and more powerful representative of the magnetic unit. ”

“ The magnetic influence of the earth acts to advantage upon the poker, by induction, only when the poker is properly held.
It no doubt occurs to the student that the end of a magnetic needle which points to the north is really opposite in nature to the north magnetic pole of the earth. The N pole of a needle, then, must be in reality a S pole to be attracted by the earth's N pole. It has been agreed, for convenience, to call the N-seeking pole of a magnet its N pole. ”

“ When no current is passing through the coil and the magnetic field is of zero strength, the needles arrange themselves in positions of stable equilibrium under their mutual forces, pointing in many different directions, so that there is no resultant magnetic moment. This represents the condition of the molecules in unmagnetized iron. If now a gradually increasing magnetizing force is applied, the needles at first undergo a stable deflection, giving to the group a small resultant moment which increases uniformly with the force ”

“ It is true that when the magnetic force acting on iron is very great the induced magnetization is no longer proportional to the external magnetic force, but this want of proportionality is quite insensible for magnetic forces of the magnitude of those due to the earth's action. ”

“ If a sufficiently strong, yet uniform, field of magnetic force could be obtained, an elongated isotropic diamagnetic body would also set itself with its longest dimension parallel to the lines of magnetic force. ”

“ Even a single electron, when in movement, creates a magnetic "field," as it is called, round its path. There is no movement of electrons without this attendant field [Pg 274] of energy, and their motion is not stopped until that field of energy disappears from the ether. The modern theory of magnetism supposes that all magnetism is produced in this way. All magnetism is supposed to arise from the small whirling motions of the electrons contained in the ultimate atoms of matter. ”

“ Although, from our view-point, magnetism represents only one 'half of a phenomenon, the other half of which is heat, we must not forget that it is itself a bipolar force. Thus, despite its apparent relation to gravity it does not represent, as gravity does, one pole of a primary polarity, with heat as the other pole. Rather must it carry certain qualities of levity which, together with those of gravity, appear in a polarically opposite manner at its two poles. ”

“ The relation between exciting power and magnetic moment is very complicated, depending not only on the dimensions and shape of the core and the manner of winding, but also on the chemical constitution of the iron of the core. ”

“ All magnetism is certainly not lost until we arrive at a white heat,* and it is manifested when iron is at a dark red heat, however different, therefore, the modifications may be which are excited in substances in their molecular state, and in the coercive force depending upon that condition in experiments of this nature, there will still remain a considerable thickness of the terrestrial stratum, which might be assumed to be the seat of magnetic currents. ”

“ He found that the laws which govern magnetism and diamagnetism are identical, that the superior attraction or repulsion of a mass in any particular direction is due to the direction in which the material particles are arranged most closely together, that the forces exerted are attractive or repulsive according as the particles are magnetic or diamagnetic, and that this law is applicable to matter in general. ”

“ Magnetism acts through intervening non-magnetic matter with undiminished energy. Thus, the attractions and repulsions of magnetic poles manifest themselves just as strongly when the poles are separated by a stratum of wood or stone as when merely air intervenes, and the attraction of small pieces of iron by a magnet takes place through the interposed palm of one’s hand without diminution. A delicately suspended needle in even a remote apartment of a large building moves whenever a cart passes in the street. ”

“ Gravity is not a separable entity, not a power per se. It is but a production, and an operation, of the same retro-action between sun-core, and earth-core. This retro-action gives rise to a stupendous magnetic circuit, as described, in which both sun and earth become the embodiments of magnetic force, or, in other words, great magnets. ”

“ The magnetic energy is not hindered by any dense or opaque body, but goes out freely and diffuses its force every whither: in the case of the terrella, and in a spherical loadstone, it extends outside the body in a circle, but, in the case of an oblong loadstone, it extends into an area of form determined by the shape of, and is everywhere equidistant from, the stone itself.
Chap. XIII. “Of the magnetic axis and poles.”
Chap. XV. “The magnetic force imparted to iron is more apparent in an iron rod than in an iron sphere or cube, or iron in any other shape.” ”

“ In heat the predominant principle is light; whereas the predominant principle in magnetism is gravitation. To these we find new powers still added, among which the mechanical and the chemical appear to be allied to gravitation and magnetism, (for the laws of mechanics are essentially connected with those of gravitation, as the chemical laws include the compositions and decompositions, the attractions and repulsions of ponderable bodies,) while electricity and galvanism, on the contrary, being more connected with light and heat, are found less inherent in terrestrial substances. ”

“ If is the intensity of magnetization, and A, B, C its components, then, by Art. 400,
We may call these the equations of magnetization, and they indicate that in the electromagnetic system the magnetic induction , considered as a vector, is the sum, in the Hamiltonian sense, of two vectors, the magnetic force , and the magnetization , multi plied by 4 π, or
In certain substances, the magnetization depends on the magnetic force, and this is expressed by the system of equations of induced magnetism given at Arts. ”