1 86 



NATURE 



[June 2i, 1 88. 



There is nothing remarkable in the bells themselves, as they 

 evidently could be rung if the armature was surrounded by a coil, 

 and w irked by an electric current from a few cells. The marvel, 

 however, is in the small steel superposed magnetic wire producing 

 by slight elastic torsions from a single wire, I millimetre in dia- 

 meter, sufficient force from mere molecular rotation to entirely 

 replace the coil and elec'ric current. 



Elastic Nature of the Ether surrounding the Magnetic Mole- 

 cules. — During these re-earches I have remarked a peculiar 

 property of magnetism, viz., that not only can the molecules be 

 rotated through any degree of arc to its maximum, or satura- 

 tion, but that, whilst it requires a comparatively strong force to 

 overcome its rigidity or resistance to rotation, it has a small field 

 of its own through which it can move with excessive freedom, 

 trembling, vibrating, or rotating through a small degree with 

 infinitely less f >rce than would be required to rotate it per- 

 manently on either side. This property is so marked and 

 general that we can observe it without any special iron or 

 apparatus. 



Let us take a flat rod of ordinary hoop-iron, 30 or more centi- 

 metres in length. If, whilst holding thi; vertically, we give 

 freedom to its molecules by torsions, vibrations, or, better 

 still, by a few blows with a wooden mallet upon its upper ex- 

 tremity, we find, as is well known, that its lower portion is 

 strongly north, anil its upper south. If «e reverse this rod, we 

 now find it neutral at both extremities. We might here suppose 

 that the earth's directing force had rotated the molecules to zero 

 or transversely, which in reality it has done, but only to the limit 

 of their comparatively free motion ; for if we reverse the rod to 

 its original position, its previous strong polarity reappears at both 

 extremities, thus the central point of its free motion is inclined 

 to the rod, giving I iy its free motion great symmetrical inclina- 

 tion and polarity in one direction, but when reversed the 

 inclination is reduced to zero. 



111 Fig. 3 n shon the bar of iron when strongly polarised by 

 earth's magnetic influence, under vibrations, with a sufficient 



FIG, 3. 



force t 1 have 1 itated its elastic centre of action, c shows the 

 same bar with its molecules at zero, or transversal, the directing 

 force of earth being insufficient without the aid of mechanical 

 vibration to allow them to change. The dotted lines of n sup- 

 pose the molecule to be in the centre of its free motion, whilst 

 at c the molecules have rotated to zero, as they are prevented 

 from further rotation by being at the extreme end of its free 

 motion 



If, now, we hold the rod vertically, as at c, giving neutrality, 

 and give a few slight blows with a wooden mallet to its upper 

 extremity, « e can give just the amount of freedom required for 

 it to produce evident polarity, and we then have equal polarity 

 no matter which end of the bar is below, the centre of its free 

 rotation here being perfect, and the rod perfectly neutral longi- 

 tudimlly when held eat and west. If, on the other hand, we 

 have given too much freedom by repeated blows of tbe mallet, 

 its centre of free motion becomes inclined with the molecules, 

 and we arrive at its first condition, except that it is now neutral 

 at p and polarised at C. From this it will be seen that we can 

 adjust this centre of action, by vibrations or blows, to any point 

 within the external directing influence. 



We can perceive this effect of free rotaiion in a limited space 

 in all classes of iron and steel, being far greater in soft Swedish 

 iron than in hard iron or steel. A similar phenomenon takes 

 placeif we magnetise a rod held vertically in the direction of 

 earth's magnetism. It then gives greater polarity than if mag- 

 netised east or west, and if magnetised in a contrary sense to 

 earth's magnetism, it is very feebly magnetised, or, if the rod is 

 perfectly soft, it becomes neutral after strong magnetisation. 

 This properly of comparative freedom, and the rotation of its 

 centre of action, can be demonstrated in a variety of ways. One 

 remarkable example of it consists in the telephone. All those 



who are thoroughly acquainted with electro-magnetism and know 

 that it requires measurable time to charge an electro-magnet to 

 saturation (about one-fifteenth of a second for those employed in 

 telegraphy), were surprised that the telephone could follow the 

 slightest change of timbre, requiring almost innumerable changes 

 of force per second. I believe the free rotation I have spoken 

 of through a limited range explains its remarkable sensitiveness 

 and rapidity of action, and, according to this view, it would also 

 explain why loud sounding telephones can never repeat all the 

 delicacy of timbre that is easily done with those only requiring a 

 force comprised in the critical limits of its free rotation. This 

 property, I have found, has a distinct critical value for each class 

 of iron, and I propose soon to publish researches upon the 

 molecular construction of steel and iron, in which I have made 

 use of this very property as a guide to the quality of the iron 

 itself. 



The elastic rotation (in a limited space) of a molecule differs 

 entirely from that known as mechanical elasticity. In perfectly 

 soft iron we have feeble mechanical elasticity, whilst in tempered 

 steel we have that elasticity at its maximum. The contrary takes 

 place as regards molecular elasticity. In tempered steel the 

 molecules are extremely rigid, and in soft iron its molecular elas- 

 ticity is at its maximum. Its free motion differs entirely from 

 that given it by tor-ion or stress. We may assume that a mole- 

 cule is surrounded by continuous ether, more of the nature of a 

 jelly than of that of a gas : in such a medium a molecule might 

 freely vibrate through small arc--, but a rotation extending 

 beyond its critical limit would involve a much greater expendi- 

 ture of force. 



The discovery of this comparatively free rotation of molecules, 

 by means of which, as I have show n, we can (without in any 

 degree disturbing the external mechanical elasticity of the mass) 

 change the axes of iheir free motion in any direction desired, has 

 led me into a series of re-earches which have only indirectly any 

 relation with the theory of magnetism. I was extremely desirous, 

 however, of finding an experimental evidence which in itself 

 should demonstrate all | ortions of the theory, and the following 

 experiment, I believe, answers this purpose. 



Let us take a squ ire soft iron rod, 5 millimetres in diameter by 

 30 or more centimetres in length, and force the molecules, by 

 aid of blows from a w ooden mallet, as previously described, to 

 have their centres of free motion in one direction, the rod will (as 

 already shown) have polarity at both ends, when held vertically ; 

 but if reversed, both ends become completely neutral. 



If now we turn the rod to its first position, in which it 

 shows strong polarity, and magnetise it whilst held vertically, 

 by drawing the 1101 th pole of a sufficiently powerful permanent 

 magnet from its upper to its lower extremity, we find that this 

 iv d, instead of having south polarity at its lower portion, as we 

 should expect from the direction of the magnetisation, is com- 

 pletely neutral at both extremities, but if we reverse the rod, its 

 fullest free powers of magnetisation now appear in the position 

 where it was previously neutral Thus, by magnetisation, we 

 have completely rotated its free path of action, and find that we 

 can rotate this path as desred in any direction by the application 

 of a sufficient directing power. 



If we take a rod as described, with its polarities evident when 

 held vertically, and its neutrality also evident when its ends are 

 reversed in the same magnetic field, we find that its polarity is 

 equal at both ends, and that it is in every way symmetrical with 

 a perfect magnet. If we gradually reverse the ends and take 

 observations of its condition through each degree of arc passed 

 over, we find an equal symmetrical diminution of evident external 

 polarity until we arrive at neutrality, when it has no external 

 trace of inherent polarity, but its inherent polarity at once 

 becomes evident by a simple return to its former position. Thus 

 the rod has passed through all the changes from polarity to 

 neutrality, and from neutrality to polarity, and these changes 

 have taken place with complete symmetry. 



The limits of this paper do not allow me to speak ot the 

 numerous theoretical evidences as shown by the u-e of my in- 

 duction balance. I believe, however, that I have cited already 

 experimental evidences to show that what has been attributed to 

 coercive force is really due to molecular freedom or rigidity ; 

 that in inherent molecular polarity we have a fact admitted by 

 Coulomb, Poisson, Ampere, De la Rive, Weber, Du Moncel, 

 Wiedermann, and Maxwell ; and that we have also experimental 

 evidence of molecular rotation and of the symmetrical character 

 of polarity and neutrality. 



The experiments which I have brought forward in this paper, 



