192 



SCIENTIFIC INTELLIGENCE. 



[1853. 



hnrizontal beam was a small glass tulie, terminaled at the object end 

 b_v a glass hook. Ihe nbjerts to he siibmittt'<l to the niagiielic force, 

 ■neic eitlier cvUnders nf l;I;iss, -nilU a tilanieut djawii oia from each, so 

 as to make a"l<in« stilt lioi.k for siisijeusion f;oni llie beam ; o. cyliu- 

 drical bulbs of glafs. ol like slin|,e, biit larger size, formed out of glass 

 tube; or i.lher inatieis. 1 lie tiue tubular cxtjeiiuties of the bulbs 

 beiug opened, the way through -was free f.om cud to end; the bulbs 

 could theu be tilled \vilh auy Huid or gas, ai d be le-submittcd many 

 times iu succession to the magnetic force. The sonrce of power em- 

 ployed was at first a laige electio-magnet ; but afterwards, iu order to 

 be certain of a constant power, and for the advantage of allowing any 

 lensjlh (f time for the observations, the great magnet, consti'ucted by 

 M. Lrgeman npoii the principles develo] ed by Dr. Elias, (and which, 

 weiahing about 1(10 lbs., could snppoit 430 lb., according to the Report 

 of the Gieat Exhibition Jury), was purchased by the Ri>yallustitutioii 

 and used iu the inquiries. Tlie magnet was so arranged that the axis 

 of power was five inches below the level of the glass beam, the inter- 

 val being traversed by tlie suspension tilamcut or hook, spoken of 

 above. When a body is submitted to the power of a magnet, it is 

 affected as to the result, not merely by tlie magnet, but also by tlie 

 medium surrounding it ; and even if that medium be changed for a 

 vacuum, the vacuum and the body still are in like relation to each 

 other. Iu fact the result is always differential; any change in the 

 medium changes the action on the object, and there are abundances of 

 substances which wlien surrounded by air are repelled, and when by 

 Tvater, are atti-acted upon the appi'oach of tlie magnet. Whei: a certain 

 small glass cylinder, weighing mily G6 grains, was submitted on the 

 torsion balance to the Logeman magnet surrounded by air, at tlie dis- 

 tance of 0-5 of an inch fi-oni the axial line, it required 15° of torsion to 

 overcome the repulsive force and restore the ol>ject to its place. When 

 a vessel of water was put into the magnetic field, and the experiment 

 repeated, the cylinder being now in the water was attracted, and 54° -5 

 of torsion were required to overcome this attraction at the given dis- 

 tance of 0-5. If the vessel had contained a fluid exactly equal in 

 diamagnetic power to the cylinder of glass, neither attraction nor re- 

 pulsion would have been exerted on tlie latter, and therefore the 

 torsion would have beeu 0°. Hence the three bodies, air, glass (the 

 especial specimen), and water, have their relative force measured in 

 reliiti*! to each other by the three experimental numbers 15°, 0° and 

 54°-.i. If other fluids are taken, as oil, ether, <fcc., and employed as 

 the media suiTounding the samr^ rflaS't cylimlcr, then the degrees of tor- 

 sion obtained with each of them respectively, shows its place in the 

 magnetic series. One great object in the con.struction of an instrument 

 dehcate as that described, was the luvestiga ion of certain points in 

 the philosophy of magnetism ; and amongst them especiaUy, that of 

 the right application of the law of tlie inverse square of the distance as 

 the universal law of magnetic action. Ordinary magnetic action may 

 be divided into two kinds : that between magnets permanently raag- 

 neti.^ed and unchangeable in their condition, and that between bodies 

 of wh ch one is a permanent unchangeable magnet, and the other, 

 having no magnetic slate of its own, receives and retains its state only 

 whilst in subjection to the first. The former kind of action appears in 

 the most rigid and pure cases, to be subject to that law ; but it would 

 be premature to assume beforehand, and without abundant evidence, 

 that the same law applies in the second set of cases also ; for a hasty 

 assumption might be iu opposition to the truth of nature, and therefore 

 injurious to the progress of science, by the creation cf a preconceived 

 conclusion. We know not wlietlier such bodies as oxygen, copper, 

 water, bismuth, <tc., owe their respective paramagnetic and diamag- 

 netic relation to a greater or less facility of conduction iu regard to the 

 lines of magnetic force, or to sometliing like a polarity of their particles 

 or mas.ses, or to some as yet unsuspected state ; and there is little hope 



of our devehiping the true conditi and therefore the cause of the 



magnetic action, if we assume liL'fnrcliiiud the unproved law of action 

 and reject the experiments tliat iilready bear upon it : — for Pliicker has 

 distinctly stated as the fact, that dianiaguelrc force increases more 

 rapiilly than maguetic force, when the power of tlie dominant magnet 

 is increased ; .and such effect is coutrary to the law above enunciated. 

 The following .ire furtlier rosulls in relation to this point. When a 

 body is submitted to the L'lr.it iinilKiiiu'inL; Logeman magnet in air 

 and in water, and tlie umiIis :iii' iclnncl in ilio centigrade scale, the 

 relation of the three siibstiincrs n-niiiiii lli.- same for the .same distance, 

 but not for different distances. The result of experiment proves that 

 the greater the dist.ance of the diamagnetic bodies from the magnet, 

 the more diamagnetic is it in relation to water, taking the 

 interval between water and air as the standard : and it would 

 further appear, if an opinion may be formed from so few experiments 

 that the more diamagnetic the body compared to air and water, the 

 grciter does this difference become. At first it was thought possible 

 that the results might be due to some previous state induced upon the 

 body, by its having been ne.ircr to or further from the magnet ; but 

 it was found that whetlier the progress of the experiments was from 

 small to large dist.ances, or the reverse ; or whether, .it auy given dis- 

 tance, the object was previous to the measurement held close up to 

 the magnet or brought from a distance, the results were the same ; — 



no evidence of a temporary induced state could in any of these way 

 be fouud. It does not follow from the experiments, if they should 

 be sustained by future researche.s, that it is the glass or the bismuth 

 only that changes in relation to the other two bodies. It may be the 

 oxygen of the air that alters, or the water, or more probably all these 

 bodies ; for if the result be a true and natural result in these cases, it 

 is probably common to all substances. The great point is that tlie 

 thiee bodies concerned, air, \\ ater, aud the subject of the experiment, 

 alter iu the degree of their magnetic relations to eacti other ; at differ- 

 ent given distances from the magnet the ratio of their magnetic power 

 does not, according to the experiments, remain the same ; aud if that 

 result be confirmed, then it cannot be included by a law of action 

 which is iuversely as the square of the distance. The cause of this 

 valuation iu the ratio of the substances, one to another, if it be finally 

 proved, ha.s still to be searched out. It may depend in some manner 

 upon the forms of the lines of magnetical force, which are different at 

 different distances; or not upon the forms of the lines out the amount 

 ot power at the different distances ; or u t upon the mere amouDt, 

 but on the circumstances that iu every case the body submitted 

 to the experiment has lines of different degrees of force passing 

 through different parts of it, (for however different the magnetic 

 or diamagnetic conditions of a body aud the fluid surrounding 

 it, they would not move at aU iu relation to each other, iu a 

 field of equal force :) but whatever be the cause, it will be a 

 concomitant of magnetic actions ; and therefore ouijht to be included 

 in the results of any law by which it is supposed that tliese actions 

 ai'e governed. On the present occasion a passage was quoted from 

 Newton which had siuce been discovered m his works, and which, 

 showing that he was an unhesitating believer in ph3'sical lines of 

 gravitating force, must from its nature, rank him amongst those who 

 sustain the physical nature of the lines of maguetic and electrical force: 

 it is as follows, iu words written to Bentley : — " That gravity should 

 be innate, inherent, and essential to matter, so that one body may act 

 upon another at a distance through a vacuum, without mediation of 

 anvthing else, by and through which their action and force may be 

 conveyed from one to ai other, it is to me so great an absurdity, that I 

 believe no m.iii who has in philosophical matters a competent faculty 

 of thinking, can ever fall into it. Gravity must be caused by an 

 agent acting constantly according to certain laws ; but whether this 

 agent be material or immaterial, I have left to the consideration of ray 

 readers." Finally, reference was to be made to Sabine's remarkable 

 observation, sustained as it has been by Wolf, Gantier, and others, of 

 certain coincidences existing between the appearance of solar spots 

 and the diurnal variation of the magnetism of the earth. Schwabe baa 

 been engaged in carefully observing the spots on the sun since the 

 year 1826. He has found them gradually to increase iu number and 

 size from v'ear to year, and then decrease, and so on in a regular 

 period of about ten _\ ears. Lamout ( Dec. 185 1 ) was induced by recent 

 researches in atmospheric magnetism, to examine the daily magnetic 

 variation in declination, and fouud that, as a whole, it increased and 

 diminished, and then increased again, having a regular variation of 

 about ten years : the 3'ear 1844 was given as a miuimum variation of 

 6''61 aud the year 1848 as presenting a maximum variation of U''15. 

 Sabine (Marcii 1859) in searching for periodical laws amongst the 

 mean effects of the larger maguetic disturbances, found a simulumeous 

 period of incre.ise aud decrease both at Hobarton and Toronto, on op- 

 posite sides of the globe ; the minimum effect w.as iu 1843, and the 

 maximum effect in 1848. according therefore almost exactly with La- 

 moiil's observations at Munich. But, besides that, he pointed out the 

 extraordiu.ary circumstances that this similar vari.atiou of the daily 

 m.guetic declination is the same iu length of period as that discovered 

 by M. Schwabe for the solar spots ; and still more that the maxima 

 aud the minima of these two most different phenomena coiucidi- ; for 

 1843 presents the least diurnal vaiiation and ti.e smallest number of 

 solar spots, and 1848 the largest magnetic variation and the greatest 

 number of solar observations. He has observed that the same period 

 of increase and decrease exists with the same epochs in the ifiurnal 

 variations of the maguetic inclination of the earth's magnetic force in 

 both hemispheres. The phenomenon is general both as regards all 

 the m.agiietic elements, and in parts of the globe most distant from 

 each other. Gantier appears to have been struck with the same coin- 

 ci ence ; but did not publish his idea until July 1852. Wolf, if Bene, 

 who has sought far into the history of the sun spots, had the same 

 thought, publishing it first at the end of Jul}- or begiuniug of August, 

 18.VJ. He endeavours to trace the general condition of the spots from 

 the year 1600, and concludes that the true length of the period is IMl 

 yerj.. As it is i'lipossible to conceive such a coincidence iu the length 

 of the period and the time of the ma.xima and minima of these two 

 greatly differing phenomena, without believing in some relation of 

 them to a common cause ; so, the observation of such a coincides 

 at this moment ought to urge us more than ever into an earnest aud 

 vigorous investigation of the true and intimate nature of magnetism; 

 by means of which we now have hopes of touching in a new direction 

 not merely this remarkable force of the eajth, but even the like powers 

 of the sun itself. 



I 



