IMAGE EVALUATION TEST TARGET (MT-S) 1.0 1.25 b;|M |2.5 2.2 I.I I "^ i^ — 6" U 1116 ii^ FJiotographic ^Sciences Corporation 23 WBST MAIN STRUT WEBSTER, N.Y. )4SS0 (716) a72-4503 r ?N^ 4' 1 CIHM Microfiche Series (Monographs) ICMH Collection de microfiches (monographies) Canadian Institute for Historical Microreproductions / Institut Canadian de microreproductions historiques r\f\ Technical and Bibliographic No;ss / Notes techniques et bibliographiques The toth The Institute has attempted to obtain the best original copy available for filming. Features of this copy which may be bibliographically unique, which may alter any of the images in the reproduction, or which may significantly change the usual method of filming, are checked below. Coloured covers/ Couverture de couleur I I Covers damaged/ Couverture endommagte D Covers restored and/or laminatod/ Couverture restaurie et/ou pellicula □ Cover title Le titre de missing/ couverture manque D D D n Coloured maps/ Caites gAographiques en couleur Coloured ink (i.e. other than blue or black)/ Encre de couleur (i.e. autre que bleue ou noire) Coloured plates and/or illustrations/ Planches et/ou illustrations en couleur 1^1 D n Bound with other material/ _J Relie avec d'autres documents Tight binding may cause shadows or distortion along interior margin/ La reliure serree peut causer de I'ombre ou de la distorsion le long de la marge interieure Blank leaves added during restoration may appear within the text. Whenevir possible, these h>ve been omitted from filming/ 11 se peut que certaines pages blanches ajouties lors d'une restauration apparaissent dans le texte, mais, lorsque cela e'lit possible, ces pages n'ont pas ete f ilmtes. Additional comments:/ Commentates supplementaires: L'Institut a microfilm^ le meilleu- exemplaire qu'il lui a iti possible de se procurer. Les details de cet exemplaire qui sont peut4tre uniques du point de vue bibliographique, qui peuvent modifier une image reproduite. ou qui peuvent exiger une modification dans la methode normaie de f ilmage sont indiques ci-dessous. □ Coloured pages/ Pages de couleur □ Pages damaged/ Pages endommag^ □ Pages restored and/or laminated/ Pages restauries et/ou pellicul^s Q Pages discoloured, stained or foxed/ Pages decolor^s, tacheties ou piquees □ Panes detached/ Pages ditachtes HShowthrough/ Transparence □ Quality of print varies/ Qualite inigale de Tim-^ression □ Continuous pagination/ Pagination continue □ Includes index(es)/ Comprifnd un (des) index Title on header taken from:/ Le titre de I'enttte provient: □ Title page of issue/ Page de titre de la livraison □ Caption of iis(i«/ Titre de depart de la Thei poss of th filmii Origi begii the li sion, othei first I sion. or illi Theli shall TINU whici IVIaps differ entire begin right requii meth( □ Masth Gener livraison Masthead/ ique (periodiques) de la livraison This Item is filmed at the reduction ratio checked below/ Ce document est filme au taux de reduction mdiqu6 cidessous, 10X My lav 12X 16X 20X 22X H JbX 30X 24 X 28X n 22t The copy filn^«d hare has been reproduced thankc to the generosity of: Douglas Library Queen's University The images appearing here are the best quality possible considering the condition and iegibifity of the original copy and in keeping with the filming contract specifications. Original copies in printed paper covers are filmed beginning with the front cover and ending on the last page with a printed or illustrated impres- sion, or the back cover when appropriate. All other original copies are filmed beginning on the first page with a printed or illustrated impres- sion, ar*d ending on the last page with a printed or illustrated impression. The last recordsd frame on each microfiche shall contain the symbol -^ (meaning "CON- TINUED"), or the symbol V (meaning "END"), whichever applies. Maps, platas, charts, etc., may be filmed at different reduction ratios. Those too large to be entirely included in one exposure are filmed beginning in the upper left hand corner, left to right and top to bottom, as many frames as required. The following diagrams illustrate the method: C'exemplaire film* fut reproduit grAce d la gtnArosit* de: Douglas Library Queen's University Les images suivantes ont 6t6 reproduites avsc le plus grand soin. compte tenu de la condition et de la nottet« de I'exemplaire film6, et en conformity avec le& conditions du contrat de filmage. Les exemplaires originaux dont la couverture en papier est imprim6e sont fiinriiAs en commandant par le nremier plat et en terminant soit par la dernlAre page qui comporte une empreit^te d'impression ou d'illustration, soit par le second plat, salon le cas. Tous les autres exemplaires originaux sont film6s en commenpant par la premiere page qui comporte une empreinte d'impressior.' ou d'illustration et en terminant par la dernidre page qui comporte une telle empreinte. Un des symboles suivants apparattra sur la dernidre image de cheque microfiche, selon le cas: le symbols — »► signifie "A SUIVRE ". le symbols V signifie "FIN". Les cartes, planches, tableaux, etc., peuvent dtre film^s A des taux de reduction diff^rents. Lorsque le document est trop grand pour dtre reproduit en un seul clich6, 11 est film6 d partir de I'angle supArieur gauche, de gauche d droite, et de haut en has, en prenant le nombre d'images ndcessaire. Les diagrammes suivants illustrent la mithode. 1 2 3 1 2 3 4 5 6 ^•VA JKe WK\j of Qrav^itvj. — BY— J. /\. ALLEN. f/Jt THE WHY OF GRAVITY. BY J. A. ALLEN. / c-T'* y KINGSTON I'KINTEI) AT THK DAILY NKWS OKHIK, lycX). \\\iVay\o.\A'3 0%%K-t j r* matt Wee we h alwai whet or in indiv parti nevei void. alwa; to b matt sepai seem real!] by th so, fc that this ( the amoi amoi thing all is , chan Now math V THE WHY OF GRAVITY.' " I "O what is gravity due ? What is its cause? Is it -*- not due to the essential oneness of matter, of all matter — to its inseparability ; for mat< r is a unit-entity. We cannot get outside of it or void it. We speak by it, we hear by it, we live by it, we are it. It is everywhere always, whether curdled into star-clusters or continents, whether hard as granite, or soft as water, or thin as air, or inexpressibly tenuous as ether. It is one universal, indivisible organic whole, from which not the smallest particle can ever be separated. We never find, and never can make, the smallest portion of space matter- void. Do what we will, matter is doggedly, persistingly, always present, just as truly as is space itself; refusing to be shut out from the one solid whole of the all matter of the universe, or, by any device or force, to be separated into disconnected parts ; for, thor h it may be seemingly cut up into discrete portions, ii i ever is so really, but is only expanded or stretched, or drawn out, by the energy of steam or powder, compelling it to be so, for though yielding, when so required, to the energy that for the moment can enforce compliance, yet, when this energy has expended itself in the work done by it, the matter soon returns to its old status quo ante, the amount of its reaction being, as always, measured by the amount of its action, and opposite to it. And so no- thing is ever really lost or gained to the universe, while all is kept in a state of perennial activity and ceaseless change — matter unfolding itself in its myriad forms. Now, Sir Isaac Newton has shown us by his masterful mathematics, that every minutest portion of matter has •A]l rights reserved. 36();22 THE WHY OF GRAVITY. the most indissoluble ties of relationship with every other portion of it, whether near or far off. Hence tiie whole of matter is bound up as one indivisible whole by the most intimate ties. And could we get to Sirius, all there would be matter still, and all the way to it, and be- yond it. Physically speaking, It is the all, " extends through all extent, Spreads undivided, operates unspent." And matter can never be separated from all-matter, for the ties that bind it in the unity of the whole are all- penetrative, all-pervasive, unbreakable, universal— the most distant star and every particle in it being bound to our earth and to every particle in it. As that marvellous product of our humanity, the great Sir Isaac Newton, says— and he proved it—" Every particle of matter in the universe attracts [holds to itj every other particle with a force directly as its mass, and inversely as the square of its distance." So intimate is the union of all matter and of every, the least, particle of it to even every smallest particle of the whole of matter— such its sensitiveness throughout the universe— the same essen- tially in every part, "As full, as perfect in a hair as heart " And here I have the audacity to change the great Newton's expression of " every particle attracts every particle " into that of every particle is united to every particle. And the whole may be written thus: " Every portion of matter in the universe is intimately bound up with every other portion of matter in the unity of the whole of matter, according to Newton's proved law of mass and distance. But is matter one and inseparable ? Is every particle of air, every drop of water, every piece of stone, as in- separable from all matter as a piece of a cube of steel from the rest of the cube ? Yes. Try to empty a vessel full of air by holding its mouth downward and shaking it ; it is of no avail. It is as full as ever. Now fill this vessel with water and turn it upside down. \V^ell ; we have got rid of the water, 'tis true, but have we got rid of the Tin-: WHY OF GRAVITY with every Hence the e whole by Sirius, all it, and be- natter, for le are all- ersal — the bound to narvellous : Newton, matter in r particle :Iy as the lion of all t to even —such its ne essen- the great :ts every to every " Every bound up ty of the ;d law of y particle le, as in- ! of steel 'essel full ? it ; it is is vessel we have id of the matter. Far from it ; the vessel is full of matter still ; of the matter of the air, which has taken the place of the matter of the water. It is here, as it is always, after every effort, only an exchange of one kind of matter for another. We may make a hole in water with our finger, but on withdrawing it, and as fast as we withdraw it, the hole closes up again ; but, while there was a hole in the water when our finger was in it, there was no hole in matter ; for the matter of my finger was there to take the place of the matter of the water, and it is only by the substitution of one piece of matter for another that we can ever separate one piece of matter from another : for all matter is fixedly united to all matter by an infinite series of links — links all-convergent, all-divergent, in- separable — the great all-sided whole, star to particle and particle to star equally. We may, indeed, separate portions of matter to almost any extent — as a stone from the earth — but only, as I said, by the substitution of other matter for tlie matter removed. But by no cunningest device can we get round Nature. No ; we cannot outwit or humbug or coax her to be what she is not. By fundamental constitution she is ever unalterably one — a plenum, a continuum, with no break or void. Who ever saw a void ? Who ever saw matter separated from matter with an interval of void-space b * v een ? With even all the resources of modern science at our command, the little glass bulbs, for the carbon filaments of our electric lights, cannot be made air-void , for even high-vacuum tubes, in spite of every effort to empty them, still contain " many millions of air-particles " ; for matter is so indissolubly bound up with all matter everywhere, that every slightest particle refuses absolutely to be torn away from the whole of matter, so strong is the adamantine tie that binds every particle to every particle everywhere in the unity of the whole. While, if we could even get rid of the particles of the air, there would still remain behind in the bulb the tenuous matter of the ether, leaving matter a con- fi Tin- WHY or GRAVITY. tinuum still. And so matter is all annealed fast together, the far and the near, all to each, and each to all l,y the strong ligaments of cohesive force ; and not at all less really are they welded in one. than are the particles, with one another, of a bar of steel. Thus far I have endeavoured to show how indissolu- bly strong ,s the tie which binds every particle of matter .n the umverse to every other particle. So great, indeed, s th,s inherent force of the union of matter with matter, that to pull apart the particles of a pound of water, we should have to employ such an a.nount of mechanical power as ,s equivalent to the raising of fourteen tons to a height of one hundred feet." so enormous is the strength of the cohesive grip that binds them together as in a vice ol steel Whereas, on the other hand, not all the me- chanical or other power or enginery of the world com- bined could avail to so separate these tiny particles from one another as to leave a void between them. For the all-mat er of the universe is an integer; and. in the es- sentiahty of its unity, can never be separated, being by inherent constitution not many discrete parts, but one entity in the unity of the whole, and every corner and cranny of nature ,s crowded io the full with the ubiquitous matter of the universe. Thus is gravity the cement of the universe, and the slightest touch at the centre of the mass-and its centre IS everywhere-is felt pulsing to the outermost rim of nature, not so much as a rate as a state. As the poet sings : *^ "The spider's touch, how exquisitely fine. ^'e«'s in each thread, and /,W5 ,i/„mM//r //Hf " For, though light travels from the sun to us at the almost inconceivable speed of 187.000 miles a second • yet what a laggard it is when compared with the travel- late. If ,t be a rate, of gravity, which bounds over its 90,000,000 of miles in the twinkle of an eye. Of this gravity Professor O. Lodge writes, that "its force is practically instantaneous and can scarcely take time on Its journey, else there would be aberration." And the THK WHY OF GRAVITY. St together, o all by the at all less e particles, V indissohi- 5 of matter ;at, indeed, ith matter, water, we mechanical sen tons to le strength s in a vice II the me- I'orld corn- icles from For the in the es- being by , but one 3rner and ibiquitous and the its centre 3t rim of the poet JS at the second ; le travel- over its Of this force is time on And the able mathematician, Arago, too, speaks of it as "instan- taneous" ; and, if matter be a unit — all in one, even this may lose somewhat of its wonder ; and how marvellous is matter, which, continuous with everything physical in the universe, is incessantly throbbing, every particle of it, with the wholesome energy of unrest. And this motion, peculiar to itself of every particle, as the spec- trum and Mr. Lockyer ms'-e known to us — this concate- nated, all-divergent, sensitive motion of vibration, may be witnessed by us, conveyed as it is by celestial tele- e;raphy through the boundless ocean of the omnipresent ether, from a particle in a star, many billions of miles away, to the brain and eye of the beholder here on earth, producing in him the same special vibration of each indi- v» ,al particle ; for the space occupied by each given particle in the star and in the eye on earth is an unin- terrupted continuum, all held together by the tie of the unity of all matter. And if this were not so ; if the chain had one severed link anywhere, we could not see the star. Hence is there no void in matter. Now, Newton proved that the force of gravity (I pre- sume to employ here, for gravity, the tie of unity) which holds a hundred weight to the earth, and which opposes the energy of our muscles to lift it from the earth, is the very same force exactly which ties the moon to the earth and the earth to the sun, by the same invisible, but no less real, bands of force. And his proofs involve this, that these bonds can never be severed, though, as I af- firm, they may be lengthened indefinitely. For as he has proved every particle in the universe attracts [is bound up with] every other particle directly as is the quantity of matter in it, and if one particle has the force of one particle, then the weight of a whole world of par- ticles — myriads of myriads of them — would have myriads of myriads of equal ties, and would be bound with a proportionately greater amount of force, as we know it would be, and from this allegiance to the unity of all matter the smallest and remoteet particle is not absolved. 8 THE WHY OF GKAVITV. Then how unassailably great must be the force of the sun, himself 500 times greater than our earth and all the planets rolled into one, and with what a grip of force must he hold our little world as we might hold a pound. And hence We may cease to wonder, that in spite of all the fearful motion-energy of our planet, as she bounds along with such headlong impetuosity in her onward course that even she can be easily bridled and restrained trom breakmg away from all control, held as she is by the strength of the tremendous grip of every one of the countless particles of his mass. From the unity of the whole, then, what could separate our earth or a single particle of it ? And is not this the real gravity-this tie of inseparability ? The earth is stubbornly reluctant to let go a hundred weight that is bound to her; but refuses absolutely to allow one particle of her matter, to be separated from all matter, now or ever. On the ground of this hypothesis, metaphvsics has no part at all. But to the idea involved in the word attract," I am not reconciled. Nor was Newton himself as a real causa causans ; but only as a kind of ad interim' provision, till such time as might be discovered the true cause, for which he had sought, but in vain. The word attract (ad traho) has a metaphysical ring about it as of a something that refuses to give content, for who can visualize even in imagination the necessary physical nexus, or see why a particle in Sirius should attract or pull towards it a particle on earth and vice versa ; but that a particle in the one should be bound, by intervening matter, to a particle of the other in the one great warp- and-woof of all things, in the veritable unity of a seamless whole, of which everything can be readily conceived, as affecting everything, and of everything in return as being attected by it, (" action and reaction being always equal and opposite ") as when a pin-prick of the finger is felt and registered in the brain— this unity seem<: a readily realizable conception. Is the other equally so ? Now, I know that manv acute thinkers ' ' -- - ' many feel a great difficulty in 4 force of the arth and all grip of force Did a pound. spite of all she bounds ler onward d restrained IS she is by every one From the jparate our lot this the he earth is ght that is one particle er, now or physics has the word :on himself, ad interim d the true The word bout it, as r who can y physical attract or /ersa ; but ntervening reat warp- a seamless iceived, as n as being vays equal ger is felt a readily ' Now, I ifficulty in THE WHY OF GRAVITY. 9 this matter of the attraction of every particle on the earth by every particle in the sun. It is to many a real pons asinorum, over which the intellect refuses to be able to cross. But does not the doctrine of the unity of all mat- ter afford such an open highway as needs no bridge at all. But that this subject of gravity may be looked at from every side, I shall now quote what others have written on the subject. And first, Humboldt writes, " The amount of matter in every celestial body gives the amount of its attractive force, and Newton succeeded in discov- ering the force from whose action the laws of Kepler necessarily result "; and Newton himself writes, " The power of gravity ari ■ from some cause which penetrates the very centre 01 the sun and planets without any diminution of its force." Again, writes Helmholtz, " In gravity we have discovered a property common to all matter." This is strong language — the language, too, of experienced, and subtile, and profound thinkers — the very luminaries of the world of science. Such is gravity, proved in very deed to be a supreme force in the Uni- verse, and I only want to learn if its great power is due to mere attraction, or if it stands always at the very heart of nature, on its own solid feet, " in se ipso totus," in single selfhood, owing nothing to anything, a primordial organic unit, that cannot be separated into disconnected parts by any power whatever. I want to see if anything underlies this great power, gravity, constituting it what it is, and, if so, what it is that does so. But why disquiet ourselves? Why not rest content with the observed fact ? Because, as Professor Tait says, "reason cannot content itself. .... with a mere series of observed facts we are forced to inquire into what may underlie them," and the ablest and most inquisitive minds in the world have, age after age, thought their time not ill-spent — from Newton to to-day — in trying to get to th.e root of thi^. matter — the came of gravity. But the great Clerk Maxwell tells us their pursuit has been fruitless. Of every such theory he lO THI- WHV OF (iRAVlTY. .haul',', 'LZuZt "'■'="""P"™ "" "-y P-' to i,„,gi„e yet ca,„„n,=l„„,i„ki„^„,,.,I,l„„k. Butwhy houU the whole as explained by him. rests on the soHd G.b.altarofvery truth itself, and. so Pope writes •' Nat...-e and nature's laws lay hid in night, God said, let Newton be and all was light " St.II. when even he turns aside to matters lying outside of the sphere of his marvellous special power, whe e 1 stands all. victorious and alone. I do not fee thlTl J equaly bound to follow him. es eciallylet e h UseTf Imd hesitated uncertain, leaving posterity to discov^ he TJ uu I: ""^"'•"'^'•ed as he was in his day with the vast weal h of knowledge which the ages after him Inve lay Horn the P.sgahs of science on the broad, cultivated Plams strewn thickly with monuments marki, g h e ' instead of bemg encouraged, by the splendour of their ccess . s,,.,, , ,^^ blighting indolence of dL ' vvhen ihc present blossoms in so many fields with fh» Howersofhope. and do nothing to relLe th: dtw: tmp: why of gravity II on this special point. And the question now before us is this : is the theory of the unity and inseparability of matter here advanced only a new apple of Sodom from the fruitful land of dreams ; or does it afford an adequate explanation of the cause of {gravity ; yea, is not gravity a very necessity of the constitution of the kind of world this is ; is it not, a priori, a foregone conclusion, involved in the conception itself of such a world as ours — a world in which nothing is unconnected, but every special thing only a part of a united whole, as united as my hand is to my head ; and that consequently, whatever seems to leave it for an instant does not leave it really, but must return, because the ties of unity cannot be severed. Thus, we see that the force of gravity, while a great reality— a thing in itself—is due to the unity, to the abso- lute inseparability of matter from all-matter, which all- matter is penetrated through and through, from centre to circumference by the indissoluble ties of force— so wholly one is it, that nothing can ever separate even one smallest particle of it from the sum-total of matter. If anyone thinks he can do so, let him show it. But I cannot say that every particle "attracts" every particle ; for that is something not provable by his math- ematics, but I do hold that every particle of matter is bound up with, is knit to, every other particle in the unity of the whole of matter. Now, let us suppose two pieces of India-rubber, the one a tiny cube weighing a pennyweight, the other a cube of a dozen pounds, and that these cubes have been joined on to one another, and let us further suppose them severally stretched by attaching to each of them— the thin penny- weight end and the great cube-end-a vice by which to draw them out by the employment of an equal energy of some kind by which to stretch, and which does stretch, them. Now, in such a case, while the pennyweight portion would become largely extended, the thick solid rube would be but slightly affected. Let us further suppose that the energy applied to stretch the two bodies has 12 THR WHY OF GRAVITY to ake then own course, would it not be found that wh,^ the B,ea. cube was extended very sfowly and shgMly „|„ ,, imperceptibly, the pennyweight portfon on the other hand-stretched to a considerable degree- won d bound back with a quick recoil to its first normal pos,t,on „s reaction being the equal of its action So too, ,n he case of a stone forced above the ear.", by an' energy (and every body above the earth, whether a sL^e on a prcjecng cliff, or a body of water on the sidetf a moun.a.n has at some time been lifted there bv an energv of some k,nd, and is, so, itself now posses'sed of uS ,„ r*' ".'J" '""^ "' "■= '""^y ''" ^Pent i elf n the work done by it andean do no more, then he body, .f notlnng nterfere to stay it, will bound ;ith sp ed o meet the earth, while the great earth itself, too ^In (and scenfs ts agree here) move slightly and slowly Ic cord,ng to a known law, to meet the sLe ; for .Lugh the l,es of matter to matter are, as such, reciprocX strong, and those of each ultimate particle for rrna^ pa c e equal, yet the incalculably greater number of ,1 e particles (and. consequently, of the ties) in the vast body of the earth, as compared with those of the stone bind .ng the earth to it, renders it correspondingly hard' to be moved out of ,ts settled normal state o( inerfia ; whereas the stone w,,hn,flnitely fewer ties or slaying ^ower Is eas.ly and rap.dly moved to a distance. And here wa must agam call to mind, that the stone in the upper ^r ia^ura 1' f '"'* '".°PP"^i"™ '» the pre-existing natural t,es of matter bmding it to the matter of the and so had tins energy, that lifted it there, stored up in i, and so was capable-as in the case of a bent bow-of returmngor of similarly expending it; i„ short was "'„ : ° ■■^■."^""f-^f ^-in^, back what had been' M teen vri.hV . ''°™" "'" ""^'''''ined it having l-een withdrawn, the stone bounds back to its normal! THE WHY or GRATITY. 13 ies are allowed be found that, ly slowly and weight portion, rable degree — its first normal ts action. So, Je earth by an 'hether a stone n the side of a e by an energy sessed of that s spent itself lore, then the tnd with speed :self, too, will id slowly, ac- '■ ; for though , reciprocally for ultimate lumber of the the vast body stone, bind- y hard to be tia ; whereas ig powers, is ^nd here we he upper air i been forced pre-existing atter of the some kind, ored up in it, Jnt bow — of short, was d been first d it having its normal, constitutional state. It is all in accord with Newton's great law of action and reaction — Newton's third law of motion being this, that " when one body exerts force upon another body, that other body reacts with equal force upon the one." But, again, though the force of the tie of ^ atter to all-matter is never reducible to nil — Sir Isaac Newton's proofs forbid that — yet a particle in Sirius, distant many billions of billions of miles, and, so, as it were, attenuated and weakened by being stretched, could not have the strength of tie, that a body on the earth close to it and unstretched would have for the earth, and, accordingly, Newton's law tells us that, as the distance diminishes, the force increases (by squares) as when, conversely, we sei^ that the light of a candle thrown through a small hole on to a screen, di- minishes in intensity by squares, as the screen is moved farther and farther from it, till at length it seems only a weak, diffused glimmer ; and vice versa. So when we wish to lift from the ground a weight of a dozen pounds, the unity of the matter with the matter of the eartij, tying it to it, demands some power on our part to lift it ; but if the weight were one of a few hundred pounds, its ties to the earth being proportionately greater, it would demand a vastly greater amount of energy to do so. For every portion of matter in the universe has to all other matter a force of tie of exactly the same equal strength as every other equal portion of matter has; but, of course, profoundly modified by distance or nearness. For, though the sun has by countless billions of billions more ties of force than the weight, yet the immeasurably greater nearness of the weight to the earth than to the sun gives the weigiit a far more than countervailing ad- vantage, and hence it falls to the near earth instead of falling into the infinitely greater mass of the distant sun ; for the great Newton's law of " inverse squares " comes in here to outweigh the greater number of the threads of tie so abnormally stretched (and, so, weakened by being so stretched,) to the vast distance of over 90,000,000 of '4 THE WHY OF GRAVITY miles, compared with that of fh. t the lifted weight • and h^= '"^ ^ '''''""" "' plained, known ,„■ be. ha ci" ' ''"'"' ''"'"'-' - left tLrbViL?::;: [:7 •'^"='--'<' - sp™ o^ or of which it had tm T, '^ -nd c„„d,„,,.„^ snn-nebula, P-t. it continues "iltor"'"""'' ' '=°"°«"=<' -me speed, and tWs contiT ! "' " '"" "■=" ^"^' '^e cated motion is so ^ ^^^^ p"','^^ """'' '^'""'"•"■i■ ■•by the simple s."onhe'^l:!r'^'"''=""'"-' heat would equal theTft T .!,=""' '" "= orbit, the of fourteen globe of coll "'t'/T "'' <^ombuslion earth in magnitude " stniTh ,""'"■ 'I""' '" ""e ^uch headlong veh>c'i,v ^I" ' '""t' /"'""^ ^'™S with c".«««.,«,i by which L 7^f ''^ """ '^"^ 0/ - that, ^..uggla'alt ma/ o'gt f: e'"; ■: T T"' more firmly „''htsucte"his'"°"lr« '''"■''" "^ "efd the vast sl-mass 7utle ^rM Z "'' ""^" ""^ move particles and masse, L ^° ""y- '"''eed. one of them from Th. n °"° ''"°"'^^' '•"t never growing as T. d^ out o the" fid' "M" ' '°' '"="• things, is in the nature of .hi '""'^^'"'""'1 °mly of ail am wro„g_a„d there are a hf '""^ ^'" '" ' Priori,i„favor„f sucha con. Presumptions, a lief that the cause rf'^-aWt^.^ri^Tl'" '""''"' "^ "=• separability of matter, I have at llai °°""' '"'' '"' known cause, to account for 1°!^".^''" ^ ""'=- => born metaphysical abstrac^o but a "Ter""" "'r' something that evervnno r^ ^®^* causa," a for himse^, a^d^kr TLZTlt'""^- ="" ""- ■' missing link," or, rather T, ? ""' "'PP'>' ">» vasive force, Ihat.'hlt' , eTll i^T"' f '"•''^^• thmgs„„„, gravitate, for ?h Jy are held T'' !^°"' '■°"' cemented whole and m., . t ,? 'eld together as one mass and distant iir'a^Vairt?"'" "^/"'""'^ '^ »' lawless chaos. But, mistake me n^''' '^™'' "P"' '•"'° ' '""^ ""^ "ot. gravity, rightly ap. Y. trds' distance of 's, however ex- i •' Spun off or '"ng sun-nebula, d a connected then with the first communi- Tyndall writes, its orbit, the he combustion equal to the ig along with y thai cable of the great sun, ■ is forced to of escaping, fish ever held ■ey than does iiay, indeed, 'r> but never ' ; for that, unity of all e. But if I umptions, a ling the be- less and in- a cause, a nere brain- i causa," a I and prove supply the Ket all-per- hows how 'ler as one on's law of apart into ■'ghtly ap. I THE WHY OF GRAVITY. 15 prehended, is for me a great reality— one of the two great powers, (Matter and Energy) that between them rule the cosmos, and, by their ceaseless antagonisms, keep things going, in a state of wholesome activity. But some one may say, how ridiculous, how grotesque, a lump of India- rubber drawn out to explain the world. It is enough to make one laugh. But, I reply, ";/o« saik est risii didiicere rkium," and a laugh or sneer is not always the highest proof of highest wisdom. But Lord Kelvin uses it, too, and even shoe-makers wax to the same end ; and why not ? Now, Clarke Maxwell, who by his own great achieve- ments, has won the open ear of the world to listen wil- lingly to what he says, and who has had the advantage of the matured thinking of all the profou.id and subtile minds who preceded him from Newton's day to the pre- sent, to give precision to his own judgment, and who believes fully in the infallibility of Newton's great law, yet expresses it by a new formula, thus : " Between every pair of particles there is a stress of the nature of a tension " ; and this, to-day, is, I conceive, the way in which physicists regard the matter. Now, though he is in full agreement with Newton, he puts Newton's concep- tion into a new form of words. And though he does not tell us why there is this "stress and tension," yet his for- mula seems to bring the matter more in sight— more nearly in accord with the theory of gravitation, which I have ventured to propose. For '« stress and tension" can scarce exist per se in isolated unrelation to anything. In void space they could not exist (with nothing to attach themselves to.) Indeed, could exist only as " stress and tension " between something and something, involving the necessary concept of something at both ends to keep the line between the pairs of particles taut. As when a string is held strained between two fixed points. Now the " pairs " of particles in the uni- verse are countless billions multiplied by countless bil- lions, between " each pair " of which (up and down, and backward and forward and crosswise) there are I6 THE WHY OK GRAVITV. these countless "stresses and tensions " anrf ,>,■ ■ ,. for every pair of ti.em two fixed 112 of """''" universality of tie-connections Z °^,'"PP°"' '■'- » found the two fixed n„in.l f "'''''^'' "« 'o be particles everywhert bu. ' ,H ""'"''' '"' '""^ P»" -' every particle of Tatter in ,b """"'""'"' "' "^^ "= »' And if this be so Tt cl^" ^' """""= °' '" "'Mer. pose. For here we havrol.n? 7" '*" "-^"^ • P™" every -stress anrtensTon '• f"'.? T'' °' ^"PP"'" '<=' particle of the universal all' Bu in" '^ "^''' °' '=™> could be neither stress nor ,Z '"'P'^ 'P'" '^ere "..nking that this theory^V: ^Tof T' ' ^^""'" "='P separability of universal matte ./ m """•' '"'' '"■ proof-is the most easily re LlbTe'bth" ''V' "' satisfying account of why bod l?,h ^, '"'""^ "^ " affect and are affected bv on. '^°"Sl"»" all nature stance ofa unified whole \°"l;"°'''"' » "- one sub- those sensitive ner>e threads that ^^ -nseparably by .hroughout re.p:xrc„rtt j;rr ■" "■^-- o.rXhLt:;pTanfrot1,p\V- '•-"- ■•» with all their individual properks" so '° '"^ '"^'''' wZd,—- re;er '-"--- tira^s sheep. wolfrh^/ttVnZ^ot'^yt'ictr^r- of n^atte, af ^f trj-^oVX: a^ nic' Tlo^T r' '°™ hn.e ; but of that universal, overlapp le matter '°;.'"' as such -that includes everv form . ■ """"^'^-■natter ■'• But there are a vasfnlt oVrpTc'S k^nd^l^'^ "' terw,th special powers and proper" es of I """'" so, some one mav noinf t„ .u "'^"' °™- And, nd this implies support, i.e., a ere are to be every pair of y of the tie of of ail matter, theory I pro- of support for 'uch, of every y space there f cannot help Jnity and in- as this is of 'e mind as a ut all nature the one sub- separably by ig the whole, rcumference, nt vibrating e include in ) the lowest, nutritious, the animal —elephant, far animal ; 'ich I have pecial form adstone, or er — matter 1 variety of ds of mat- »wn. And, lufactured) 2 product, institution so, pr eoc- THE WHY OF GRAVITY. 17 cupied by current ideas ot the inherent force of attraction of all matter for all-matter, may ask if this case of the loadstone is not a clear instance of attraction of matter for matter by direct natural endowment. To this I reply, no. The loadstone does not really (but only seems to) attract iron to it. "Terrestrial magnetism is due," Lord Kelvin tells us, " to the greatness and rotation of the earth." " Any linear current of electricity," says Professor Lodge, "magnetises at right angles to it every- thing that surrounds it." And Ampere says, " around each molecule of a magnet a current circulates in planes perpendicniar to the axis of each molecule ; and magnet- ism is nothing more than a whirl of electricity; and an electric whirl exists in every magnet and in every part of it, and is the cause of its properties. A magnet is merely an assemblage of polarized particles." In a whirlpool of electricity iron fillings will be sucked up, and, if the elec- tric charge be made strong enough, pieces of iron will be drc ,n up into it, but this is not attraction, but only something incidental to the electric vortex, which by its power and velocity whirls them up into itself. But this whirling motion is no more attraction in any proper sense of the word than can that of the many scattered sticks and straws on the edge of a whirlpool, when get- ting sucked into it, and so whirled into contact with one another, be called the attraction of sticks and straws for sticks and straws, or of these for water ; so " things are not always what they seem." So, too, gravity, real and omnipotent as it is— one of the two coequal powers of the universe— may be found, if we look behind and below mere phenomena, not to stand iu regal isolation by right divine, the one great incomprehensible over-lord, but may be only the necessary outcome of the primordial con- stitution of things, owing to the essential unity of all things. Now, Newton did not believe that gravity was of it- self a force so boundlessly dominant by virtue of native constitution, that it could overleap empty space ; though i8 THE WHY OF GRAVITY. mass and distlL V T-'^"' ''°""' '')' Wm" of tl.at (here musl ba som! 'T "^- '""-did intervene ; enable gravT.y „ ' ° ,nd '"' ""1^' '° '<"" ^P=« 'o from sear to star TJ-^'TT ''""' ""' '" ^"'h -"<' omnipresent ether „1 i^' "" T"'^"^'' ^"'P'>' '»' "'' roadways through alU,M "k""""' '"^'"'■^■'= °f "sy ready to conve^tstnt ea^h^T."""" " "'^^"""' mas^ to .ass a^nd ^^ ^^e t^ r^,:"'^ ™''°" '"" Newt^s^ot:^or;:^;vr:l^'.^T^ ^^- -- where, in a letter to Bentlev hr *^ . ■ """ """<''• writes: " that gravitv ,h uL ^'■"' '^""'^' ''^ H-us sential to matter s'"-' - -'"""'' '"'"''"' ""'' ='• be conveyed from one ,o anothe I ^ ""' '"" ""^ <.6s»>-«(v that I beh-ev, n„ '""' 'f "> me m jto< „ matters'. c™,/i: ri^V;" 7.'''' "as in philosophical So that, according io Sn h^' ""' 7"'"" """ "" lieve in an ether has nn,T "'^" "''° ^°^^ ""t be- On which Lord Ke vta . """"' ^'"='"'>' <" """"ms- giving out his great Iw ITTl " '^'"'^ '^='''™' ■" mat.fr cannotTc: whit u"!:. ""'"'" d'''^''^'' ''■^' Kelvin again tells us ••,!,.. ' ""'' 'f- as Lord a" space! as far aVL rt^^^rsrar:.."^*'' ^"^ why matter always eravifaf«e , conceive mg all space, i.'^'b::„"?p' wUh' ^.^d't^^an ' " ""■ Ci^erywhere. with a .,fr^n„^», r . . °^ ^" '"^"er ate to the ,ual yVf le J.e '",• 'tT^ """""■'"■ a«rac.switVrCercr™i.?s^.r"-frr if a stick be Hffhte' if a ^f u . That is, • I "S'lie , It a stone be heavipr ft fl„ * sinks accordindv Hpvm„ f "^^^'er, it floats or 'J'ngiy. Having fewer particles in a given Y. d exist, and did ^vn by him" of inference that -did intervene ; span space to Jn to earth and d amply by the ►'liads of easy ■ is everywhere itimation from ? i better give is own words, ritic, he thus lerent and es- upon another diation of any - iiid force may e w great an philosophical ■yfall into it." does not be- ' of thinking. Newton, in le idea, that if, as Lord al which fills an conceive ause, as fill- all matter proportion- number of 3f the ties of :le of matter • That is, it floats or in a given THE WHY OF GRAVITY. 19 space, as compared with the water, it floats ; but if hav- ing more particles in the same space, ix., if having more ties binding it to the great earth, it sinks. A cannon-ball lying on the earth is tied to it by gravity, but on being shot upward from the earth by the energy of powder, it is stretched, elongated, doignhl to a certain height before it begins to fall. Now, I wish to represent to myself and to you what takes place on this oc- sion. The ball is held to the earth by Newton's law of mass {i.e., of the number of particles that compose that mass) and by that other " law of inverse squares," which, since the ball is on the earth, gives it great force. Now, the ball is driven upward by the motion imparted to it by the separating and expanding motion of the molecules of the propelling powder, in oppo- sition to the mutual forces of the gravitation of the earth and of the ball combined, while every tie of the earth and of the ball holds it down opposingly. Let us represent to ourselves the tie of gravity, that holds the great earth and the ball together— a tie strong in the exact propor- tion to the quantity of matter in both. A stone forced from the earth into the upper air by an energy is yet tied to the earth— really tied to it, as a consequence of the essential oneness and inseparability of all matter, which is a universal integer, an undivided, indissoluble whole, that no power on earth has ever been able to break up into unconnected parts or to create a vacuum there, its native build forbidding that. And the stone is the more strongly tied to it and by it, by reason of the immeasur- ably greater mass of the earth with its consequent in- numerably greater number of ties— the more the matter the more the ties, the more the inertia— and these ties are further strengthened by the nearness of the two bodies to one another, in accordance with Newton's law of inverse squares. But when an energy {e.g., the separative energy of powder) forces the stone above the earth, in spite of the restraining, but ever yielding, ties of matter, those ties are 30 THE WHY OF GRWITY. theni-elasticitvbll h ^"""^"''^ of elasticity in when bein. ^^st:!::::^ '''''r'' -^^ '-'y no Gulliver was ever mnr V ''"" °^ '"^'■''^- And 'he one to ...e JZ ZITZT' ''""^'^' "'"''•"^ intimalelv related n»,-,. .J ""''-one vast whole of ticularcalareneve; In """ '" '"' ^""^t par- -nd whether dose aVs'e, or't"'''' ■"" °"'^ "°''"< always one „,att!r . V- ■ "°"^ " "'= ^ther, are wn.':::';rc:.r:tttr ■■'''■;-" -- wood or steel when bent) H f" °' * P'"« "f by ...e ,aw or the s;a:::!;f t,^" i:S"'"|;; .-^'"e" tial consideration is this th,f ,. ^"""- '''" "« essen- is one, and refuses o be sp, t „o"' '" "' "'' ""■'-- connected parts „„H„ "^ ^ °' separated into un- a" 'heresoS:cTs s en'eVa'::'""^"""^ "''""^'■' -" availing to deprive a „ aU t? Tf^'>«''""y P'o»=d u„. i' contains, so Is to re^dert", "' "'" '" "'^ ^" can I help rejrardi, e Z,"- ' "'"?, ^'"P'^" ^Pa«- Nor this rupt^rele^s „„ fy w i', Z "'"" """ .»» '^-' "^ ■"ally, it will, as soon as ,h ' ^l 1;.;',J= """■"' '^■">^- upon itself, and hence aJin, .l ^ amoved, return , The ether whLrflir Vaf, ^T "' '""'' the most tenuous of all bodies and allT"'"' ''"'" possesses, as Clerk Maxwell tells „s ■• J/. T""' ^" nacty." Lord Kelvin, too. „ es Lat 'TT '•"" '=• -.>at:^v.t.°"^:f r-- ^ --.•tya„ds„t.:^.°^,VtTfhret:i^?---- Y. kened, as in the on being simi- ch threads, so 3f elasticity iu ively of a b)dy inertia. And the earth, by 3 "11 iie to our iHunerable ties tide, binding vast whole of smallest par- only eloigned, the ether, are ssolubly one. by an energy )f a piece of is modified ut the essen- the universe ted into un- latever, and ^ proved un- n all the air jpace. Nor an e/fcci of ' '-'f'. abnor- ved, return equal. 3test star," vasive, yet :ity and te- I-uminifer- dent of in and that is >w, just as THE WHY OF GRAVITY. ai 1 I I do not regard our world either in its axial oi orbital movements, as slipping through or sliding under our at- mosphere, but as carrying it with it as itself moves ; so may I not believe that any portion of that ether which is never absent anywhere, interpenetrating all parts of all bodies, is ever severed from the whole body of it ; but that the ether, infinitely light and tenuous " one million times lighter than our atmosphere here" is not split up or disrupted by our planet or by any other body, but only accompanies them ever. It is true that [.ord Kel- vin may not hold this view. Still, he is hardly assertive of the contrary, but only says that " perhaps the lumi- niferous ether is split up by a comet passing thrcjgh it." But here he only says "perhaps." And, though h again speaks of " cracks in the ether." yet all this I relc^ ite to the limbo of unverified hypotheses. He himself tells us he looks on it as " hardly more than a vague scientific dream." Still, he holds that " the ether itself is a scien- tific reality." Even the material of Encke's comet, " if forty-five billions times less dense than air at atmosph ric pressure," is still continuous. May it not be that through the ether (inconceivably light and perennially elastic as It is) continuous without a break, no body ever passes ; but that it yields, and yields always, with less resistanre than even the film of a soap-bubble. So may we con- ceive of the ether, which, if left to itself, simply, i.e., r no energy keeps it strained, must spring back elastically. and, so, fulfil Newton's law of reaction being the equal of action. And if, as we know, the great sun in his onward journey through space draws along with him all the planets, satellites and comets of his proper system, why not draw with him him the ether, too ? And, if our world carries with it through the heavens its " cloud of all-sustaining air," why not carry the ether also ? From the centre of nature— and its centre is everywhere— to the utmost bounds or no bounds of the Universal All, gravity rules over mass and particle equally ; for the ties of matter to matter are so universal and unbreakable, 22 THE WHY OF GRAVITY. noticeaWe iLTr '"'"^ °" "^ ^^W ^e scarce ble be'ar^nJ h ^ """""» i" ''. 'bat the wl.olc bub- vanish „',:" a nrbo o'f \h I*"""'^' '"''' "' ""''■ '° other ..eon-es hav^ ol tj^' Ve"; c^Tf ^0.77 --^tre^^s^rr-;:-:^-^;'? a great feat— o »«.. i. "'^- ^^ '^ not claimed to be pared wUlThr'' '""'" °"'' '"'^^^^' '^ °"<^ ^^ all-com- m asfers 'so ence" llr^' achievements of the real for us the myi:: -^s If'the^.vt:: '' ""''' " "-''^^'^ Lordrelv'r'LT'f ""'/^ ^^^^^•" -"^'^-n^. wri.es it notT nT;. ■ P^'""^ °" '^'' ^°^t^^ theory." were It not fo. certam msuperable difficulties • "hnt nV. « Dost " uld fall to tlie presumptions gravity. Still, why not give crated by abler the whole bub- ir of truth, to 'here so many an I not help 1 thought that claimed to be e at all — com- i of the real h to unriddle itions, writes heory," were Jut no finger- can possibly a turning of as discover- ked for from ie separative he earth, in s of matter, retched and ndia-rubber threads, so elasticity in ly of a body ertia. Of Le Sage's theory of push, even if there be allowed to be in the universe those ever flying corpuscles, Nicola Tesla says, that coming from all directions, they would neutralize one another, and could, so, have no effect. Let me add, too, that Newton himself disavowed a push theory. Now, a body, as we have seen, driven out of a state of rest by an energy will react with equal force —New- ton's third law of motion being this, "that when one body exerts force upon another body, that other body reacts with equal force upon the one." And so, when a cannon ball is driven upward by the separative energy of powder, and when the powder has expended its separative heat- energy, in the work done by it, in lifting the ball, then at length comes into play, reactively, the opposite influ- ence acting on it, and it begins to fall, with accelerated motion, stage by stage, corresponding exactly to that with which it had, stage by stage, ascended, and when it strikes the earth and can go no further its molar motion, as a single body, is converted into molecular or heat- motion, and so, as it had begun in separative heat- motion, so it ends, too, in separative heat-motion, and so action and reaction are seen to be equal and oppoiiite. But we must ever bear in mind that this elasticity of the ether is a state of the ether, a property of it and of every molecule of it always ; and Lord Kelvin tells us, that, un- less the perfect elasticity of the ultimate molecules of matter be admitted, the doctrine of the conservation of energy could not be maintained. But elasticity is not something new imparted to the ether ab extra (as motion- energy may be imparted to matter) but is an ever inex- haustible property of it — its own inherently and always, though a secondary one. This is true, for matter is one and inseparable. And gravity, truly interpreted, is the refusal of any one particle of the all to separate itself from the unity of the whole— but must return — no rebel particle anywhere. 24 THE WHY OF GRAVITY. But this ether-clasticity, unlike the energy pf the su-i polarized," writes Faralv - ^^ Particles when verse order in which thev left it •' Th '''"°" '" ^''^ le- power equal to the power that first stretched f nil t'.e wind, now with ,,. izTJrj:\:z''''T amount of i.s power and of us J an. ' Bn T ' owe everytlnng to our ..eat trted ,h" t:: =."£t:=st£i Sir- -nys.er as," is all ,„e world to look o'non ; n d pa fS a certain assun.ptiou. Newton had proved 1.' -i-n)in^ ca»srt c«/«rt«s was still the unanswered ergy pf the sun, as a negative, rated from the hich, though it cts, as soon as d, natural, first on to which it iperious energy ^articles when reed state and ition in the re- 'inpose of the nade on it by e vibrations of tched, eloignf'd dered, but al- I'ith a risilient d it. But how m my youth rs of science 5 Newton, at ir lad, trying now against to learn the But do we hinkers, but rds, Joules, !. etc. And 'as the great •unced New. hers, to dis- fall physical dispair. On his theory What really unanswered THE WHY OF GRAVITY. 2.5 ^M question, as himself tells us. Yet if all matter be, as it is, always one, an indivisible whole, the cannon ball resting on the earth and shot upward is not really severed from the earth, but only eloigned from it for a second; for if reaction be the opposite and equal of action {i e., of the energy that carried it up) then as it seems to me, the cause of gravity is answered ; that is, the ball must return to the earth which it had been forced (apparently) to leave for an instant. It was thus that having lighted on a conception, which, I could not help thinking, had its great trunk-root deep down in the lowest soil of Nature, and which was draw- ing its nutriment, not from a mere sapless "conceptus mathematicus" but whose smallest and remotest fibres to employ the strong words of Newton himself— had "penetrated to the very centre of the sun planets ;" and if action and reaction are equal and opposite, then the ball, whenever it had reached the end of its tether, must, I conceived, come back to its status quo ante, and so the cause of gravity, seemed to me to stand fully revealed. And Newton's "concept" worked out by him with a power and a brilliancy almost super-human in its massive grandeur and completeness, being now b^ised on reality, on the very underlying catisa causans itself, which he had been always seeking, but which, though never losing full faith in its existence as a great reality, he had never been able to visualize in idea— but, being now made known, all his mathematics stand for ever sure. Through his great penetrative genius, it was to him "the evidence of things not seen." Now let me put, in the place of the elastic air and ether, which we cannot see, a thin screen or sheet of elastic india-rubber which we can see, and can observe how it acts; and let us suppose, further, this rubber held firmly to the ground, though a foot or two above it, and with a thin veneer of wood a couple of feet square, under the rubber. Then let an energy of some kind— steam, or powder— be put under the veneer. Now, as the expanding 26 THE WHY OF GRAVITY energy presses against the wood, and the wood against o e" rio ; '•"'^^r'^P^"'^ ^'^^^'^^"^' -^ -"''n- oon as the en"^ '' ''" '""^^ " unexpended. But as soon as the energy ,s spent in the work done in the ex- reaction being the opposite and equal of action-the S !° '°-.^'^""v stored up potentially in the rubber for the enegy imparted to anything is stored up in the body to which It has been imparted) begins to act in a ^^:K::^\;l::ft:a rr ^^"^' " ''-' ^^^ mm. ^ ' "^'' ^^^°^^ expanded, and the to i sZ" ^""'^""-Jf'-'-aHy bn-ngs down'.he wood to Its first position. r/„i, then, and not tlie attraction of matter for matter, of wl.ich „e know nothingand of which Newton knew nothing ; but only (on certaingrounds v^u>na ly bn.lt up h,s magnificent scheme of the cosmos. 7-te as I have been endeavouring to show, is the real (.hough misnamed) gravity, which, besides being sol div harinTiL , r* 'k"""""' " '^ "'= "^» of ' body having had to leave the earth, under compulsion again returning to ,t because it m„st-al„ays must, so l^nf ^ cr rpl'rtr ' A '™'"° nr- """ ^^''^"^'^ ■"'"<«- Crete parts. A cannon ball shot skyward never reallv leaves the earth behind it, but is held to it ever by te of auta t'e'r';''' n ''"^' "=^ "' '"^ ""-verabL Jn^on T,r^l, T ' '""'='■• "'"■'='' '^ '^''P'ble of being ^t, etched to any required length, but cannot be rupturld so as to leave a v.id between, as Faraday says, " We can no. procure a space perfectly free from ma.'e "^L," mllh '",,1"; *''''" "'""'' '=" "=• '"=" '•" 'ha naustion, there are " many millions of air particles " Now Newton himself writes that the theory of aiTrac on ^hich in his hands, answered so admirably as a good work' ■ng hypothesis, ye, failed to satisfy him.' He regarded it' ■3 I as ^W"».iw*\um^(^^ THE WHY OF GRAVITY. 27 e wood against , and continues jnded. But as one in the ex- len, conversely, of action — the ^ in tlie rubber, >red up in the ns to act in a 1 to that with nded, and the lown the wood the attraction othing and of ertain grounds its truth pro- of the cosmos, v, is the real being solidly le mathemati- ise of a body >uIsion, again il, so long as ible into dis- never really ever by the erable union ble of being be ruptured, 's. " We can- ter"— cannot that in the en after ex- r particles." •f attraction, I good work- regarded it as "only a mathematical concept" — "matliematicus duntaxit conceptus" — and said further, that the grounds of these "properties of gravity he had not yet been able to deduce,' nor, for the two centuries since, has any one been able to do so; and yet the cause of gravity was, all the time,' as simple as it was near to each of us. And, if the theory I propose be true, then this mystery of the ages will be resolved, while the powerful mathematical reasoning of this wonderful man, founded, as it will be, on the solid truth of things, will lose no whit of its force, and satis- fied reason will rest henceforth content. What Newton did is to me simply marvellous. Of him his great per- sonal foe, Leibnitz, affirme 1 that " taking mathematics from the beginning of the world to the time when Newton lived, what he had done was much the better half." A stone lying on the earth, and a stone separated from the earth {i.e. above it) are in two wholly different physi- cal states. The first is inert, cannot move itself: the other has stored up in it the energy that lifted it to where it is, and through this energy (nov its own energy) it can react oppositely, as could a stretched india-rubber string. So, too, a piece of india-rubber has itself no energy, but when stretched, it has in it the energy of the stretcher, and owing to this imparted energy it can, when left to itself, react. It was through not seeing this that that very able man, Professor Tait and his fellows made their very serious mistake of making all energy (kinetic and potential), only kinetic — indentifying, as Grant Allen has pointed out, "energy with motion instead of with separ- ation," (or with the energy that caused the separation) "as if kinetic energy were the normal form, and potential energy a peculiar manifestation of it," whereas potential energy, as in the case of a bent bow, is the real parent and cause of all energy. And a stone forced from the earth into the upper air by an energy is yet really, tied to the earth, as a consequence of the essential oneness and insepar- ability of all matter, which no power on earth has ever- 28 THE WHY OF GRATITY. been able to break up into unconnected parts or to create a vacuum th re-its native build forbidding that! And ^ea on of the immeasurably greater mass of the e^rth C when°""'""' innumerably greater number of tTes But when an energy (e.g., the separative energy of now dei) forces the stone above the earfh in •» ? T" are^neve,. r.,u,re,. and ,„e s.one .aturns .^ .he ea'^: »I,.!!°T' ' '? "° ™"'" compelling me to believe thai a noweier lap.dly, sets asideorsplits the ether which yields Pla ceTbv or;""""'- "■ '■"=" ■' '^ "" ™P'-ed ofd/s! at of an bodf • "" """'' °' ""^"""^ ^l'- ; but the light- Xays ' ^™"'"'"""'«='astic everywhere 'and Now, the two great antagonistic powers which divide between them the empire of "the All" are Ma er and Eneigy-separative energy-Energy which as he,, -parates the particles of water in'fo ste m' o „ .^h' as expanding powder or steam, will separate a s,o„ cannon ball from the earth, by lifting tfn.o t ,e ai b^^ wh,ch, when so lifted, the inseparaJe nnity o al ma.^e w,ll at once bring down again to the earth' Ye "dl enough, as ,t seems to me, our scientists have been seei '"g lo manufacture, out of the energies-the r,/, t powers of the world-that gravity of ma." er „,'w, ■ ' Tf passive, tnert, never moving, unless when compelled bv an energy to do so, and ,heu instantly returning o i's old vtote ,„„. But this great Newton, though he hJw not what specifically was rt. cause of gravitation , ho I he tells us himself, that "he had no' be ye.' I Ho ravi^tr-^'d^T" ,"""'"°" °' '"» P™P-''=' °f men was .. ' , ' "'T"^ "'^ ^'" »'"' achieve- ment was merely a mathematical concept." Still it arts or to create I'ng that. And t and by it, by s of the earth lumber of ties, energy of pow- in spite of the ■ ter, those ties s to the earth ' beheve that a a cannon ball 3r which yields jptured or dis- but the light- 'erywhere and > which divide re Matter and ch, as heat, m, or which, ite a stone or the air; but of all matter Yet, oddly ve been seek- i — the active < which is of led power — ompelled by irning to its ?h he knew ion, though yet able to roperties of at achieve- ." Still it THE WHY OF GRAVITY. 29 was far more than this, for he felt in every fibre of his being that there was an underlying cause, ever present and resistless, to which all the marvellous power of gravity was due— a power, he tells us, " that penetrated to the very centre of the sun and the planets [and of al suns and all planets] without any diminution of its force ;" and in this I conceive there was something better than the attraction of matter, even the very union itself of all matter with all matter — a union organic, insepa- rable, eternal. And this unwavering faith that there was a cause adequate to sustain the whole weight of all phe- nomena was the really essential thing, and he accordingly proceeded with his great monumental work ; knowing, as he did, that in the background of everything was the true reality — the great causa causans — which compelled them to be, as his mathematical genius had shown them to be. What matter, then, if, knowing not what the special cause was, his undoubting faith was that such a cause existed. But to return. Even that prince of physicists, Faraday, was so misled as to seek for the cause of gravity among the energies, and, at a late period of his life, to make electricity responsible for gravity ; and, to that end, presented a paper on the subject to his fellows of the Royal Society. But his paper was after- wards withdrawn, at the instance, I think, of Sir George Stokes, as little likely to add to the great man's repu- tation. Now, this question of stored up energy is of such deep importance in our present inquiry, that, even at the risk of being tedious, I must again dwell on it. A stone lying on the earth is in a state of inertia ; it cannot move itself, it is devoid of energy ; but, if lifted above the earth by the energy of my arm, it has my energy in it ; and, owing to the possession of this energy, it can move. Again, if I fling a stone at anything, my energy is in the flying stone now become the stone's energy; and if a pane of glass or the face of a man stands in the way, it or he will experi- 30 THE WHY OF GRAVITY. ence the effect of the stone's energy-an energy which I had .mparted to it. Thus it is that the energy'in^p rted And so t IS that a stone on the earth and a stone above the earth are :n wholly different states physically. The one cannot act; the other can. ^ In the first part of this little brochure, I sought more particularly to show that Jl the matter of the Univ re was by prmiordial constitution, one and inseparable- And the same lesson .s impressed on .me when I look at an object near or far; at a flower near me or a star a njWhon million of miles distant. Now. what really tL e P a e ,n such a case ? Is it not this, vibration after vi! of the i' i" •! f"' '•"'• °' ^^^ "'^^•^ intermediate matter of the mfimtely tenuous, ubiquitous ether; link after link an unbroken chain from flower and star to the sensitive bra.n cells, wh.ch thrill responsive with similar vibrations very object seen and recorded ; just as a photographic plate must passively receive and represent the object presented to U ? But, were only one U of the vibra "g matter severed from the rest by a vacuum, neither flow^ nor star could be seen by the spectator, for matter mu" alwatfir^^Tr''^"' ^ '"^' ^"^^'^«^^' j-^ - -^"er writes «' h. ' ''■ '"'P'"*' "'""^'" 't^^^f' P'°f- Tait writes, the conservation of matter means this, that, do what we may. we cannot alter the mass or quantity c^f a C^o" 1?" :•• '^^ r ^'^"^^ '^^ ^--' ^'--•- entuely alter Us appearance and properties; but its quanity remains unchanged The'only ot'herli g isi^ mTtti"re^r'l'r^T''" ^'^ --- -rTaif .n^ 5 , ^^ * ' • the other objective reality." i-rofessor Lodge, "a radiant force emitted from the sun with the vebc tv of hVlif" tv^^ i "•" me sun '>^ oi ngnt — ib7,ooo miles a second— "the Y. energy which I lergy imparted ed accordingly. I a stone above lysically. The I sought more the Universe inseparable — amantine ties. I'hen I look at [le or a star a t really takes ation after vi- lediate matter ink after link, the sensitive lar vibrations, Jcialty of the photographic It the object the vibrating •either flower matter must St as matter ', Prof. Tait his, that, do uantity of a dimensions, >es) we may es ; but its other thing n the same ive reality." ity," writes om the sun cond — "the THE WHY OF GRAVITY. 31 force experienced would come from a point a little in advance of the sun, and, so, there would be aberration. But gravity appears to be practically instantaneous." So, too, writes Arago ; for is not gravity, indeed, a state of matter, which forbids any real separation — that "feels in each thread and lives along the line," a oneness all-per- vasive, whose centre is everywhere always ? But return- ing to the question of the necessity for the continuity of intervening vibrating matter between us and flower or star in order to our seeing them at all, and, therefore, of the necessity of the continuity of the matter itself that vibrates, I add that, just as in the case of a chain of many links fastened to a log with a horse at the other end at- tached to it to draw it, the rupture of a single link would render the purpose of the chain as unavailing, as if the chain had been wholly absent. But matter is one, insep- arable, continuous ; united to the matter that goes before and which comes after, and with all the matter all round of the universe everywhere. Hence is universal gravity a universal necessity. When a pendulum-bob, attached to a given point by a string, and in a state of rest or inertia, is carried round by the hand a quarter of a circle from its place of repose, and then allowed to take its own natural course, it moves half a circle round in the opposite direction, owing to the energy that first lifted it having been imparted to it, and, so, been laid up in it as its own energy. This acquired energy then carries it back again to the point from which it had first started, and so (if nothing in the point from which it was suspended, has impeded it, and if the air be regarded as eliminated) it would continue to repeat its motion forward and backward, action and reaction being equal and opposite, and the energy renewable and renew- ed at every swing of the bob. Now the bob, you will ob- serve, when it falls, does not fall passively, but actively, compelled at the end of each swing indifferently, when it had reached the end of its tether, tc swing back again 32 THE WHY OF GRAVITY. stored up n ,t for a new start. Now let all tliis be care fully we.fihed i„ all its bearings o„ the current ic eas of R.av.ta ,on. and let unprejudiced judgment say to whicl he scale .ncl.nes. And, ./ what, in this little treaUs have wruten on gravity-its mode and cause-be L he whole quest.on will have to be carefully reconsid d vithT.T' r '"^ '' ^'^ P"^'''^' '-'-^ -"-'e n^ysel^ w.th the thought-;^«n. am ,na,.n-tU,t even the great ought to have been. Sir Willir.n) Petty, a very clever man and a Co Fellow with Newton of tL Royal So It wrote of h.m thus: " Poor Mr. Newton. I l,ave not me w.th one man who put an extraordinary value on h book "-the immortal Principia-" I would g ve five hundred pounds to have been the author of it/' Even he able Huygens thought it strange that Newton should have wasted so much ,.od mathematics on a theory Jh ' seemed to h.m, on the face of it, " absurd." But. wftlou thorough fa>rnessofmind and clearness of iudgmntven grea mathematical ability can prevent no man from greatly mistaken views. " It has been the good fortune ' wntes Ta.t, h.mself a great mathematician. «'of but a ve''y few even amongst the most gifted of mathematicians to be able to thread their way in safety tnrough the countless able till they have done their worst in every part ofeverv region of this fascinating domain." -^ ^^ ' ^ °» every Mathematics, ever since the times of Copernicus Kepler. Galilei and Newton, has held a deservedly IWgh place in the estimation of mankind, and when in L ap propnate sphere of spacial relations can. in the hands of a rea master, do wonders, as it has done in the past but outs.de of that sphere, I would far more trust a Faraday w.h h.s keen observations and experimental tests, than l' would any mathematician without them. " Faraday," V. i each time and all this be care- :urreiit ideas of It say to which little treatise I :ause— be true, ly leconsideid. console myself even the great r valued as he a very clever Koyal Society have not met V value on his uld give five of it." Even lewton should I a theory that But, without idgment, even no man from :ood fortune," "of but a very iticians to be 1 the countless 1 undiscover- part of every Copernicus, iervedly high len in its ap- the hands of the past, but t a Faraday, tests, than I " Faraday," THE-: WHY OF GRAVITY. 33 says Lord Kelvin, " without mathematics, divined the results of mathematical investigation, and, what has proved of infinite value to the mathi.inaticians tliem- selves,'he has given them an articulate language in which to express their results." And Clerl. Maxwell allowed that Faraday's mode of proceeding by experiment was a method superior to his own, the mathematical. And Huxley says, I think, somewhere that, after all, you get nothing in such cases out of mathematics but v/hat you first put into them, or something to that effect. And we should always bear in mind what Professor Tait warns us of, "the countless traps and pitfalls which lurk un- noticed," in mathematics, " even by the most gifted." Energy is a power which bodies have owing to their separation, but which they have not, but lose in the act of combination. A compound, then, is a body that having parted with its energy is passive, inert. The ele- ment fluorine is so energetic that it can scarcely be held in almost any vessel as a single substance, so bent is it on combining with the material of the vessel got to hold it ; yet when combined with lime as a fluoride of calcium how tame it is. As fluor or Derbyshire spar how very ineJt. Water, too, one of the most perfect of com- pounds is unenergetic — a slave to every impression made on it by any outside energy. Yet when water is resolved into its elementary constituents (oxygen and hydrogen, each in an unlike polar state — the oxygen negative, and the hydrogen positive — how energetic they are: separated by electric energy into single elementary bodies they have, as in all such cases, stored up in each of them the energy that se()araled them, and when they again, owing to their opposite polarites, combine, they give up their energies, and are hencetorth, as being a compound, inert. As Herbert Spencer says, during "the combination of oxygen and hydrogen there is an un- paralleled evolution [and loss] of heat." 34 THE WHY OF GRAVITY. Now, in contravention of Grant Alhn'e fj energy is senarafiv^ .. „ ^ ^"^" ^ tli€ory, that mists tell us thaf m,n ,. ■ ^y"amite. Now, che- it as a mixture (Z gu tLef T„" , '" 'f '"^'"''■ of then, are not comZnnds at all b I ^ ^'^ '""' their way to becoming"^ such \vt'„ .1 ■ " °" several elements rsfill in ,k • """'' ^<"'^'^> partments, cotil ' , emi X""'': "t ="""' '"'"• have we a chemical compound •wih.'h' ""' "" """' on explosion, of their ener^v tT , ^°"^="ely expe'lrd'fhat' H,''mrt"r'°',"""^^' """'^ '" "« s.ro„gbarrierof re c ::;::,"; '^ "^^ "■"'°"' " counter to ordinarv hZ, r ' ''''"""'S'' " '' ''oes, wholly new s.a"dLoi„t R J'""""' """ '«'"^'' f"™ a our estimation cerWn vet'L "' "' "'°'' "°' '^^ ""^ °' often vex the somuT "='>■ "^y-an passions, which too way of t:?r b^at^ed^Tudgt °r^\T;s^"^ rf '" '"= great Harvev that nftul .^ "^"*- " '^ related of the not one of tTe^ o ove Z fi v':" °' ^ r^'^"' °' '^'^ ^''^-^' ever believed in hk^l ^°'^'> "five years of age at the time reaojr and high applause. Y. n's tlieory, that cted by an able npotmd chloride dy- Bu?chlor- mpound at all. let us take the e. Now, che- ical compound, case of Dyna- to distinguish 5rt, they both but only on their several ■ several com- not till then, nsequent loss, read with care liat this is as I •ng the loss it is no con. er absolutely hardly to be ad without a g, as it does, reated from a lot lay out of s, which too stand in the ;lated of the id of his day, ' at the time :overy of the lis was Joule of the Royal ks and sky-