By Sir Oliver Lodge 
 
 Life and Matter 
 Continuity 
 
CONTINUITY 
 
 THE PRESIDENTIAL ADDRESS 
 TO THE BRITISH ASSOCIA- 
 TION FOR 1913 
 
 BY 
 
 SIR OLIVER LODGE 
 
 AUTHOR OF "LIFE AND MATTER," ETC. 
 
 SUPPLEMENTED BY EXPLANATORY NOTES 
 
 G. P. PUTNAM'S SONS 
 
 NEW YORK AND LONDON 
 
 IRnfcfeerbocfeer press 
 
 1914 
 
COPYRIGHT 1914 
 
 BY 
 
 G. P PUTNAM'S SONS 
 
 "Cbe fmicfeerbocfcer ipress, Hew Korfe 
 
SUMMARY OF THE ARGUMENT 
 
 A marked feature of the present scientific 
 era is the discovery of, and interest in, va- 
 rious kinds of Atomism; so that Continuity 
 seems in danger of being lost sight of. 
 
 Another tendency is toward comprehen- 
 sive negative generalisations from a limited 
 point of view. 
 
 Another is to take refuge in rather vague 
 forms of statement, and to shrink from 
 closer examination of the puzzling and the 
 obscure. 
 
 Another is to deny the existence of any- 
 thing which makes no appeal to organs of 
 sense, and no ready response to laboratory 
 experiment. 
 
 Against these tendencies the author con- 
 tends. He urges a belief in ultimate con- 
 tinuity as essential to science; he regards 
 scientific concentration as an inadequate 
 basis for philosophic generalisation; he 
 
iv Summary of the Argument 
 
 believes that obscure phenomena may be 
 expressed simply if properly faced; and he 
 points out that the non-appearance of any- 
 thing perfectly uniform and omnipresent 
 is only what should be expected, and is 
 no argument against its real, substantial 
 existence. 
 
Natura non vincitur nisi parendo 
 
CONTINUITY 
 
 FIRST let me lament the catastrophe 
 which has led to my occupying the Chair 
 here in this City. Sir William White was 
 a personal friend of many here present, 
 and I would that the citizens of Bir- 
 mingham could have become acquainted 
 with his attractive personality, and heard 
 at first hand of the strenuous work which 
 he accomplished in carrying out the be- 
 hests of the Empire in the construction 
 of its first line of defence. 
 
 Although a British Association Address 
 is hardly an annual stocktaking, it would 
 be improper to begin this year of Office 
 without referring to four more of our 
 losses: One that cultured gentleman, 
 amateur of science in the best sense, who 
 was chosen to preside over our Jubilee 
 meeting at York thirty-two years ago. 
 Sir John Lubbock, first Baron Avebury, 
 cultivated science in a spirit of pure 
 enjoyment, treating it almost as one of the 
 
2 Presidential Address 
 
 Arts; and he devoted social and political 
 energy to the welfare of the multitude 
 of his fellows less fortunately situated 
 than himself. 
 
 Through the untimely death of Sir 
 George Darwin the world has lost a 
 mathematical astronomer whose work 
 on the Tides and allied phenomena is a 
 monument of power and achievement. 
 So recently as our visit to S. Africa he 
 occupied the Presidential Chair. 
 
 Within the last month I have heard of 
 the premature death of John Milne, who 
 was apparently at the height of his 
 energy and usefulness. His enthusiasm 
 and persevering work for Seismology has 
 resulted in an international organisation 
 centring round his personality. He has, 
 I am told, left 1000 to help continue 
 the work, and it behoves us to see that 
 no sinews of war shall be lacking to 
 assist survivors in organising and con- 
 tinuing the attack in this immensely 
 important field of combined and co- 
 operative research. 
 
Continuity 3 
 
 By the fourth of our major losses, I 
 mean the death of the brilliant Mathe- 
 matician of a neighbouring nation who 
 took so comprehensive and philosophic a 
 grasp of the intricacies of physics, and 
 whose eloquent -though sceptical exposi- 
 tion of our laws and processes, and of the 
 modifications entailed in them by recent 
 advances, will be sure to attract still 
 more widespread attention among all to 
 whom the rather abstruse subject-matter 
 is sufficiently familiar. I cannot say that 
 I find myself in agreement with all that 
 Henri Poincar6 wrote or spoke in the 
 domain of physics, but no physicist can 
 help being interested in his mode of 
 presentation; and I may have occasion 
 to refer, in passing, to some of the topics 
 with which he dealt. 
 
 And now, eliminating from our purview, 
 as is always necessary, a great mass of 
 human activity, and limiting ourselves 
 to a scrutiny on the side of pure science 
 alone, let us ask what, in the main, is 
 the characteristic of the promising though 
 
4 Presidential Address 
 
 perturbing period in which we live. 
 Different persons would give different 
 answers, but the answer I venture to give 
 is Rapid progress, combined with Fun- 
 damental scepticism. 
 
 Rapid progress was not characteristic 
 of the latter half of the nineteenth 
 century, at least not in physics. Fine 
 solid dynamical foundations were laid, 
 and the edifice of knowledge was con- 
 solidated; but wholly fresh ground was 
 not being opened up, and totally new 
 buildings were not expected. 
 
 In many cases the student was led to believe 
 that the main facts of nature were all known, 
 that the chances of any great discovery being 
 made by experiment were vanishingly small, and 
 that therefore the experimentalist's work con- 
 sisted in deciding between rival theories, or in 
 finding some small residual effect, which might 
 add a more or less important detail to the 
 theory. Schuster. 
 
 With the realisation of predicted ether 
 waves in 1888, the discovery of X-rays in 
 1895, spontaneous radioactivity in 1896, 
 
Continuity 5 
 
 and the isolation of the electron in 1898, 
 expectation of further achievement be- 
 came vivid; and novelties, experimental, 
 theoretical, and speculative, have been 
 showered upon us ever since this century 
 began. That is why I speak of rapid 
 progress. 
 
 Of the progress I shall say little, 
 there must always be some uncertainty 
 as to which particular achievement per- 
 manently contributes to it; but I will 
 speak about the fundamental scepticism. 
 
 Let me hasten to explain that I do not 
 mean the well-worn and almost antique 
 theme of Theological scepticism: that 
 controversy is practically in abeyance 
 just now. At any rate the major con- 
 flict is suspended ; the forts behind which 
 the enemy has retreated do not invite 
 attack; the territory now occupied by 
 him is little more than his legitimate pro- 
 vince. It is the scientific allies, now, who 
 are waging a more or less invigorating 
 conflict among themselves; with Phi- 
 losophers joining in. Meanwhile the 
 ancient foe is biding his time and hoping 
 
6 Presidential Address 
 
 that from the struggle something will 
 emerge of benefit to himself. Some posi- 
 tions, he feels, were too hastily abandoned 
 and may perhaps be retrieved; or, to 
 put it without metaphor, it seems possible 
 that a few of the things prematurely 
 denied, because asserted on inconclusive 
 evidence, may, after all, in some form or 
 other, have really happened. Thus the 
 old theological bitterness is mitigated, 
 and a temporising policy is either advo- 
 cated or instinctively adopted. 
 
 To illustrate the nature of the funda- 
 mental scientific or philosophic contro- 
 versies to which, I do refer, would require 
 almost as many addresses as there are 
 Sections of the British Association; or 
 at any rate as many as there are chief 
 cities in Australia; and perhaps my suc- 
 cessor in the Chair will continue the 
 theme; but, to exhibit my meaning very 
 briefly, I may cite the kind of dominating 
 controversies now extant, employing as 
 far as possible only a single word in each 
 case so as to emphasise the necessary 
 brevity and insufficiency of the reference. 
 
Continuity 7 
 
 In Physiology the conflict ranges round Vital- 
 ism. (My immediate predecessor dealt with 
 the subject at Dundee.) 
 
 In Chemistry the debate concerns Atomic 
 structure. (My penultimate predecessor is 
 well aware of pugnacity in that region.) 
 
 In Biology the dispute is on the laws of In- 
 heritance. (My nominated successor is 
 likely to deal with this subject; probably 
 in a way not deficient in liveliness.) 
 
 And besides these major controversies, debate 
 is active in other sections : 
 
 In Education, Curricula generally are being 
 overhauled or fundamentally criticised, and 
 revolutionary ideas are promulgated con- 
 cerning the advantages of freedom for 
 infants. 
 
 In Economic and Political Science, or Soci- 
 ology, what is there that is not under dis- 
 cussion? Not property alone, nor land alone, 
 but everything, back to the garden of Eden 
 and the inter-relations of men and women. 
 
 Lastly, in the vast group of Mathematical 
 and Physical Sciences, "slurred over rather 
 than summed up as Section A," present- 
 day scepticism concerns what, if I had to 
 express it in one word, I should call Con- 
 tinuity. The full meaning of this term will 
 hardly be intelligible without explanation, 
 and I shall discuss it presently. 
 
8 Presidential Address 
 
 Still more fundamental and deep-rooted 
 than any of these sectional debates, 
 however, a -critical examination of scien- 
 tific foundations generally is going on; 
 and a kind of philosophic scepticism is in 
 the ascendant, resulting in a mistrust of 
 purely intellectual processes and in a 
 recognition of the limited scope of science. 
 
 For science is undoubtedly an affair of 
 the intellect, it examines everything in the 
 cold light of reason; and that is its 
 strength. It is a commonplace to say that 
 science must have no likes or dislikes, 
 must aim only at truth; or as Bertrand 
 Russell well puts it, 
 
 The kernel of the scientific outlook is the 
 refusal to regard our own desires, tastes, and 
 interests as affording a key to the understanding 
 of the world. 
 
 This exclusive single-eyed attitude of 
 science is its strength; but, if pressed 
 beyond the positive region of usefulness 
 into a field of dogmatic negation and 
 philosophising, it becomes also its weak- 
 ness. For the nature of man is a large 
 
Continuity 9 
 
 thing, and intellect is only a part of it: 
 a recent part too, which therefore ne- 
 cessarily, though not consciously, suffers 
 from some of the defects of newness and 
 crudity, and should refrain from imagin- 
 ing itself the whole perhaps it is not 
 even the best part of human nature. 
 
 The fact is that some of the best things 
 are, by abstraction, excluded from Science, 
 though not from Literature and Poetry; 
 hence perhaps an ancient mistrust or 
 dislike of science, typified by the Pro- 
 methean legend. Science is systematised 
 and metrical knowledge, and in regions 
 where measurement cannot be applied 
 it has small scope; or, as Mr. Balfour 
 said the other day at the opening of 
 a new wing of the National Physical 
 Laboratory: 
 
 Science depends on measurement, and things 
 not measurable are therefore excluded, or tend 
 to be excluded, from its attention. But Life 
 and Beauty and Happiness are not measurable. 
 [And then characteristically he adds:] If there 
 could be a unit of happiness, Politics might 
 begin to be scientific. 
 
io . Presidential Address 
 
 Emotion and Intuition and Instinct 
 are immensely older than science, and in 
 a comprehensive survey of existence they 
 cannot be ignored. Scientific men may 
 rightly neglect them, in order to do their 
 proper work, but philosophers cannot. 
 
 So Philosophers have begun to question 
 some of the larger generalisations of 
 science, and to ask whether in the effort 
 to be universal and comprehensive we 
 have not extended our laboratory induc- 
 tions too far. The Conservation of En- 
 ergy, for instance, is it always and 
 everywhere valid; or may it under some 
 conditions be disobeyed? It would seem 
 as if the second law of Thermodynamics 
 must be somewhere disobeyed at least 
 if the age of the Universe is both ways 
 infinite, else the final consummation 
 would have already arrived. 
 
 Not by Philosophers only, but by scien- 
 tific men also, ancient postulates are 
 being pulled up by the roots. Physicists 
 and Mathematicians are beginning to 
 consider whether the long-known and well 
 established laws of mechanics hold true 
 
Continuity 1 1 
 
 everywhere and always, or whether the 
 Newtonian scheme must be replaced by 
 something more modern, something to 
 which Newton's laws of motion are but 
 an approximation. 
 
 Indeed a whole system of non-New- 
 tonian Mechanics has been devised, 
 having as its foundation the recently 
 discovered changes which must occur in 
 bodies moving at speeds nearly com- 
 parable with that of light. It turns out 
 in fact that both Shape and Mass are 
 functions of Velocity. As the speed 
 increases the mass increases and the shape 
 is distorted, though under ordinary con- 
 ditions only to an infinitesimal extent. 
 
 So far I agree; I agree with the state- 
 ment of fact; but I do not consider it so 
 revolutionary as to overturn Newtonian 
 Mechanics. After all, a variation of Mass 
 is familiar enough, and it would be a 
 great mistake to say that Newton's 
 second law breaks down merely because 
 Mass is not constant. A raindrop is an 
 example of variable mass; or the earth 
 may be, by reason of meteoric dust; or 
 
12 Presidential Address 
 
 the sun, by reason of radioactivity; or 
 a locomotive, by reason of the emission of 
 steam. In fact, variable masses are the 
 commonest, for friction may abrade any 
 moving body to a microscopic extent. 
 
 That Mass is constant is only an ap- 
 proximation. That Mass is equal to 
 ratio of Force and Acceleration is a de- 
 finition, and can be absolutely accurate. 
 It holds perfectly even for an electron 
 with a speed near that of light ; and it is 
 by means of Newton's second law that 
 the variation of Mass with Velocity has 
 been experimentally observed and com- 
 pared with theory. 
 
 I urge that we remain with, or go back 
 to, Newton. I see no reason against 
 retaining all Newton's laws, discarding 
 nothing, but supplementing them in the 
 light of further knowledge. 
 
 Even the laws of Geometry have been 
 overhauled, and Euclidean Geometry is 
 seen to be but a special case of more 
 fundamental generalisations. How far 
 they apply to existing space, and how far 
 Time is a reality or an illusion, and 
 
Continuity 13 
 
 whether it can in any sense depend on the 
 motion or the position of an observer: 
 all these things in some form or other are 
 discussed. 
 
 The Conservation of Matter also, that 
 mainmast of nineteenth century chem- 
 istry, and the existence of the Ether of 
 Space, that sheet-anchor of nineteenth 
 century physics, do they not sometimes 
 seem to be going by the board? 
 
 Professor Schuster, in his Indian lec- 
 tures, commented on the modern receptive 
 attitude as follows: 
 
 The state of plasticity and flux a healthy 
 state, in my opinion, in which scientific thought 
 of the present day adapts itself to almost any 
 novelty, is illustrated by the complacency with 
 which the most cherished tenets of our fathers 
 are being abandoned. Though it was never an 
 article of orthodox faith that chemical elements 
 were immutable and would not some day be 
 resolved into simpler constituents, yet the con- 
 servation of mass seemed to lie at the very 
 foundation of creation. But nowadays the 
 student finds little to disturb him, perhaps too 
 little, in the idea that mass changes with 
 velocity; and he does not always realise the 
 
14 Presidential Address 
 
 full meaning of the consequences which are 
 involved. 
 
 This readiness to accept and incorpo- 
 rate new facts into the scheme of physics 
 may have led to perhaps an undue amount 
 of scientific scepticism, in order to right 
 the balance. 
 
 But a still deeper variety of compre- 
 hensive scepticism exists, and it is argued 
 that all our laws of nature, so laboriously 
 ascertained and carefully formulated, are 
 but conventions after all, not truths: 
 that we have no faculty for ascertaining 
 real truth, that our intelligence was not 
 evolved for any such academic purpose; 
 that all we can do is to express things in a 
 form convenient for present purposes and 
 employ that mode of expression as a 
 tentative and pragmatically useful ex- 
 planation. 
 
 Even explanation, however, has been 
 discarded as too ambitious by some men 
 of science, who claim only the power to 
 describe. They not -only emphasise the 
 how rather than the why, as is in some 
 sort inevitable, since explanations are 
 
Continuity 15 
 
 never ultimate but are satisfied with 
 very abstract propositions, and regard 
 mathematical equations as preferable to, 
 because safer than, mechanical analogies 
 or models. 
 
 To use an acute and familiar expression of 
 Gustav Kirchhoff, it is the object of science 
 to describe natural phenomena, not to explain 
 them. When we have expressed by an equation 
 the correct relationship between different natural 
 phenomena we have gone as far as we safely can, 
 and if we go beyond we are entering on purely 
 speculative ground. 
 
 But the modes of statement preferred 
 by those who distrust our power of going 
 correctly into detail are far from satis- 
 factory. Professor Schuster describes 
 and comments on them thus: 
 
 Vagueness, which used to be recognised as 
 our great enemy, is now being enshrined as an 
 idol to be worshipped. We may never know 
 what constitutes atoms, or what is the real 
 structure of the ether; why trouble, therefore, 
 it is said, to find out more about them? Is it not 
 safer, on the contrary, to confine ourselves to a 
 general talk on entropy, luminiferous vectors, 
 
16 Presidential Address 
 
 and undefined symbols expressing vaguely cer- 
 tain physical relationships? What really lies at 
 the bottom of the great fascination which these 
 new doctrines exert on the present generation is 
 sheer cowardice; the fear of having its errors 
 brought home to it . . 
 
 I believe this doctrine to be fatal to a healthy 
 development of science. Granting the impos- 
 sibility of penetrating beyond the most super- 
 ficial layers of observed phenomena, I would put 
 the distinction between the two attitudes of 
 mind in this way: One glorifies our ignorance, 
 while the other accepts it as a regrettable 
 necessity. 
 
 With this criticism I am in accord. 
 In further illustration of the modern 
 sceptical attitude, I quote from Poincare : 
 
 Principles are conventions and definitions in 
 disguise. They are, however, deduced from 
 experimental laws, and these laws have, so to 
 speak, been erected into principles to which our 
 mind attributes an absolute value. . . . 
 
 The fundamental propositions of geometry, 
 for instance Euclid's postulate, are only conven- 
 tions; and it is quite as unreasonable to ask if 
 they are true or false as to ask if the metric 
 system is true or false. Only, these conventions 
 are convenient. . 
 
Continuity 17 
 
 Whether the ether exists or not matters little, 
 let us leave that to the metaphysicians ; what 
 is essential for us is that everything happens as 
 if it existed, and that this hypothesis is found to 
 be suitable for the explanation of phenomena. 
 After all, have we any other reason for believing 
 in the existence of material objects? That, too, 
 is only a convenient hypothesis. 
 
 A needed antidote against over-pressing 
 these utterances, however, is provided by 
 Sir J. Larmor in his Preface: 
 
 There has been of late a growing trend of 
 opinion, prompted in part by general philo- 
 sophical views, in the direction that the theoreti- 
 cal constructions of physical science are largely 
 factitious, that instead of presenting a valid 
 image of the relations of things on which further 
 progress can be based, they are still little better 
 than a mirage. . . . 
 
 The best method of abating this scepticism 
 is to become acquainted with the real scope and 
 modes of application of conceptions which, in the 
 popular language of superficial exposition and 
 even in the unguarded and playful paradox of 
 their authors, intended only for the instructed 
 eye often look bizarre enough. 
 
 One thing is very notable, that it is 
 
1 8 Presidential Address 
 
 closer and more exact knowledge that 
 has led to the kind of scientific scepticism 
 now referred to ; and that the simple laws 
 on which we used to be working were thus 
 simple and discoverable because the full 
 complexity of existence was tempered to 
 our ken by the roughness of our means of 
 observation. 
 
 Kepler's laws are not accurately true, 
 and if he had had before him all the data 
 now available he could hardly have dis- 
 covered them. A planet does not really 
 move in an ellipse but in a kind of hypo- 
 cycloid, and not accurately in that either. 
 
 So it is also with Boyle's law, and 
 the other simple laws in Physical Chem- 
 istry. Even Van der Waals' general- 
 isation of Boyle's law is only a further 
 approximation . 
 
 In most parts of physics simplicity has 
 sooner or later to give place to complexity: 
 though certainly I urge that the simple 
 laws were true, and are still true, as far 
 as they go, their inaccuracy being only 
 detected by further real discovery. The 
 reason they are departed from becomes 
 
Continuity 19 
 
 known to us; the law is not really dis- 
 obeyed, but is modified through the 
 action of a known additional cause. 
 Hence it is all in the direction of progress. 
 It is only fair to quote Poincare again, 
 now that I am able in the main to agree 
 with him : 
 
 Take for instance the laws of reflection. 
 Fresnel established them by a simple and at- 
 tractive theory which experiment seemed to con- 
 firm. Subsequently, more accurate researches 
 have shown that this verification was but 
 approximate ; traces or elliptic polarisation were 
 detected elsewhere. But it is owing to the first 
 approximation that the cause of these anomalies 
 was found, in the existence of a transition layer; 
 and all the essentials of Fresnel' s theory have 
 remained. We cannot help reflecting that all 
 these relations would never have been noted if 
 there had been doubt in the first place as to the 
 complexity of the objects they connect. Long 
 ago it was said : If Tycho had had instruments 
 ten times as precise, we would never have had a 
 Kepler, or a Newton, or Astronomy. It is a , 
 misfortune for a science to be born too late, when 
 the means of observation have become too per- 
 fect. That is what is happening at this moment 
 with respect to physical chemistry: the founders 
 
20 Presidential Address 
 
 are hampered in their general grasp by third 
 and fourth decimal places; happily they are 
 men of robust faith. As we get to know the 
 properties of matter better we see that continuity 
 reigns. ... It would be difficult to just- 
 ify [the belief in continuity] by apodeictic 
 reasoning, but without it all science would be 
 impossible. 
 
 Here he touches on my own theme, 
 Continuity; and, if we had to summarise 
 the main trend of physical controversy 
 at present, I feel inclined to urge that it 
 largely turns on the question as to which 
 way ultimate victory lies in the fight 
 between Continuity and Discontinuity. 
 
 On the surface of nature at first we 
 see discontinuity; objects detached and 
 countable. Then we realise the air and 
 other media, and so emphasise continuity 
 and flowing quantities. Then we detect 
 atoms and numerical properties, and dis- 
 continuity once more makes its appear- 
 ance. Then we invent the ether and are 
 impressed with continuity again. But 
 this is not likely to be the end ; and what 
 the ultimate end will be, or whether there 
 
Continuity 21 
 
 is an ultimate end, is a question difficult 
 to answer. 
 
 The modern tendency is to emphasise 
 the discontinuous or atomic character of 
 everything. Matter has long been atomic, 
 in the same sense as Anthropology is 
 atomic; the unit of matter is the atom, 
 as the unit of humanity is the individual. x 
 Whether men or women or children 
 they can be counted as so many " souls. " 
 And atoms of matter can be counted too. 
 
 Certainly, however, there is an illusion 
 of continuity. We recognise it in the 
 case of water. It appears to be a con- 
 tinuous medium, and yet it is certainly 
 molecular. It is made continuous again, 
 in a sense, by the ether postulated in its 
 pores, for the ether is essentially con- 
 tinuous; though Osborne Reynolds, it 
 is true, invented a discontinuous or 
 granular Ether, on the analogy of the 
 sea shore. The sands of the sea, the 
 hairs of the head, the descendants of a 
 
 1 In his recent Canadian Address, Lord Haldane em- 
 phasised the national and social continuity of the human 
 race as opposed to individual discontinuity. 
 
22 Presidential Address 
 
 Patriarch, are typical instances of nu- 
 merable, or rather innumerable, things. 
 The difficulty of enumerating them is 
 not that there is nothing to count, but 
 merely that the things to be counted 
 are very numerous. So are the atoms 
 in a drop of water, they outnumber 
 the drops in an Atlantic Ocean, and, 
 during the briefest time of stating their 
 number, fifty millions or so may have 
 evaporated; but they are as easy to 
 count as the grains of sand on a shore. 
 
 The process of counting is evidently 
 a process applicable to discontinuities, 
 i. e., to things with natural units; you 
 can count apples and coins, and days and 
 years, and people and atoms. To apply 
 number to a continuum you must first 
 cut it up into artificial units; and you 
 are always left with incommensurable 
 fractions. Thus only is it that you can 
 deal numerically with such continuous 
 phenomena as the warmth of a room, the 
 speed of a bird, the pull of a rope, or the 
 strength of a current. 
 
 But how, it may be asked, does discon- 
 
Continuity 23 
 
 tinuity apply to number? The natural 
 numbers, i, 2, 3, etc., are discontinu- 
 ous enough, but there are fractions to 
 fill up the interstices; how do we know 
 that they are not really connected by 
 these fractions, and so made continuous 
 again? 
 
 (By number I always mean commensur- 
 able number; incommensurables are not 
 numbers: they are just what cannot be 
 expressed in numbers. The square root 
 of 2 is not a number, though it can be 
 readily indicated by a length. Incom- 
 mensurables are usual in physics and are 
 frequent in geometry; the conceptions of 
 geometry are essentially continuous. It 
 is clear, as Poincare says, that "if the 
 points whose co-ordinates are commen- 
 surable were alone regarded as real, the 
 in-circle of a square and the diagonal 
 of the square would not intersect, since 
 the co-ordinates of the points of inter- 
 section are incommensurable.") 
 
 I want to explain how commensurable 
 fractions do not connect up numbers, nor 
 remove their discontinuity in the least. 
 
24 Presidential Address 
 
 The divisions on a foot rule, divided as 
 closely as you please, represent commen- 
 surable fractions, but they represent none 
 of the length. No matter how numerous 
 they are, all the length lies between them; 
 the divisions are mere partitions and have 
 consumed none of it ; nor do they connect 
 up with each other, they are essentially 
 discontinuous. The interspaces are in- 
 finitely more extensive than the barriers 
 which partition them off from one another ; 
 they are like a row of compartments 
 with infinitely thin walls. All the incom- 
 mensurables lie in the interspaces; the 
 compartments are full of them, and they 
 are thus infinitely more numerous than 
 the numerically expressible magnitudes. 
 Take any point of the scale at random, 
 that point will certainly lie in an inter- 
 space: it will not lie on a division, for the 
 chances are infinity to I against it. 
 
 Accordingly incommensurable quanti- 
 ties are the rule in physics. Decimals do 
 not in practice terminate or circulate, 
 in other words vulgar fractions do not 
 accidentally occur in any measurements, 
 
Continuity 25 
 
 for this would mean infinite accuracy. 
 We proceed to as many places of decimals 
 as correspond to the order of accuracy 
 aimed at. 
 
 Whenever, then, a commensurable number 
 is really associated with any natural phe- 
 nomenon, there is necessarily a noteworthy 
 circumstance involved in the fact, and it 
 means something quite definite and ulti- 
 mately ascertainable. Every discontinuity 
 that can be detected and counted is an 
 addition to knowledge. It not only means 
 the discovery of natural units instead of 
 being dependent on artificial ones, but it 
 throws light also on the nature of phe- 
 nomena themselves. 
 
 For instance: 
 
 The ratio between the velocity of light 
 and the inverted square root of the pro- 
 duct of the electric and magnetic con- 
 stants was discovered by Clerk Maxwell 
 to be i ; and a new volume of physics was 
 by that discovery opened. 
 
 Dalton found that chemical combina- 
 tion occurred between quantities of dif- 
 ferent substances specified by certain 
 
26 Presidential Address 
 
 whole or fractional numbers; and the 
 atomic theory of matter sprang into sub- 
 stantial though at first infantile existence. 
 
 The hypothesis of Prout, which in some 
 modified form seems likely to be sub- 
 stantiated, is that all atomic weights are 
 commensurable numbers; in which case 
 there must be a natural fundamental 
 unit underlying, and in definite groups 
 composing, the atoms of every form of 
 matter. 
 
 The small number of degrees of freedom 
 of a molecule, and the subdivision of its 
 total energy into equal parts correspond- 
 ing thereto, is a theme not indeed without 
 difficulty but full of importance. It is 
 responsible for the suggestion that energy 
 too may be atomic! 
 
 Mendelejeff's series again, or the detec- 
 tion of a natural grouping of atomic 
 weights in families of seven, is another 
 example of the significance of number. 
 
 Electricity was found by Faraday to be 
 numerically connected with quantity of 
 matter ; and the atom of electricity began 
 its hesitating but now brilliant career. 
 
Continuity 27 
 
 Electricity itself i. e., electric charge 
 strangely enough has proved itself to be 
 atomic. There' is a natural unit of 
 electric charge, as suspected by Faraday 
 and Maxwell and named by Johnstone 
 Stoney. Some of the electron's visible 
 effects were studied by Crookes in a 
 vacuum; and its weighing and measuring 
 by J. J. Thomson were announced to the 
 British Association meeting at Dover in 
 1899 a striking prelude to the twentieth 
 century. 
 
 An electron is the natural unit of 
 negative electricity, and it may not be 
 long before the natural unit of positive 
 electricity is found too. But concerning 
 the nature of the positive unit there is at 
 present some division into opposite camps. 
 One school prefers to regard the unit of 
 positive electricity as a homogeneous 
 sphere, the size of an atom, in which elec- 
 trons revolve in simple harmonic orbits 
 and constitute nearly the whole effective 
 mass. Another school, while appreci- 
 ating the simplicity and ingenuity and 
 beauty of the details of this conception, 
 
28 Presidential Address 
 
 and the skill with which it has been 
 worked out, yet thinks the evidence more 
 in favour of a minute ' central positive 
 nucleus, or nucleus-group, of practically 
 atomic mass; with electrons, larger i. e., 
 less concentrated and therefore less 
 massive than itself, revolving round it in 
 astronomical orbits. While from yet an- 
 other point of view it is insisted that 
 positive and negative electrons can only 
 differ skew-symmetrically, one being like 
 the image of the other in a mirror, and 
 that the mode in which they are grouped 
 to form an atom remains for future dis- 
 covery. But no one doubts that elec- 
 tricity is ultimately atomic. 
 
 Even magnetism has been suspected 
 of being atomic, and its hypothetical unit 
 has been named in advance the magneton: 
 but I confess that here I have not been 
 shaken out of the conservative view. 
 
 We may express all this as an invasion 
 of number into unexpected regions. 
 
 Biology may be said to be becoming 
 atomic. It has long had natural units 
 in the shape of cells and nuclei, and some 
 
Continuity 29 
 
 discontinuity represented by body -bound- 
 aries and cell-walls; but now, in its laws 
 of heredity as studied by Mendel, number 
 and discontinuity are strikingly apparent 
 among the reproductive cells, and the 
 varieties of offspring admit of numerical 
 specification and prediction to a surpris- 
 ing extent; while modification by con- 
 tinuous variation, which seemed to be of 
 the essence of Darwinism, gives place to, 
 or at least is accompanied by, mutation, 
 with finite and considerable and in ap- 
 pearance discontinuous change. So far 
 from Nature not making jumps, it be- 
 comes doubtful if she does anything else. 
 Her hitherto placid course, more closely 
 examined, is beginning to look like a kind 
 of steeplechase. 
 
 Yet undoubtedly Continuity is the 
 backbone of evolution, as taught by all 
 biologists no artificial boundaries or de- 
 marcations between species a continuous 
 chain of heredity from far below the 
 amoeba up to man. Actual continuity 
 of undying germ-plasm, running through 
 all generations, is taught likewise; though 
 
3Q Presidential Address 
 
 a strange discontinuity between this 
 persistent element and its successive 
 accessory body-plasms a discontinuity 
 which would convert individual organisms 
 into mere temporary accretions or excre- 
 tions, with no power of influencing or 
 conveying experience to their generating 
 cells is advocated by one school. 
 
 Discontinuity does not fail to exercise 
 fascination even in pure Mathematics. 
 Curves are invented which have no 
 tangent or differential coefficient, curves 
 which consist of a succession of dots or of 
 twists ; and the theory of commensurable 
 numbers seems to be exerting a dominance 
 over philosophic mathematical thought 
 as well as over physical problems. 
 
 And not only these fairly accepted 
 results are prominent, but some more 
 difficult and unexpected theses in the same 
 direction are being propounded, and the 
 atomic character of Energy is advocated. 
 We had hoped to be honoured by the 
 presence of Professor Planck, whose 
 theory of the quantum, or indivisible unit 
 or atom of energy, excites the greatest 
 
Continuity 31 
 
 interest, and by some is thought to hold 
 the field. 1 
 
 Then again Radiation is showing signs 
 of becoming atomic or discontinuous. 
 The corpuscular theory of radiation is 
 by no means so dead as in my youth we 
 thought it was. Some radiation is cer- 
 tainly corpuscular, and even the etherial 
 kind shows indications, which may be 
 misleading, that it is spotty, or locally 
 concentrated into points, as if the wave- 
 front consisted of detached specks or 
 patches; or, as J. J. Thomson says, "the 
 wave-front must be more analogous to 
 bright specks on a dark ground than to a 
 uniformly illuminated surface, " thus sug- 
 gesting that the Ether may be fibrous in 
 structure, and that a wave runs along 
 lines of electric force; as the genius of 
 Faraday surmised might be possible, in 
 his "Thoughts on Ray Vibrations. " In- 
 deed Newton guessed something of the 
 same kind, I fancy, when he superposed 
 ether-pulses on his corpuscles. 
 
 Whatever be the truth in this matter, a 
 
 1 Se;e page 37. 
 
32 Presidential Address 
 
 discussion on Radiation, of extreme 
 weight and interest, though likewise of 
 great profundity and technicality, is ex- 
 pected on Friday in Section A. We wel- 
 come Professor Lorentz, Dr. Arrhenius, 
 Professor Jeans, Professor Pringsheim, 
 and others, some of whom have been 
 specially invited to England because of 
 the important contributions which they 
 have made to the subject-matter of this 
 discussion. 
 
 Why is so much importance attached 
 to Radiation? Because it is the best- 
 known and longest-studied link between 
 matter and ether, and the only property 
 we are acquainted with that affects the 
 unmodified great mass of ether alone. 
 Electricity and magnetism are associated 
 with the modifications or singularities 
 called electrons. Heat and sound are 
 connected still more directly with matter. 
 Radiation, however, though excited by an 
 accelerated electron, is subsequently let 
 loose in the ether of space, and travels as 
 a definite thing at a measurable and 
 constant pace a pace independent of 
 
Continuity 33 
 
 everything so long as the ether is free, 
 unmodified and unloaded by matter. 
 Hence radiation has much to teach us, 
 and we have much to learn concerning its 
 nature. 
 
 How far can the analogy of granular, 
 corpuscular, countable, atomic, or dis- 
 continuous things be pressed? There 
 are those who think it can be pressed very 
 far. But to avoid misunderstanding let 
 me state, for what it may be worth, that 
 I myself am an upholder of ultimate Con- 
 tinuity, and a fervent believer in the 
 Ether of Space. 
 
 We have already learnt something 
 about the ether; and although there may 
 be almost as many varieties of opinion 
 as there are people qualified to form one, 
 in my view we have learnt as follows: 
 
 The Ether is the universal connecting 
 medium which binds the universe to- 
 gether, and makes it a coherent whole 
 instead of a chaotic collection of inde- 
 pendent isolated fragments. It is the 
 vehicle of transmission of all manner of 
 force, from gravitation down to cohesion 
 
34 Presidential Address 
 
 and chemical affinity; it is therefore the 
 storehouse of potential energy. 
 
 Matter moves, but Ether is strained. 
 
 What we call elasticity of matter is 
 only the result of an alteration of con- 
 figuration due to movement and read- 
 justment of particles, but all the strain 
 and stress are in the ether. The ether 
 itself does not move, that is to say it does 
 not move in the sense of locomotion, 
 though it is probably in a violent state 
 of rotational or turbulent motion in its 
 smallest parts; and to that motion its 
 exceeding rigidity is due. 
 
 As to its density, it must be far greater 
 than that of any form of matter, millions 
 of times denser than lead or platinum. 
 Yet matter moves through it with per- 
 fect freedom, without any friction or 
 viscosity. There is nothing paradoxical 
 in this: viscosity is not a function of 
 density; the two are not necessarily 
 connected. When a solid moves through 
 an alien fluid it is true that it acquires 
 a spurious or apparent extra inertia 
 from the fluid it displaces; but, in the 
 
Continuity 35 
 
 case of matter and ether, not only is even 
 the densest matter excessively porous 
 and discontinuous, with vast interspaces 
 in and among the atoms, but the consti- 
 tution of matter is such that there appears 
 to be no displacement in the ordinary 
 sense at all; the ether is itself so modified 
 as to constitute the matter in some way. 
 Of course that portion moves, its inertia 
 is what we observe, and its amount de- 
 pends on the potential energy in its 
 associated electric field, but the motion 
 is not like that of a foreign body, it 
 is that of some inherent and merely 
 individualised portion of the stuff itself. 
 Certain it is that the ether exhibits no 
 trace of viscosity. 1 
 
 Matter in motion, Ether under strain, 
 constitute the fundamental concrete 
 things we have to do with in physics. 
 The first pair represent kinetic energy, 
 the second potential energy; and all the 
 
 1 For details of my experiment on this subject see Phil. 
 Trans. Roy.Soc. for 1893 and 1897; or a very abbreviated 
 reference to it, and to the other matters above-mentioned, 
 in my small book The Ether of Space. 
 
36 Presidential Address 
 
 activities of the material universe are 
 represented by alternations from one 
 of these forms to the other. 
 
 Whenever this transference and trans- 
 formation of energy occur, work is done, 
 and some effect is produced, but the 
 energy is never diminished in quantity: 
 it is merely passed on from one body to 
 another, always from ether to matter 
 or vice versa, except in the case of 
 radiation, which simulates matter, and 
 from one form to another. 
 
 The forms of energy can be classified 
 as either a translation, a rotation, or a 
 vibration, of pieces of matter of different 
 sizes, from stars and planets down to 
 atoms and electrons; or else an etherial 
 strain which in various different ways is 
 manifested by the behaviour of such 
 masses of matter as appeal to our senses. J 
 
 Some of the facts responsible for the 
 suggestion that energy is atomic seem to 
 me to depend on the discontinuous nature 
 of the structure of a material atom, and 
 
 1 See, in the Philosophical Magazine for October, 1879, 
 my article on a Classification of the forms of energy. 
 
Continuity 37 
 
 on the high velocity of its constituent 
 particles. The apparently discontinu- 
 ous emission of radiation is, I believe, 
 due to features in the real discontinuity 
 of matter. Disturbances inside an atom 
 appear to be essentially catastrophic; 
 a portion is liable to be ejected with 
 violence. There appears to be a critical 
 velocity below which ejection does not 
 take place; and, when it does, there also 
 occurs a sudden rearrangement of parts 
 which is presumably responsible for some 
 perceptible etherial radiation. Hence it 
 is, I suppose, that radiation comes off 
 in gushes or bursts ; and hence it appears 
 to consist of indivisible units. The 
 occasional phenomenon of new stars, as 
 compared with the steady orbital mo- 
 tion of the millions of recognised bodies, 
 may be suggested as an astronomical 
 analogue. 
 
 The hypothesis of quanta was devised 
 to reconcile the law that the energy of a 
 group of colliding molecules must in the 
 long run be equally shared among all 
 their degrees of freedom, with the ob- 
 
33 Presidential Address 
 
 served fact that the energy is really shared 
 into only a small number of equal parts. 
 For if vibration-possibilities have to be 
 taken into account, the number of de- 
 grees of molecular freedom must be very 
 large, and energy shared among them 
 ought soon to be all frittered away; 
 whereas it is not. Hence the idea is 
 suggested that minor degrees of freedom 
 are initially excluded from sharing the 
 energy, because they cannot be supplied 
 with less than one atom of it. 
 
 I should prefer to express the fact by 
 saying that the ordinary encounters of 
 molecules are not of a kind able to excite 
 atomic vibrations, or in any way to dis- 
 turb the ether. Spectroscopic or lumin- 
 ous vibrations of an atom are excited only 
 by an exceptionally violent kind of col- 
 lision, which may be spoken of as chemi- 
 cal clash; the ordinary molecular orbital 
 encounters, always going on at the rate 
 of millions a second, are ineffective in 
 that respect, except in the case of phos- 
 phorescent or luminescent substances. 
 That common molecular deflexions are 
 
Continuity 39 
 
 ineffective is certain, else all the energy 
 would be dissipated or transferred from 
 matter into the ether ; and the reasonable- 
 ness of their radiative inefficiency is 
 not far to seek, when we consider the 
 comparatively leisurely character of 
 molecular movements, at speeds com- 
 parable with the velocity of sound. 
 Admittedly, however, the effective 
 rigidity of molecules must be complete, 
 otherwise the sharing of energy must 
 ultimately occur. They do not seem 
 able to be set vibrating by anything less 
 than a certain minimum stimulus; and 
 that is the basis for the theory of quanta. 
 Quantitative applications of Planck's 
 theory, to elucidate the otherwise shaky 
 stability of the astronomically consti- 
 tuted atom, have been made; and the 
 agreement between results so calculated 
 and those observed, including a deter- 
 mination of series of spectrum lines, is 
 very remarkable. One of the latest con- 
 tributions to this subject is a paper by 
 Dr. Bohr in the Philosophical Maga- 
 zine for July, 1913. 
 
40 Presidential Address 
 
 To show that I am not exaggerating 
 the modern tendency towards discon- 
 tinuity, I quote, from M. Poincare's 
 Dernieres Pensees, a proposition which 
 he announces in italics as representing a 
 form of Professor Planck's view of which 
 he apparently approves: 
 
 A physical system is susceptible of a finite 
 number only of distinct conditions; it jumps 
 from one of these conditions to another without 
 passing through a continuous series of inter- 
 mediate conditions. 
 
 Also this from Sir Joseph Larmor's 
 Preface to Poincare's Science and 
 Hypothesis: 
 
 Still more recently it has been found that 
 the good Bishop Berkeley's logical jibes against 
 the Newtonian ideas of fluxions and limiting 
 ratios cannot be adequately appeased in the 
 rigorous mathematical conscience, until our 
 apparent continuities are resolved mentally 
 into discrete aggregates which we only partially 
 apprehend. The irresistible impulse to atomise 
 everything thus proves to be not merely a dis- 
 ease of the physicist: a deeper origin, in the 
 nature of knowledge itself, is suggested. 
 
Continuity 41 
 
 One very valid excuse for this preva- 
 lent attitude is the astonishing progress 
 that has been made in actually seeing or 
 almost seeing the molecules, and study- 
 ing their arrangement and distribution. 
 
 The laws of gases have been found to 
 apply to emulsions and to fine powders in 
 suspension, of which the Brownian move- 
 ment has long been known. This move- 
 ment is caused by the orthodox molecular 
 bombardment, and its average amplitude 
 exactly represents the theoretical mean 
 free path calculated from the "molecular 
 weight" of the relatively gigantic particles. 
 The behaviour of these microscopically 
 visible masses corresponds closely and 
 quantitatively with what could be pre- 
 dicted for them as fearfully heavy atoms, 
 on the kinetic theory of gases; they may 
 indeed be said to constitute a gas with a 
 gram-molecule as high as 200,000 tons; 
 and, what is rather important as well as 
 interesting, they tend visibly to verify 
 the law of equipartition of energy even 
 in so extreme a case, when that law 
 is properly stated and applied. 
 
42 Presidential Address 
 
 Still more remarkable the application 
 of X-rays to display the arrangement of 
 molecules in crystals, and ultimately the 
 arrangement of atoms in molecules, as 
 initiated by Professor Laue with Drs. 
 Friedrich and Knipping, and continued 
 by Professor Bragg and his son and by 
 Dr. Tutton, constitute a series of re- 
 searches of high interest and promise. 
 By this means many of the theoretical 
 anticipations of our countryman, Mr. 
 William Barlow, and working with him 
 Professor Pope, as well as of those dis- 
 tinguished crystallographers von Groth 
 and von Fedorow, have been confirmed 
 in a striking way. These brilliant re- 
 searches, which seem likely to constitute 
 a branch of Physics in themselves, and 
 which are being continued by Messrs. 
 Moseley and C. G. Darwin, and by Mr. 
 Keene and others, may be called an apo- 
 theosis of the atomic theory of matter. 
 
 One other controversial topic I shall 
 touch upon in the domain of physics, 
 though I shall touch upon it lightly for 
 it is not a matter for easy reference as 
 
Continuity 43 
 
 yet. If the "Principle of Relativity" in 
 an extreme sense establishes itself, it 
 seems as if even Time would become dis- 
 continuous and be supplied in atoms, as 
 money is doled out in pence or centimes 
 instead of continuously; in which case 
 our customary existence will turn out to 
 be no more really continuous than the 
 events on a kinematograph screen; 
 while that great agent of continuity, the 
 Ether of Space, will be relegated to the 
 museum of historical curiosities. 
 
 In that case differential equations 
 will cease to represent the facts of nature, 
 they will have to be replaced by Finite 
 Differences, and the most fundamen- 
 tal revolution since Newton will be 
 inaugurated. 
 
 Now in all the debatable matters of 
 which I have indicated possibilities I 
 want to urge a conservative attitude. I 
 accept the new experimental results on 
 which some of these theories such as the 
 Principle of Relativity are based, and 
 am profoundly interested in them, but 
 I do not feel that they are so revolution- 
 
44 Presidential Address 
 
 ary as their propounders think. I see a 
 way to retain the old and yet embrace 
 the new, and I urge moderation in the 
 uprooting and removal of landmarks. 
 
 And of these the chief is Continuity. 
 I cannot imagine the exertion of mechan- 
 ical force across empty space, no matter 
 how minute; a continuous medium seems 
 to me essential. I cannot admit dis- 
 continuity in either Space or Time, nor 
 can I imagine any sort of experiment 
 which would justify such a hypothesis. 
 For surely we must realise that we know 
 nothing experimental of either space or 
 time, we cannot modify them in any 
 way. We make experiments on bodies, 
 and only on bodies, using "body*' as an 
 exceedingly general term. 
 
 We have no reason to postulate any- 
 thing but continuity for space and time. 
 We cut them up into conventional units 
 for convenience sake, and those units 
 we can count; but there is really nothing 
 atomic or countable about the things 
 themselves. We can count the rotations 
 of the earth, or the revolutions of an 
 
Continuity 45 
 
 electron, or the vibrations of a pendulum 
 or the waves of light. All these are con- 
 crete and tractable physical entities; but 
 space and time are ultimate data, ab- 
 stractions based on experience. We know 
 them through motion, and through 
 motion only, and motion is essentially 
 continuous. We ought clearly to dis- 
 criminate between things themselves and 
 our mode of measuring them. Our 
 measures and perceptions may be af- 
 fected by all manner of incidental and 
 trivial causes, and we may get confused 
 or hampered by our own movement; 
 but there need be no such complication 
 in things themselves, any more than a 
 landscape is distorted by looking at it 
 through an irregular window-pane or 
 from a travelling coach. It is an ancient 
 and discarded fable that complications 
 introduced by the motion of an observer 
 are real complications belonging to the 
 outer universe. 
 
 Very well, then, what about the Ether; 
 is that in the same predicament? Is that 
 an abstraction, or a mere convention, or 
 
46 Presidential Address 
 
 is it a concrete physical entity on which 
 we can experiment? 
 
 Now it has to be freely admitted that 
 it is exceedingly difficult to make experi- 
 ments on the ether. It does not appeal 
 to sense, and we know no means of getting 
 hold of it. The one thing we know 
 metrical about it is the velocity with 
 which it can transmit transverse waves. 
 That is clear and definite, and thereby 
 to my judgment it proves itself a physical 
 agent; not indeed tangible or sensible, 
 but yet concretely real. 
 
 But it does elude our laboratory grasp. 
 If we rapidly move matter through it, 
 hoping to grip it and move it too, we 
 fail: there is no mechanical connection. 
 And even if we experiment on light we 
 fail too. So long as transparent matter 
 is moving relatively to us, light can be 
 affected inside that matter; but when 
 matter is relatively stationary to matter 
 nothing observable takes place, however 
 fast things may be moving, so long as 
 they move together. 
 
 Hence arises the idea that motion with 
 
Continuity 47 
 
 respect to Ether is meaningless: and the 
 fact that only relative motion of pieces 
 of matter with respect to each other has 
 so far been observed is the foundation of 
 the Principle of Relativity. It sounds 
 simple enough as thus stated, but in its 
 developments it is an ingenious and com- 
 plicated doctrine embodying surprising 
 consequences which have been worked 
 out by Professor Einstein and his disciples 
 with consummate ingenuity. 
 
 What have I to urge against it? Well, 
 in the first place, it is only in accordance 
 with common sense that no effect of 
 the first order can be observed with- 
 out relative motion of matter. An 
 Ether-stream through our laboratories is 
 optically and electrically undetectable, 
 at least as regards first-order observa- 
 tion; this is clearly explained for general 
 readers in my book The Ether of 
 Space, Chapter TV. But the Principle of 
 Relativity says more than that, it says 
 that no effect of any order of magnitude 
 can ever be observed, without the rela- 
 tive motion of matter. 
 
48 Presidential Address 
 
 The truth underlying this doctrine is 
 that absolute motion without reference 
 to anything is unmeaning. But the 
 narrowing down of " any thing" to mean 
 any piece of matter is illegitimate. The 
 nearest approach to absolute motion 
 that we can physically imagine is motion 
 through or with respect to the Ether of 
 Space. It is natural to assume that the 
 Ether is on the whole stationary, and to 
 use it as a standard of rest; in that sense 
 motion with reference to it may be called 
 absolute, but in no other sense. 
 
 The Principle of Relativity claims that 
 we can never ascertain such motion: in 
 other words it practically or pragmati- 
 cally denies the existence of the Ether. 
 Every one of our scientifically observed 
 motions, it says, are of the same nature 
 as our popularly observed ones, viz., 
 motion of pieces of matter relatively to 
 each other; and that is all that we can 
 ever know. Everything goes on says 
 the Principle of Relativity as if the 
 Ether did not exist. 
 
 Now the facts are that no motion with 
 
Continuity 49 
 
 reference to the ether alone has ever yet 
 been observed: there are always curious 
 compensating effects which just cancel 
 out the movement-terms and destroy or 
 effectively mask any phenomenon that 
 might otherwise be expected. When 
 matter moves past matter observation 
 can be made; but, even so, no consequent 
 locomotion of ether, outside the actually 
 moving particles, can be detected. 
 
 (It is sometimes urged that rotation 
 is a kind of absolute motion that can be 
 detected, even in isolation. It can so be 
 detected, as Newton pointed out; but 
 in cases of rotation matter on one side 
 the axis is moving in the opposite direc- 
 tion to matter on the other side of the 
 axis; hence rotation involves relative 
 material motion, and therefore can be 
 observed.) 
 
 To detect motion through ether we 
 must use an etherial process. We may 
 use radiation, and try to compare 
 the speeds of light along or across the 
 motion; or we might try to measure the 
 speed, first with the motion and then 
 
50 Presidential Address 
 
 against it. But how are we to make the 
 comparison? If the time of emission 
 from a distant source is given by a dis- 
 tant clock, that clock must be observed 
 through a telescope, that is by a beam of 
 light; which is plainly a compensating 
 process. Or the light from a neighbouring 
 source can be sent back to us by a distant 
 mirror ; when again there will be compen- 
 sation. Or the starting of light from a 
 distant terrestrial source may be tele- 
 graphed to us, either with a wire or with- 
 out; but it is the ether that conveys the 
 message in either case, so again there 
 will be compensation. Electricity, Mag- 
 netism, and Light, are all effects of the 
 ether. 
 
 Use Cohesion, then; have a rod stretch- 
 ing from one place to another, and 
 measure that. But cohesion is trans- 
 mitted by the ether too, if, as believed, 
 it is the universal binding medium. 
 Compensation is likely; compensation 
 can, on the electrical theory of matter, 
 be predicted. 
 
 Use some action not dependent on 
 
Continuity 51 
 
 Ether, then. Very well, where shall we 
 find it? 
 
 To illustrate the difficulty I will quote 
 a sentence from Sir Joseph Larmor's 
 paper before the International Congress 
 of Mathematicians at Cambridge last 
 year. 
 
 If it is correct to say with Maxwell that all 
 radiation is an electrodynamic phenomenon, 
 it is equally correct to say with him that all 
 electrodynamic relations between material bod- 
 ies are established by the operation, on the 
 molecules of those bodies, of fields of force which 
 are propagated in free space as radiation and in 
 accordance with the laws of radiation, from one 
 body to the other. 
 
 The fact is we are living in an epoch 
 of some very comprehensive generalisa- 
 tions. The physical discovery of the 
 twentieth century, so far, is the Electrical 
 Theory of Matter. This is the great new 
 theory of our time; it was referred to, 
 in its philosophical aspect, by Mr. Bal- 
 four in his Presidential Address at Cam- 
 bridge in 1904. We are too near to it to 
 be able to contemplate it properly; it 
 
52 Presidential Address 
 
 has still to establish itself and to develop 
 in detail, but I anticipate that in some 
 form or other it will prove true. x 
 
 Here is a briefest possible summary of 
 the first chapter (so to speak) of the 
 Electrical Theory of Matter. 
 
 (1) Atoms of Matter are composed of elec- 
 trons, of positive and negative electric 
 charges. 
 
 (2) Atoms are bound together into molecules 
 by chemical affinity which is intense elec- 
 trical attraction at ultra-minute distances. 
 
 (3) Molecules are held together by cohesion, 
 which I for one regard as residual or differ- 
 ential chemical affinity over molecular dis- 
 tances. 
 
 (4) Magnetism is due to the locomotion of 
 electrons. There is no magnetism with- 
 out an electric current, atomic or otherwise. 
 There is no electric current without a 
 moving electron. 
 
 (5) Radiation is generated by every accel- 
 erated electron, in amount proportional to 
 the square of its acceleration; and there is 
 no other kind of radiation, except indeed 
 
 1 For a general introductory account of the electrical 
 theory of matter my Romanes lecture for 1903 (Claren- 
 don Press) may be referred to. 
 
Continuity 53 
 
 a corpuscular kind; but this depends on 
 the velocity of electrons, and therefore 
 again can only be generated by their accel- 
 eration. 
 
 The theory is bound to have curious 
 consequences; and already it has con- 
 tributed to some of the uprooting and 
 uncertainty that I speak of. For, if it 
 be true, every material interaction will 
 be electrical, i. e., etherial; and hence 
 arises our difficulty. Every kind of 
 force is transmitted by the ether, and 
 hence, so long as all our apparatus is 
 travelling together at one and the same 
 pace, we have no chance of detecting the 
 motion. That is the strength of the 
 Principle of Relativity. The changes are 
 not zero, but they cancel each other out of 
 observation. 
 
 Many forms of statement of the 
 famous Michelson-Morley experiment 
 are misleading. It is said to prove that 
 the time taken by light to go with the 
 ether-stream is the same as that taken 
 to go against or across it. It does not 
 show that. What it shows is that the 
 
54 Presidential Address 
 
 time taken by light to travel to and fro 
 on a measured interval fixed on a rigid 
 block of matter is independent of the 
 aspect of that block with respect to any 
 motion of the earth through space. A 
 definite and most interesting result: but 
 it may be, and often is, interpreted 
 loosely and too widely. 
 
 It is interpreted too widely, as I think, 
 when Professor Einstein goes on to as- 
 sume that no non-relative motion of 
 matter can be ever observed even when 
 light is brought into consideration. The 
 relation of light to matter is very curious. 
 The wave front of a progressive wave 
 simulates many of the properties of 
 matter. It has energy, it has momentum, 
 it exerts force, it sustains reaction. It 
 has been described as a portion of the 
 mass of a radiating body, which gives 
 it a curiously and unexpectedly corpuscu- 
 lar ' ' feel. ' ' But it has a definite velocity. 
 Its velocity in space relative to the ether 
 is an absolute constant independent of 
 the motion of the source. This would 
 not be true for corpuscular light. 
 
Continuity 55 
 
 Hence I hold that here is something 
 with which our own motion may theoreti- 
 cally be compared; and I predict that 
 our motion through the ether will some 
 day be detected by help of this very 
 fact, by comparing our speed with that 
 of light: though the old astronomical 
 aberration, which seemed to make the 
 comparison easy, failed to do so quite 
 simply, because it is complicated by the 
 necessity of observing the position of a 
 distant source, in relation to which the 
 earth is moving. If the source and 
 observer are moving together there is 
 no possibility of observing aberration. 
 Nevertheless I maintain that when mat- 
 ter is moving near a beam of light we 
 may be able to detect the motion. For 
 the velocity of light in space is no func- 
 tion of the velocity of the source, nor of 
 matter near it; it is quite unaffected 
 by motion of source or receiver. Once 
 launched it travels in its own way. If 
 we are travelling to meet it, it will be 
 arriving at us more quickly; if we travel 
 away from it, it will reach us with some 
 
56 Presidential Address 
 
 lag. That is certain; and observation 
 of the acceleration or retardation is 
 made by aid of Jupiter's satellites. We 
 have there the dial of a clock, to or from 
 which we advance or recede periodically. 
 It gains while we approach it, it loses 
 while we recede from it, it keeps right 
 time when we are stationary or only 
 moving across the line of sight. 
 
 But then of course it does not matter 
 whether Jupiter is standing still and we 
 are moving, or vice versa: it is a case of 
 relative motion of matter again. So it 
 is if we observe a Doppler effect from the 
 right and left hand limbs of the rotating 
 sun. True, and if we are to permit no 
 relative motion of matter we must use a 
 terrestrial source, clamped to the earth 
 as our receiver is. And now we shall 
 observe nothing. 
 
 But not because there is nothing to 
 observe. Lag must really occur if we 
 are running away from the light, even 
 though the source is running after us at 
 the same pace: unless we make the 
 assumption true only for corpuscular 
 
Continuity 57 
 
 light that the velocity of light is not 
 an absolute thing, but is dependent on 
 the speed of the source. With corpuscu- 
 lar light there is nothing to observe ; with 
 wave light there is something, but we 
 cannot observe it. 
 
 But if the whole solar system is moving 
 through the ether I see no reason why 
 the relative ether drift should not 
 be observed by a differential residual 
 effect in connection with Jupiter's satel- 
 lites or the right and left limbs of the 
 sun. The effect must be too small to 
 observe without extreme precision, but 
 theoretically it ought to be there. In- 
 asmuch however as relative motion of 
 matter with respect to the observer is 
 involved in these effects, it may be held 
 that the detection of a uniform drift of 
 the solar system in this way is not con- 
 trary to the Principle of Relativity. It 
 is contrary to some statements of that 
 Principle; and the cogency of those 
 statements breaks down, I think, when- 
 ever they include the velocity of light; 
 because there we really have something 
 
58 Presidential Address 
 
 absolute (in the only sense in which the 
 term can have a physical meaning) with 
 which we can compare our own motion, 
 when we have learnt how. 
 
 But in ordinary astronomical transla- 
 tion translation as of the earth in 
 its orbit all our instruments, all our 
 standards, the whole contents of our 
 laboratory, are moving at the same rate 
 in the same direction ; under those condi- 
 tions we cannot expect to observe any- 
 thing. Clerk Maxwell went so far as 
 to say that if every particle of matter 
 simultaneously received a graduated 
 blow so as to produce a given constant 
 acceleration all in the same direction, we 
 should be unaware of the fact. He did 
 not then know all that we know about 
 radiation. But apart from that, and 
 limiting ourselves to comparatively slow 
 changes of velocity, our standards will 
 inevitably share whatever change occurs. 
 So far as observation goes, everything 
 will be practically as if no change had 
 occurred at all ; though that may not be 
 the truth. All that experiment estab- 
 
Continuity 59 
 
 lishes is that there have so far always been 
 compensations; so that the attempt to 
 observe motion through the ether is being 
 given up as hopeless. 
 
 Surely, however, the minute and curi- 
 ous compensations cannot be accidental, 
 they must be necessary. Yes, they are 
 necessary ; and I want to say why. Sup- 
 pose the case were one of measuring 
 thermal expansion; and suppose every- 
 thing had the same temperature and the 
 same expansibility; our standards would 
 contract or expand with everything else, 
 and we could observe nothing ; but expan- 
 sion would occur nevertheless. That is 
 obvious, but the following assertion is not 
 so obvious. If everything in the Uni- 
 verse had the same temperature, no 
 matter what that temperature was, 
 nothing would be visible at all ; the exter- 
 nal world, so far as vision went, would not 
 appear to exist. Visibility depends on 
 radiation, on differential radiation. We 
 must have differences to appeal to our 
 senses, they are not constructed for uni- 
 formity. 
 
60 Presidential Address 
 
 It is the extreme omnipresence and 
 uniformity and universal agency of the 
 ether of space that makes it so difficult to 
 observe. To observe anything you must 
 have differences. If all actions at a dis- 
 tance are conducted at the same rate 
 through the ether, the travel of none of 
 them can be observed. Find something 
 not conveyed by the ether and there is a 
 chance. But then every physical action 
 is transmitted by the ether, and in every 
 case by means of its transverse or radi- 
 ation-like activity. 
 
 Except perhaps Gravitation. That 
 may give us a clue some day, but at 
 present we have not been able to detect 
 its speed of transmission at all. No plan 
 has been devised for measuring it. No- 
 thing short of the creation or destruction 
 of matter seems likely to serve: creation 
 or destruction of the gravitational unit, 
 whether it be an atom or an electron or 
 whatever it is. Most likely the unit of 
 weight is an electron, just as the unit 
 of mass is. 
 
 The so-called non-Newtonian Median- 
 
Continuity 61 
 
 ics, with mass and shape a function of 
 velocity, is an immediate consequence of 
 the electrical theory of matter. The de- 
 pendence of inertia and shape on speed 
 is a genuine discovery and, I believe, 
 a physical fact. The Principle of Rela- 
 tivity would reduce it to a conventional 
 fiction. It would seek to replace this real 
 change in matter by imaginary changes in 
 time. But surely we must admit that 
 Space and Time are essentially unchange- 
 able: they are not at the disposal even of 
 mathematicians; though it is true that 
 Pope Gregory, or a Daylight-saving Bill, 
 can play with our units, can turn the ^d 
 of October in any one year into the I4th, 
 or can make the sun South sometimes at 
 eleven o'clock, sometimes at twelve. 1 
 
 But the changes of dimension and mass 
 due to velocity are not conventions but 
 
 1 In the historical case of governmental interference with 
 the calendar, no wonder the populace rebelled. Surely 
 some one might have explained to the authorities that 
 dropping leap-year for the greater part of a century would 
 do all that was wanted, and that the horrible inconven- 
 ience of upsetting all engagements and shortening a single 
 year by eleven days could be avoided. 
 
62 Presidential Address 
 
 realities; so I urge, on the basis of the 
 electrical theory of matter. The Fitz- 
 gerald -Lorentz hypothesis I have an af- 
 fection for; I was present at its birth. 
 Indeed I assisted at its birth ; for it was in 
 my study at 21 Waverley Road, Liver- 
 pool, with Fitzgerald in an arm-chair, and 
 while I was enlarging on the difficulty 
 of reconciling the then new Michelson 
 experiment with the theory of astronomi- 
 cal aberration and with other known 
 facts, that he made his brilliant surmise: 
 "Perhaps the stone slab was affected by 
 the motion." I rejoined that it was a 45 
 shear that was needed. To which he 
 replied, " Well that's all right, a simple 
 distortion. " And very soon he said, 
 "And I believe it occurs, and that the 
 Michelson experiment demonstrates it." 
 A shortening long-ways, or a lengthening 
 cross-ways would do what was wanted. 
 (See Nature for 16 June, 1892.) 
 
 And is such a hypothesis gratuitous? 
 Not at all: in the light of the electrical 
 theory of matter such an effect ought to 
 occur. The amount required by the 
 
Continuity 63 
 
 experiment, and given by the theory, is 
 equivalent to a shrinkage of the earth's 
 diameter by rather less than three inches, 
 in the line of its orbital motion through 
 the ether of space. An oblate spheroid 
 with the proper eccentricity has all the 
 simple geometrical properties of a station- 
 ary sphere; the eccentricity depends in 
 a definite way on speed, and becomes 
 considerable as the velocity of light is 
 approached. 
 
 All this Professors Lorentz and Lar- 
 mor very soon after, and quite independ- 
 ently, perceived; though this is only one 
 of the minor achievements in the electri- 
 cal theory of matter which we owe to 
 our distinguished visitor Professor H. A. 
 Lorentz. 
 
 The key of the position, to my mind, 
 is the nature of cohesion. I regard co- 
 hesion as residual chemical affinity, a 
 balance of electrical attraction over re- 
 pulsion between groups of alternately 
 charged molecules. Lateral electrical 
 attraction is diminished by motion; so 
 is lateral electric repulsion. In cohesion 
 
64 Presidential Address 
 
 both are active, and they nearly balance 
 At anything but molecular distance they 
 quite balance, but at molecular dis- 
 tance attraction predominates. It is the 
 diminution of the predominant partner 
 that will be felt. Hence while longi- 
 tudinal cohesion, or cohesion in the direc- 
 tion of motion, remains unchanged, lateral 
 cohesion is less ; so there will be distortion, 
 and a unit cube x y z moving along x with 
 velocity u becomes a parallelepiped with 
 sides i/k 2 , k, k; where i/k 6 = i - u 2 /v 2 . ' 
 The electrical theory of matter is a 
 positive achievement, and has positive 
 results. By its aid we make experiments 
 which throw light upon the relation be- 
 tween matter and the Ether of Space. 
 The Principle of Relativity, which seeks 
 to replace it, is a principle of negation, a 
 
 1 Different modes of estimating the change give slightly 
 different results; some involve a compression as well as a 
 distortion in fact the strain associated with the name of 
 Thomas Young ; the details are rather complicated and this 
 is not the place to discuss them. A pure distortion, as 
 specified in the text, is simplest, it appears to be in accord 
 with all the experimental facts including some careful 
 measurements by Bucherer, and I rather expect it to 
 survive. 
 
Continuity 65 
 
 negative proposition, a statement that 
 observation of certain facts can never be 
 made, a denial of any relation between 
 matter and ether, a virtual denial that 
 the ether exists. Whereas if we admit 
 the real changes that go on by reason of 
 rapid motion, a whole field is open for 
 discovery; it is even possible to investi- 
 gate the changes in shape of an electron 
 appallingly minute though it is as it 
 approaches the speed of light ; and prop- 
 erties belonging to the Ether of Space, 
 evasive though it be, cannot lag far 
 behind. 
 
 Speaking as a physicist I must claim 
 the Ether as peculiarly our own domain. 
 The study of molecules we share with the 
 chemist, and matter in its various forms is 
 investigated by all men of science, but a 
 study of the ether of space belongs to 
 physics only. I am not alone in feeling 
 the fascination of this portentous en- 
 tity. Its curiously elusive and intangible 
 character, combined with its universal 
 and unifying permeance, its apparently 
 infinite extent, its definite and perfect 
 
66 Presidential Address 
 
 properties, make the ether the most inter- 
 esting as it is by far the largest and most 
 fundamental ingredient in the material 
 cosmos. 
 
 As Sir J. J. Thomson said at Winnipeg: 
 
 The ether is not a fantastic creation of the 
 speculative philosopher ; it is as essential to us 
 as the air we breathe. . . . The study of this 
 all-pervading substance is perhaps the most 
 fascinating and important duty of the physicist. 
 
 Matter it is not, but material it is; it 
 belongs to the material universe and is 
 to be investigated by ordinary methods. 
 But to say this is by no means to deny 
 that it may have mental and spiritual 
 functions to subserve in some other order 
 of existence, as Matter has in this. 
 
 The ether of space is at least the great 
 engine of continuity. It may be much 
 more, for without it there could hardly 
 be a material universe at all. Certainly, 
 however, it is essential to continuity; 
 it is the one all-permeating substance 
 that binds the whole of the particles 
 of matter together. It is the uniting 
 
Continuity 67 
 
 and binding medium without which, if 
 matter could exist at all, it could only 
 exist as chaotic and isolated fragments: 
 and it is the universal medium of com- 
 munication between worlds and between 
 particles. And yet it is possible for 
 people to deny its existence, because it is 
 unrelated to any of our senses, except 
 sight, and to that only in an indirect and 
 not easily recognised fashion. 
 
 To illustrate the thorough way in 
 which we may be unable to detect what 
 is around us unless it has some link or 
 bond which enables it to make appeal, 
 let me make another quotation from Sir 
 J. J. Thomson's Address at Winnipeg in 
 1909. He is leading up to the fact that 
 even single atoms, provided they are 
 fully electrified with the proper atomic 
 charge, can be detected by certain deli- 
 cate instruments their field of force 
 bringing them within our ken whereas a 
 whole crowd of unelectrified ones would 
 escape observation. 
 
 The smallest quantity of unelectrified matter 
 ever detected is probably that of neon, one of 
 
68 Presidential Address 
 
 the inert gases of the atmosphere. Professor 
 Strutt has shown that the amount of neon in 
 1/20 of a cubic centimetre of the air at ordinary 
 pressures can be detected by the spectroscope; 
 Sir William Ramsay estimates that the neon 
 in the air only amounts to one part of neon in 
 100,000 parts of air, so that the neon in 1/20 
 of a cubic centimetre of air would only occupy at 
 atmospheric pressure a volume of half a mil- 
 lionth of a cubic centimetre. When stated in 
 this form the quantity seems exceedingly small, 
 but in this small volume there are about ten 
 million million molecules. Now the population 
 of the earth is estimated at about fifteen hun- 
 dred millions, so that the smallest number of 
 molecules of neon we can identify is about 7000 
 times the population of the earth. In other 
 frords, if we had no better test for the existence 
 of a man than we have for that of an unelectri- 
 fied molecule we should come to the conclusion 
 that the earth is uninhabited. 
 
 The parable is a striking one, for on 
 these lines it might legitimately be con- 
 tended that we have no right to say posi- 
 tively that even space is uninhabited. 
 All we can safely say is that we have no 
 means of detecting the existence of non- 
 planetary immaterial dwellers, and that 
 
Continuity 69 
 
 unless they have some link or bond with 
 the material they must always be physic- 
 ally beyond our ken. We may therefore 
 for practical purposes legitimately treat 
 them as non-existent until such link 
 is discovered, but we should not dog- 
 matise about them. True agnosticism 
 is legitimate, but not the dogmatic and 
 positive and gnostic variety. 
 
 For I hold that Science is incompetent 
 to make comprehensive denials, even 
 about the Ether, and that it goes wrong 
 when it makes the attempt. Science 
 should not deal in negations: it is strong 
 in affirmations, but nothing based on 
 abstraction ought to presume to deny 
 outside its own region. It often happens 
 that things abstracted from and ignored 
 by one branch of science may be taken 
 into consideration by another: 
 
 Thus, Chemists ignore the Ether. 
 
 Mathematicians may ignore experi- 
 mental difficulties. 
 
 Physicists ignore and exclude live 
 things. 
 
70 Presidential Address 
 
 Biologists exclude Mind and Design. 
 
 Psychologists may ignore human origin 
 and human destiny. 
 
 Folk-lore students and comparative 
 Mythologists need not trouble about 
 what modicum of truth there may be 
 in the legends which they* are collecting 
 and systematising. 
 
 And Microscopists may ignore the 
 stars. 
 
 Yet none of these ignored things should 
 be denied. 
 
 Denial is no more infallible than asser- 
 tion. There are cheap and easy kinds 
 of scepticism, just as there are cheap 
 and easy kinds of dogmatism; in fact 
 scepticism can become viciously dog- 
 matic, and science has to be as much on 
 its guard against personal predilection in 
 the negative as in the positive direction. 
 An attitude of universal denial may be 
 very superficial. 
 
 To doubt everything or to believe everything 
 are two equally convenient solutions; both dis- 
 pense with the' necessity of reflection. 
 
Continuity 71 
 
 All intellectual processes are based on 
 abstraction, that is on concentrated 
 attention directed to a selected portion, 
 with limitation of scope, and elimination 
 of whatever may be regarded as unessen- 
 tial or irrelevant. For instance, History 
 must ignore a great multitude of facts 
 in order to treat any intelligently: it 
 selects. So does Art; and that is why a 
 drawing is clearer than reality. Science 
 makes a diagram of reality, displaying the 
 works, like a skeleton clock. Anatomists 
 dissect out the nervous system, the blood- 
 vessels, and the muscles, and depict them 
 separately, there must be discrimin- 
 ation for intellectual grasp, but in life 
 they are all merged and co-operating 
 together; they do not really work separ- 
 ately, though they may be studied separ- 
 ately. A scalpel discriminates: a dagger 
 or a bullet crashes through everything. 
 That is life, or rather death. The laws 
 of nature are a diagrammatic frame- 
 work, analysed or abstracted out of the 
 full comprehensiveness of reality. 
 
 Hence it is that Science has no au- 
 
72 Presidential Address 
 
 thority in denials. To deny effectively 
 needs much more comprehensive know- 
 ledge than to assert. And abstraction is 
 essentially not comprehensive: one can- 
 not have it both ways. Science employs 
 the methods of abstraction and thereby 
 makes its discoveries. 
 
 The reason why some physiologists 
 insist so strenuously on the validity and 
 self-sufficiency of the laws of physics and 
 chemistry, and resist the temptation to 
 appeal to unknown causes even though 
 the guiding influence and spontaneity of 
 living things are occasionally conspicuous 
 as well as inexplicable is that they are 
 keen to do their proper work; and their 
 proper work is to pursue the laws of 
 ordinary physical Energy into the intri- 
 cacies of "colloidal electrolytic structures 
 of great chemical complexity" and to 
 study its behaviour there. 
 
 What we have clearly to grasp, on their 
 testimony, is that for all the terrestrial 
 manifestations of life. the ordinary phys- 
 ical and chemical processes have to serve. 
 There are not new laws for living matter, 
 
Continuity 73 
 
 and old laws for non-living, the laws are 
 the same; or if ever they differ, the 
 burden of proof rests on him who sustains 
 the difference. The conservation of en- 
 ergy, the laws of chemical combination, 
 the laws of electric currents, of radiation, 
 etc., etc., all the laws of Chemistry and 
 Physics, may be applied without hesita- 
 tion in the Organic domain. Whether 
 they are sufficient is open to question, 
 but as far as they go they are necessary; 
 and it is the business of the physiologist 
 to seek out and demonstrate the action 
 of those laws in every vital action. 
 
 This is clearly recognised by the leaders, 
 and in the definition of Physiology by 
 Burdon Sanderson he definitely limited 
 it to the study of "ascertainable char- 
 acters of a chemical and physical type." 
 In his Address to the Sub-section of 
 Anatomy and Physiology at York in 
 1 88 1 he spoke as follows: 
 
 It would give you a true idea of the nature 
 of the great advance which took place about the 
 middle of this century if I were to define it as 
 the epoch of the death of ' 'vitalism." Before 
 
74 Presidential Address 
 
 that time, even the greatest biologists e.g., 
 J. M tiller recognised that the knowledge bio- 
 logists possessed both of vital and physical 
 phenomena was insufficient to refer both to a 
 common measure. The method, therefore, was 
 to study the processes of life in relation to each 
 other only. Since that time it has become 
 fundamental in our science not to regard any 
 vital process as understood at all unless it can 
 be brought into relation with physical standards, 
 and the methods of physiology have been based 
 exclusively on this principle. The most efficient 
 cause [conducing to the change] was the progress 
 which had been made in physics and chemistry, 
 and particularly those investigations which led 
 to the establishment of the doctrine of the Con- 
 servation of Energy. ...- . . 
 
 Investigators who are now working with such 
 earnestness in all parts of the world for the ad- 
 vance of physiology, have before them a definite 
 and well-understood purpose, that purpose being 
 to acquire an exact knowledge of the chemical 
 and physical processes of animal life and of the 
 self-acting machinery by which they are regu- 
 lated for the general good of the organism. The 
 more singly and straightforwardly we direct our 
 efforts to these ends, the sooner we shall attain 
 to the still higher purpose the effectual applica- 
 tion of our knowledge for the increase of human 
 happiness. 
 
Continuity 75 
 
 Professor Gotch, whose recent loss we 
 have to deplore, puts it even more 
 strongly: 
 
 It is essentially unscientific [he says] to say 
 that any physiological phenomenon is caused 
 by vital force. 
 
 I observe that by some critics I have 
 been called a vitalist, and in a sense I am ; 
 but I am not a vitalist if vitalism means 
 an appeal to an undefined ''vital force" 
 (an objectionable term I have never 
 thought of using) as against the laws 
 of Chemistry and Physics. Those laws 
 must be supplemented, but need by no 
 means be superseded. The business of 
 science is to trace out their mode of 
 action everywhere, as far and as fully as 
 possible; and it is a true instinct which 
 resents the mediaeval practice of freely 
 introducing spiritual and unknown causes 
 into working science. In science an 
 appeal to occult qualities must be illegiti- 
 mate, and be a barrier to experiment and 
 research generally; as, when anything is 
 called an Act of God and when no more is 
 
76 Presidential Address 
 
 said. The occurrence is left unexplained. 
 As an ultimate statement such a phrase 
 may be not only true but universal in 
 its application. But there are always 
 proximate explanations which may be 
 looked for and discovered with patience. 
 So, lightning, earthquakes, and other 
 portents are reduced to natural causes. 
 No ultimate explanation is ever attained 
 by science: proximate explanations only. 
 They are what it exists for; and it is the 
 business of scientific men to seek them. 
 
 To attribute the rise of sap to vital 
 force would be absurd, it would be giving 
 up the problem and stating nothing at all. 
 The way in which osmosis acts to produce 
 the remarkable and surprising effect is 
 discoverable and has been discovered. 
 
 So it is always in science, and its pro- 
 gress began when unknown causes were 
 eliminated and treated as non-existent. 
 Those causes, so far as they exist, must 
 establish their footing by direct investiga- 
 tion and research; carried on in the first 
 instance apart from the long recognised 
 branches of science, until the time when 
 
Continuity 77 
 
 they too have become sufficiently definite 
 to be entitled to be called scientific. 
 Outlandish Territories may in time be in- 
 corporated as States, but they must make 
 their claim good and become civilised 
 first. 
 
 It is well for people to understand this 
 definite limitation of scope quite clearly, 
 else they wrest the splendid work of 
 biologists to their own confusion, helped 
 it is true by a few of the more robust or 
 less responsible theorisers, among whom 
 are some who should be better informed 
 and more carefully critical in their philo- 
 sophising utterances. 
 
 But, as is well known, there are more 
 than a few biologists who, when taking 
 a broad survey of their subject, clearly 
 perceive and teach that before all the 
 actions of live things are fully explained, 
 some hitherto excluded causes must be 
 postulated. Ever since the time of J. R. 
 Mayer it has been becoming more and 
 more certain that as regards performance 
 of work, a living thing obeys the laws of 
 physics, like everything else; 'but un- 
 
78 Presidential Address 
 
 doubtedly it initiates processes and pro- 
 duces results that without it could not 
 have occurred, from a bird's nest to a 
 honeycomb, from a deal box to a warship. 
 The behaviour of a ship firing shot and 
 shell is explicable in terms of energy, but 
 the discrimination which it exercises be- 
 tween friend and foe is not so explicable. 
 There is plenty of physics and chemistry 
 and mechanics about every vital action, 
 but for a complete understanding of it 
 something beyond physics and chemistry 
 is needed. 
 
 And life introduces an incalculable 
 element. The vagaries of a fire or a 
 cyclone could all be predicted by La- 
 place's Calculator, given the initial 
 positions, velocities, and the law of accel- 
 eration of the molecules; but no mathe- 
 matician could calculate the orbit of a 
 common house-fly. A physicist into whose 
 galvanometer a spider had crept would be 
 liable to get phenomena of a kind quite 
 inexplicable, until he discovered the super- 
 natural, i.e., literally superphysical, cause. 
 I will risk the assertion that Life intro- 
 
Continuity 79 
 
 duces something incalculable and purpose- 
 ful amid the laws of physics; it thus 
 distinctly supplements those laws, though 
 it leaves them otherwise precisely as they 
 were and obeys them all. 
 
 We see only its effect, we do not see 
 Life itself. Conversion of Inorganic into 
 Organic is effected always by living 
 organisms. The conversion under those 
 conditions certainly occurs, and the pro- 
 cess may be studied. Life appears nec- 
 essary to the conversion; which clearly 
 takes place under the guidance of life, 
 though in itself it is a physical and 
 chemical process. Many laboratory con- 
 versions take place under the guidance of 
 life, and, but for the experimenter, would 
 not have occurred. 
 
 Again, putrefaction, and fermentation, 
 and purification of rivers, and disease, 
 are not purely and solely chemical pro- 
 cesses. Chemical processes they are, but 
 they are initiated and conducted by 
 living organisms. Just when medicine is 
 becoming biological, and when the hope 
 of making the tropical belt of the earth 
 
8o Presidential Address 
 
 healthily habitable by energetic races 
 is attracting the attention of people of 
 power, philosophising biologists should 
 not attempt to give their science away 
 to Chemistry and Physics. Sections D 
 and H and I and K are not really sub- 
 servient to A and B. Biology is an 
 independent science, and it is served, not 
 dominated, by Chemistry and Physics. 
 
 Scientific men are hostile to supersti- 
 tion, and rightly so, for a great many 
 popular superstitions are both annoying 
 and contemptible; yet occasionally the 
 term may be wrongly applied to practices 
 of which the theory is unknown. To a 
 superficial observer some of the practices 
 of biologists themselves must appear 
 grossly superstitious. To combat malaria 
 Sir Ronald Ross does not indeed erect an 
 altar ; no, he oils a pond, making libation 
 to its presiding genii. What can be more 
 ludicrous than the curious and evidently 
 savage ritual, insisted on by United States 
 Officers, at that hygienically splendid 
 achievement the Panama Canal, the 
 ritual of punching a hole in every dis- 
 
Continuity 81 
 
 carded tin, with the object of keeping 
 off disease! What more absurd, again 
 in superficial appearance than the prac- 
 tice of burning or poisoning a soil to make 
 it extra fertile ! 
 
 Biologists in their proper field are 
 splendid, and their work arouses keen 
 interest and enthusiasm in all whom they 
 guide into their domain. Some of them 
 do their work by intense concentration, 
 by narrowing down their scope, not by 
 taking a wide survey or a comprehensive 
 grasp. Suggestions of broader views and 
 outlying fields of knowledge seem foreign 
 to the intense worker, and he resents them^ 
 For his own purpose he wishes to ignore 
 them, and practically he may be quite 
 right. The folly of negation is not his, 
 but belongs to those who misinterpret or 
 misapply his utterances, and take him as 
 a guide in a region where, for the time at 
 least, he is a stranger. Not by such aid 
 is the universe in its broader aspects to be 
 apprehended. If people in general were 
 better acquainted with science they would 
 not make these mistakes. They would 
 
82 Presidential Address 
 
 realise both the learning and the limita- 
 tions, make use of the one and allow for 
 the other, and not take the recipe of a 
 practical worker for a formula wherewith 
 to interpret the Universe. 
 
 What appears to be quite certain is that 
 there can be no terrestrial manifestation 
 of life without matter. Hence naturally 
 they say, or they approve such sayings as, 
 "I discern in matter the promise and 
 potency of all forms of life." Of all 
 terrestrial manifestations of life, certainly; 
 how else could it manifest itself save 
 through matter? "I detect nothing in 
 the organism but the laws of Chemistry 
 and Physics," it is said. Very well: 
 naturally enough. That is what they 
 are after; they are studying the physical 
 and chemical aspects or manifestations 
 of life. But life itself life and mind and 
 consciousness they are not studying, 
 and they exclude them from their pur- 
 view. Matter is what appeals to our 
 senses here and now; Materialism is ap- 
 propriate to the material world; not as a 
 philosophy but as a working creed, as a 
 
Continuity 83 
 
 proximate and immediate formula for 
 guiding research. Everything beyond 
 that belongs to another region, and must 
 be reached by other methods. To explain 
 the Psychical in terms of Physics and 
 Chemistry is simply impossible; hence 
 there is a tendency to deny its existence, 
 save as an epiphenomenon. But all such 
 philosophising is unjustified, and is really 
 bad Metaphysics. 
 
 So if ever in their enthusiasm scientific 
 workers go too far and say that the things 
 they exclude from study have no existence 
 in the universe, we must appeal against 
 them to direct experience. We ourselves 
 are alive, we possess life and mind and 
 consciousness, we have first-hand experi- 
 ence of these things quite apart from 
 laboratory experiments. They belong to 
 the common knowledge of the race. 
 Births, deaths, and marriages are not 
 affairs of the biologist, but of humanity; 
 they went on before a single one of them 
 was understood, before a vestige of 
 science existed. We ourselves are the 
 laboratory in which men of science, 
 
84 Presidential Address 
 
 psychologists and others, make experi- 
 ments. They can formulate our processes 
 of digestion, and the material concomi- 
 tants of willing, of sensation, of thinking; 
 but the hidden guiding entities they do 
 not touch. 
 
 So also if any philosopher tells you that 
 you do not exist, or that the external 
 world does not exist, or that you are an 
 automaton without free will, that all 
 your actions are determined by outside 
 causes and that you are not responsible, 
 or that a body cannot move out of its 
 place, or that Achilles cannot catch a 
 tortoise, then in all those cases appeal 
 must be made to twelve average men, 
 unsophisticated by special studies. There 
 is always a danger of error in interpreting 
 experience, or in drawing inferences from 
 it; but in a matter of bare fact, based on 
 our own first-hand experience, we are 
 able to give a verdict. We may be mis- 
 taken as to the nature of what we see; 
 stars may look to us like bright specks in 
 a dome; but the fact that we see them 
 admits of no doubt. So also Conscious- 
 
Continuity 85 
 
 ness and Will are realities of which we are 
 directly aware, just as directly as we are 
 of motion and force, just as clearly as we 
 apprehend the philosophising utterances 
 of an Agnostic. The process of seeing, 
 the plain man does not understand; he 
 does not recognise that it is a method of 
 etherial telegraphy; he knows nothing of 
 the ether and its ripples, nor of the retina 
 and its rods and cones, nor of nerve and 
 brain processes; but he sees and he hears 
 and he touches, and he wills and he thinks 
 and is conscious. This is not an appeal 
 to the mob as against the philosopher; 
 it is appeal to the experience of untold 
 ages as against the studies of a generation. 
 How consciousness became associated 
 with matter, how life exerts guidance 
 over chemical and physical forces, how 
 mechanical motions are translated into 
 sensations, all these things are puzzling, 
 and demand long study. But the fact 
 that these things are so admits of no doubt ; 
 and difficulty of explanation is no argu- 
 ment against them. The blind man 
 restored to sight had no opinion as to 
 
86 Presidential Address 
 
 how he was healed, nor could he vouch 
 for the moral character of the Healer, 
 but he plainly knew that whereas he was 
 blind now he saw. About that fact he 
 was the best possible judge. So it is also 
 with "this main miracle that thou art 
 thou, With power on thine own act and 
 on the world." 
 
 But although Life and Mind may be 
 excluded from Physiology, they are not 
 excluded from Science. Of course not. 
 It is not reasonable to say that things 
 necessarily elude investigation merely 
 because we do not knock against them. 
 Yet the mistake is sometimes made. 
 The ether makes no appeal to sense, 
 therefore some are beginning to say that 
 it does not exist. Mind is occasionally 
 put into the same predicament. Life is 
 not detected in the laboratory, save in its 
 physical and chemical manifestations; 
 but we may have to admit that it guides 
 processes nevertheless. It may be called 
 a catalytic agent. 
 
 To understand the action of life itself, 
 the simplest plan is not to think of a 
 
Continuity 87 
 
 microscopic organism, or any unfamiliar 
 animal, but to make use of our own 
 experience as living beings. Any positive 
 instance serves to stem a comprehensive 
 denial; and if the reality of mind and 
 guidance and plan is denied because they 
 make no appeal to sense, then think how 
 the world would appear to an observer to 
 whom the existence of men was unknown 
 and undiscoverable, while yet all laws 
 and activities of nature went on as they 
 do now. 
 
 Suppose, then, that man made no 
 appeal to the senses of an observer of this 
 planet. Suppose an outside observer 
 could see all the events occurring in the 
 world, save only that he could not see 
 animals or men. He would describe 
 what he saw much as we have to describe 
 the activities initiated by life. 
 
 If he looked at the Firth of Forth, for 
 instance, he would see piers arising in 
 the water, beginning to sprout, reaching 
 across in strange manner till they actually 
 join or are joined by pieces attracted 
 up from below to complete the circuit (a 
 
88 Presidential Address 
 
 solid circuit round the current) . He would 
 see a sort of bridge or filament thus con- 
 structed, from one shore to the other, and 
 across this bridge insect-like things crawl- 
 ing and returning for no very obvious 
 reason. 
 
 Or let him look at the Nile, and recog- 
 nise the meritorious character of that 
 river in promoting the growth of vegeta- 
 tion in the desert. Then let him see a 
 kind of untoward crystallisation growing 
 across and beginning to dam the benefi- 
 cent stream. Blocks fly to their places 
 by some kind of polar forces; "we cannot 
 doubt" that it is by helio- or other tropism. 
 There is no need to go outside the laws of 
 mechanics and physics, there is no diffi- 
 culty about supply of energy none what- 
 ever, materials in tin cans are consumed 
 which amply account for all the energy; 
 and all the laws of physics are obeyed. 
 The absence of any design, too, is mani- 
 fest; for the effect of the structure is to 
 flood an area upsteam which might have 
 been useful, and to submerge a structure 
 of some beauty; while down stream its 
 
Continuity 89 
 
 effect is likely to be worse, for it would 
 block the course of the river and waste it 
 on the desert, were it not that fortunately 
 some leaks develop and a sufficient supply 
 still goes down goes down in fact more 
 equably than before : so that the ultimate 
 result is beneficial to vegetation, and 
 simulates intention. 
 
 If told concerning either of these struc- 
 tures that an engineer, a designer in 
 London, called Benjamin Baker, had 
 anything to do with it, the idea would be 
 preposterous. One conclusive argument 
 is final against such a superstitious hypo- 
 thesis he is not there, and a thing 
 plainly cannot act where it is not. But 
 although we, with our greater advantages, 
 perceive that the right solution for such 
 an observer would be the recognition of 
 some unknown agency or agent, it must 
 be admitted that an explanation in terms 
 of a vague entity called vital force would 
 be useless, and might be so worded as to 
 be misleading; whereas a statement in 
 terms of mechanics and physics could be 
 clear and definite and true as far as it 
 
90 Presidential Address 
 
 went, though it must necessarily be 
 incomplete. 
 
 And note that what we observe, in 
 such understood cases, is an Interaction 
 of Mind and Matter; not Parallelism nor 
 Epiphenomenalism nor anything strained 
 or difficult, but a straightforward utilisa- 
 tion of the properties of matter and energy 
 for purposes conceived in the mind, and 
 executed by muscles guided by acts of will. 
 
 But, it will be said, this is unfair, for 
 we know that there is design in the Forth 
 Bridge or the Nile Dam, we have seen the 
 plans and understand the agencies at 
 work : we know that it was conceived and 
 guided by life and mind, it is unfair to 
 quote this as though it could simulate an 
 automatic process. 
 
 Not at all, say the extreme school of 
 biologists whom I am criticising, or ought 
 to say if they were consistent, there is 
 nothing but Chemistry and Physics at 
 work anywhere; and the mental activ- 
 ity apparently demonstrated by those 
 structures is only an illusion, an epi- 
 phenomenon; the laws of chemistry 
 
Continuity 91 
 
 and physics are supreme, and they are 
 sufficient to account for everything! 
 
 Well, they account for things up to a 
 point ; they account in part for the colour 
 of a sunset, for the majesty of a mountain 
 peak, for the glory of animate existence. 
 But do they account for everything com- 
 pletely? Do they account for our own 
 feeling of joy and exaltation, for our sense 
 of beauty, for the manifest beauty existing 
 throughout nature? Do not these things 
 suggest something higher and nobler and 
 more joyous, something for the sake of 
 which all the struggle for existence goes 
 on? 
 
 Surely there must be a deeper meaning 
 involved in natural objects. Orthodox 
 explanations are only partial, though 
 true as far as they go. When we examine 
 each particoloured pinnule in a peacock's 
 tail, or hair in a zebra's hide, and realise 
 that the varying shades on each are so 
 placed as to contribute to the general de- 
 sign and pattern, it becomes exceedingly 
 difficult to explain how this organised 
 co-operation of parts, this harmonious 
 
92 Presidential Address 
 
 distribution of pigment cells, has come 
 about on merely mechanical principles. 
 It would be as easy to explain the sprout- 
 ing of the cantilevers of the Forth Bridge 
 from its piers, or the flocking of the stones 
 of the Nile Dam by chemiotaxis. Flowers 
 attract insects for fertilisation; and fruit 
 tempts birds to eat it in order to carry 
 seeds. But these explanations cannot 
 be final. We have still to explain the 
 insects. So much beauty cannot be 
 necessary merely to attract their atten- 
 tion. We have further to explain this 
 competitive striving towards life. Why 
 do things struggle to exist? Surely the 
 effort must have some significance, the 
 development some aim. We thus reach 
 the problem of Existence itself, and the 
 meaning of Evolution. 
 
 The mechanism whereby existence en- 
 trenches itself is manifest, or at least has 
 been to a large extent discovered. Natur- 
 al Selection is a vera causa, so far as it goes; 
 but if so much beauty is necessary for in- 
 sects, what about the beauty of a land- 
 scape or of clouds? What utilitarian 
 
Continuity 93 
 
 object does that subserve ? Beauty in gen- 
 eral is not taken into account by science. 
 Very well, that may be all right, but it 
 exists nevertheless. It is not my function 
 to discuss it. No ; but it is my function 
 to remind you and myself that our studies 
 do not exhaust the Universe, and that if 
 we dogmatise in a negative direction, and 
 say that we can reduce everything to 
 physics and chemistry, we gibbet our- 
 selves as ludicrously narrow pedants, 
 and are falling far short of the richness 
 and fulness of our human birthright. 
 How far preferable is the reverent atti- 
 tude of the Eastern Poet 
 
 The world with eyes bent upon thy feet stands 
 in awe with all its silent stars. 
 
 Superficially and physically we are 
 very limited. Our sense organs are 
 adapted to the observation of matter; 
 and nothing else directly appeals to us. 
 Our nerve-muscle-system is adapted to 
 the production of motion in matter, in 
 desired ways; and nothing else in the 
 material world can we accomplish. Our 
 
94 Presidential Address 
 
 brain and nerve systems connect us with 
 the rest of the physical world. Our 
 senses give us information about the 
 movements and arrangements of matter. 
 Our muscles enable us to produce changes 
 in those distributions. That is our equip- 
 ment for human life; and human history 
 is a record of what we have done with 
 these parsimonious privileges. 
 
 Our brain, which by some means yet 
 to be discovered connects us with the 
 rest of the material world, has been 
 thought partially to disconnect us from 
 the mental and spiritual realm, to which 
 we really belong but from which for a 
 time and for practical purposes we are 
 isolated. Our common or social associ- 
 ation with matter gives us certain oppor- 
 tunities and facilities, combined with 
 obstacles and difficulties which are them- 
 selves opportunities for struggle and 
 effort. 
 
 Through matter we become aware of 
 each other, and can communicate with 
 those of our fellows who have ideas suffi- 
 ciently like our own for them, to be stimu- 
 
Continuity 95 
 
 lated into activity by a merely physical 
 process set in action by ourselves. By a 
 timed succession of vibratory movements 
 (as in speech and music), or by a static 
 distribution of materials (as in writing, 
 painting, and sculpture), we can carry on 
 intelligent intercourse with our fellows; 
 and we get so used to these ingenious 
 and roundabout methods, that we are 
 apt to think of them and their like as not 
 only the natural but as the only possible 
 modes of communication, and to imagine 
 that anything more direct would disar- 
 range the whole fabric of science. 
 
 It is clearly true that our bodies con- 
 stitute the normal means of manifesting 
 ourselves to each other while on the 
 planet; and that if the physiological 
 mechanism whereby we accomplish ma- 
 terial acts is injured, the conveyance 
 of our meaning and the display of our 
 personality inevitably and correspond- 
 ingly suffer. 
 
 So conspicuously is this the case that 
 it has been possible to suppose that the 
 communicating mechanism, formed and 
 
96 Presidential Address 
 
 worked by us, is the whole of our exist- 
 ence; and that we are essentially nothing 
 but the machinery by which we are 
 known. We find the machinery utilising 
 nothing but well-known forms of energy, 
 and subject to all the laws of chemistry 
 and physics, it would be strange if it 
 were not so, and from that fact we try to 
 draw valid deductions as to our nature, 
 and as to the impossibility of our exist- 
 ing apart from and independent of these 
 temporary modes of material activity and 
 manifestation. We so uniformly employ 
 them, in our present circumstances, that 
 we should be on our guard against de- 
 ception due to this very uniformity. Ma- 
 terial bodies are all that we have any 
 control over, are all that we are experi- 
 mentally aware of; anything that we 
 can do with these is open to us; any con- 
 clusions we can draw about them may be 
 legitimate and true. But to step outside 
 their province and to deny the existence 
 of any other region because we have no 
 sense organ for its appreciation, or be- 
 cause (like the Ether) it is too uniformly 
 
Continuity 97 
 
 omnipresent for our ken, is to wrest 
 our advantages and privileges from their 
 proper use and apply them to our own 
 misdirection. 
 
 But if we have learnt from science that 
 Evolution is real, we have learnt a great 
 deal. I must not venture to philoso- 
 phise, but certainly from the point of 
 view of science Evolution is a great 
 reality. Surely evolution is not an illu- 
 sion; surely the universe progresses in 
 time. Time and Space and Matter are 
 abstractions, but are -none the less real: 
 they are data given by experience; and 
 Time is the keystone of evolution. ' ' Thy 
 centuries follow each other, perfecting a 
 small wild flower. " 
 
 We abstract from living moving 
 Reality a certain static aspect, and we 
 call it Matter; we abstract the element 
 of progressiveness, and we call it Time. 
 When these two abstractions combine, 
 co-operate, interact, we get reality again. 
 It is like Poynting's theorem. 
 
 The only way to refute or confuse the 
 theory of Evolution is to introduce the 
 
98 Presidential Address 
 
 subjectivity of time. That theory in- 
 volves the reality of time, and it is in this 
 sense that Prof. Bergson uses the great 
 phrase " Creative Evolution.'* 
 
 I see the whole of material existence as 
 a steady passage from past to future, only 
 the single instant which we call the pre- 
 sent being actual. The past is not non- 
 existent however, it is stored in our 
 memories, there is a record of it in matter, 
 and the present is based upon it; the 
 future is the outcome of the present, and 
 is the product of evolution. 
 
 Existence is like the output from a 
 loom. The pattern, the design for the 
 weaving, is in some sort "there" already; 
 but whereas our looms are mere machines, 
 once the guiding cards have been fed 
 into them, the Loom of Time is compli- 
 cated by a multitude of free agents who 
 can modify the web, making the product 
 more beautiful or more ugly according as 
 they are in harmony or disharmony with 
 the general scheme. I venture to main- 
 tain that manifest imperfections are thus 
 accounted for, and that freedom could be 
 
Continuity 99 
 
 given on no other terms, nor at any less 
 cost. 
 
 The ability thus to work for weal or woe 
 is no illusion, it is a reality, a responsible 
 power which conscious agents possess; 
 wherefore the resulting fabric is not 
 something preordained and inexorable, 
 though by wide knowledge of character it 
 may be inferred. Nothing is inexorable 
 except the uniform progress of time; the 
 cloth must be woven, but the pattern is 
 not wholly fixed and mechanically cal- 
 culable. Where inorganic matter alone 
 is concerned, there everything is deter- 
 mined. Wherever full consciousness has 
 entered, new powers arise, and the facul- 
 ties and desires of the conscious parts of 
 the scheme have an effect upon the whole. 
 It is not guided from outside but from 
 within, and the guiding power is imma- 
 nent at every instant. Of this guiding 
 power we are a small but not wholly in- 
 significant portion. 
 
 That evolutionary progress is real is 
 a doctrine of profound significance, and 
 our efforts at social betterment are justi- 
 
ioo Presidential Address 
 
 fied because we are a part of the scheme, a 
 part that has become conscious, a part 
 that realises, dimly at any rate, what it is 
 doing and what it is aiming at. Planning 
 and aiming are therefore not absent from 
 the whole, for we are a part of the whole, 
 and are conscious of them in ourselves. 
 
 Either we are immortal beings or we 
 are not. We may not know our destiny, 
 but we must have a destiny of some sort. 
 Those who make denials are just as likely 
 to be wrong as those who make assertions: 
 in fact, denials are assertions thrown into 
 negative form. Scientific men are looked 
 up to as authorities, and should be care- 
 ful not to mislead. Science may not be 
 able to reveal human destiny, but it cer- 
 tainly should not obscure it. Things are 
 as they are, whether we find them out 
 or not; and if we make rash and false 
 statements, posterity will detect us if 
 posterity ever troubles its head about 
 us. I am one of those who think that the 
 methods of Science are not so limited in 
 their scope as has been thought : that they 
 can be applied much more widely, and that 
 
Continuity 101 
 
 the Psychic region can be studied and 
 brought under law too. Allow us anyhow 
 to make the attempt. Give us a fair 
 field. Let those who prefer the material- 
 istic hypothesis by all means develop 
 their thesis as far as they can; but let us 
 try what we can do in the Psychical 
 region, and see which wins. Our meth- 
 ods are really the same as theirs the 
 subject-matter differs. Neither should 
 abuse the other for making the attempt. 
 Whether such things as intuition and 
 revelation ever occur is an open ques- 
 tion. There are some who have reason to 
 say that they do. They are at any rate 
 not to be denied offhand. In fact, it is 
 always extremely difficult to deny any- 
 thing of a general character, since evi- 
 dence in its favour may be only hidden 
 and not forthcoming, especially not forth- 
 coming at any particular age of the 
 world's history, or at any particular stage 
 of individual mental development. Mys- 
 ticism must have its place, though its re- 
 lation to Science has so far not been found. 
 They have appeared disparate and discon- 
 
102 Presidential Address 
 
 nected, but there need be no hostility 
 between them. Every kind of reality 
 must be ascertained and dealt with by 
 proper methods. If the voices of Socrates 
 and of Joan of Arc represent real psy- 
 chical experiences, they must belong to 
 the intelligible universe. 
 
 Although I am speaking ex cathedra, as 
 one of the representatives of orthodox 
 science, I will not shrink from a personal 
 note summarising the result on my own 
 mind of thirty years' experience of psy- 
 chical research, begun without predi- 
 lection indeed with the usual hostile 
 prejudice. This is not the place to enter 
 into detail or to discuss facts scorned by 
 orthodox science, but I cannot help re- 
 membering that an utterance from this 
 chair is no ephemeral production, for it 
 remains to be criticised by generations 
 yet unborn, whose knowledge must inevi- 
 tably be fuller and wider than our own. 
 Your President therefore should not be 
 completely bound by the shackles of 
 present-day orthodoxy, nor limited to be- 
 liefs fashionable at the time. In justice 
 
Continuity 103 
 
 to myself and my co-workers I must 
 risk annoying my present hearers, not 
 only by leaving on record our conviction 
 that occurrences now regarded as occult 
 can be examined and reduced to order by 
 the methods of science carefully and per- 
 sistently applied, but by going further 
 and saying, with the utmost brevity, that 
 already the facts so examined have con- 
 vinced me that memory and affection are 
 not limited to that association with mat- 
 ter by which alone they can manifest 
 themselves here and now, and that per- 
 sonality persists beyond bodily death. 
 The evidence nothing new or sensa- 
 tional, but cumulative and demanding 
 prolonged serious study to my mind 
 goes to prove that discarnate intelligence, 
 under certain conditions, may interact 
 with us on the material side, thus indi- 
 rectly coming within our scientific ken; 
 and that gradually we may hope to attain 
 some understanding of the nature of a 
 larger, perhaps etherial, existence, and 
 of the conditions regulating intercourse 
 across the chasm. A body of responsible 
 
104 Presidential Address 
 
 investigators has even now landed on the 
 treacherous but promising shores of a new 
 continent. 
 
 Yes, and there is more to say than that. 
 The methods of science are not the only 
 way, though they are our way, of being 
 piloted to truth. "Uno itinere non poles t 
 perveniri ad tarn grande secretum." 
 
 Many scientific men still feel in pug- 
 nacious mood towards Theology, because 
 of the exaggerated dogmatism which our 
 predecessors encountered and overcame 
 in the past. They had to struggle for 
 freedom to find truth in their own way; 
 but the struggle was a deplorable neces- 
 sity, and has left some evil effects. And 
 one of them is this lack of sympathy, this 
 occasional hostility, to other more spiri- 
 tual forms of truth. We cannot really 
 and seriously suppose that truth began to 
 arrive on this planet a few centuries ago. 
 The pre-scientific insight of genius 
 of Poets and Prophets and Saints was 
 of supreme value, and the access of those 
 inspired seers to the heart of the universe 
 was often profound. But the camp fol- 
 
Continuity 105 
 
 lowers, the scribes and pharisees, by 
 whatever name they may be called, had 
 no such insight, only a vicious or a foolish 
 obstinacy; and the prophets of a new era 
 were stoned. 
 
 Now at last we of the new era have 
 been victorious, and the stones are in our 
 hands. But for us to imitate the old 
 ecclesiastical attitude would be folly, for 
 it cannot be sustained; humanity would 
 ultimately rise against us, and there 
 would come yet another period of reac- 
 tion, in which for a time we should be 
 worsted. Through the best part of two 
 centuries there has been a revolt from 
 religion, led by Voltaire and other great 
 writers of that age; but let us see to it 
 that the revolt ceases when it has gone far 
 enough. Let us not fall into the mistake 
 of thinking that ours is the only way of 
 exploring the multifarious depths of the 
 universe, and that all others are worthless 
 and mistaken. The universe is a larger 
 thing than we have any conception of, 
 and no one method of search will exhaust 
 its treasures. 
 
io6 Presidential Address 
 
 Men and brethren, we are trustees of 
 the truth of the physical universe as 
 scientifically explored: let us be faithful 
 to our trust. Genuine religion has its 
 roots deep down in the heart of humanity 
 and in the reality of things. It is not sur- 
 prising that by our methods we fail to 
 grasp it: the actions of the Deity make 
 no appeal to any special sense, only a 
 universal appeal; and our methods are, 
 as we know, incompetent to detect com- 
 plete uniformity. There is a Principle of 
 Relativity here, and unless we encounter 
 flaw or jar or change, nothing in us re- 
 sponds ; we are deaf and blind therefore to 
 the Immanent Grandeur, unless we have 
 insight enough to recognise in the woven 
 fabric of existence, flowing steadily from 
 the loom in an infinite progress towards 
 perfection, the ever-growing garment of a 
 transcendent God. 
 
THE BRITISH ASSOCIATION 
 PRESIDENTIAL ADDRESS 
 
 1913 
 
 EXPLANATORY NOTES BY THE PRESIDENT 
 Page i 
 
 The Chair of the British Association at Birmingham was 
 to have been filled by Sir William White, F.R.S., late Chief 
 Constructor of the British Navy, who had been made 
 President Elect at the previous Meeting in Dundee in 
 1912; but his unexpected death in the spring of 1913 
 necessitated a fresh election, and the rule of the Association 
 against a local president was broken by the selection of 
 the Principal of the University of Birmingham from the 
 short list of those whose presidency was not likely to be 
 long delayed. This explains the opening paragraph. 
 
 Pages 4, 13, and 15 
 
 The quotations are from a set of four lectures which Dr. 
 Arthur Schuster gave to the University of Calcutta in 
 1908, now published by the Cambridge University Press 
 under the title The Progress of Physics during jj years 
 (1875-1908). 
 
 Page 7 
 
 The immediate predecessor spoken of is Professor 
 Schafer, the physiologist whose address at Dundee in 1912 
 107 
 
io8 Presidential Address 
 
 on the subject of Life, and on the possibility of artificially 
 producing it or of formulating its origin, excited so wide- 
 spread an interest. The penultimate predecessor is Sir 
 William Ramsay, the chemist who presided over the British 
 Association in 1911 at Portsmouth and whose experiments 
 on the influence of radio-active bodies in promoting the 
 transformation of one element into others have been re- 
 ceived with varying degrees of caution. The nominated 
 successor spoken of is Professor Bateson, the biologist who 
 before the Birmingham Meeting was nominated, and who 
 at Birmingham was elected, to preside over the British 
 Association during its meeting in Australia, and who is a 
 well-known authority on heredity, especially from the 
 Mendelian point of view. 
 
 Page 10 
 
 The second law of Thermodynamics relates to the work- 
 ing power of heat, and asserts the fact that only bodies at 
 high temperature can be usefully employed as sources of 
 heat. A hydraulic analogy is roughly useful as a first 
 approximation: water at high level can be used to drive 
 machines and give power, but water at average or sea level 
 cannot be so used. Hydraulic working power, therefore, 
 depends on two things, the amount of available water, and 
 its head or height above zero level. So it is also with heat. 
 The work which, by a heat engine like a steam or gas or oil 
 engine, can be extracted from it depends upon its quantity 
 and upon its temperature above some practicable zero, say 
 the ordinary average temperature. Only in the impossible 
 case of the practical zero being the absolute zero a fear- 
 fully low temperature approximated to by skilled experi- 
 menters but not actually attained could all of any given 
 quantity of heat be utilised in the performance of work. 
 
 And yet heat is a form of energy, and a form which is 
 liable to be generated as a bye-product during every kind 
 
Explanatory Notes 109 
 
 of material activity. Energy is protean in change of form, 
 but when once converted into heat it is likely to retain 
 that form, unless some ingenious machine is employed 
 to transform it into other forms of energy and to assist 
 it to do work, as when the vapour of boiling water is en- 
 abled to pump a mine or drive a flywheel by aid of a steam 
 engine. Moreover, there is a tendency for all contiguous 
 bodies, unless specially prevented, to become equal in 
 temperature, a condition in which no more work can be 
 obtained by any thermal process; and the energy is then 
 said to be degraded or dissipated. 
 
 Ultimately therefore, in process of time, it has been sug- 
 gested that all the energy of the Universe may be expected 
 to take the low form of heat at a uniform temperature, *. e. 
 practically at an exceedingly low, nearly zero, temperature 
 an epoch being foreshadowed at which every activity 
 will thus ultimately cease. 
 
 This dismal foreboding is not, or should not be, set for- 
 ward with any certainty; because processes whereby energy 
 may be pumped up again, as it were, from lower to higher 
 forms through the agency of life perhaps, or through the 
 agency of special intelligence for which the crude average 
 terms heat and temperature have no dominating meaning 
 can be imagined, and it only remains for us to discover 
 them in action somewhere. 
 
 A description of how such intelligences could act was 
 first given by Clerk Maxwell, and was vividly elaborated 
 by Lord Kelvin. They are known as " Maxwell's demons." 
 Some biologists have suspected the real existence of such, 
 agents, in nitrifying bacteria and the like; and although no 
 definite discovery of agencies which will reverse results 
 attributed to the second law of Thermodynamics has yet 
 been made, it would be a mistake to limit the possibility of 
 discovery. 
 
 And anyhow the material universe is manifestly in full 
 blast at present; it has not by any means reached the stage 
 
no Presidential Address 
 
 of decadence when the sun and all bodies are at one and the 
 same temperature and when every activity has ceased. 
 (Cf. page 59.) The Universe is undoubtedly still a going 
 concern, and yet it has presumably already lasted an 
 infinite time for all we know to the contrary. 
 
 As to the first law of Thermodynamics, that is merely 
 the conservation of energy applied to heat. It was the 
 experimental and quantitative inclusion of heat as a form 
 of energy which allowed the law of Conservation of Energy 
 to be definitely formulated by Joule. 
 
 Page II 
 
 The most important of Newton's Laws of Motion is 
 that the acceleration of a body is proportional to the 
 resultant force which acts upon it and is in the same di- 
 rection. The ratio of force to acceleration is called the 
 mass or inertia of the body, and in ordinary Newtonian 
 Mechanics it is treated as constant. There is a sense in 
 which the remarkable constancy of mass, no matter what 
 happens to it, in the way of boiling, freezing, decom- 
 position, burning, or solution, is synonymous with the 
 fundamental postulate of the conservation of matter. But 
 there are other senses in which it is not difficult to allow for 
 a possible variation of mass of a moving body, and hence to 
 get a variable ratio between the force applied to it and the 
 acceleration produced. 
 
 Recently it has been found that electrons moving near 
 the speed of light have an increased mass. The result has 
 been arrived at both theoretically and experimentally. 
 It was in fact first predicted mathematically and after- 
 wards confirmed experimentally, and may be taken as 
 quite undoubted. 
 
 Mass therefore becomes a function of speed. At all 
 ordinary speeds it is practically constant; but at excessive 
 speeds, far beyond that of a cannon ball, it begins very 
 
Explanatory Notes in 
 
 slightly to increase; at speeds expressed in thousands of 
 miles per second it begins to increase faster; and at the 
 speed of light it suddenly appears to become infinite 
 whatever that may mean. Hence there are some who 
 think that bodies can never move through the ether faster 
 than the velocity of light. 
 
 Page 12 
 
 In Euclidian Geometry only one straight line can be 
 drawn through a given point parallel to another straight 
 line. That no more than one is possible has never been 
 proven: it was a definite postulate or axiom made by 
 Euclid, but it seemed incapable of proof. Within recent 
 times pure mathematicians have found it possible to devise 
 other more general systems of Geometry, in which two or 
 many such lines can be drawn. Thus Euclidian Ge- 
 ometry, which still appears to suit our own spatial expe- 
 rience very well, can be regarded as a special case of more 
 generalised and comprehensive theoretical systems. 
 
 Abstract propositions may be absolutely and completely 
 true: practical experience can approximate to them more 
 or less precisely in Geometry more precisely than in any 
 other subject. The relation between our systems of 
 thought on the one hand, and our actual experience on the 
 other, is well illustrated by the following quotation from 
 Poincare": 
 
 "The principles of geometry are not experimental facts. 
 . . . Euclid's postulate cannot be proved by experiment. 
 ... If Lobatschewsky's geometry is true, the parallax of a 
 very distant star will be finite. If Riemann's is true, it will 
 be negative. These are results which seem within the 
 reach of experiment, and some have hoped that astronomi- 
 cal observations may enable us to decide between the 
 geometries. But what we call a straight line in astronomy 
 is simply the path of a ray of light. If, therefore, we were 
 
ii2 Presidential Address 
 
 to discover negative parallaxes, or to prove that all par- 
 allaxes are higher than a certain limit, we should have a 
 choice between two conclusions : we could give up Euclid- 
 ean geometry, or modify the laws of optics, and suppose 
 that light is not rigorously propagated in a straight line. 
 It is needless to add that everyone would look upon this 
 solution as the more advantageous. Euclidean geometry, 
 therefore, has nothing to fear from fresh experiments. " 
 
 Page 1 6 
 
 By "Euclid's Postulate" is meant the famous postulate 
 or axiom above referred to. It is commonly called ' ' Axiom 
 12" in textbooks of Euclid elements. It lies at the base of 
 all his doctrine of parallels, and it leads direct to the con- 
 clusion that the three angles of a triangle are together 
 equal to two right angles. In fact it is another form of 
 stating that proposition. 
 
 Page 17 
 
 The "Preface" referred to is the Introduction by Sir 
 Joseph Larmor, M.P., Lucasian Professor of Mathematics 
 in the University of Cambridge, to the English translation 
 of Pomcare"'s book called Science and Hypothesis (Scott). 
 
 Page 28 
 
 Boyle's Law is that the volume of a gas varies inversely 
 with the pressure to which it is subjected. It is a natural 
 consequence of the kinetic theory of gases in its simplest 
 form; but, when considered strictly, it is seen to involve 
 the assumption that the gaseous particles are infinitely 
 small so small that they can never become the least 
 crowded, however great the pressure, and further that 
 there is no attractive force or incipient cohesion acting 
 
Explanatory Notes 113 
 
 between them, so that never would the effect of pressure 
 be assisted by the action of internal forces. In all actual 
 gases the particles have some intrinsic size of their own; 
 and cohesion becomes sooner or later conspicuous, so that 
 ultimately liquefaction is possible. The further a gas is 
 from showing any sign of molecular cohesion, the more 
 ' nearly is it considered "perfect" as a gas. An imperfect 
 gas exhibits already an incipient tendency towards ulti- 
 mate liquefaction. A corrected form of Boyle's law, applic- 
 able not only to imperfect gases but also to liquids, was 
 devised by the great Dutch physicist Van der Waals, whose 
 treatment, though not even yet finally accurate, was pro- 
 foundly interesting and instructive. 
 
 Page 19 
 
 The way in which Kepler discovered his famous laws, 
 from elaborate discussions of the planetary observations of 
 Tycho Brahe, is explained in many books: among others, 
 in the author's own semi-popular volume called Pioneers 
 of Science (Macmillan). 
 
 Page 21 
 
 The familiar behaviour of a wet sandy beach, when 
 walked over, is very curious; the pressure of a foot dries it, 
 while relaxation of pressure moistens it. In other words, 
 pressure applied to a collection of granular particles tends 
 to increase the spaces between them, and so enables them 
 to hold more water in their interstices. Relaxation and 
 constraint allow the molecules to adjust themselves closer 
 together, and so to squeeze some of the liquid out again. 
 Just opposite to the behaviour of a sponge. 
 
 It was on a highly developed superstructure based on 
 this foundation that Professor Osborne Reynolds of Man- 
 chester devised his scheme, wherein "the ether" was sup- 
 
 8 
 
H4 Presidential Address 
 
 posed to consist of rigid granules in contact, and where 
 "matter " was the hollows or cavities or regions of greater 
 interstitial capacity existing among them. These regions 
 could readily travel about from one part of the granular 
 structure to another; and this represented the motion of 
 matter in the scheme. Such an ether is very unlike any 
 contemplated by the author. 
 
 Page 22 
 
 In the Physical Review for August, 1913, Professor R. 
 A. Millikan summarises the results of most recent and 
 trustworthy determinations of molecular magnitudes, and 
 among them of Avogadro's constant. It may be conven- 
 ient to quote some of them here: 
 
 Unit of electric charge, e =4.774X10 I0 electrosta- 
 tic units. 
 
 Number of molecules 
 
 per gramme molecule, N =6.062 Xio a *. 
 Molecules per cubic 
 centimetre of gas at o 
 and 76, n =2.705 Xio 1 '. 
 
 Planck's constant h =6.62 Xio 2 ?cgs. 
 
 The number of H 2 O molecules in a cubic centimetre, or 
 say 15 grains, of water is therefore -33Xio 23 ; and the 
 number of atoms io 2 3. 
 
 Now io 2 3 cubic centimetres of water weigh lo 1 ? tons, 
 = io 8 cubic kilometres, 
 =25 million cubic miles, 
 
 which would form an ocean 6000 miles long, 2000 miles 
 wide, and 2 miles deep, corresponding therefore very 
 fairly to the North Atlantic Ocean. 
 
 Page 23 
 
 For a further discussion of incommensurable quantities, 
 and of the impossibility of expressing the majority of 
 
Explanatory Notes 115 
 
 physical ratios by any actual number, the author's text- 
 book of Arithmetic and Algebra for General Readers, 
 called Easy Mathematics (Macmillan), may be referred to, 
 in chapter xx and elsewhere. 
 
 Page 26 
 
 By the "degrees of freedom" of a body are meant the 
 independent modes of motion of which it is susceptible. 
 A rigid body has six degrees of freedom, which can be thus 
 enumerated: a translation or locomotion in each of three 
 directions, the three dimensions of space, up and down, to 
 and fro, right and left; and three rotations, viz., rotation 
 about each of these three directions considered as axes. 
 A particle however meaning a body of no size has only 
 three degrees of freedom; it can only move in the sense of 
 locomotion, it cannot spin ; or rather it may spin as much as 
 it likes and no one will care, its spinning will consume no 
 energy. A perfectly smooth sphere is in much the same 
 predicament; while a smooth dumb-bell has five degrees of 
 freedom, one of its rotations being ineffective. But a tun- 
 ing fork, or body susceptible of vibration, has many^ore 
 degrees of freedom than a rigid body can have; and inas- 
 much as molecules appear susceptible of vibration, as 
 evidenced by the spectra they emit, it might be supposed 
 that during their ordinary mutual collisions in a perfect 
 gas many of these vibratory movements would be called 
 out and take part in the action. If so, they would be 
 entitled to some of the energy. Indeed a mechanical 
 theory of Clerk Maxwell's proves that after a great number 
 of prefectly random collisions all the energy imparted to a 
 group of similar bodies will be equally shared, on an aver- 
 age, among all the degrees of freedom which they possess 
 (strictly speaking, among all the degrees of freedom which 
 are effective during collision). If, therefore, a given 
 quantity of energy, say heat, is imparted to a gas, it might 
 
n6 Presidential Address 
 
 be expected that it would be split up into so many equal 
 fractions that the translatory energy of the molecules 
 i.e. the motion upon which "temperature" depends 
 would be increased to only an insignificant extent. But it 
 is not so. Experiment on the velocity of sound through 
 various gases shows that the energy imparted by acoustic 
 compression raises the temperature quite decidedly, and is 
 therefore only divided into quite a moderate number of 
 parcels. The number is found to be 3 for monatomic 
 molecules, which therefore to that extent behave like 
 smooth spheres; 5 for diatomic molecules, which therefore 
 behave like smooth dumb-bells; and 6 for molecules con- 
 sisting of 3 or more atoms, which therefore behave like the 
 general rigid body. 
 
 How it can come about that vibratory degrees of free- 
 dom are excluded from the sharing, even after the lapse of 
 some time, has long been a subject of controversy; and the 
 fact that it is so has thrown doubt upon the equi-partition 
 theorem itself. The answer suggested by Professor Planck, 
 the eminent physicist of Berlin, is that fractions of a unit 
 of energy cannot exist, so that the attempt to subdivide a 
 given portion of energy into an immense number of frac- 
 tions must fail; only those degrees of freedom that can re- 
 ceive a whole unit can be effective: it is a case of all or none, 
 and those subsidiary modes of motion that can only receive 
 a fraction will not get any. 
 
 This is an exceedingly crude and partial account of the 
 initial stages of a large and complex subject, which has 
 been highly developed and is arousing much interest. The 
 unit of energy called "Planck's constant "enters into very 
 many parts of Physics, and appears to be a reality, how- 
 ever it be accounted for; but I consider that the explana- 
 tion is to be found in specific properties of matter, and not 
 in the really atomic character of energy itself. 
 
 The fact that vibratory molecular energies are not ef- 
 fective in an ordinary gas, are not evoked by ordinary 
 
Explanatory Notes 117 
 
 molecular collision, seems to be clear; but the cause of it 
 may be put differently by different people. (See pages 37 
 and 38.) 
 
 Pages 29 and 30 
 
 The reference here is to the extreme doctrine of Professor 
 Weismann, at one time urged upon us, that no character- 
 istic acquired during the life of an individual or series of 
 individuals could be transmitted by inheritance. The 
 truth underlying this doctrine is that unless the sperm or 
 germ cells are affected, mere alteration of body tissue is 
 ineffective for anything beyond the individual. That is 
 manifest. The cells which transmit vitality to the off- 
 spring must naturally be modified if modifications are to be 
 conveyed by them. But it is unreasonable to suppose that 
 deep-seated changes in somatic or bodily structure can be 
 caused without at least running the risk of affecting the 
 more permanent transmission cells also to some extent. 
 Mere defective or injudicious nourishment may have its 
 due influence in this direction. A microscope may not 
 show any difference, some other test must be applied ; and 
 by far the most sensitive test for the actual occurrence of 
 such alteration consists in observing whether inheritance is 
 really affected or not. On that question specific experi- 
 ments are desirable and ought to be made. If surround- 
 ings have no effect on the race, except a survival effect, 
 if the individual can acquire nothing which is transmissible, 
 it will be very extraordinary; but the test can only be 
 made by direct experiment and observation. Hence we 
 are thrown back on actual experience in every instance, 
 and we cannot generalise and say that no sort of character 
 acquired by the individual can be handed down to his or 
 her descendants. What I suggest in the text is that the 
 discontinuity between reproductive and bodily cells is not 
 likely to be as complete as that. 
 
n8 Presidential Address 
 
 Page 34 
 
 ' Matter is essentially that which moves. We are 
 acquainted with no portion of matter which is really 
 stationary. A statement of the speed and direction of 
 motion can be included among the elements of description 
 of any piece of matter. Ether in the same sense cannot be 
 moved, but it can be strained. It is strained when a bow 
 is bent; and it is also strained, though less obviously, when 
 a weight is raised, or when gunpowder is kept without the 
 release afforded by pulling the trigger. In all these cases 
 particles of matter are put into constrained positions with 
 reference to each other, and the seat of the static energy 
 involved is the ether between and near the particles. 
 When it is released kinetic energy results, for the matter is 
 then more or less violently moved. Kinetic energy belongs 
 to matter, Static or Potential to ether. The arguments 
 for high density of ether, and for the extraordinarily filmy 
 or gossamer-like character of matter compared to it, will 
 be found in my small book, The Ether of Space, (Harper 
 & Bros.). 
 
 Page 37 
 
 Part of the basis of Planck's theory of quanta, or indivisi- 
 ble units of energy, is given, in rudimentary fashion, in 
 the note to Page 26. 
 
 Page 41 
 
 The Brownian movement, long known as a constant 
 fidget of minute particles suspended in liquid and viewed 
 through a high-power microscope, has acquired great 
 interest of late by the discovery that all the laws of gases 
 apply to those visible material aggregates, consisting as they 
 must of billions of atoms, as well as to the almost infinitely 
 smaller and quite invisible things, the atoms and molecules 
 
Explanatory Notes 119 
 
 themselves. An interesting account of all these matters 
 will be found in a scientific book by M. Jean Perrin, Pro- 
 fessor of Physical Chemistry in the University of Paris, 
 which has been translated into English by Mr. Soddy, 
 F.R.S., and published by Taylor & Francis under the title: 
 Brownian Movement and Molecular Reality. 
 
 Pages 43 to 64 
 
 It is as difficult to convey to general readers some idea of 
 the Principle of Relativity, and its virtual supersession 
 of the Ether, as it was to explain about the equi-partition 
 of energy and quanta, but a rough attempt may again be 
 made. It has long been a moot point whether the Ether 
 was or was not carried forward to any extent by moving 
 matter. The question was discussed mathematically by 
 Fresnel at the beginning of last century; and Fizeau found 
 experimentally that light travelled quicker down running 
 water than when it travelled against the stream about 
 half (more accurately y/i6ths) of the speed of the water 
 being added to the light, quite in accordance with the 
 teachings of Fresnel. But whether this sort of effect 
 could be detected in the immediate neighbourhood of 
 moving matter, without going actually inside it, was quite 
 unknown; and in and about 1892 and subsequent years at 
 Liverpool I made a serious attempt to examine the ques- 
 tion experimentally. The experiments are described in the 
 Philosophical Transactions of the Royal Society for 1893 
 and 1897, and the conclusion is that when a mass of iron 
 or steel is spinning so fast that it is liable to fly to pieces, 
 and when light is sent by mirrors round and round many 
 times in its immediate neighbourhood, so close as to be 
 actually grazing the spinning disks in some instances, 
 not the slightest effect of acceleration is manifested by the 
 beam of light, however delicately it be tested by means of 
 interference bands. Interference is arranged between 
 
120 Presidential Address 
 
 beams which have travelled half with and half against 
 the motion, for many yards; but, after spurious results are 
 allowed for, there is no shift of the bands; proving that the 
 velocity is not affected by so much as one tenth of one per 
 cent, of the velocity of the moving matter. Practically we 
 may say that the Ether of space is never carried forward 
 presumably not even by a planet; for the Fizeau effect, 
 properly interpreted, means the same thing. 
 
 Professor Michelson of Chicago, however, one of the 
 most brilliant experimental physicists in America which 
 is saying a good deal tried a totally different experiment, 
 examining whether light sent to and fro over a fixed dis- 
 tance in the direction of the earth's planetary motion 
 through space, took any longer on its double journey than 
 it did when sent to and fro over the same distance across 
 the motion. The result was likewise negative : no difference 
 could be perceived; though the delicate experiment was 
 performed with the utmost care and skill, and was after- 
 wards repeated still more elaborately by Professor Michel- 
 son and Mr. Morley in collaboration. This negative 
 result, however, is in apparent or superficial opposition 
 to the other negative result : it seemed difficult to suppose 
 that they could both be true. Because if the Ether is not 
 carried forward by the earth at all, it must be relatively 
 streaming past the earth with a speed of many miles per 
 second, as many as 30 sometimes ; and accordingly an effect 
 ought to be obesrved. The negative result of Michelson, 
 therefore, superficially suggests that the Ether in the 
 neighbourhood of the earth is stagnant which in this 
 case is the opposite of stationary i.e. that it clings to the 
 earth and is carried forward by it. Many difficulties 
 would arise if that were true, and the theory of ordinary 
 astronomical aberration would be complicated; the Ether 
 would no longer be behaving as a perfect fluid, but would be 
 exhibiting what is called viscosity. Planets could hardly 
 move through it without resistance, and astronomical 
 
Explanatory Notes 121 
 
 theory would have to be overhauled. Moreover, my 
 experiment with steel disks, designed to detect a trace of 
 viscosity, failed to show any: in fact negatived the idea. 
 So the FitzGerald-Lorentz hypothesis was devised in 
 order to explain the negative result of Professor Michelson 
 in another way, by postulating a minute change of shape 
 or distortion of all bodies as they move through the Ether 
 of space at any excessive speed ; and there is a great deal 
 to be said in favour of such a hypothesis. Some physicists, 
 however, consider it only a hyper-ingenious and imagin- 
 ative device of evading awkward and irreconcilable facts. 
 Many other experiments have been made to detect the 
 effect of an etherial movement relatively to the earth; 
 and they have all uniformly failed. So at length Professor 
 Einstein first, and now many others, have supposed that 
 the Universe is so adjusted that an observation of this 
 kind is for ever impossible. They boldly make the postu- 
 late or axiom that although motion of matter with respect 
 to matter is readily perceived, motion of matter with re- 
 spect to ether is impossible to observe and is in fact mean- 
 ingless. They formulate the principle that nothing 
 but relative motion of pieces of matter with respect-to 
 each other can ever be detected, and that no change 
 in the velocity of light can ever be observed except when 
 there is relative motion of matter. This principle, en- 
 throned as the Principle of Relativity, has become the 
 foundation of a mathematical erection, with far-reaching 
 and in some cases surprising and almost paradoxical con- 
 sequences, affecting the going of clocks and even the nature 
 of Time. 
 
 The difficult part of the theory of Relativity is connected 
 with the deduction of all these remarkable consequences: 
 the fact that motion with respect to the ether is difficult 
 to observe, together with the familiar fact of the extreme 
 ease of observing the relative motion of pieces of matter 
 with respect to each other, constitutes the superficial and 
 
1 22 Presidential Address 
 
 primary foundation for the Principle of Relativity. The 
 Principle goes on to translate difficulty, in the first case, into 
 impossibility, and then to make elaborate mathematical 
 deductions. 
 
 The mode in which I would explain the admitted fact 
 that nothing but relative motion of pieces of matter has so 
 far been observed, is indicated on pages 47 et seq.; the cause 
 of all the negative experimental results, on which founda- 
 tion of the Principle rests, is to be found in the complete 
 uniformity of the ether and in its universal activity and 
 prevalence. This has led to the Principle which virtually 
 denies its existence. The last thing that a deep-sea fish 
 could discover would be water. (See also page 106.) 
 
 Page 46 
 
 The second paragraph on this page is another refer- 
 ence to my Ether-gripping experiment, referred to in the 
 above note and page 35, and briefly described in my book 
 The Ether of Space. The word " hope " can only be used 
 in a special sense in connection with any experiment: the 
 object of that experiment was of course to ascertain 
 whether the ether is to any degree attached to moving 
 matter or not. I was not aware of having any expectation 
 of a positive result. What I was anxious about was to 
 make sure of a definite answer one way or the other. 
 
 Page 49 
 
 Rotation of an isolated non-rigid body can be detected 
 by its bulging under centrifugal force: as when a bucket is 
 twisted the liquid surface becomes parabolic. Again, the 
 non-spherical shape of the earth or of Jupiter is immedi- 
 ately connected with their periods of rotation, i.e., with 
 the length of their respective "days. The oblateness of the 
 earth was thus quantitatively predicted by Newton long 
 
Explanatory Notes 123 
 
 before it was geodetically observed by accurate surveying. 
 See, for instance, Pioneers of Science, previously referred 
 to. 
 
 Page 54 
 
 The pressure exerted by light was predicted by Clerk 
 Maxwell, and by Bartoli, and first observed by Nicholls 
 and Hull. The consequent or associated momentum 
 conveyed by a wave front, and a number of the effects 
 deducible from this process, have been worked out most 
 instructively by Professor J. H. Poynting, who has pub- 
 lished a little book on the subject called The Pressure of 
 Light (S.P.C.K.). 
 
 Pages 62 and 63 
 
 The Michelson-Morley experiment detects no difference 
 between a journey to and fro and a journey right and left, 
 if one is facing the hypothetical ether stream presumably 
 caused relatively to the earth by its rapid motion through 
 space, and if one is sending a beam of light in these direc- 
 tions by means of mirrors mounted on some rigid body, 
 such as a block of stone or metal. (See also Note to pp. 
 43-64.) But elementary arithmetic shows that it ought 
 to take slightly longer, going up and down the stream, 
 than there and back across it. Hence, either there is no 
 such ether stream, or else the block on which the mirrors 
 and other optical appliances are mounted changes, so as to 
 be shorter by a compensating amount in the direction of 
 motion as compared with its breadth in the transverse 
 direction. The required change is exceedingly small, 
 equivalent to a shrinkage of three inches in 8000 miles, 
 yet on the electric theory of matter something of this mag- 
 nitude almost certainly ought to occur. This is the famous 
 FitzGerald-Lorentz hypothesis, referred to in the text. 
 (See pp. 53 and 64; also my book Electrons, chapter 
 xvi., about cohesion.) 
 
124 Presidential Address 
 
 The algebraic expression given on page 64 for the 
 amount of the change is not quite the usual orthodox 
 expression for it; but it is one which I have reason for 
 putting forward, and is not a misprint. 
 
 Page 76 
 
 The long-standing puzzle as to how vegetable sap is 
 raised against gravity from the ground to the tops of the 
 highest trees has been practically settled by recent workers, 
 notably by Professor H. H. Dixon of Trinity College, 
 Dublin, who has made a clear statement of the way in 
 which osmosis, or molecular diffusion through semi-per- 
 meable membranes, enables it to occur. 
 
 Page 80 
 
 Higher plants can only assimilate inorganic material 
 after it has been first incorporated into more lowly organ- 
 isms. Harsh treatment of a soil is found helpful to the 
 beneficent and manuring bacteria; for, being low in the 
 scale of existence, they are hardier and more resistant to 
 hostile influences than the still microscopic foes which feed 
 upon them. Wherefore treatment which slays the one 
 indirectly benefits the other. This explanation is not yet 
 proven, but the facts suggest it as likely. 
 
 Page 80 
 
 The larval stage of the mosquito is passed in water, and 
 the larvae cling to and perforate the surface in order to 
 breathe. If the surface is oiled the surface tension is 
 diminished, the surface does not support them, and they 
 keep on sinking till they drown. But not every puddle or 
 dribble of liquid can be oiled, and so breeding places can be 
 guarded against partly by drainage and partly by allowing 
 no unperf orated vessel to remain as a trap for accumulated 
 water. 
 
Explanatory Notes 125 
 
 Page 84 
 
 The ancient arguments of Zeno and other philosophers 
 are of the nature of a reductio ad absurdum, and were di- 
 rected against the trivial arguments of certain opposing 
 philosophers. The contention that motion cannot occur 
 because an object must be in either one place or another, 
 and the contention that a quick runner cannot pass a slow 
 one because the space between them is infinitely subdivis- 
 ible and some time is needed to cover every division were 
 not put forward as statements of fact absurdly contrary to 
 experience, but as arguments in favour of continuity of 
 space and against a static idea of time. All these ancient 
 paradoxes are really ingenious weapons of dialectic, and 
 are not to be taken as a sign of philosophic stultification, as 
 unfortunately they sometimes are. 
 
 Page 86 
 
 By a catalytic agent is signified in Chemistry something 
 which promotes a process or chemical change without 
 taking part in it: that is to say, a material substance which 
 by its presence facilitates a reaction while itself remaining 
 unchanged, apparently, or at any rate ultimately, inert. 
 Such instances are very common; one of the best known 
 being the action of manganese dioxide in the liberation of 
 oxygen from potassic chlorate. If every-day illustrations 
 are helpful, a broker may be called a catalytic agent in a 
 Stock Exchange transaction; and the same epithet might 
 be applied to a parson at a wedding. 
 
 Now in the various interactions which occur between the 
 two great conserved entities, energy and matter, life and 
 living bodies seem to act in a catalytic fashion; for they 
 contribute no energy, but they direct it, and thereby facili- 
 tate operations that without their aid would have been 
 difficult or impossible. The simple act of lifting a fallen 
 
126 Presidential Address 
 
 body may be adduced as an instance of such an operation, 
 without ascending to the more striking case of engineering 
 works; while in a chemical or physical or biological labora- 
 tory innumerable so to speak "unnatural" things are done, 
 and the ordinary operations of nature designedly inter- 
 fered with. 
 
 Page 91-92 
 
 Some examples of purely inorganic crystallisation, 
 especially when viewed by polarised light, are extraordin- 
 arily beautiful, and sometimes simulate the appearance of 
 gorgeous vegetation or of feather markings. It must be 
 admitted that to draw a clear line between such purely 
 automatic molecular arrangements and those which are 
 brought about through the agency of life is by no means 
 easy. The material world itself when closely examined is 
 found to be saturated with beauty as well as with law and 
 order, and it is far from surprising that the purely inorganic 
 realm has to many investigators seemed sufficient to ac- 
 count for everything. Until we know more clearly in 
 what way life acts as it does, until we understand more 
 fully the method of the interaction of mind and matter, 
 these things must remain a matter of empirical experience 
 admitted but not explained. The formulation of a 
 satisfactory theory must await the attainment of deeper 
 knowledge. Meanwhile all the careful investigation that 
 is going on, in biology, in psychology, and in every direc- 
 tion, is all to the good by whatever provisional hypothesis 
 the worker is guided. 
 
 Page 93 
 
 The quotation here, and that on page 97 also, are from 
 the writings of Rabindranath Tagore in his book called 
 Gitanjali, which he wrote both in Hindustani and in 
 English, and which constitutes an implicit message of peace 
 
Explanatory Notes 127 
 
 and harmony and mutual understanding from the East to 
 the West. 
 
 Page 95 
 
 Professor Miinsterberg for instance has indicated his 
 feeling that although he is open to conviction about the 
 reality of telepathy if he be forced to it by absolute demon- 
 stration, yet the fact would be so novel, the revolution so 
 great, and the disarrangement of organised knowledge so 
 profound, that almost any other hypothesis seems to 
 him preferable and more likely. I admit that telepathy 
 when universally accepted will constitute an important 
 enlargement of human knowledge, as well as an addition to 
 recognised human powers, but I cannot see that it is psy- 
 chologically and scientifically so revolutionary as it evi- 
 dently appears to the eminent philosopher of Harvard. 
 I trust that as opportunity offers he will pursue his studies 
 in this domain and will ultimately be convinced by facts. 
 
 Page 96 
 
 It appears to me very probable that telepathy or thought 
 transference is a form of direct communication between 
 mind and mind, apart from the usual physical or material 
 concomitants. If so, it is a vitally important discovery, 
 and should be confirmed by each one for himself through 
 careful experiment and observation, whenever opportunity 
 occurs; so that gradually it may be recognised as an 
 assured fact, not only by the few who have as yet taken the 
 trouble to study it, but by all. 
 
 Communication with discarnate minds is a further step 
 and needs separate and most critical proof, but if any such 
 communication ever occurs it would seem to be rendered 
 possible by the exercise of telepathic power. Such com- 
 munication does not anyhow appear easy, but it is prob- 
 ably by some method akin to telepathy that it can 
 
128 Presidential Address 
 
 sometimes be brought about. Mental and spiritual opera- 
 tions, such as prayer, realised as efficacious by religious 
 people, appear to be partially of this nature. 
 
 Page 97 
 
 The semi-jocular parable about "Poynting's Theorem" 
 here interjected will only be appreciated by physicists. It 
 is a mathematical theorem that when electric and magnetic 
 fields are superposed at right angles to each other a third 
 element is at once introduced, an element of progression 
 or advance of energy at right angles to both, and of value 
 equal to their vector product. It is in this way that light 
 advances, and that telegraphic messages, wireless and other, 
 are conveyed. Of the three elements, electricity, mag- 
 netism, and motion, when any two are supplied the third 
 necessarily supervenes. This is the basis of ordinary dy- 
 namos and of electric motors, as well as of many other more 
 recondite things. The Theorem with many illustrations 
 was published in the Philosophical Transactions of the 
 Royal Society for 1884. 
 
 Page 98 
 
 The human evil in the world can be regarded as the price 
 to be paid for human freedom. The highest product of 
 evolution is not a set of automata mechanically con- 
 strained or coerced to go right, but human beings, knowing 
 good and evil, who can go wrong if they choose, and whose 
 will to do right gradually develops; at a cost in suffering 
 and error, great indeed, but not too great for the worth- 
 whileness of the ultimate product. This point of view is 
 more fully explained in my book Man and the Universe 
 and other such writings. 
 
 The outstanding difficulty always felt about reconciling 
 freedom with fixed law is dealt with in the first article of 
 
Explanatory Notes 129 
 
 my book called Modern Problems (Methuen), where what 
 I have to say, whether it be considered useful or not, re- 
 presents or summarises the results of very careful con- 
 sideration. 
 
 Page 103 
 
 It will be said, it has indeed been frequently said, that 
 the evidence ought here to have been adduced. To this 
 there are two fairly obvious replies. The first is that the 
 evidence for any kind of scientific statements is quite 
 inappropriate to an address; a summary and an allusion is 
 all that can be allowed, and nothing more is attempted in 
 any part of an address of this kind; study of the evidence 
 is necessarily a long and laborious undertaking. The 
 second is that even though some parts of the evidence were 
 offered, not in an address but in a paper to one of the Sec- 
 tions, it would as yet not be admitted. The attempt has 
 been made. Sir William Barrett in the year 1876 read a 
 paper on the evidence for telepathy before the British 
 Association at Glasgow, but its publication was prevented. 
 
 No, the time is not ripe for discussing the evidence for 
 supernormal psychical experience except in connection with 
 a scientific society formed for the purpose. The subject is 
 only emerging from the stage expressed by the first para- 
 graph on page 77, though under the guidance of the critical 
 leaders of the Society for Psychical Research it is emerging 
 rather fast. The members of that Society are aware that 
 the evidence already published the carefully edited and 
 sifted evidence published by their own organisation 
 occupies some 40 volumes of Journal and Proceedings ; and 
 some of them know that a great deal more evidence exists 
 than has been published, and that some of the best evi- 
 dence is not likely to be published, not yet at any rate. 
 It stands to reason that the best evidence must often be of 
 a very private and family character. Many, however, are 
 the persons who are acquainted with facts in their own 
 
130 Presidential Address 
 
 experience which appeal to them more strongly than any- 
 thing that has ever been published. No records can sur- 
 pass first-hand direct experience in cogency. 
 
 Nevertheless members of the Society for Psychical 
 Research are also aware, or ought to be, that no one crucial 
 episode can ever be brought forward as deciding such a 
 matter. That is not the way in which things of import- 
 ance are proven. Evidence is cumulative, it is on the 
 strength of a mass of experience that an induction is ulti- 
 mately made and a conclusion provisionally arrived at; 
 though sometimes it happens that a single exceptionally 
 strong instance, or series of instances, may clinch it for 
 some individual. 
 
 But indeed the evidence in one form and another has 
 been crudely before the human race from remote antiquity, 
 only it has been treated in ways more or less obfuscated by 
 superstition. The same sort of occurrences as were known 
 to Virgil and many another seer the same sort of experi- 
 ences as are found by folk-lore students, not only in history 
 but in every part of the earth to-day are happening now 
 in a scientific age and sometimes under scientific scrutiny. 
 Hence it is that from the scientific point of view progress 
 is at length being made, and any one with a real desire to 
 know the truth need not lack evidence if he will first read 
 the records with an open mind and then bide his time and 
 be patient till an opportunity for first-hand critical observ- 
 ation is vouchsafed him. The opportunity may occur at 
 any time: the readiness is all. Really clinching evidence 
 in such a case is never in the past; a prima facie case for 
 investigation is established by the records, but real con- 
 viction must be attained by first-hand experience in the 
 present. 
 
 Page 104 
 
 The quotation is from the writings of Symmachus, an 
 important personage in the 4th century A.D.; not the Pope 
 
Explanatory Notes 131 
 
 of that name, but a pagan proconsul rather hostile to 
 official Christianity. The reference is Epp., x., 54. The 
 passive voice of the verb is not a misprint; it appears 
 intended to convey the sense not merely of arriving at 
 truth but of being assisted or guided thereto. 
 
Publications by 
 
 Sir Oliver Lodge 
 
 The Ether of Space 
 
 An account of the most recent researches into the prop- 
 erties of the fundamental medium of which the material 
 Universe appears to be composed. 1909. 
 
 Modern Views of Electricity 
 
 A well-known exposition of fundamental electrical prin- 
 ciples. New edition 1907. 
 
 Pioneers of Science 
 
 A course of popular lectures on Astronomical biography, 
 being sketches of the lives of the famous early astrono- 
 mers and their work, with numerous illustrations. 
 
 Life and Matter 
 
 A discussion of the scientific foundations of religion; 
 being an answer to Haeckel and a speculation concerning 
 the nature of life. 1905. 
 
 Modern Views on Matter 
 
 Being the Romanes Lecture to the University of Oxford, 
 delivered in 1903, on the new discoveries in electricity in 
 connection with Radium and other such phenomena. A 
 pamphlet. 
 
 Electrons 
 
 Or the nature and properties of Negative Electricity. 
 A treatise on the most recent discoveries in the pure 
 science of Electricity. 1906. 
 
 Easy Mathematics; Chiefly Arithmetic 
 
 A comprehensive summary specially addressed to 
 teachers, parents, self-taught students, and adults. In- 
 tended to make the subject interesting. 1905. 
 
Signalling through Space without Wires 
 
 First published in 1894 under the title " The Work of 
 Hertz and his Successors " ; being a pioneer treatise on 
 what has become Wireless Telegraphy. 1906. 
 
 Lightning Conductors and Lightning 
 Guards 
 
 A technical treatise on electric waves and discharges 
 generally, for Architects, Electrical Engineers, and 
 Physicists. 1892. 
 
 Elementary Mechanics 
 
 A text-book for Schools and Matriculation Candidates. 
 
 School Teaching and School Reform 
 
 A course of lectures delivered in Birmingham to Teach- 
 ers of the Midland District. 1905. 
 
 Parent and Child 
 
 A short Treatise on the Moral and Religious Education 
 of Children. 
 
 The Substance of Faith allied with 
 Science 
 
 A Catechism for Parents and Teachers. 1907. 
 
 Man and the Universe 
 
 A Study of the Influence of the Advance in Scientific 
 Knowledge upon our understanding of Christianity. 
 
 The Survival of Man 
 
 A Study in unrecognized Human Faculty. 
 
 Reason and Belief 
 
 Dealing with Incarnation, and with the truth underlying 
 ancient doctrines. 
 
 Modern Problems 
 
 Essays on a large number of controversial topics. 1912,. 
 
The Argument against Materialism 
 
 Life and Matter 
 
 A Criticism of Professor Haeckel's 
 "A Riddle of the Universe" 
 
 By Sir Oliver Lodge 
 
 Crown 8vo. $1.00 net. By mail $x.io 
 
 The author fully acknowledges Haeckel's service to scien- 
 tific thought in introducing Darwinism into Germany, and 
 he admits that to advanced students Haeckel's writings can 
 do nothing but good. He believes, however, that to some 
 general readers they may do harm, unless accompanied by a 
 suitable qualification or antidote, especially an antidote 
 against the bigotry of their somewhat hasty and destructive 
 portions. 
 
 " Deserves to rank with the best contributions by Huxley 
 to scientific literature; while from the scientific standpoint 
 it is timely in its appearance, brilliant in its conception, and 
 admirable in execution. It should be welcomed by all who 
 are interested in the development of true science, but who 
 have no patience for blatant materialism. . . The ut- 
 terance of a scientist eminent for his wonderful researches. 
 
 . . . The book is full of interest and information." 
 
 Rev. James M. Owen, Lynchburg, Va. 
 
 " A fascinating reply to Haeckel's materialistic philosophy 
 of life. The arguments are sane and sound. Lodge is a 
 profound scientist, but he does not allow his scientific know- 
 ledge to obscure his general judgment." 
 
 Providence Journal, 
 
 New York Q. P. Putnam's Sons London 
 
" One of the classics of the nineteenth century." 
 
 The Evolution of Man 
 
 A Popular Scientific Study 
 By Ernst Haeckel 
 
 Professor at Jena University 
 
 Translated from the Fifth (enlarged) Edition by 
 Joseph McCabe 
 
 Two volumes, 8vo, with 30 Colored Plates and 512 other Illustra- 
 tions, together with 60 Genealogical Tables . . Net, $10.00 
 New Cheaper Edition. 2 vols. Illustrated. Net, $5.00 
 
 The work is a comprehensive statement of the scientific 
 grounds for evolution as applied to man. It does not deal 
 with religious controversies, and is scientific throughout. 
 The work is unique in design, which is carried out in the 
 last edition with the highest degree of Haeckel's literary 
 and artistic skill. Haeckel has always been distinguished 
 for pressing the combination of the evidence from embry- 
 ology with the evidence of zoology and paleontology. In 
 the present work he devotes one volume broadly to embry- 
 ology, or the evolution of the individual, and the second to 
 the evolution of the human species, as shown in the com- 
 parative anatomy, zoology, and paleontology. The last few 
 chapters deal in detail with the evolution of particular 
 organs right through the animal kingdom: the eye, ear, 
 heart, brain, etc. Every point is richly illustrated from 
 Haeckel's extensive knowledge of every branch of biology 
 and his well-known insistence on comparative study. 
 
 The work is written for the general reader, all technical 
 terms being explained, and no previous knowledge being 
 assumed ; but the scientific reader, too, will find it a unique 
 presentation of all the evidence for man's evolution, and 
 especially as a study of embryonic development in the light 
 of race-development. 
 
 In this edition, to which Haeckel gave six months* hard 
 work, the plan is carried out with great skill, and the illus- 
 trations are very fine. All the most recent discoveries in 
 every branch of science involved are included. It is a 
 thoroughly up-to-date, non-controversial, most comprehen- 
 sive, and scientific treatise On the evolution^ man by the 
 greatest living authority on the subject. 
 
 New York Q. P. Putnam's Sons London 
 
The most valuable production since Darwin's " Origin 
 of Species." 
 
 The Nature of Man 
 
 Studies in Optimistic Philosophy 
 By Elie Metchnikoff 
 
 Sub-Director of the Pasteur Institute, Paris 
 
 Translated with an Introduction by 
 
 P. Chambers Mitchell 
 
 Secretary of the Zoological Society 
 Octavo. Illustrated. Popular Edition. $1.50 net. By mail, $x.Cg 
 
 It Is not often that a scientific book may be read with 
 ease, profit, and pleasure by the general reader, so that 
 M. Metchnikoft's book comes in the nature of an agreeable 
 surprise. It is marked by a refreshing nawet& and a large 
 simplicity which are characteristically Russian. The scien- 
 tific importance of this work is so great that it is spoken of 
 in England as the most valuable production since Darwin's 
 Origin of Species. 
 
 Opinions of the Press 
 
 *'An extremely interesting and typical book. ... With a distin- 
 guished frankness, M. Metchnikoff defines his attitude to our universal 
 prepossessions. It is his theory that the infirmities of age are to be 
 overcome. If there be ground for this conception, humanity is to be 
 profoundly changed and what we call life now, will be the childhood 
 and youth of that longer and larger life." H. G. WELLS, in London 
 Speaker. 
 
 " Undoubtedly a great book (in some quarters it has been hailed as 
 the greatest since Darwin's famous message to the world) and should 
 be read by all intelligent men and women." The Nation. 
 
 " A book to be set side by side with Huxley's Essays, whose spirit It 
 carries a step further on the long road towards its goal." Mail and 
 Express. 
 
 New York Q. P, Putnam's Sons London 
 
" Remarkable for its simple language and clear 
 style, ^ , , Bears the stamp of a production of 
 an erudite scientist and a deep t hin ker," Science. 
 
 THe Prolongation of 
 Life 
 
 Optimistic Essays 
 
 By Elie MetcHniKoff 
 Author of "The Mature of Man/' etc. 
 
 8vo. Illustrated Popular Edition. $1.7 5 net 
 By mail, $1.90 
 
 M. filie Metchnikoff is one of those rare scientists who 
 have found a way to lay hold of and present to the world in 
 untechnical phraseology, intelligible to the lay mind, such 
 results of his researches as are of universal interest and go 
 straight home to the bosoms and business of intelligent men. 
 The Nature of Man, by the same author, was one of the most 
 fascinating books, at once popular, and scientific, which have 
 appeared for decades. The book here in question will stand 
 beside it as a worthy companion volume. It is satisfactory 
 to report that, absorbed as Metchnikoff is in '* material " 
 problems, and deep as he is in the mysteries of the physical 
 universe, these essays show him to be an optimist who speaks 
 with no uncertain voice. 
 
 A great deal of attention is given in The Prolongation of 
 Human Life to the subject of old age and its causes, with 
 scientific observations of special cases among human beings 
 and the lower animals. The author suggests means of pro- 
 longing life and health, while contemplating natural death 
 with serenity, and finding that agreeable sensations accompany 
 its approach. Beyond a certain point it seems to him a dis- 
 advantage to prolong life. Passing on from these mortuary 
 lucubrations, the essays concern themselves with psychological 
 matters, with optimism and pessimism and in general with 
 questions of science and morals. The temperaments of certain 
 great men are analyzed in studies that have for their subjects 
 respectively Byron, Leopardi, Schopenhauer, and Goethe. In 
 the preface the author says that he has avoided, as far as 
 possible, repeating points which have been sufficiently treated 
 in The Nature of Man. 
 
 G. P. PUTNAM'S SONS 
 
 NEW YORK LONDON 
 
UNIVERSITY OF CALIFORNIA LIBRARY 
 BERKELEY 
 
 Return to desk from which borrowed. 
 This book is DUE on the last date stamped below. 
 
 DEC 9 1947 
 
 2lJan'boH 
 AN8 1953 L 
 
 
 4UN 8 1953 
 
 25:.lay'57AS 
 REC 
 
 MA i 23 
 
 LD 21-100m-9,'47(A5702sl6)476 
 
i^CL- oj 
 
 l 5 ^ M 
 
 287946 
 
 ) 
 
 Lt 
 
 m 
 
 UNIVERSITY OF CALIFORNIA LIBRARY