NOTICES OP THE PEOCEEDINGS AT THE MEETINGS OF THE MEMBERS OP THE Ivo^al Xnstttutixin of #reat Britain WITH ABSTKACTS OF THE DISCOUESES DBLIVBRED AT THE EVENING MEETINGS VOLUME XIX 1908—1910 LONDON PRINTED BY WILLIAM CLOWES AND SONS LIMITED 1912 patron. HIS MOST EXCELLENT MAJESTY KING GEOEGE V. t — The Duke of Northumberland, KG. P.O. D.C.L. LL.D. F.R.S. Treasurer — Sir James Crichton-Broavne, J.P. M.D. LL.D. D.Sc. F.R.S.— F.P. Honorary Secretary — Sir William Crookes, O.M. LL.D. D.Sc. F.R.S.— F.P. Managers. 1912-1913. Henry E. Armstrong, Esq., Ph.D. LL.D. F.R.S. The Right Hon. Lord Avebury, P.C. D.C.L. LL.D. F.R.S.— F.P. J. H. Balfour Browne, Esq., K.C. W. A. Burdett-Coutts, Esq., M.P. M.A. Sir David Gill, K.C.B. LL.D. D.Sc. F.R.S. The Right Hon. The Earl of Hals- bury, P.O. D.C.L. LL.D. F.R.S.— F.P. Donald William Charles Hood, Esq., C.V.O. M.D. F.R.C.P.-7.P. Alexander C. lonides, Esq. Sir Francis Laking, Bart., G.C.V.O. M.D. LL.D.— F.P. Henry F. Makins, Esq., F.R.G.S.— F.P. The Right Hon. Viscount Iveagh, K.P. G.C.V.O. LL.D. F.R.S. Sir Alexander 0. Mackenzie, Mus.Doc. D.C.L. LL.D. Alan A. Campbell Swinton, Esq., M.Inst.C.E. Alexander Siemens, Esq., M.Inst.C.E. —F.P. The Right Hon. Sir James Stirling, P.C. LL.D. F.R.S. Visitors. 1912-1913. Dugald Clerk, Esq., D.Sc. F.R.S. M.Inst.C.E. Francis Darwin, Esq., M.A. LL.D. F.R.S. William A. T. Hallowes, Esq., M.A. Arthur Croft Hill, Esq., M.D. M.R.C.S. W. Adams Frost, Esq., F.R.C.S. H. R. Kempe, Esq., M.Inst.C.E. J. G. Gordon, Esq., F.C.S. Charles Edward Groves, Esq., F.R.S. Robert Kaye Gray, Esq., M.Inst.C.E. Sir Robt. Hadfield, F.R.S. M.Inst.C.E. C. E. Melchers, Esq. Major Percy A. MacMahon, R.A. Sc.D. F.R.S. WiUiam Stone, Esq., M.A. F.L.S. F.C.S. Major G. J. W. Noble. Harold Swithinbank, Esq., J.P. F.R.S.E. Honorary Professor of Natural Philosophy — The Right Hon. Lord Rayleigh, O.M. P.C. M.A. D.C.L. LL.D. Sc.D. F.R.S. &c. Professor of Natural Philosophy— Sm J. J. Thomson, O.M. M.A. LL.D. D.Sc. F.R.S. &c. Fullerian Professor of Chemistry — Sir James Dewar, M.A. LL.D. D.Sc. F.R.S. &c. Fullerian Professor of Physiology— ^tlialm. Bateson, Esq., M.A. D.Sc. F.R.S. Keeper of the Library and Assistant Secreta/ry — Mr. Henry Young. Assista7it in the Library — Mr. Ralph Cory. Assistant in the Laboratory— 'Mr. J. W. Heath, F.C.S. CONTENTS 1908. 1908. PAGE Jan. 17. — Professor T. E. Thorpe — The Centenary of Davy's Discovery of the Metals of the AlkaUs ... 1 „ 24. — Colonel David Bruce — The Extinction of Malta Fever U „ 31. — Professor Ernest Rutherford — Recent Re- searches on Radio-activity ... ... ... 27 Feb. 3. — General Meeting 39 „ 7. — Humphry Ward, Esq. — Napoleon and the Louvre 45 „ 14. — Caleb Williams Saleeby, Esq. — Biology and History 47 „ 21. — Sir Oliver Lodge — The Ether of Space ... 61 „ 28. — Professor William Arthur Bone — Explosive Combustion, with special reference to that of Hydrocarbons ... ... ... ... ... 73 March 2.— General Meeting 88 „ 6. — Professor A. E. H. Love — The Figure and Constitution of the Earth ... ... ... 92 „ 13. — Chevalier G. Marconi — Transatlantic Wireless Telegraphy 107 „ 20. — Professor John Milne — Recent Earthquakes ... 131 „ 27. — Hon. Robert John Strutt — Radio-active Change in the Earth 147 April 3. — The Rioht Hon. Lord Montagu of Beaulieu — The Modern Motor-car 154 „ ,6. — General Meeting 167 40I4G IV CONTENTS. 1908. PAGE April 10. — Professor Joseph John Thomson — The Carriers of Positive Electricity ... ... ... ... 171 May 1. — Annual Meeting 202 „ 1. — Professor Joseph Larmor — The Scientific Work of Lord Kelvin 203 4. — General Meeting 239 8. — John Young Buchanan, Esq. — Ice and its Natural History... 243 15. — Herbert Timbrell Bulstrode, Esq. — The Past and Future of Tuberculosis 277 22. — Professor Dr. J. C. Kapteyn — Recent Re- searches in the Structure of the Universe ... 300 29. — Sir Ralph Payne-Gall wey, Bart. — Ancient and Mediaeval Projectile Weapons other than Fire- arms ... ... ... ... ... ... 316 June 1.- — General Meeting ... ... ... ... ... 335 „ 5. — Professor Sir James Dewar — The Nadir of Temperature, and Allied Problems ... ... 413 July 6.— General Meeting 338 Nov. 2.— General Meeting 342 Dec. 7.— General Meeting 349 „ 7. — Hodgldns Trust — Essay by Professor H. E. Armstrong on Low Temperature Research at the Royal Institution, 1900-1907 354 1909. 1909. Jan. 22. — Alfred Russel Wallace, Esq. — The World of Life : as Visualised and Interpreted by Darwinism 423 „ 29. — Colonel Sir Frederic L. Nathan — Improve- ments in Production and Application of Gun- Cotton and Nitro- Glycerine ... ... ... 430 CONTENTS. V 1909. PAGE Feb. 1. — General Meeting 445 „ 5. — Peofessor James George Frazer — The Influ- ence of Superstition on the Growth of Institutions 450 „ 12. — Professor Harold Albert Wilson — The Electrical Properties of Flame ... ... ... 465 „ 19. — Sir Henry Cunynghame — Recent Advances in Means of Saving Life in Coal Mines ... ... 469 „ 26. — Professor H. L. Callendar — Osmotic Pheno- mena and their Modern Physical Interpretation 485 March 1. — General Meeting 496 „ 5. — The Right Hon. A^iscount Esher — The Letters of Queen Victoria ... ... ... ... 500 „ 12. — Sidney George Brown, Esq. — Modern Submarine Telegraphy ... ... ... ... ... 524 „ 19. — Richard Threlfall, Esq. — Experiments at High Temperatures and Pressures ... ... ... 541 „ 26. — Arthur Stanley Eddington, Esq. — Recent Results of Astronomical Research ... ... 561 April 2. — Professor Sir J. J. Thomson — Electrical Stria- tions 577 „ 5. — General Meeting ... ... ... ... ... 586 „ 23. — Alexander Siemens, Esq. — Tantalum and its Industrial Apphcations ... ... ... ... 590 „ 30.— Edmund Gosse, Esq.— The Pitfalls of Biography 598 May 1.— Annual Meeting 600 „ 3. — General Meeting 601 „ 7. — Major Ronald Ross — The Campaign against Malaria 605 ' „ 14. — Professor George E. Hale — Solar Vortices and Magnetic Fields 615 „ 21. — Hon. Ivor Churchill Guest, M.P. — Afforesta- tion 631 VI CONTENTS. 1909. PAGE May 28. — J. Emerson Reynolds, Esq. — Advances in our Knowledge of Silicon as an Organic Element ... 642 June 4. — Professor J. A. Flemino — Researches in Radio- telegraphy ... ... ... ... ... 651 „ 7.— General Meeting 683 „ 11. — Professor Sir James Dewar — Problems of Helium and Radium ... ... ... ... 724 June 18. — A. Henry Savage Landor, Esq. — Recent Visit to the Panama Canal ... ... ... ... 687 July 5. — General Meeting 710 Nov. 1.— General Meeting 713 Dec. 6.— General Meeting 720 1910. 1910. Jan. 21. — Professor Sir James Dewar — Light Reactions at Low Temperatures ... ... ... ... 921 „ 28. — The Rev. Canon Beechinq — The Spiritual Teaching of Shakespeare ... ... ... 735 Feb. 4. — Professor William Bateson — The Heredity of Sex 735 „ 7.— General Meeting 736 „ 11. — Charles E. S. Phillips, Esq. — Electrical and other Properties of Sand ... ... ... 742 „ 18. — Professor H. H. Turner — Halley's Comet ... 753 „ 25. — The Right Hon. Lord Rayleigh — Colours of Sea and Sky ... 765 March 4. — Charles Chreb, Esq. — Magnetic Storms ... 772' 7.— General Meeting 787 „ 11. — H. Brereton Baker, Esq. — lonisation of Gases and Chemical Change ... ... ... ... 791 CONTENTS. Vll 1910. PAGE March 18. — Professor Sir J. J. Thomson — The Dynamics of a Golf-Ball ... 795 April 4. — Greneral Meeting ... ... ... ... ... 811 „ 8. — Professor Percival Lowell — Lowell Observa- tory : Photographs of the Planets ... ... 815 „ 15. — Professor William J. Pope — The Chemical Significance of Crystal Structure ... ... 823 „ 22.— T. Thorne Baker, Esq.— The Telegraphy of Photographs, Wireless and by Wire ... ... 835 „ 29. — Tempest Anderson, Esq. — Matavanu : A New Volcano in Savaii (German Samoa) ... ... 856 Mc^y 2. — Annual Meeting 857 „ 6. — Sir Almroth E. Wright — Auto-inoculation ... 858 [/?2 consequence of the lamented death of His Majesty King Edicard, the Patron of the Institution, the Evening Meetings v^ere dis- continued for two iveehs.'] „ 9.— General Meeting 859 „ 23. — Adjourned General Meeting ... ... ... 863 „ 27. — Captain Robert F. Scott — The Forthcoming Antarctic Expedition ... ... ... ... 864 June 3. — The Right Hon. Sir Rennell Rodd — Renais- sance Monuments in the Roman Churches, and their Authors 872 6.— General Meeting 888 „ 10.— Dr. H. Deslandres — The Progressive Disclosure of the Entire Atmosphere of the Sun ... ... 892 {In French) July 4. — General Meeting 908 Nov. . 7. — General Meeting 911 Dec. 5. — General Meeting 917 Index to Volume XIX 929 VUl PLATES PAGE Thermal Expansion of Ice (Figs. 1, 2) 254 Morteratsch Grotto (Figs. 3, 4, 5) 263, 264 View of San Antonio after Rainless Years, and after a Storm (Figs. 6a, 6b) 273 ^ Rock on Chilian Coast (Fig. 7) 274 Charts of Tuberculosis... 284 Figure illustrating Distance of Stars (Figs. 1-4) 308 Portrait of Sir James Dewar in the Laboratory 354 Photographs of Sun-Spots (Figs. 1-4, 6) 622, 626 Tower Telescope on Mount Wilson ... ... ... ... 624 Interior of Pasadena Laboratory 627 Sun-Spot Spectra 628 Siliceous Spicules in Sponges (Figs. 1, 2) 650 Panama Canal — Photographs, Maps, etc. ... 688, 690, 694 Problems of Helium and Radium (Figs. 1-5) ... ... ... 724 Photographs of Sand (Figs. 1-6) 742 Sand Electrical Machine (Fig. 7) 744 Sand Pihng, etc. (Figs. 8-11) 746, 748, 750 Crystal Structure (Figs. 2-5) 826,832 Photo-Telegraphic Apparatus ... ... ... ... ... 836 Drawings Transmitted by Telautograph (Plates II.-III.) ... 840 Atmosphere of the Sun (Plates I.-IV.) .^ ... 902 Light Reactions at Low Temperatures (Plates I. -V.) 928 Hn^al Snstituttatt 0f (BuBt IBrifent. ^*"* *'\o WEEKLY EVENING MEETINGl/-^. ^a#3:>' cO^ Friday, January 17, 1908. ^'i^:$:^J>^ George Matthey, Esq., F.R.S., Manager, in the Chair. Professor T. E. Thorpe, C.B. Ph.D. LL.D. D.Sc. F.R.S. M.R.L The Centenary of Davifs Discovery of the Metals of the Alkalis. A hundred years ago last October, there happened one of those events to which the term epoch-making may, without cavil or question, be fittingly applied. As it was an occurrence with which the name and fame of the Royal Institution are inseparably bound up, the Managers have thought it only proper tliat its centenary should not pass unnoticed here, and it is by their wish, therefore, that I appear on this the first possible opportunity after the actual date of its hundredth anniversary to give you some account of it, and to state, so far as I am able and within the limits of an hour, the fruitful consequences that have flowed from it. Let me, in the first place, attempt to recall the circumstances which led up to that cardinal discovery of which to-nient we celebrate the centenary. These are connected partly with tie Institution itself, and partly with the state of science in the early years of the 19th century. In the year 1807 this Institution was entering upon the eighth year of its existence. As you doul)tless know, the Royal Institution grew out of a proposal to deal with the question of the unemployed — namely, by forming in London by private subscription an establishment for feeding the poor and giving tliem useful employment, and also for furnishing food at a cheap rate to others who may stand in need of such assistance, connected with an institution for introducing and bringing forward into general use new inventions and improvements, particularly such as relate to the management of heat and the saving of fuel, and to various other mechanical contrivances by which domestic comfort and economy may be promoted. Such was the original prospectus, but, like many other prospectuses, it failed to equal the promise its projectors held out. Eventually the promoters decided, on the initiation of Count Rumf ord, that the Associated Institution would, as they expressed it, be " too conspicuous and too interesting and important, to be made an appendix to any other existing establishment," and therefore it ought to stand alone, on its own proper basis. Vol. XIX. (No. 102) b •2 Professor T. E. Thorpe [Jan. 17, Accordingly the problem of the unemployed still remains with us, whilst the new institution took the form of converting Mr. Mellish's house in Albemarle Street into a place where, by regular courses of philosophical lectures and experiments, the applications of the new discoveries in science to the improvement of the arts and manufactures might be taught, so as to facilitate the means of procuring the comforts and conveniences of life. The Royal Institution had a troubled infancy. Like the poor it was originally designed to succour, it suffered much in the outset from lack of nourishment. To add to its miseries, the little starve- ling was caricatured by Gillray, lampooned by Peter Pindar, and ridiculed by Lord Brougham ; and it was literally in the throes of dissolution when new life was breathed into it by the opportune arrival, in 1801, of a small spare youth of 22, from Bristol, whom the Managers had engaged at a salary of 100 guineas a year. The youth was Humphry Davy, who had acted as assistant to Dr. Beddoes, of the Pneumatic Institution, and who had already made some slight stir in scientific circles by his discovery of a characteristic property of nitrous oxide. In announcing his arrival to the Managers, Count Rumford reported that he had purchased a cheap second-hand carpet for Mr. Davy's room, together with such other articles as appeared to him necessary to make the room habitable, and among the rest a new sofa-bed, which, in order that it may serve as a model for imitation, had been made complete in all its parts. Six weeks after his arrival Davy was called upon to lecture, aud a descriptive para- graph er of the period thus chronicles his success in the PhiJosophical Magazme for 1801 : — " It must give pleasure to our readers to learn that this new and useful institution, the object of which is the application of Science to the common purposes of life, may l)e now considered as settled on a firm basis. . . . " We have also to notice a course of lectures, just commenced at the institution, on a new branch of philosophy — we mean the Galvanic Phenomena. On this interesting branch, Mr. Davy (late of Bristol) gave the first lecture on the 25th of April. He began with the history of Galvanism, detailed the successive discoveries, and de- scribed the different methods of accumulating galvanic influence. .... He showed the effect of galvanism on the legs of frogs, and exhibited some interesting experiments on the galvanic effects on the solution of metals in acids. Sir Joseph Banks, Count Rumford, and other distinguished philosophers were present. The audience were highly gratified, and testified their satisfaction by general applause. Mr. Davy, who appears to be very young, acquitted himself admirably well ; from the sparkling intelligence of his eye, his animated manner, and the tout ensemUe, we have no doubt of his attaining a distinguished eminence." And what was of more immediate consequence, this confident 1908] on Davifs Discovery of the Metals of tlie AlJcalis. 3 assurance was shared also by the Managers, for at a subsequent meeting they unanimously resolved "that Mr. Humphry Davy, Director of the Chemical Laboratory, having given satisfactory proofs of his talents as a lecturer, should be appointed, and in future denominated, Lecturer in Chemistry at the Royal Institution, instead of con- tinuing to occupy the place of Assistant Lecturer, which he has hitherto filled." That such shrewd experienced men of the world as Sir Joseph Banks and Rumf ord, who were the moving spirits in the management of the Institution and genuinely solicitous for its welfare, should thus entrust its fortunes, then at their lowest ebb, to the power and ability of a young and comparatively unknown man, barely out of his teens, seems, even in .an age which was familiar with the spectacle of " a proud boy " as a Prime Minister, like the desperate throw of a gambler. But Banks and Rumf ord had, doubtless, good reason for the faith that was in them. For a happy combination of circumstances had served to bring the Cornish youth within the range of many who could be of service to him in that search for the fame for which he hungered. His connection with the Beddoes brouglit him the friend- ship of the Edge worths, and it is amusing to trace how the good- humoured patronage of the gifted Maria quickly passed into amazement and ended in awe as her acquaintance with him ripened. Living in Bristol, he was at once brought into that remarkable literary coterie which distinguished that city at the close of the eighteenth century. Southey spoke of him as a miraculous young man, whose talents he could only wonder at. Cottle, the publisher, on one occasion said to Coleridge, " You have doubtless seen a great many of what are called the cleverest men — how do you estimate Davy in comparison with these ? " Mr. Coleridge's reply was strong and expressive. " Why, Davy can eat them all ! There is an energy, an elasticity, in his mind which enables him to seize on and analyse all questions, pushing them to their legitimate consequences. Every subject in Davy's mind has the principle of vitality. Living thoughts spring up like turf under his feet." Davy's experimental work on " the pleasure-giving air " had made him known to the Watts and the Wedgewoods. Priestley, then in exile, and Hope of Edinburgh, were greatly impressed with the philosophical acumen of the author of phosoxygen, and he had a powerful friend in his own countyman Davies Gilbert, who succeeded him in the Presidential Chair of the Royal Society. We need be in no doubt, therefore, as to the influences which conspired to bring Davy into what he termed " the great hot-bed of human power called London." The mention of Davy's first course of lectures in this Institution brings me at once to the proper subject of this discourse. The first year of the last century is memorable for the invention B.2 4 Professor T. E. Thorpe [Jan. 17, of the voltaic battery and for its immediate application by Nicholson and Carlisle in this country to the electrolytic decomposition of water. Davy himself has said, " The voltaic i3attery was an alarm bell to experimenters in every part of Europe ; and it served no less for demonstrating new properties in electricity, and for establishing the laws of this science, than as an instrument of discovery in other branches of knowledge ; exhibiting relations between subjects before apparently without connection, and serving as abend of unity betAveen chemical and physical philosophy." We owe it to Sir Joseph Banks that Yolta's great discovery was first made known to English men of science, and the study of the phenomena of Galvanic Electricity was at once entered upon by a score of experimenters in this country. Among them was Davy. Even before he left Bristol he was hard at work on the subject, sending the results of his observations to Nicholson's Journal in a series of short papers. He resumed his inquiries immediately on his arrival in London, and was doubtless well prepared, therefore, for his opening course of lectures. In 1801 he sent his first communication to the Royal Society on " An Account of Some Galvanic Combinations Formed by ^ the Arrangement of Single Metallic Plates and Fluids, Analogous to the NcAv (ialvanic Ajjparatus of Mr. Yolta." Although the work was con- tinually interrupted by requests made to him l)y the Managers to carry out their own ideas of facilitating the means of procuring the comforts and conveniences of life, he never lost sight of the subject of voltaic electricity, and in spite of innumeral)le distractions due to the precarious position of the Institution, he gradually accumulated the material, out of which grew his first Bakerian Lecture " On Some Chemical Agencies of Electricity," read before the Royal Society on November 2oth, 1806. I have ventured elsewhere to express my opinion of this paper. In my judgment it constitutes, in reality, Davy's greatest claim as a philosopher to our admiration and grati- tude, for in it he, for the first time, succeeded in unravelling the fundamental laws of electro-chemistry, and thereby imported a" new order of conceptions, altogether unlocked for and undreamt of, into science. I am only at the moment concerned with this memoir in its re- ktion to the discovery of which to-night we celebrate the centenary. The isolation of the metals of the alkalis was unquestionably an achievement of the highest brilliancy, and as such appeals strongly to the popular imagination. But it was only the necessary and con- sequential link in a chain of discovery which, bad Davy neglected to make it, would have been immediately forged by another. The publication of Davy's first "^ Bakerian Lecture produced a great sensation, both at home and abroad. Berzelius, years after- wards, spoke of it as one of the most remarkable memoirs that had ever enriched the theory of chemistry. Very significant, too, of the 1908] on Davy's Discovery of the 3IetaU of the Alkalis. 5 impression it made on the world of science was the action of the French Institute. Bonaparte, then First Consul, had announced his intention of founding a medal " for the best experiment which should be made in the course of each year on the galvanic fluid," and a committee of the Institute, consisting of Laplace, Halle, Coulomb, Hauj, and Biot, was appointed to consider the best means of giving effect to the wishes of the First Consul. To the young man, with the little brown head, like a boy (as Lady Brownrigg described him), now 28 years of age, was awarded the medal. All the Institute got from the founder of the medal was, what Maria Edgeworth termed, " a rating all round in imperial BiUingsgate." There was no entente cordiale in those days ; indeed, the feehng of animosity was intense. Of course, there were persons who said that patriotism should forbid the acceptance of the award. Davy's own view was more sensible and politic : " Some people," he said to his friend Poole, " say I ought not to accept this prize ; and there have been foolish paragraphs in the papers to that effect ; but if the two countries or governments are at war, the men of science are not. That would, indeed, be a civil war of the worst description ; we should rather, through the instru- mentality of men of science, soften the asperities of national hostility." Thanks to the kindness of Dr. Humphry Davy Rolleston, the grandson of Dr. John Davy, the brother of Su- Humphry, who has also been so good as to lend me this admirable bust of the great chemist by Chantrey, and this charming portrait by Jackson, I am able to show you this evening this historically interesting medal. What Davy looked like at this period of his life may be seen from the picture I now project upon the screen. It is a reproduction of the large portrait which hangs in the vestibule, and which the Institution owes to the thoughtful kindness of the late Mr. Graham Young. As the applications of voltaic electricity seemed in 1806 to have no immediate bearing on the comforts and conveniences of life, Davy, during the greater part of the following year, was required to direct his attention to other matters. But in the late summer of 1807 he was able to resume his work with the voltaic battery, and he commenced to study its action on the alkalis. That the alkalis— potash and soda — would turn out to be com- pound substances was not an unfamiliar idea at the time, and it is signiticant that almost immediately after Nicholson and Carlisle had resolved water into its elements by the action of voltaic electricity, Henry, of Manchester, the friend and collaborator of Dalton, should have made the attempt to apply the same agency to the separation of the presumed metallic principle of potash. The conception that what the older chemists called " earths " might be made to yield metals was at least as old as the time of Boyle, and probably dates back from the earliest days of alchemy. The relation of the earths to the metals was part of the doctrine of Becher and Stahl : it was no less a 6 Professor T. E. Thorpe [Jan. 17, part of the antiphlogistic doctrine of Lavoisier, although the points of view were diametrically opposed. Neumann attempted to obtain a metal from lime, Bergman considered that baryta was, like lime, a metallic calx, and Baron that alumina contained a metal. From their many analogies to these substances it was not unreasonable, there- fore, to surmise that potash and soda might also contain metallic principles. I have elsewhere pointed out that there is some evidence that whilst at Bristol Davy had akeady attacked the problem of the resolution of the alkalis by means of voltaic electricity. What pre- cise idea he had in again attacking it, or what expectation he had of a definite result, is difficult to determine. In one of his lectures on Electro-chemical Science, delivered some time subsequently, he said he had a suspicion at the time that potash might turn out to be " phosphorus or sulphur united to nitrogen," conceiving, that as tne volatile alkali was composed of the light inflammable hydrogen united to nitrogen, so the fixed and denser alkalis might be composed of the denser inflammable bodies — phosphorus and sulphur — also united to nitrogen. Davy once said that " analogy was the fruitful parent of error," and few more striking instances of perverted analogy are to be met with in science than this. In another of his lectures he said of the alchemists that " even their failures developed some unsought-for object partaking of the marvellous " ; and if such had been his reasoning, the statement is no less true of himself. So far as can be ascertained, it was on October 10, 1807, that he obtained his first decisive result. This is thus described in Davy's own handwriting in the I^aboratory Journal, which has been pre- erved for us by the pious care of Faraday, and which is one of the most precious of the historical possessions of the Royal Institution : "When potash was introduced into a tube having a platina wire attached to it, so [fig.], and fused into the tube so as to be a con- ductor— i.e. so as to contain just water enough, though solid — and inserted over mercury, when the platina was made negative, no gas was formed and the mercury became oxydated, and a small quantity of the alkaligen was produced round the platina wire, as was evident from its quick inflammation by the action of water. When the mercury was made the negative, gas was developed in great quantities from the positive wire, and none from the negative mercury, and this gas proved to be pure oxygen — a capital experiment, proving the decomposition of potash," On the 19th of the follo^\ing month he delivered what is generally regarded as the most memorable of all his Bakerian Lectures. It is entitled " On some New Phenomena of Chemical Changes produced by Electricity, particularly the Decomposition of the fixed Alkalies ; and the Exhibition of the new substances which constitute their bases ; and on the general Nature of Alkaline Bodies." 1908] on Dav if s Discovery of the 3Ietals of the Allcalis. 7 Few discoveries of like magnitude have been made and perfected in so short a time, and few memoirs have been more momentous in result than that which, put together in a few hours, gave the results of that discovery to the world. The whole work was done under conditions of great mental ex- citement. His cousin, Edmund Davy, who at the time acted as his assistant, relates that when he saw the minute globules of the quicksilver-like metal burst through the crust of potash and take fire, his joy knew no bounds ; he actually danced about the room in ecstasy, and it was some time before he was sufficiently composed to continue his experiments. The rapidity with which he accumulated results, after this first feeling of delirious delight had passed, was extraordinary, and he had obtained most of the leading facts concerning the physics and chemistry of the new substances before the middle of November. He began his lecture with a f ehcitous reference to the concluding remarks of one of the previous year, namely : " That the new methods of investigation promised to lead to a more intimate knowledge than had hitherto been obtained concerning the true elements of bodies. This conjecture, then sanctioned only by strong analogies, I am now happy to be able to support by some conclusive facts." In the first attempts he made to decompose the fixed alkalis he acted upon concentrated aqueous solutions of potash and soda with the highest electrical power he could then command at the Royal Institution, viz., from voltaic batteries containing 2:> plates of copper and zinc of 12 inches square, 100 plates of 6 inches, and 150 of 4 inches, charged with solutions of alum and nitric acid ; but although there was high intensity of action, nothing but hydrogen and oxygen was disengaged. He next tried potash in igneous fusion, and here the results were more encouraging : there were obvious and striking signs of decomposition ; combustible matter was produced, accom- panied with flame and a most intense light. He had observed that, although potash, when dry, is a non-conductor, it readily con- ducts when it becomes damp by exposure to air, and in this state " fuses and decomposes by strong electrical powers." Let me state in his own words, for the words are classical, what followed : — " A small piece of pure potash, which had been exposed for a few seconds to the atmosphere, so as to give conductive power to the sur- face, was placed upon an insulated disc of platina, connected with the negative side of the battery of the power of 250 of 6 and 4 [that is 100 plates of 6 inches square and 150 plates of 4 inches square] in a state of intense activity ; and a platina wire communicating with the positive side was l)rought in contact with the upper surface of the alkali .... Underthese circumstances a vivid action was soon observed to take place. The potash began to fuse at both its points of electriza- tion. There was a violent effervescence at the upper surface ; at the 8 Professor T. E. Thorpe [Jan. 17, lower, or negative surface, there was no liberation of elastic fluid ; but small globules, having a high metallic lustre, and being precisely similar in visible characters to quicksilver, appeared, some of which burnt with explosion and bright flame, as soon as they were formed, and others remained, and were merely tarnished, and finally covered by a white film which formed on their surfaces." He goes on to say : — " Soda, when acted upon in the same manner as potash, exhibited an analogous result ; but the decomposition demanded greater inten- sity of action in the batteries, or the alkali was required to be in much thinner and smaller pieces. " The substance produced from potash remained fluid at the temperature of the atmosphere at the time of its production : that from soda, which was fluid in the degree of heat of the alkali during its formation, became soHd on cooling, and appeared having the lustre of silver." It would seem from this description of its properties that the potassium Davy first obtained was alloyed with sodium owing to the fact that the potash contained soda. Potassium is solid up to 143° F., whereas, as Davy was the first to show, an alloy of potassium and sodium is fluid at ordinary temperatures. On account of their alterability in contact with air, Davy had considerable difficulty in preserving and confining the new substances so as to examine their properties. As lie says, like the Alkahests imagined by the Alchemists, they acted more or less upon almost every body to which they were exposed. Eventually, he found they might be preserved in mineral naphtha. The " basis " of potash was described by him as a soft malleable soUd with the lustre of polished silver. " At about the freezing point of water it becomes harder and brittle, and when broken in fragments, exhibits a crystallised texture which in the microscope seems composed of beautiful facets of a perfect whiteness and high metallic splendour. It may be converted into vapour below a red heat, and may be distilled unchanged, and is a perfect conductor of heat and electricity. Its most marked differ- ence from the common run of metals is its extraordinary low specific gravity." At the time of its discovery, it was the hghtest solid known. The " basis " of soda was found to have somcAvhat similar properties. It was slightly heavier than the " basis " of potash, and fused at a higher temperature. Davy next examined the behaviour of the new substances towards a large number of reagents, but as his observations are now the common property of the text-books, it is unnecessary here to dwell upon them. He then enters upon some general observations on the relations of the " bases " of potash and soda to other bodies : 1908] on Davy's Discovery of the Metals of the Alkalis. 9 " Should the bases of potash and soda be called metals ? The greater number of philosophical persons," he says, "to whom this question has been put, have answered in the affirmative. They agree with metals in opacity, lustre, malleability, conducting powers as to heat and electricity, and in their qualities of chemical combination. " Their low specific gravity does not appear a sufficient reason for making them a new class ; for amongst the metals themselves there are remarkable diiferences in this respect. ... In the philosophical division of the classes of bodies, the analogy between the greater number of properties must always be the foundation of arrangement. " On this idea, in naming the bases of potash and soda, it will be proper to adopt the termination which by common consent has been applied to other newly discovered metals, and which, though originally Latin, is now naturalised in our language. " Potasium {sic) and sodium are the names by which I have ven- tured to call the new substances ; and whatever changes of theory, with regard to the composition of bodies, may hereafter take place, these terms can scarcely express an error ; for they may be considered as implying simply the metals produced from potash and soda. I have consulted with many of the most eminent scientific persons in this country upon the methods of derivation, and the one I have adopted has been the one most generally approved. It is perhaps more significant than elegant. But it was not possible to found names upon specific properties not common to both ; and though a name for the basis of soda might have been borrowed from the Greek, yet an analogous one could not have been applied to that of potash, for the ancients do not seem to have distinguished between the two alkalies." Such, then, are the more significant features of one of the greatest discoveries ever made l)y a British chemist, as these are set forth in one of the most remarkable papers in the Philosophical Transactions of the Royal Society. Sir James Dewar has been so good as to have prepared for me a photographic reproduction of a water-colour drawing of tiie labonitory of the Royal Institution as it existed in Davy's time, showing the actual spot where the isolation of the metals of the alkalis was first effected. The publication of Davy's discovery created an extraordinary sensation throughout the civilised world, a sensation not less pro- found, and certainly more general from its very nature, than that which attended his lecture of the previous year. But at the very moment of his triumph, it seemed that the noise of the universal acclaim with which it was received was not to reach him. I have already made reference to the condition of mental excitement under which the discovery was made and prosecuted. Almost immediately after the delivery of his lecture he collapsed, struck down by an ill- ness which nearly proved fatal, and for weeks his life hung on a 10 Professor T. E. Thorpe [Jiiii. 17, thread. He had been in a low feverish condition for some time previously, and a great dread had fallen upon him that he should die before he had completed his discoveries. It was in this condition of body and mind that he had applied himself to the task of putting together an account of his results. Four days after this was given to the world he took to his bed, and he remained there for nine weeks. Such a blow following hard on the heels of such a triumph aroused the liveliest sympathy. The doors of the Royal Institution were beset by anxious inquirers, and written reports of his condition at various periods of the day had to be posted in the hall. The strength of the feeling may be gleaned, too, from the sentences with which the Rev. Dr. Dibdin, who had been hurriedly engaged to take his place in the theatre, began the lecture introductory to the Session of 1808. " The Managers of this Institution have requested me to impart to you that intelligence, which no one who is alive to the best feelings of human nature can hear without the mixed emotion of sorrow and delight. "Mr. Davy, whose frequent and powerful addresses from this place, supported by his ingenious experiments, have been so long and so well known to you, has, for the last five weeks, been struggling between life and death. The effects of these experiments recently made in illustration of his late splendid discovery, added to con- sequent bodily weakness, brought on a fever so violent as to threaten the extinction of life. Over him it might emphatically be said in the language of our immortal Milton, that ' . . , . Death his dart Shook, but delayed to strike.' " If it had pleased Providence to deprive the world of all further benefit from his original talents and intense application, there has certainly been sufficient already effected by him to entitle him to ]je classed among the brightest scientific luminaries of his country." After having, " at the particular request of the Managers," given an outline of Davy's investigations, Dr. Dibdin proceeded to say : — " These may justly be placed among the most brilliant and valuable discoveries which have ever been made in chemistry, for a great chasm in the chemical system has been filled up ; a blaze of light has been diffused over that part which before was utterly dark ; and new views have been opened, so numerous and interesting, that the more any man who is versed in chemistry reflects on them, the more he finds to admire and heighten his expectation of future important results. " Mr. Davy's name, in consequence of these discoveries, will be always recorded in the annals of science amongst those of the most illustrious philosophers of his time. His country, with reason, will be proud of him, and it is no small honour to the Royal Institu- 1908] on Davy's Discovery of the Metals of the Alkalis. 11 tion that these great discoveries have been made within its walls — in that laboratory, and bj those instruments which, from the zeal of promoting useful knowledge, have, with so much propriety, been placed at the disposal and for the use of its most excellent professor of chemistry." And now, in the few minutes that remain to me, let me indicate what has been the outcome of this great and fundamental discovery. How far has the expectation of future important results been realised ? Have sodium and potassium at all justified the hope that they would facilitate the means of procuring the comforts and conveniences of life ? I have not the time, even if I had the intention, to attempt to follow the many changes in the metallurgy of the metals of the alkalis of the past century. Let me at once proceed to slQw how the matter stands at the end of a hundred years. The general properties and chemical activities of potassium and sodium are so very similar that as a matter of commercial production that metal which can be most economically obtained is necessarily the one most largely manufactured, and of the two that metal is sodium. To-day, sodium is made by thousands of tons, and by a process which in principle is identical with that by which it was first made by Davy, i.e. by the electrolysis of fused caustic soda. It is very significant that after a series of revolutions in its manufacture, sodium, having been produced from time to time on a manufacturing scale by a variety of metallurgical methods involving purely thermal processes of reduction and distillation, entirely dissociated from electricity, we should have now got back to the very principle of the process which first brought the metal to light. And that this has been industrially possible is entirely owing to another of Davy's discoveries — possibly indeed tlie greatest of them all— Michael Faraday. As we all gratefully acknowledge, it is to the genius and labours of Faraday — Davy's successor in this place — that the astonishing development of the application of electrical energy which characterises this age has taken its rise. The modern method of production of sodium is based, therefore, as regards principles upon the conjoint labours of Davy and Faraday. These principles took their present form of application at the hands of a remarkably talented American — Mr. Hamilton Y. Castner — ^ whose too early death, in the full vigour of his intellectual powers, was an incalculable loss to metallurgical chemistry. It is by Castner's process that all the sodium of to-day is manufactured. In the Castner process melted caustic soda produced by the electrolysis of a solution of common salt by a metliod also devised by Castner, is brought into an iron vessel shaped like a large cauldron, mounted in brickwork, and provided with an extension adapted to receive the negative electrode. Suspended directly above the cathode is an iron vessel attached to a lid ; to its lower edge is secured iron 12 Professor T. E. Thorpe [Jan. 17, wire gauze, which, when the receptacle is in position, completely surrounds the cathode. The positive electrode is connected with the lid of the vessel, which is provided with openings for the escape of the gases resulting from the electrolysis, and is suital)ly insulated. As the electrolysis proceeds the alkah metal, being much lighter than the molten caustic, rises from the negative electrode and passes into the receiver, the gases escaping around the edges of the cover. The molten metal collects on the surface of the caustic, and is removed by means of a large perforated spoon, the perforations enabling the melted caustic to flow out, while the metal remains in the spoon. As the several vessels are thus skimmed in succession the fused sodium is collected into an iron vessel, whence it is poured into moulds in which it congeals, forming blocks of the size and shape of an ordinary building brick. These, after being trimmed to remove adherent oxide, are immersed in paraffin oil, and are then packed into large iron drums holding about 6 or 7 cwt., capable of being closed air-tight, and protected in transit by an outer casing of wood. The due regulation of the volume and intensity of the current is a matter of the greatest importance in order to obtain the most economical yield of the metal. Xo very high temperature is needed ; indeed, the temperature of the fused caustic soda should not be much higher than that of its melting point. By suitably regulating the current, the soda, in fact, may l)e maintained at the proper temperature and in the proper degree of fluidity without extraneous heat. Fresh melted caustic soda is added to the vessel from time to time to replace the metal removed, and in this manner the process is made con- tinuous. The Oastner process is now worked in England at Wallsend-on- Tyne, and at Weston Point, in Cheshire ; at Rheinfelden, in Germany ; at Clavaux, in France ; also in Switzerland, and at Niagara, in America. The present yearly output amounts to about 5000 tons, but the plant already laid down is capable of producing at least twice this quantity. The greater quantity of the sodium made in England is sent to Glasgow, where it is converted into sodium cyanide by the Cassel Cyanide Company for use in the extraction of gold. As gold is, I suppose, generally considered the principal material factor in pro- curing the comforts and conveniences of life, Davy's great discovery may be thus said to have secured the primary object which the pro- jectors of the Royal Institution had in view. Other important uses of sodium are in the manufacture of peroxide for bleaching purposes, of artificial indigo, and of a number of other synthetic dye stuffs and of drugs like antipyrin. It need hardly be said that this extraordinary development of the manufacture has not been without its influence on the price of sodium. A quarter of a century ago it was a comparatively rare metal, and a stick of it was regarded as a chemical curiosity, to be 1908] on Davy's Discovery of the Metals of the AlJcalis. 13 handled with circumspection and care. Even as late as 1890 its selling price was as high, as 8s. per lb. To-day it is 8^. Sodium now takes rank, therefore, witli zinc, tin, copper, or aluminium as a common, ordinary metal of conmierce. I am indebted to the directors of the Castner-Kellner Company, and in particular to my friends Sir Henry Roscoe and Mr. Beilby, for affording me the opportunity, in connection with this lecture, of actually witnessing the modern process of manufacturing sodium as it is carried out at ^Yallsend ; and I am further indebted to Mr. Beilby for the loan of the lantern slides and specimens with which I have sought to illustrate that process. And in concluding may I be permitted to recall here the feelings to which that visit to Wallsend gave rise. There, grouped together on the very spot where ended the old wall— the visible symbol of the power and might of a civilisation long since passed away — were some of the characteristic signs of another civilisation ampler and more beneficent. Before me, stretching down to the river, was the factory where a score of workers, clad in helmets and gauntlets and swathed like so many Knights Templar, travel-stained and war-worn, their visages lit up by the yellow soda flames, and their ears half- deafened with the sound of exploding hydrogen — a veritable inferno — were repeating on a Gargantuan scale the little experiment first made a century ago in the cellars of this building ; turning out, day and night, hundredweights of the plastic metal in place of the little pin-heads which then burst upon the astonished and delighted gaze of Davy. Behind me was the magnificent power-house — one of the most magnificent of its kind in the world —furnishing not only the electrical energy which transformed the soda into sodium, but diffusing this energy for a multitude of other purposes over an entire district — a noble temple to the genius and prescience of Faraday. Surely one might here say, if you desire to see the monuments of these men, look around ! And to my right, and close at hand, was the huge building slip just vacated by the Mauretania, herself a symbol of the supremacy of an empire, far mightier, more world-wide, and more potent for good than that which massed its legions behind the old wall. [T. E. T.] 14 Colonel David Bruce [Jan. 24, WEEKLY EVENING MEETING, Friday, January 24, 1908. Sir Jaxes Crichton-Browne, M.D. LL.D. F.R.S., Treasurer and Vice-President, in the Chair. Colonel David Bruce. R.A.M.C. C.B. D.Sc. F.R.S. The Extinction of Malta Fever. The subject of this evening's discourse is the Extinction of Malta Fever, and I propose to brino* before you in this paper the various steps in the investigation of tliis disease wliich led up to the discovery of its mode of spread, and so to its prevention and extinction. Historical. This fever has been studied in various ways for the last quarter of a century, but it was not until 1904 that the Government, alarmed by the great wastage in man caused by it, took the matter up seriously, and asked the Royal Society to undertake a thorough investigation of the disease. This the Royal Society agreed to do, and early in the summer of the same year sent out to Malta a small Connnission for this purpose ; and it is princi])ally the result of the work of the Connnission which I have the honour of Ininging before you this evening. It seems a pity that this research was not undertaken twenty years earlier, as during this time, some 14,000 or 15,000 soldiers and sailors have suffered from the disease. It is to be hoped that the result of this work will bring home to the Government the great good to be gained by introducing scientific methods of research into the study of disease in the Army. This, strange as it may seem, has not yet come home to Government departments. If an application was made to the Treasury to-morrow for, say, 100/. for such scientific purposes, the answer would be that it was not the function of the Royal Army Medical Corps to engage in scientific research, but that their duty was to attend to the sick soldiers. This waiting till a man is sick is fatal. It ought to be our chief duty to anticipate and prevent sickness. Before I leave the subject of the Commission, I may remark tliat its work went on for three years before the successful result was attained. But now to return to Malta fever. 1908] on the Extinction of Malta Fever. 15 Desceiption of Malta Fever. At the outset it will be necessary to give a short description of this fever, in order that you may know what we are dealing with. Malta fever is no trivial complaint, but is a severe and dangerous disease, which lasts a long time, and is accompanied by a good deal of pain. To give yon an idea of the long duration of this fever, I may tell you that our soldiers remain under treatment in hospital with it on an average for 120 days, and it is by no means uncommon for a patient to suffer almost continually from it for two or even more years. During the whole course of his illness the patient is apt to suffer from severe rheumatic pains in the joints, and neuralgia in various nerves, and this combined with the long-continued fever, brings about a condition of extreme emaciation and weakness, from which recovery is slow. In order to show you to what a degree of emaciation a few weeks of this fever may bring a man, I will take the liberty of throwing on the screen a photograph of a soldier who has been suffering from it for a few weeks. [Here a picture of a man extremely thin and evi- dently very ill was thrown on the screen.] On admission to hospital this man was a robust and muscular soldier, and now see what a few weeks have brought him to. Incidence of Malta Fever in the Garrison. Next I would draw your attention to the number of cases of this fever which occur among our sailors and soldiers in Malta, in oi'der to impress upon you the importance of this disease to the State. Among our soldiers, who number about 7000, there have been on an average 312 adlnissions to hospital every year from Malta fever alone, and among the sailors about the same number. This means that 624 soldiers and sailors have been treated in hospital 120 days each, which makes about 75,000 days of illness per annum. To illustrate this I throAv on the screen a diagram (Fig. 1). Now I have said enough to show you that we are dealing with a severe and important form of disease. Study of Malta Fever from the Epidemiological Point of View. Before we begin the experimental investigation of this fever, it is well that we should know as much as possible about it from a general point of view. For example : In what parts of the world is it found ; under what conditions of climate ; whether any connection can be 16 Colonel David Bruce [Jan. 24, made out between it and the temperature or rainfall ; whether age or sex render a person more liable ; whether occupation or social position has any bearing on it ; whether a difference in sanitary con- ditions has any effect, as, for example, do people living in small villages without any proper system of water supply suffer more than those living in towns supplied with pure water and a modern drainage system? Now it is clearly impossible for me to go into all these points with the time at my disposal, but I would like to bring before you a few facts which bear on the problem we have before us. 1899x0 1905. 1905. ^ § i ^ 1 1 ^ § y ? § 1 to 88 ' — ^ 25 — 20 — — 10 1 ^1 r 1 1 1 1 1 1 1 1 1 1 § 1 ^ •^ ^ 1 ^ § ^ 1 § 90 - ^B SO 1 70 ^^M rto 50 - ! 40 - - 50 rr :_ ■ — ■io T 1 1 Fig. 1. -Chart of Incidence in 1899-1905, AND 1905. Geographical Distrihution.—Yov example, it is interesting to know that Malta fever is not confined to Malta, but occurs in most parts of the world. Climatic Conditions.— Then again in regard to the effect of climate. Malta is extremely hot and dusty in the summer, and correspondingly cold and wet in winter. But, although the number of cases of Malta fever do show an increase in summer, yet it is a disease which is prevalent all the year round, one-third as many cases occurring in the coldest and rainiest months, as in the hottest and dustiest. Another fact of importance, is that if we study the occurrence of Malta fever in individual years, we are struck by its irregularity, a number of cases appearing in December or February or other of the cold and rainy months. 1908] 0)1 the Extinction of Malta Fever, 17 Social Position. — Another curious fact in regard to this disease is, that the better the social position of a person the more risk is there of catching this fever. Officers and their wives and children, living in large, airy and clean houses, suffer more frequently than the men in their more crowded barrack-rooms. In fact the chance of a naval or military officer taking this fever was more than three times as great as in the case of the men. This is shown on this diagram!(Fig. 2). MALTA r£V£R fNTHc CARRfSON RAT/O per /OOO. 1897 TO 1905 Fig. 2. — Incidence in Officers, Men and Women, FOR 1887-1905. Distribution of Malta Fever among the Civil Population. — Another important fact is the distribution of Malta fever among the civil popu- lation. Until recently it was supposed by many of us that it was restricted to the inhabitants of the cities surrounding the Grand Har- bour. This was in the days when the theory was held that the poison which causes this fever was found in the air. As the Grand Harbour at that time was in a very dirty condition, the drainage of Yaletta and the three cities falling into it, there was some excuse for this belief. Malta fever is now known to occur in every part of Malta, and. in fact, the general distribution of this disease is very striking. It is not the cities round the harbours which are struck most heavily, some of the inland towns and villages showing a much higher fever-rate. This is illustrated by the following diagram (Fig. 3). Vol. XIX. (No, 102) 0 18 Colonel David Bruce [Jan. 24, Summary of Epidemiological Evidence. What, then, have we learned from the stndv of this fever from the general point of view ? We have found that Malta fever depends on no local conditions, as it occurs in many parts of the world. It cannot have any great dependence on cUmatic conditions, as it occurs in the cool and rainy months almost as frequently as in the hot, dusty and rainless. Map of Malta and Gozo. showing tbe Distribution. of Malta Fever id the various Towns and Villages o< the two Islands Fig. 3. — Incidence in Civil Population. Poverty and insanitary surroundings do not predispose ; in fact, the well-to-do classes have been shown to be more liable to take the fever than the poor. It has no connection with water supply or systems of drainage, as it breaks out as frequently in the smallest country villages as in the large cities. What then, is the cause of this fever ? 1908] on the Extinction of 3Ialta Fever. 19 Study of Malta Fever by the Experimental Method. Discovery of the Parasite. — I^et us approach this problem from the experimental side. The first step to be taken is to discover if any parasite or micro-organism is associated with this fever. To do this we examine the blood and the tissues of the various organs, both microscopicallj and by means of cultivation, on suitable media, to find out if anything can be seen or grown. In this way, as long ago as 1887, it was discovered that a minute organism to which the name of iMicrococciis melitensis was given, is the cause of this disease. Description of the Micrococcus Melitensis. — There is not much to be said about this micro-organism, except that it is very minute, only becoming visible under a magnification of 1000 diameters. It is round or oval in shape, and non-motile. It is found in every case of Malta fever, and if injected under the skin of monkeys gives rise in them to a fever similar to that in man. Characteristics of the Micrococcus Melitensis. Behaviour outside the Body. — Now, having found the micro- organism, it is necessary to study its characteristics. It is found to survive outside the body for some time. For ex- ample, it can retain its vitality and virulence in a dry condition in dust or on clothing for at least two or three months. It can also live in a moist condition ; in water — tap-water or sea-water — for a some- what shorter period. The important thing to be noted is, that it does not increase out- side the body ; it merely survives for some time, and then dies off ; and that, if exposed to direct sunlight, it disappears in a few hours. Many attempts were made to discover it outside the body, under natural conditions. As the generally accepted theory was that it was conveyed in air, naturally the air of fever wards or of places where cases had occurred was examined with great care. It was also looked for in the dust of suspected places and in the water of the harbour ; but with no success. It is evidently what is known as a facultative parasite, or one which depends on a host for its existence. Thus, then, the first important step in our discovery of a means of preventing Malta fever has been taken. We now know the cause of the disease, and can look with some chance of success for the source whence man obtains it. The next steps are to find out how this micrococcus leaves, and how it gains entrance to the body. 0 2 20 Colonel David Bruce [Jan. 24, HoAv Does the Micrococcus Melitensis Leave THE Body ? In regard to the first of these, it is conceivable that it might leave the body by way of the expired air, in the saliva, in mucus from the lungs, as in consumption, in the secretion of the skin, as in scarlet fever, in the renal secretion, or by way of the intestinal tract. Or it might leave the body by way of the blood, by the agency of mosqui- toes or other biting flies. Many experiments were made along all these lines, and finally it was decided that this micro-organism leaves the body principally in the renal secretion, and in the blood taken out of the body by blood- sucking insects. The result, therefore, of this experimental work was to give rise to the belief that the disease was either conveyed from the sick to the healthy by contact, or by inhalation of infected dust, or, lastly by the agency of mosquitoes. How Does the Micrococcus Melitensis Gain Entrance to the Body? The investigation of these various modes of infection was there- fore undertaken. By Contact. — Let me first consider infection by contact. Experi- ments were made by placing monkeys, one affected by Malta fever, the other healthy, in more or less intimate contact, and it was found that if the monkeys lived together in the same cage infection did take place. If, on the other hand, the monkeys were kept in the same cage, but separated by a wire screen, so that, although they could touch each other, contamination of the healthy monkey's food by the sick monkey could not take place, then infection did not take place. In regard to this question of conveyance by contact, there is one argument against it which has always seemed to me unanswerable, and that is, that thousands of cases of Malta fever have been invalided home to England, and treated in our naval and military hospitals, without, as far as I am aware, a single case of the fever arising among the patients, orderlies, or nursing sisters. It was, therefore, concluded that contact with Malta fever patients, or the handling of infected clothing or discharges, is not the mode of infection. Then the question of infection by contaminated dust was taken up. By Dust Contaminated hy the Micrococcus Melitensis. — For some time it was considered probable that this would prove to be the common method of infection. The fact that the micrococcus with- stands drying for a long time, the dusty nature of Malta, and the 1908] on the Extinction of Malta Fever. 21 probability that gross contamination of the surface of the soil takes place by infective discharges, rendered this view likely. Experiments were made to put the theory to the test. Dust was artificially contaminated with micrococci and blown about a room in which monkeys were confined, or blown into their nostrils or throat. Several of these experiments were successful. It was therefore proved that dust artificially contaminated with 7nicrococcus melitensis could give rise to the disease. This, however, was no proof that this mode of infection occurs in nature. The artificially contaminated dust contained myriads of micrococci. Under natural conditions, they could seldom be numer- ous, and the powerful Maltese sunlight would tend to kill them off rapidly. The dust blown about by the wind must also dilute the micrococci to an enormous extent, so that it is only possible to con- ceive of a micrococcus here and there in a vast quantity of dust. Experiments were therefore made with dust naturally contaminated, in order more closely to resemble natural conditions. Dust contami- nated in this way, and also that collected from suspicious places and blown about the cages, sprinkled on food, or injected under the skin, always gave negative results. The conclusion was therefore again come to that conveyance of the infective germ by means of contaminated dust could only rarely, if ever, give rise to the disease. Btj Mosquitoes or other Biting Insects. — As already mentioned, the theory had been strongly advanced that Malta fever, like yellow fever or plague, might be conveyed by blood-sucking insects. The fact that the micrococci are frequently found in the peripheral blood, gave some colour to the belief. This point was therefore fully investigated and numerous experiments made with the different species of mosquitoes found in Malta, and also with other blood- sucking insects. The results, again, were all negative, and it was therefore decided that Malta fever is not conveyed by contact, by contaminated dust, or by mosquitoes. What, then, could be the mode of spread ? By Way of the Alimentary Canal.— li had long been known that the smallest quantity of the micrococci introduced under the skin or applied to a scratch would give rise to the disease in man or monkeys, but some work by previous observers had led us to believe that infection did not take place by way of the mouth in food or drink. They had fed monkeys on milk contaminated by the micro- cocci, and stated that in no case had infection taken place. This observation kept the Commission at first from making feeding experi- ments. As infection, however, did not appear to take place by contact, by the inhalation of infected dust, or by mosquitoes, it was clearly necessary to repeat these feeding experiments. 22 Colojiel David Bruce [Jan. 24, Feeding Experimenth. Here is a table showing the result of some of these feeding ex- periments, and you see it is abundantly proved that Malta fever can be conveyed to healthy animals by way of the alimentary canal. Even a single drink of a fluid containing few micrococci almost cer- tainly gives rise to the disease (Fig. 4). Malta Fever ProtMblr time >hlch Result Spedci of Modtormrwtioa eUfxed be. -f Inrectlon i^Dlmtl U. • II. iMliiflwto ore Inffctlon - KolnfK- Monkey 39 Feeding on potato con- 30 - ., «o Do. do. 31 + .. 66 Aecideot&l feediog . . + ., 72 Milk + M. ; stomach tube + „ 113 Dust + Mediterranean leTer urine. Dried - „ 114 Do. do. .. 119 1 Oust + Mediterrenean + (ever urine Moist ,. 124 Potato + M. Irom epleeo + .. 125 Do. do. + „ 126 PoUto + ' M. trom urine ^ .. 127 Do. do. -t 2 Milk ♦ M + 4 Do. + 6 Do. + .. 99 Do. + 6 Culture .f 7 Do. + e Do. + 9 Do. + 19 Do. is + .. IBa Do. 83 + * Kid 9 Uilk - .. 19a Motber"! miU _ Oo«t 13 Cnltnre from milk . . + 13 Mediterrenean ferer urine and dust + 14 Do. do. + « Milk + culture + Fig. 4. Feeding Experiments. From the results, then, of all these experiments it seemed most probable that the micrococcus gained an entrance to the body by way of the alimentary canal, and therefore by some infected food or drink. This led to an examination of food stuffs, and among these the milk of the goat is one of the most important. 1908] on the Extinction of Malta Fever. 23 Infection by Means of Goat's Milk. The goat is very much in evidence in Malta, and suppHes practic- ally all the milk used. There is, I believe, one goat to every ten of the population, so that, as there are 200,000 inhabitants there must be 20,000 goats. Flocks of them wander about the streets from morning till night, and are milked as required at the customers' doors (Fig. 5). It must be confessed there seemed little hope that an examination of these animals would yield any result. The goats appeared perfectly healthy, and they have the reputation of being little susceptible to disease of any kind. Fig. 5. — Milking Goats. To put the matter to the test several goats were inoculated with the micrococcus, and the result watched. There was no rise of tem- perature, no sign of ill-health in any way, but in a week or two the blood was found to be capable of agglutinating the specific micro- organism. This raised our suspicions, and a small herd of apparently healthy goats was then procured and their blood examined to see if they were all healthy. Several of them were found to react naturally to the agglutination test, and this led to the examination and the discovery of the Micrococcus melitensis in their blood, urine and milk. Fig. 6 shows the enormous number of these microbes found in goat milk. Each of the tiny dots represents a colony of micrococcus. 24 Colonel David Bruce [Jan. 24, MiCEOcocci m Goat's Milk. Some thousands of goats in Malta were then examined, and the astounding discovery was made that 50 per cent, of the goats re- sponded to the agglutination test, and that actually 10 per cent, of them were secreting the micrococci in their milk. Monkeys fed on milk from an affected goat, even for one day, almost invariably took the disease. s.s. "Joshua Nicholson." At this time, curiously enough, an important experiment on the drinking of goat's milk by man took place accidentally. Shortly, the story is as follows : In 1905 the s.s. ' Joshua Nicholson,' shipped Fig. 6. — Growth of Milk on Agar Plate. sixty-five goats at Malta for export to America. The milk was drunk in large quantities by the captain and the crew, with the result that practically everyone who drank the milk was struck down by Malta fever. Sixty of the goats (five having died) on arrival in America were examined, and thirty-two found to give the agglutination reaction, while the Micrococcus meliteusis was isolated from the milk of several of them. This epidemic of Malta fever on board the s.s. ' Joshua Nicholson ' therefore clinched the fact, that the goats of Malta act as a reservoir of the virus of Malta fever, and that man is infected by drinking the milk of these animals. 1908] on the Extinction oj Malta Fever. 25 Epidemiological Features. Here, then, at last was discovered a mode of infection which explains the curious features of Malta fever — the irregular seasonal prevalence, the number of cases which occur during the winter months, when there are no mosqnitoes and little dust. It is true there are more cases in summer than in winter, but this may be ex- plained bj the fact that more milk is used at that time of the year for fruit, in ice-creams, etc. It also explains the fact that officers are more liable than the men, as the former consume more milk than the latter. It also explains the liability of hospital patients, milk entering so largely into a hospital dietary. 1899 TO 1905. ^ ^ ^ 1 ^ 1 1 1 T . ^ ri ^^ 1 ■ SB i ~ ■ - — -2" ^ ^■h t -- ■ 1 ■ -1 1 1 Fig. 7.— Chart of Incidence in 1899-1905, and 1905. Result of Measures Directed Against THE Use of Goat's Milk. As soon as goat's milk was discovered to be the source of infec- tion, preventive measures were begun. The result is very striking, as is shown in the charts thrown on the screen, which give the number 26 The Extinction of Malta Fever. [Jau 24, of cases of Malta fever among the soldiers in the garrison before and after the preventive measures came into action. Here is a chart of the incidence of Malta fever among the soldiers each month before the preventive measures were put into force (Fig. 7). And here is another (Fig. 8) showing the incidence of this fever ARMY 1907. i907. ^ §1 1 1 1 ^ § y 1 ! 1 ? i ^ 1 1 1 § 1 ' " ' — 41 au "" \mi '-■ 40 _ __ 1 _ _ _ _ SB — — 1 — — — — •>!< — — — — 30 z;t — 1 — — — — — — — — 13 — — — — — - 10 9 - ^^^^j — H — — — — — — — — — - - — TChtrs MO CAStS. Fig. 8. — Chakt of Soldiers aisD Sailors, 1907. among the soldiers and sailors in Malta since goat's milk has been banished from their dietary. With this chart, which shows the practical extinction of Malta fever, my discourse comes to a close. [D. B.] 1908] Recent Researches in Radio-activity. 27 WEEKLY EVENING MEETING, Friday, Januaiy ol, 1908. ^The Right Hon. Lord Kayleigij, O.M. P.C. M.A. D.O.L. LL.D. Sc.D. Pres.R.S., in the Chair. Professor Ernest Rutherford, M.A. LL.D. D.Sc. F.R.S. Recent Researches in Radio-activity. In 1904 I had the honour of giving an address at the Royal Institu- tion on the subject of Radio-activity. In the interval steady and rapid progress has been made in unravelling the tangled skein of radio-active phenomena. In the present lecture I shall endeavom* to review very shortly some of the more important advances made in the last few years, but as I cannot hope to mention, even briefly, the whole additions to our knowledge in the various branches of the subject, I shall confine my attention to a few of the more salient facts in the development of which I have taken some small share. In my previous lecture I leased the explanation of radio-active phenomena on the disintegration theory put forward in 190o by Rutherford and Soddy, which supposes that the atoms of the radio- active bodies are unstable systems which break up with explosive violence. This theory has stood the test of time, and has been invaluable in guiding the experimenter through the maze of radio- active complications. In its simplest form, the theory supposes that every second a certain fraction (usually very small) of the atoms present become unstable and explode with great violence, expelling in many cases a small portion of the disrupted atom at a high speed. The residue of the atom forms a new atomic system of less atomic weight, and possessing physical and chemical properties which markedly distinguish it from the parent atom. The atoms com- posing the new substance formed by the disintegration of the parent matter are also unstable, and break up in turn. The process of degradation of the atom, once started, proceeds through a number of distinct stages. These new products formed by the successive dis- integrations of the parent matter are in most cases present in such extremely minute quantity that they cannot be investigated by ordinary chemical methods. The radiations from these substances, however, afford a very delicate method of qualitative and quantitative analysis, so that we can obtain some idea of the physical and chemical properties of substances existing in an amount which is far below the limit of detection of the balance or spectroscope. 28 Professor Ernest Rutherford [Jan. 31, The law that governs the breaking up of atoms is very simple and universal in its appKcation. For any simple substance, the average number of atoms l^reaking up per second is proportional at any time to the number present. In consequence, the amount of radio-active matter decreases in a geometrical progression with the time. The " period " of any radio-active product, i.e. the time for half the matter to be transformed, is a definite and characteristic property of the product which is uninfluenced by any of the laboratory agents at our command. In fact, the period of any radio-active product, for example, the radium emanation, if determined with sufficient accuracy, might well be taken as a definite standard of time, independent of all terrestrial influences. The law of radio-active transformation can be very simply and aptly illustrated by an hydraulic analogy. Suppose we take a vertical cylinder filled with water, with an opening near the base through which the water escapes through a high resistance.* When the dis- charge is started, the amount of water escaping per second is pro- portional to the height of water above the zero level of the cylinder. The height of water decreases in a geometrical progression with the time in exactly the same way as the amount of radio-active matter decreases. We can consequently take the height of the column of water as representing the amount of radio-active matter A present at any time. The quantity of water escaping per second is a measure of the rate of disintegration of A and also of tlie amount of the new substance B formed per second by the disintegration of A. The " period " of the substance is controlled by the amount of resistance in the discharge circuit. A high resistance gives a small flow of water and a long period of transfoi'mation, and vice versa. By a suitable arrangement we can readily trace out the decay curve for such a case. A cork carrying a light vertical glass rod is floated on the water in the cylinder. A light camel's hair brush is attached at right angles, and moves over the surface of a smoked-glass plate. A vertical line drawn on the glass through the point of contact of the brush gives the axis of ordinates, while a horizontal line drawn through the brush when the water has reached its lowest level gives the axis of abscissae. If the glass plate is moved with uniform velocity from the moment of starting the discharge, a curve is traced on the glass which is identical in shape with the curve of decay of a radio-active product, where the ordinates at any time represent the relative amount of active matter present, and the abscissae time. With such an apparatus we can illustrate in a simple way the increase Avith time of radio-active matter B, which is supplied by the trans- formation of a substance A. This will correspond, for example, to the growth of the radium emanation with time in a quantity of radium initially freed from emanation. Let us for convenience * A short glass tube in which is placed a plug of glass wool is very suitable. 1908] on Recent Researches m Radio-aciivlty. 29 suppose that A has a much longer period than B. In the hydrauhc analogy A is represented by a high head of water discharging at its base through a circuit of high resistance into the top of another cylinder representing the matter B. The water from the cylinder B escapes at its base through a lower resistance. Suppose that initially only A is present. In this case the water in the cylinder B stands a zero level. On opening the stop-cock connecting with A, water flows into B. The rise of water with time in the cylinder B is traced out in the same way as before by moving the glass plate at a constant rate across the tracing brusli. If the period of A is very long com- pared with that of B the water is supplied to B at a constant rate, and the water in B reaches a constant maximum height when the rate of supply to B equals the rate of escape from the latter. The curve traced out in that case is identical in shape with the " recovery cur^'e " of a radio-active product supplied at a nearly constant rate. The quantity of matter reaches a maximum when the rate of supply equals its own rate of transformation. The relative height of the columns of water in A and B represents at any time the relative amounts of these substances present. If the period is comparable with that of B, the height of water in B after reaching a maximum falls again, since as the height of A diminishes, the supply to B decreases. Ultimately, the height of B will decrease in a geometrical progression with the time at a rate corresponding to the longer period of the two. Tliis is an exact illustration of the way the amount of a radio-active substance B varies when initially only the parent substance A is present. By using a number of cylinders in series, each with a suitable resistance, we can in a similar way illustrate in a quantitative manner the variation in amount with time of a number of products arising from successive disintegrations of a primary substance. By suitably adjusting the amount of resistance in the discharge circuits of the various cylinders, the curves could be drawn to scale to imitate approximately the variation in amount of the various products with time when the initial conditions are given. During the last few years a very large amount of work has been done in tracing the remarkable succession of transformations that occur in the various radio-active substances. The known products of radium, thorium, actinium, and uranium are shown graphically below, together with the periods of tlie products and the character of the radiations they emit. It will be seen that a large list of these unstable bodies are now known. It is probable, however, that not many more remain to be discovered. The main uncertainty lies in the possibility of overlooking a product of rapid transformation following or succeeding one with a very slow period. In tracing out the succession of changes, the emanations or radio-active gases con- tinuously evolved by radium, thorium, and actinium have marked a very definite and important stage, for these emanations can be easily 30 Profpssor Ernest Rutherford [Jan. 81, removed from the radio-active body and their further transformations studied quite apart from the parent element. The analysis of the transformation of the radium emanation has yielded results of great importance and interest. After passing through three stages, radium A, B, and C, of short period, a substance, radium D, of long period, makes its appearance. This is transformed through two stages E and F of short period into radium G, of period 140 days. Meyer and Schweidler have conclusively shown that radium D is the primary constituent of the radio-active substance separated by Hofmann, and called bv him radio-lead. Radium G is identical with the first radio- o-o RAD 4 PAD 8 RADC RAO D RAO£ R60f &4DC 26WINS ISMINS «orRS (DATS *M)A« NOOAT& a a a RAOlOlEAO a CL POlONIUM THORIUM MtSOTH. RAOU TH ^» X EMANAllON TH A TH B lO'YRS a 600 DAYS a 3 7 DATS a i4SLCi MHRS IHRS active substance separated from pitch-blende by Madame Curie, viz. polonium. We are thus sure that these bodies are transformation products of radium. It will be seen that I have added another pro- duct of period -1-5 days between radium D and polonium. The presence of such a product has been shown by Meyer and Schweidler. In the case of thorium, a very long list of products is now known. For several years thorium X was thought to be the first product of thorium, but Hahn has recently shown that at least two other products of slow transformation intervene, which he has called mesothorium and radiothorium. The radiothorium emits a rays, and 1908] on Recent Researches in Radio-activity. 81 has a period of more than 800 days. Mesothoriiim apparently emits /? rays, and has a still longer period of transformation, the exact value of whicli has not yet been accurately determined. Since thorium is used commercially on a large scale, there is every prospect that we shall soon be able to obtain considerable quantities of very active preparations of mesothorium and radiothorium. The separa- tion of these bodies from thorium does not in any way alter its commercial value. It is to be hoped that if these active preparations are separated in c^uantity, the physicist and chemist may be able to obtain a supply of very active material at a reasonable cost, and that there will not be an attempt to compete Avith the ridiculously liigh prices charged for radium. From the radio-active point of view, the radio-elements are only distinguished from their families of products by their comparatively long period of transformation. Now we have reason to believe that radium itself is transformed according to the laws of other radio- active products with a period of about 2000 years. If this be the case, in order to keep up its supply in a mineral, radium must be produced from another substance of relatively long period of trans- formation. The search for this elusive parent of radium has been one of almost dramatic interest, and illustrates tlie great importance of the theory as a guide to the experimenter. The view that radium was a substance in continuous transformation was put forward by Rutherford and Soddy in 1903. The most probable parent of radium appeared to be uranium, which has a period of transformation of the order of 1000 million years. If this were the case, uranium, initially freed from radium, should in the course of time grow radium, i.e. radium should again appear in the uranium. This has been tested independently by Soddy and Boltwood, and both have shown that in carefully prepared uranium solutions there is no appreciable growth of radium in the course of several years. The rate of production of radium, if it occurs at all, is certainly less than rgVo ^^ the amount to be expected from theory. This would appear at first sight to put out of count the view that uranium is the parent of radium. This, however, is by no means the case, for such a result could be very easily explained if one or more substances of very slow period of transformation appeared between uranium and radium. It is obvious that the necessity of forming such an intermediate product would greatly lengthen the time required before an apj^reciable amount of radium appeared. There is, however, another indirect but very simple method of attack to settle the parentage of radium. If radium is derived from the transformation of uranium, however many unknown products intervene, the ratio between the amount of .radium and uranium in old minerals should be a definite constant. This is obviously the case, provided sufficient time has elapsed for the amount of radium to have reached its equilibrium value. The constancy of this relation 32 Professor Ernest Piutherford [Jan. 31, has been completely substantiated by the independent work of Boltwood, Striitt, and McCoy. It has been shown that the quantity of uranium corresponding to 1 gram of radium is 3*8 x 10 ~' grana, and is the same for minerals obtained from all parts of the world. Since the radium is always distributed throughout the mass of uranium, we cannot expect to find nuggets of radium like nuggets of gold, unless by some chance the radium has been dissolved out of radio-active minerals and redeposited within the last few thousands of years. To those who had faith in the distintegration theory, this unique constant relation between the amounts of two elements was a satisfactory proof that radium stood in a genetic relation with uranium. A search was then made for the unknown intervening product wliich, if isolated, must grow radium at a rapid rate. A year or so ago Boltwood observed that a preparation of actinium separated from a uranium mineral did grow radium at a constant but rapid rate. It thus appeared as if actinium were the long-looked-for parent of radium, and that actinium and its long family of products inter- vened between uranium X and radium. I was, however, able to show that actinium itself was not responsible for the growth of radium, but another unknown substance separated with it. These results were confirmed by Boltwood, who finally succeeded in isolating a new substance from uranium minerals, which was slowly transformed into radium. This substance, which he termed " ionium,"' has apparently chemical properties similar to those of thorium, and emits a rays of penetrating power less than those of uranium. The main previsions of the theory have thus been experimentally verified. Radium is a changing substance the amount of which is kept up by the disintegration of another element, ionium. In order to complete the chain of evidence, we require to show that uranium grows ionium, and it is probable that evidence in this direction will soon be forthcoming. We thus see that we are able to link uranium, ionium, radium, and its long line of descendants, into one family, with uraniimi as its first parent. As uranium has a period of trans- formation of more than one thousand million years, it will not be profitable at the moment to try and trace back the family further. It appears almost certain that, from the radio-active point of view, uranium and thorium must be considered as two independent elements. The case of actinium is difiPerent, for Boltwood has shown that the amount of actinium in minerals, like the amount of radium, is proportional to the amount of uranium. This indicates that actinium stands in a genetic relation with uranium. Unless our experimental evidence is at fault, it does not appear probable that actinium belongs to the main line of descent of uranium, for the activity of actinium separated from a mineral compared with radium is only about one-quarter of what we should expect under such con- ditions. I think that a suggestion Avhich I put forward some time ago may account for the obvious connection of actinium with 1908] on Recent Researches in Radio-activity. 38 uranium, and at the same time for the anomaly observed. This supposes that actinium is a branch descent from some member of the uranium family. It does not appear improbable that at one stage of the disintegration two distinct substances may be produced, one in greater quantity than the other. After the expulsion of an a particle, it may happen that there are two possible arrangements of temporary stability of the residual atom. The great majority of the atoms may fall into one arrangement, and the remainder into the other. Actinium in this case would correspond to the substance in lesser quantity. It would act as a distinct element, and would break up in a different way from the main amount. It is probable that a large amount of accurate work will be required before the position of actinium in the scheme of changes can be fixed with certainty. It is a matter of remark how closely actinium resembles thorium in its series of transformations. It would appear that the atom of actinium has many points in common with thorium, or rather with its product, mesothorium. The recent observations on the growth of radium offer a very simple and straightforward method of determining experimentally the period of radium. Suppose that we take a uranium mineral and determine by the emanation method the quantity of radium contained in it. If the immediate parent of radium (i.e. ionium) is next com- pletely separated from the uranium and radium, it will begin to grow radium at a constant rate. Now the rate of growth of radium observed is a measure of the rate of breaking up of the radium parent in the mineral, since before separation the rate of production was equal to the rate of breaking up. Now the growth of radium observed for a short interval, for example, a year, divided by the quantity present in the mineral, gives the fraction of the radium breaking up per year. Proceeding in this way, Boltwood found that the fraction breaking up ])er yeai- is about uoVo» ^^^^^ that the period of radium is about 20(»0 years — a value which Hes between the most ])i'obable values deduced from quite distinct data. From an inspection of the radio-active families, it will be seen that out of twenty-six radio-active substances that have been identified, seventeen give out a rays or a and ^ rays, four give out only p rays, and five emit no rays at all. The rayless and /3-ray products are transformed according to the same law as the a-ray pro- ducts, and there is the same sudden change of physical and chemical properties as the result of the transformation. In the case of the substances which tlu'ow off atoms of matter in the form of a particles, there are obvious reasons for anticipating a change in [)]'operties of the substance, but this is not the case for the ray-less or ^-ray products. We must either suppose that the mass of the atom is not appreciably changed by tlie transformation, which consists in an internal rearrangement of the parts of the atom, oi- that the atom expels a particle at too low a velocity to be appreciated by the Vol. XIX. (No. Iu2) D 34 Professor Ernest Rutherford [Jan. 31, electrical methods. Unfortunately, it is very difficult to study the rayless products with care, as in practically every case they are succeeded by a ray product of comparatively rapid transformation. The rayless products are of great interest as indicating the possibility of transformations which can occur without any detectable radiation. In the course of the analysis of radio-active changes, special methods have been developed for the separation of the various pro- ducts from each other. It is only in a few cases, however, that we can hope to obtain a sufficient quantity of the substance to examine by means of the balance. It should be possible to obtain workable quantities of actinium, radium D (radio-lead), and radium CI (polonium), but the isolation of these substances in any quantity has not yet been eifected. Sir William Ramsay and Mr. Cameron have made a number of important investigations of the properties and volume of the radium emanation, freed so far as possible from any traces of known gases. The remarkable initial contraction of the volume due to the emanation shows that there is still much to be done to obtain a clear understanding of the behaviour of this intensely radio-active gas when obtained in a pure state. Simultaneously with the work on the analysis of radio-active changes, a large number of investigations have been made on the laws of absorption by matter of the three primary types of radiation from active matter, viz. the a, y8, and y rays, and the secondary radiations to which they give rise. It has generally been accepted for some years that the y rays are a type of penetrating X-rays. The latter are supposed to consist of electro-magnetic pulses in the ether, set up by the impact or escape of electrons from matter, and akin in many respects to very short waves of ultra-violet light. Recently, however, Bragg has challenged this view, and has suggested that the y rays (and probably also the X-rays) are mainly corpuscular in character, and consist of uncharged particles, or " neutral pairs," as he terms them, projected at a high velocity. Such a view serves to explain most of the experimental observations equally well as the pulse theory ; Bragg has recently brought forward additional evidence, based on the direction of the secondary radiation from the y rays, which he considers to be inexplicable by the pulse theory. AVe must await further data before this important question can be settled definitely, but the theory of Bragg, which carries many important consequences in its train, certainly deserves very careful examination. From the radio-active point of view, the a rays are by far the most important type of radiation emitted by active matter, although their power of penetration is insignificant compared with the /i or y rays. They consist of veritable atoms of matter projected at a speed, on an average, of 6000 miles per second. It is the great energy of motion of these swiftly expelled masses that gives rise to the heating effect of radium. In addition, they are responsible for the greater part of the ionisation observed near an uncovered radio-active sub- 1908] on Recent Researches in Radio-activity. 35 stance. On account of their importance in radio-active phenomena, I shall devote some little attention to the behaviour of these rays. The work of Bragg and Kleeman, of Adelaide, first gave us a clear idea of the nature of the absorption of these rays by matter. The a particles from a very thin film of any simple kind of radio-active matter are all projected at an identical speed, and lose their power of ionising the gas or of producing phosphorescence or photographic action after they have traversed exactly the same distance, which may conveniently be called the " range " of the a particle. Now every product emits a particles at an identical speed among themselves, but different from every other product. For example, the swiftest a particles from the radium family, viz. that from radium 0, travels 7 cm. in air under ordinary conditions before it is stopped, while that from radium itself is projected at a slower speed, travelling only 3 • 5 cm. We may regard the a particle as a projectile travelling so swiftly that it plunges through every molecule in its path, producing positively and negatively charged ions in the process. On an average, an a particle before its career of violence is stopped breaks up about 100,000 molecules. So great is the kinetic energy of the a projectile that its collisions with matter do not sensibly deflect it, and in this respect it differs markedly from the ^ particle, which is apparently easily deflected by its passage through matter. At the same time, there is undoubted evidence that the direction of motion of some of the a particles is slightly changed by their passage through matter. The sudden cessation of the ionising power produced by the a particle after traversing a definite distance of air has been shown by Bragg to be a powerful method of analysis of the number of a-ray products present in a substance. For example, suppose the amount of ionisation in the gas produced by a narrow pencil of a rays is examined at varying distances from the radium. At a distance of 7 cm. there is a sudden increase in the amount of ionisation, for at this distance the a particles from radium C enter the testing vessel. There are again sudden changes in the ionisation at distances of 4*8 cm., 4*3 cm., and 3 '5 cm. These are due to the rays from the radium A, the emanation and radium itself respectively entering the testing vessel. The a-ray analysis thus discloses four types of a rays present in radium in equilibrium — a result in conformity with the more direct analysis. This method allows us to settle at once whether more than one a-ray product is present in a given radio-active material. For example, an analysis by Hahn by this method of the radiation from the active deposit of thorium has disclosed the existence of two a-ray products instead of one as previously supposed. We can consequently gain information on the complexity of radio- active material, even though no chemical methods have been found to separate the products concerned. The range of the a particle from each product is a definite constant which is characteristic of each product, D 2 36 Professor Ernest Rutherford [Jan. >\1, The a particle decreases in velocity as it passes through matter. Tliis result is clearly brought out by photographs showing the deflec- tion of a homogeneous pencil of a rays in a magnetic field before and after passing through an absorbing screen. The greater divergence of the trace of the a rays on the plate, after passing through the screen, shows that their velocity is reduced, while the sharpness of the band shows that the a particles still move at an identical speed. In order to make an accurate determination of the constants of the tt particles, it is necessary to work with homogeneous rays, and we consequently require to use a thin layer of matter of one kind. For experiments of this character, a wire coated with a thin film of radium C by exposure to the radium emanation is very suitable. The velocity of the a particle and the value e/m^ the ratio of the charge carried by the a particle to its mass, can be deduced by observing the deflections of a pencil of a rays exposed in a magnetic and in an electric field of known strengths. The deflection of a pencil of a rays in an electric field is small under normal conditions, and special care is needed to determine it with accuracy. In this way I have calculated the velocity and value of ejm for a number of a-ray products. The velocity of expulsion varies foi' different products, but is connected by a simi)le relation with the range of the a particle in air. Tlie value of elm has been determined for selected products of radium, thorium, and actinium, and in each case the same value has been found. This shows that the a particles expelled from radio-active substances in general are identical in con- stitution. They have all the same mass, but differ from one another in the initial \'elocity of their projection. Although we are sure tliat the a particles, from whatever soui'ce, are identical atoms of matter, we are still unable to settle definitely the true nature of the a particle. The value of e/ni found by experiment is nearly 5 x 10=^. Xow the value of eJm for the hydrogen atom in the electi'olysis of water is 10'. If the charge carried by the a particle and the hydrogen atom is the same, the mass of the a j)article is twice that of the hydrogen atom, i.e. a mass equal to the hydrogen molecule. But we are not certain that they do carry the same charge. Here we are, unfortunately, confronted by a number of possibilities, for the magnitude of m for the a particle is conditioned by the value assumed for e. If the charge of the a particle is assumed to be twice the value of the hydrogen atom, the mass comes out four times the hydrogen atom — the value found for the helium atom. The weight of evidence still supports the view that the a particle is in some way (X)nnected with the helium atom. If the a particle is a helium atom Avith twice the ionic charge, we must regard the helium produced by radio-active bodies as actually the collected a particles the charges of which have been neutralised. This at once offers a reasonable explanation of the production of heUum by actinium as well as by radium. In addition, Strutt uas recently contributed strong evidence that helium is a 1908] on Recent Researches in Radio-activity. 37 ]»ro(lucfc of thorium. Such results are only to be expected on the aljove view, since the a particle is the only common product of these elements. The determination of the true character of the a particle is one of the most pressing- unsolved prol^lems in radio-activity, for a number of important consequences follow from its solution. Unfortunately, a direct experimental proof of its true character appears to be very difficult unless a new method of attack is found. We have seen that if the charge carried by the a particle could be experimentally deter- mined, the actual value of m could be determined in terms of the hydrogen atom, since the value of the charge carried by the latter is known. This could be done if we could devise a method of detecting the emission of a single a particle, and thus counting the number of particles expelled from a known quantity of a radio-active sul)stauce, for example, from radium. In considering a possible method of attack of this question, the remarkable property of the a particles of pro- ducing scintillations in zinc sulphide at once suggests itself. Apart from the difficulty of counting the scintillations, it is very doubtful whether more than a small fraction of the a particles which strike the screen produce the scintillations. Viewed from the electrical side, a simple calculation from the data at our disposal shows that the ionisation produced in a gas by a single a particle should be detectable. The electrometer or electroscope used for measurement would, how- ever, require to be extremely sensitive, and under such conditions it is known that small electrical disturbances are very difficult to avoid. In order to obtain a reasonably large effect, we require some method of magnifying the ionisation produced by the a particle. In conjunction with Dr. Hans (reiger, I have recently developed a method whereby the electrical effect produced by the a particle can be magnified several thousand times. From the work of Townsend it is known that if a strong electric held acts on gas at low pressure, any ions generated in the gas by an external agency are set in motion by the electric field, and under the proper conditions produce fresh ions by collision with the gas molecules. The negative ion is the most effective ioniser in weak fields, but when the voltage is increased near the point at which a discharge passes, the positive ion also pro- duces fresh ions by collision. In the experimental arrangement the a particle from the active matter is fired through a small opening about 2 mm. in diameter, covered with a thin layer of mica, into a cylinder 60 cm. long and 2*5 cm. in diameter, in which the gas pressure is about o cm. of mercury. A thin insulated wire connected to the electrometer is fixed centrally in the cylinder. If the outside cylinder is charged negatively, for a difference of potential of about 1000 volts any ionisation produced in the cylinder is increased about 2000 times by collision. This can be simply illustrated by using the y rays of radium as a source of ionisation. When a difference of potential is applied to the cylinder, the ionisation produced by the y 38 Professor Rutherford on Radio-activity. [Jan. 31, rays onlj causes a slight movement of the electrometer needle. By applying, however, a voltage nearly equal to that required for a dis- charge through the gas there is a very rapid movement of the needle. On removing the radium there is no appreciable current through the gas. On placing a source of a rays near the small opening in the cylinder so that some of the a particles can be fired along the axis of the cylinder, the electrometer needle does not move uniformly, but with a succession of rapid throws with a considerable interval in between. Each of these throws is due to the discharge produced by a single a particle entering the cylinder, increased several thousand times by the intermediary of the strong electric field. If a sheet of paper which stops the a rays is placed before the opening, the electro- meter needle at once comes to rest. The interval of time between the throws is not uniform. This is exactly what we should expect if the number of a particles entering such a small opening is governed by the laAV of probability. On the average, a certain number of a particles are fired through the opening per minute, but in some cases the interval is less than the average, in others much greater. In fact, by observing the intervals between the entrance of a large number of a particles, we should be able to determine accurately the "probability" curve of distribution of the a particles with time. For purposes of measurements, the active material, in the form of a thin film covering a small area, is placed in an exhausted tube connected in series with the ionisation cylinder, and at a considerable distance from the hole. The number of a particles entering the opening per minute is counted, and from this tlie total number expelled can be calculated. Preliminary measurements show that the number of a particles expelled from a known weight of radium is of the same order as the calculated value. When the measurements are completed it should be possible to determine the charge carried l)y each a particle, since the total charge carried by the a particles from 1 gram of radium is known. In this way it may be possible to settle whether the a particle is a helium atom or not. In any case, it is a matter of some interest to be able to detect by its electrical effect a single atom of matter, and so to determine directly with a minimum of assumption the magnitude of some of the most important quantities in radio- active phenomena. [E. R.] 1908] General 3Ionthly Meetinrj. 39 GENERAL MONTHLY MEETING, Monday, February 3, 1908. Sir James Crichton-Browne, M.D. LL.D. F.R.S., Treasurer and Yice-President, in the Chair. The Rt. Hon. Lord Ellenborough, Alfred Mosely, Esq., C.M.G. were elected Members of the Royal Institutiou. The Special Thanks of the Members were returned to W. J. Russell, Esq., Ph.D. F.R.S., for his Donation of £100 to the General Fund ; and to Charles Hawksley, Esq., M.Inst.C.E., for his Donation of £100 (in commemoration of the 100th anniversary of the birth, on July 12th, 1807, of Thomas Hawksley, F.R.S., Civil Engineer), to the Fund for the Promotion of Experimental Research at Low Temperatures. The Honorary Secretary reported the decease of the Right Hon. Lord Kelvin, O.M. G.C.Y.O. P.C. D.C.L. LL.D. D.Sc^ F.R S., Grand Officer of the Legion of Honour, Chancellor of the University of Glasgow, on the 17th of December, 1907, and the following Reso- lution, passed by the Managers at their Meeting held this day, wa>s read and unanimously adopted : — Resolved, That the Managers of the Koyal Institution of Great Britain desire to record at this, their first Meeting subsequent to his death, their sense of the great loss sustained by the Institution and by Science in the decease of Lord Kelvin. Lord Kelvin became a Member of the Royal Institution in 1886. He gave his first lecture at the Royal Institution at the time when Faraday was engaged in his epoch-making researches on Electricity and Magnetism ; and between the years 1856 and ] 900 Lord Kelvin delivered a Course of Lectures on The Electric Telegraph in 1863, and no less than nine Friday Evening Discourses on the following subjects : " The Origin and Transformations of Motive Power " (1856), "Atmospheric Electricity" (1860), "Tides" (1875), "Effects of Stress on Magnetisation of Iron, Nickel and Cobalt " (1878), " The Sorting Demon of Maxwell" (1879), "Elasticity viewed as possibly a Mode of Motion" (1881), " Isoperimetrical Problems " (1893), "Contact Electricity of Metals" (1897), " Nineteenth Century Clouds over the Dynamical Theory of Heat and Light " (1900). On the occasion of the celebration of the Jubilee of his appointment to the Chair of Natural Philosophy in the University of Glasgow, an address of congratulation was presented to Lord Kelvin on behalf of the Members of the Royal Institution, expressing their high appreciation of the conspicuous ser- vices rendered by him in the extension and diffusion of Scientific Knowledge. When Lord Kelvin resigned his Professorship and came to reside in London 40 General Mnvthh/ Meeting. [Feb. 3, he took much interest in the Royal Institution, and became a Manager in 1892. The Managers desire to offer on behalf of the Members of the Royal Insti- tution the expression of the most sincere sympathy with Lady Kelvin and the family in their bereavement. The (Jhairmaii announced that the ^Managers had appointed Kenneth Robert Hay, Esq., M-B. (Caniliridge), Medical Officer to the Royal Institution in succession to the late Dr. AVoodhonse Brainc, who held the appointment for thirty-six years. The Honorary Secretary read the following Letters received from the Honorary Members who were elected at the General Meeting on December 2, 1907 : — Paris, December 7, 11)07. Sir, and honoured Colleague, I am greatly touched by the high honour which the Royal Institution of Great Britain has just done me by enrolling me amongst its Honorary Members, and I beg that you will communicate my best feelings of gratitude to His Grace the Duke of Northumberland and to your fellow Members. Accept, my dear Colleague, the expression of my very devoted sentiments. A. Haller. Paris, December 8, 1907. My dear Colleague, Will you be good enough to express my best thanks for my election as Honorary Member of the Royal Institution of Great Britain, which you announce to me. Accept, my dear Colleague, the expression of my most distinguished sentiments. L. Troost, Member of the Institute. Mr. William Croukes, Secretary of the Royal Institution. Liege, Deccwbcr U, l'J07. Dear Sir, and most honoured Colleague, I have received, after some delay, due to absence on my part, the letter dated the 2nd of this month in which you were good enough to inform me that the IMcmbers of the Royal Institution of Great Britain had done the marked honour of associating me with themselves in the capacity of Honorary Member. This high distinction is inexpressibly valuable to me in view of the world- wide reputation with which the Royal Institution is invested. I am pro- foundly touched and sincerely grateful. I have always professed enthusiastic admiration for the admirable work done by English men of Science for so many generations, the importance of which has never diminished, so that Great Britain remains a shining star in the scientific world, as it is indeed in every domain of intellectual activity. Will you, Mr. Secretary, be good enough to interpret my feelings to your illustrious colleagues, and thank them most cordially for the honour they have done me. I would be happy if the powers still at my disposal permit me to rise as I should like to do, to the distinction which has just been conferred on me, and to afford proof of the interest I bear towards the prosperity of the Royal Institution. Accept, dear Sir, the assurance of my high consideration, and the expres- sion of my best and most fraternal sentiments. W. Spring. 1008] Gpiiprnl Mo)ii},}ii Mppthfj, 41 The Presents received since the last Meeting were laid on the table, and the thanks of the Meinb(U'S returned for the same, viz. : — FKOM The Secretani of State for iiuZia -Records of the Geological Survey of India, Vol. XXXV. Part 1; Vol. XXXVI. Part 1. 8vo. 1907. Memoirs of Department of Agriculture, Chemical Series, Vol. I. No. 5 ; Botanical Series, Vol. II. No. 2. 8vo. 1907. Madras Government Museum, Bulletin, Vol. V. No, 3. 8vo. 1907. Accademia dei Lincei, Beak, Roma — Classe di Scieuze Fisichc, IMatematichc c Natural!. Atti, Serie Quinta : Rendiconti. Vol. XVI. 2^ Semestre, Fasc. 10-12 ; Vol. XVII. 1" Semestre, Fasc. 1. Svo. 1907-8. Classe di Scieuze IMorali, Serie Quinta, Vol. XVI. Fasc. 6-8. Svo. 1907. Alleghcnii Observatory — Publications, Vol. I. No. 1. 4to. 1907. American Academy of Arts and Sciences — Proceedings, Vol. XLIII. Nos. 7-12. Svo. 1907. American Geographical Society — Bulletin, Vol. XXXIX. Nos. 11-12. Svo. 1907. American PhilosopJiical Society — Transactions, Vol. XXI. Part 4. 4to. 1907. Anglo-American Oil Co., Ltd. — The Petroleum Lamp. By J. H. Thomson and B. Redwood. Svo. 1902. Asiatic Society, Roj/al — Journal for Jan. 1908. Svo. Astronomical Society, Royal — ]Monthlv Notices, Vol. LXVIII. Nos. 1-2. Svo. 1907. Automobile Club — Journal for Dec-Jan. 1907-8. Svo. Bankers Institute— Journal, Vol. XXVIII. Part 9; Vol. XXIX. Parts 1-2. Svo. 1907-8. List of INIembers, 1908. Svo. Berlin, Royal Prussian Academy of Sciences — Sitzungsbcrichte, 1907, Nos. 39-53. Svo. Biddlecombe,A.,Esq. {the Author) — Thoughts on Natural Philosophy. (2 copies.) Svo. 1907. Birmingham and Midland Institute — Report for the year 1907. Svo. 1908. Boston Public Library — Monthly Bulletin for Dec-Jan. 1907-8. Svo. Boston Society of Natural History — Proceedings, Vol. XXXIII. Nos. 3-9. Svo. 1906-7. British Architects, Royal Institute of — Journal, Third Series, Vol. XV. Nos. 3-6. 4to. 1907. British Astronomical Association — Journal, Vol. XVIII. Nos. 2 3. Svo. 1907. Buenos Aires — Monthly Bulletin of Statistics, Sept. -Oct. 1907. 4to, Burgoyne, A. II., Esq. {the Editor) -The Navy League Annual, 1907-S. Svo. 1907. Cambridge Philosophical Society — Transactions, Vol. XX. Nos. 15-16. 4to. 1907-8. Canada, Geological Survei/ — Reports, etc., Nos. 949, 953-971 and 977. Svo. 1907. Caj)e of Good Hope, Agent-General /or— Cape Colony To-day. Bv A. R. E. Burton. Svo. 1907. Carnegie Institution — Contributions from Solar Observatorv, No. 20. Svo. 1907. Chapman, Mrs. E. J. — A Drama of Two Lives, The Snake Witch, and other Poems. By E. J. Chapman. Svo. 1899. A Sequel to Christabel. A Review by L. Svo. 1899. Chemical Industry, Society o/— Journal, Vol. XXVI. Nos. 22-24 ; Vol. XXVII. No. 1. Svo. 1907-8. Chemical Society — Journal for Dec. -Jan. 1907-8. Svo. Proceedings, Vol. XXIII. Nos. 332-334 ; Vol. XXIV. No. 335. Svo. 1907-S. Civil Engineers, Institution o/— Proceedings, Vol. CLXIX. Svo. 1907. 42 General Monthly Meeting. [Feb. 3, Clinical Society — Transactions, Vol. XL. 8vo. 1907. Cracovie, Academic cles Sciences — Bulletin, 1907 : Philologie, Nos. 3-7 ; Sciences Matheniatiques, Nos. 4-8. Svo. 1907. Dewar, Sir James, M.A. D.Sc. F.B.S. M.R.I.—The Labyrinth of Animals. By Dr. A. A. Gray. Vol. I. Svo. 1907. Dickson, J. H., Esq. {the Author) — On the Joule-Kelvin Inversion of Tempera- ture and Olszewski's Experiment. Svo. 1908. Editors— kexona,\it\cQ\ Journal for Jan. 1908. Svo. Agricultural Economist for Jan. 1908. 4to. American Journal of Science for Dec-Jan. 1907-8. Svo. Analyst for Dec-Jan. 1907-8. Svo. Astrophysical Journal for Nov.- Dec 1907. Svo. Athenaeum for Dec-Jan. 1907-S. 4to, Author for Dec-Jan. 1907-8. Svo. Automobile Owner for Jan, 1908. Svo. British Homoeopathic Review for Dec-Feb. 1907-8. Svo. Chemical News for Dec-Jan. 1907-8. 4to. Chemist and Druggist for Dec-Jan. 1907-8. Svo. Concrete for Jan, 1908. Svo. Dioptric Review for Dec-Jan. 1907-8. Svo. Dyer and Calico Printer for Dec-Jan. 1907-8. 4to. Electrical Contractor for Dec-Jau. 1907-8. Svo. Electrical Engineer for Dec-Jan. 1907-8. 4to. Electrical Engineering for Dec-Jan. 1907-8. 4to. Electrical Industries for Dec-Jan. 1907-8. 4to. Electrical Review for Dec-Jan. 1907-8. 4to. Electrical Times for Dec-Jan. 1907-8. 4to. Electricity for Dec-Jan. 1907-S. Svo. Engineer for Dec-Jan. 1907-8. fol. Engineer-in-Charge for Dec-Feb. 1907-8. Svo. Engineering for Dec-Jan. 1907-8, fol. Horological Journal for Dec -Jan, 1907-8. Svo, Illuminating Engineer for Jan. 1908. Svo. Journal of the British Dental Association for Dec-Jau, 1907-8, Svo. Journal of Physical Chemistry for Jan, 1908, Svo, Journal of State Medicine for Dec-Jan. 1907-8. Svo. Law Journal for Dec-Jan. 1907-8. Svo, London University Gazette for Dec-Jan, 1907-S. 4to. Model Engineer for Dec-Jan, 1907 -8. Svo. Motor Car Journal for Dec-Jan, 1907-8. 4to. Musical Times for Dec-Jan. 1907-8, Svo. Nature for Dec-Jan. 1907-8. 4to. New Church Magazine for Jan. 1908. Svo. Nuovo Cimento for Nov. 1907. Svo, Page's Weekly for Dec-Jan, 1907-8, Svo, Photographic News for Dec-Jan. 1907-8. Svo. Physical Review for Dec. -Jan 1907-8. Svo. Revue d'Electrochimie for Oct.-Dec 1907. Svo, Science Abstracts for Dec, 1907. Svo, Terrestrial Magnetism for Sept. 1907. Svo, Zoophilist for Dec 1907. 4to. Essex ArchcBological Society — Transactions, Vol. X. Part 3. Svo, 1907, Fleet Fines for Essex, Part VIII, Svo. 1907, Index to Archaeological Papers, 1906, Svo, 1907, Florence Biblioteca Nazionale — Bulletin for Nov. -Dec-Jan. 1907-8, Svo. Franklin Bistitute— 3 omn&l, Vol. CLXIV. No, 6 ; Vol, CLXV, No, 1, Svo. 1907-8. 1908] General Monthly Meeting. 43 Geographical Society, RoT/al— J omnsd, Vol. XXX. No. 6; Vol. XXXI. No. 1. 8vo. 1907-8. Geological Society — Abstracts of Proceedings, Nos. 851-851. 8vo. 1907. Quarterly Journal, Vol. LXIII. Part 4. 8vo. 1907. List of Fellows, 1907. 8vo. Goppelsroeder, F. {the Author) — Neue Capillar und Capelluranalytsche Unter- suchungen. 8vo. 1907. Gottingcn Academy of Sciences — Nachrichten, 1907, Mat.-Phys. Klasse, Heft 4 ; Geschaftliche Mittheilungen, Heft 2. 8vo. Herbert, P. Z., Esq., M.D. C.M. {the Author)— Killing off the Unfit. 8vo. 1907. Imperial Institute—'Bulletin, Vol. V. No. 3. 8vo. 1907. Iron and Steel Institute — Journal, Vol. LXXV. 8vo. 1907. Jefferson Physical Laboratory — Contributions, Vol. IV. 8vo. 1907. Johns Hopkins University, Baltimore — Studies : Series XXV. Nos. 6-7. 8vo. 1907. Circulars, 1907, Nos. 7-8. 8vo. 1907. Jordan, W. Leighton, Esq., M.R.I, {the Author)— The Sling. 8vo. 1907. Junior Institution of Engineers — Journal, Vol. XVII. 8vo. 1907. Life-Boat Institution, Royal National — Journal for Feb. 1908. 8vo. Linnean Society — Journal, Zoologv, Vol. XXXI. No. 203 ; Botany, Vol. XXXVIII. No. 265. 8vo. 1907-8. London County Council—G&zette for Dec. -Jan. 1907-8. 4to. Madrid, Royal Academy of Sciences — Revista, Tom. VI. Nos. 1-4. 8vo. 1907. Manchester Steam Users' Association— Tyventy-ionvth. Annual Report of the Board of Trade on the working of the Boiler Explosions Acts, 1882 and 1890, Nos. 1574-1627. 4to. 1907. Mexico, Secretaria de Gomunicaciones — Anales, No. 16. 8vo. 1907.. Mexico, Sociedad Cientifica ^^ Antonio Alzate" — ^Meniorias, Tome XXIV. Nos. 10-12; Tome XXV.' No. 1. 8vo. 1907. Microscopical Society, Royal — Journal, 1907, Part 6. 8vo. Monaco, Ulnstitut Oceanographiq;ue — Bulletin, Nos. 105-108. 8vo. 1907. National Church League — Church Gazette for Jan. 1908. 8vo. Navy League — Navy League Journal for Dec-Jan. 1907-8. 8vo. Neio York, Society of Experimental Biology — Proceedings, Vol. V. No. 1. 8vo. 1907. North of England Institute of Mining Engineers — Transactions, Vol. LV. Part 7; Vol. LVI. Parts 5-6; Vol. LVII. Parts 4-6; Vol. LVIII. Part 1. 8vo. 1907. Annual Report, 1906-7. 8vo. Index of Mining Literature, 1902. 8vo. 1907. Onnes, Dr. H. Kamerlingli, Hon. M.R.I, {the Author) — Communications from the Physical Laboratory at the University of Leiden, Nos. 98-99. 8vo. 1907. Paris, Socid6 d' Encouragement pour V Industrie Nationale — Bulletin for Nov.- Dec. 1907. 4to. Pharmaceutical Society of Ghxat Britain — The Calendar, 1908. 8vo. Journal for Dec-Jan. 1907-8. 8vo. Philadelphia, Acadeyny of Natural Sciences — Proceedings, Vol. LIX. Part 2 8vo. 1907. Photographic Society, i?o?/aZ— Journal, Vol. XLVII. No. 11; Vol. XL VIII. No. 1. 8vo. 1907-8. Rockefeller Institute of Medical i?esea;-c/i— Reprints, Vol. VII. 8vo. 1907. Rolleston, Humphry Davy, Esq., M.D. — Syllabus of a Course of Lectures on Chemistry by Sir Humphry Davy, 1802, Annotated, probably by Sir H. Davy. 8vo. Rome, Ministry of Public TForfes— Giornale for Sept.-Dec. 1907. 8vo. Royal Engineers' Institute — Journal, Vol. VII. Nos. 1-2. 8vo. 1908. Royal Irish Academy — Proceedings, Vol. XXVI. Section B, No. 10; Vol. XXVII. Section A, Nos. 3-7. 8vo. 1907. 44 General Monthly Jfeefinf/. [Feb. o. Royal Society of Ediiiburgh^Froceedings, Vol. XXVIII. Nos. 1-2. 8vo. 1908. Transactions, Vol. XLV. Parts 2-3. 4to. 1907. Royal Society of London — Philosophical Transactions, A, Vol. CGVII. Nos. 420-424 ; B" Vol. CXGIX. Nos. 257-258. 4to. 1907-8. Proceedings, Vol. LXXX. Series A, No. 535 8vo. 1907. (S7. Paulo, Brazil — Dados Cliniatologicos, Serie 2, No. 1. 8vo. 1907. Si. Petersbonrg, Iniperial Academy of Sciences — Bulletin, VP Serie, 1907, Nos. 17-18; 1908, No. 1. 4to. 1907-8.- Comptes Kendus de la Commission Sismique, Tome II. Lief 3. 4to. 1907. Saleeby, C. W., Esq., M.D. F.R.S.E. {the Autlior) — The Conquest of Cancer. 8vo. 1907. Salford, Borougliof — Fifty-ninth Annual Report of the Museums and Lihrarics Committee, 190G-7. 8vo. 1908. Sanitary Institute, Royal — Journal, Vol. XXVIII. Nos. 11-12. 8v(^. 1907-8. Scottish Meteorological Society — Journal, Vol. XIV. Third Series, No. 24. 8vo, 1907. Scottish Society of Arts, Royal — Journal, Vol. XVII. No. 12. 8vo. 1907. Selborne Society — Nature Notes for Dec.-Jan.-Feh. 8vo. 1907-8. Smith, B. Leigh, Esq., M.R.I. — The Scottish Geographical Magazine, Vol. XXIII. No. 12 ; Vol. XXIV. No. 1 8vo. 1907-8. Socicta dcgli Sj^ettroscojnsti Italiani — Memorie, Vol. XXXVI. Disp. 12. 4to. 1907. Society of Arts, Royal — Journal for Dec-Jan. 1907-8. 8vo. Statistical Society, Royal — Journal, Vol. LXX. Part 4. 8vo. 1907. Sweden, Royal Academy of Sciences — Handlingar, Band XLII. No. 8. 4to. o 1907. Arsbok for 1907. 8vo. Arkiv: Matematik, Band III. Heft 3-4. 8vo. 1907. Les Prix Nobel en 1905. 8vo. 1907. United Service Institution, Royal — Journal for Dec- Jan. 1907-8. 8vo. United States Department of Agriculture— 'Ei^])Qx\Taent Station Record, Vol. XIX. Nos. 2-3. 8vo. 1907. Report of the Chief of the Weather Bureau, 1905-6. 4to. 1907. Monthly Weather Review for Sept. 1907. 4to. Weather Bureau Bulletin, No. 372. 4to. 1907. United States Department of Commerce and Labour — Bulletin of the Bureau of Standards, Vol. IV. No. 1. 8vo. 1907. United States Department of the Interior — Jxeport of the Commissioner of Education, 1905. 2 vols. 8vo. 1907. Report of the Secretary of the Interior for 1906. 8vo. 1906-7. Geologic Atlas of the United States, Nos. 141-150. fol. 1907. United States Patent 0#:cc— Ofhcial Gazette, Vol. CXXXI. Nos. 4-9; Vol. CXXXII. Nos. 1-3. 8vo. 1907-8. Upsala, Royal Society — Bibliographia Linuaeaua, Partie I. Liv. 1. 8vo. 1907. Vcrein zur Befiirdcrung des Geicerbfleisses in P/-e?fcsscH— Verhandlungen, 1907, Heft 12 ; 1908, Heft 1. 4to. Vienna Imperial Geological Institute — Jahrbuch, 1907, Band LVII. Heft 4. 8vo. Verhandlungen, 1907, Nos. 11-14. 8vo. Wasliington Academy of Sciences — Proceedings, Vol. X. pp. 1-50. 8vo. 1907-8. Washington Philosophical Society — Bulletin, Vol. XV. pp. 57-74. 8vo. 1907. Wcstei-n Australia, Agent-General — Supplement to Government Gazette for Nov.-Dcc. 1907. 4to. Monthly Statistical Abstract for Sept.-Oct.-Nov. 1907. 4to. ]Vcstern Society of Engineers — Journal, Vol. XII. No. 5. 8vo. 1907. Yorkshire Archaeological Society — Journal, Vol. XIX. Part 4; Part 76. 8vo. 1907. Report for 1907. 8vo. 1908. 1908] Napoleon and the Louvre. 45 AVEKKLY EVENING MEETING, Friday, Fel)niaiT 7, 1908. Sir James Criohtox-Browxh. M.]). LL.l). E.R.S., Tmisuivr and Vice-President, in the C^liair. IIiT.AEPHRY Ward, Esq., ]\I.A. Napoleon and llie Louvre. The lecturer tonched upon the early attempts, under Louis XY. and Louis XYL, to form a museum in the Salon Carrc'^ and the Long (vallery, and described how, on the motion of Barere, this was first carried out by the Conveution in 1791. At first the nuiseum contained only the Avorks of art belonging to the Crown, mostly removed from Yersailles ; but three years later, during the campaigns in the Netherlands, the Republican Government formally adopted the policy of seizing and annexing any masterpieces in the invaded countries. The Representatives of the People with the armies of the north boldly declared that any masterpieces existing in the countries "where the victorious armies of the French Republic have just chased away hordes of slaves hired by tyrants," could find their only proper home " in the dwelling ]>lace and in the possession of free men," i.e. in Paris ; and accordingly their Commissioner, Lieutenant Barbiei", took all the Rubenses and Yan Uycks he could find, and justified liimself at the l»ar of tlie Convention ]jy de(;laring tliat '' these masterpieces had been too long sullied by beholding servitude." The same treatment was applied to tlie libraries and galleries of Aix-la-Chapelle, Tjouvain, and Cologne ; and from the Cniversity of Louvain alone 5000 vohnnes were taken. So was the whole collec- tion of the Statholder AVilliam Y. when he left Holland on the approach of the French troops. In Italy, from the very beginning of the campaign, Bonai)arte adopted the same policy, and carried it out with amazing thoroughness, although some protests were raised in Paris, and the well-known scholar, Quatremere de Quincy, got fifty artists to join him in a petition that works of art should iiot be taken. The lecturer showed lantern slides from engravings of the time representing the stripping of the Parma Gallery, the taking away uf the bronze horses from St. Mark's in Yenice, and the journey of a convoy down the Tiber valley ; and he proceeded to describe Bonaparte's Treaty of Tolentino, in 1797, by which he forced the Pope to surrender a hundred works of art at the conqueror's choice. 46 Napoleon and the Louvre. [Feb. 7 Another slide showed the famous F^te de la Liberte, in which the procession of cars bearing these trophies was received in Paris on its way to the Louvre. The lecturer then spoke of the stripping of the German and Austrian galleries after Austerlitz and Jena, when 299 pictures were taken from Cassel alone ; and he briefly described the Musee when it was at last completed in 1810, and as it was when crowds of English visitors, including artists such as Lawrence and Chan trey, visited it in 1814. Up to this point he had drawn chiefly on the writings of the late Eugene Miintz, the late Frederic Yillot, and M. Saunier, who has collected all the documents in his book, ' Les Conquetes Artistiques de la Revolution et de I'Empire ' ; and he also showed a fine copy of the splendid official publication, ' Le Musee Francais.' In his description of the breaking up of the museum by the victorious Allies, he partly followed Saunier and partly the ' Letters and Papers ' of the Scotch miniature painter, Andrew Robertson, who was an eye-witness. On the first Restora- tion, in 1814, the xillies agreed not to disturb the museum ; but the Hundred Days changed the position, and after Waterloo they determined to claim their own, Bliicher and his Prussians being particularly unbending, supported, in the interests of Belgium and Holland, by the Duke of Wellington. The dramatic interest of the story, said the lecturer, lay in the courage and ingenuity with which the interests of the Musee were defended by its celebrated adminis- trator, Vivant Denon, who fought a losing battle with extraordinary skill, and succeeded in the end in saving a great many pictures and other works of art which ought by rights to have gone back. His resistance in Paris was at all events so ol^stinate that it probably prevented the Allies from seeking to break up the provincial museums, many of which still contain works taken by the French armies. The lecturer concluded by an account of that curious affair, the removal of the bronze horses of St. Mark's from their position on the top of the Triumphal Arch in the Place du Carrousel, which was carried out by the Austrians, as rulers of Venice, and excited the Parisian population almost to insurrection. In the end the horses were returned to their place, as were the Raphaels to Rome, the Correggios to Parma, and the Rembrandts to Cassel ; and since that time, by a sort of tacit agreement among the nations, works of art have never been regarded as the proper spoils of war. [H. W.] 1908] Biology and History. 47 WEEKLY EVENING MEETING, Friday, FebriiarT 14, 1908. Alexander Siemens, Esq., M.Inst.,C.E., Yice-President, in the Chair. Caleb Williams Saleeby, Esq., M.D.. F.R.S.E. Biology and History. [abstract.] You will not expect me to insult you this evening with any dis- cussion of the garbage and gossip, records of scoundrels and courts and battles, murder and theft, wliich we were taught at school under the name of History. If history be, as nearly all historians have conceived it, and as Gibbon defined it, " little more than the register of the crimes, folhes and misfortunes of mankind," it is an empty and contemptible study, save for the social pathologist. But if history, without by any means ignoring great men or underrating their influence, is, or should be, the record of the past life of man- kind, of progi-ess and decadence, the rise and fall of empires and civilisations, and their mutual reactions ; if it be the record of the intermittent ascent of man, "sagging but pertinacious"; if this record be subject to the law of causation, and therefore susceptible, in theory at least, of explanation as well as description ; if its factors are at work to-day, and will shape the destiny of all the to-morrows ; if it be neither phantasmagoria, nor panorama, nor pageant, nor pro- cession, but process — in short, an organic drama — then, indeed, it is a supreme study. Especially must it appeal to us, who boast a tradi- tion greater than the world has ever yet seen, and kinship with men who represent the utmost of which the human spirit has yet shown itself capable — who speak the tongue that Shakespeare spake, but to whom the names of all our imperial predecessors, from Babylon to Spain, serve as a perpetual memento mori. My special question, this evening, is whether there are inherent and necessary reasons why our predecessors' fate must sooner or later be ours ? Must i-aces die ? — or, if we are sceptical about races, and more especially about the so-called Anglo-Saxon race, must civilisations, states or nations die? Nations, races, civilisations rise, we shall all agree, because to in- herent virtue of breed they add sound customs and laws, acquirements of discipline and knowledge. But, these acquirements made, power 4s Dr. G. W. Sahebtj [Feb. 14. established, and crescent from year to year — why do they then fall ? If they can maJce a place for themselves, how much easier should it not be to maintain it ? Two explanations, each falsely asserting itself to be rooted in biological fact, have long Ijeen cited, and are still cited, in order to account for these supreme tragedies of history. The first— cited by no less a thinker than Mr. Balfour the other day — may claim Plato and Aristotle as its founders, and consists of an argument from analogy. Races may be conceived in similar terms to individuals. There are many resemblances between a society — a " social organism," to use Herbert Spencer's phrase— and an individual organism. Just, then, as the individual is mortal, so is the race. Each has its beginning, its period of youth and growth, its maturity, and finally, its decadence, senility and death. So runs the connnon argument. ]>iology, however, so far from confirming it, declares as the capital fact which contrasts the individual and the race, that whilst the individual is doomed to die from inherent causes, the race is naturally immortal. The tendency of life is not to die, but to live. If individuals die, that is doubtless because more life and fuller is thus attained than if life l)odied itself in immoi'tal forms ; but the germ-plasm is innnortal ; it has no inherent tendency either to degenerate or to die. Species exist and fiourish now which are millions of years older than mankind. ** The individual withers, the race is more and more." The most conspicuously persistent of all races during the last two millenia, the Jews, have survived one empire after another of their oppressors, but have never had an empire of tiieir own. Thus, so far as the historian is concerned, it is not races that die, but civilisiitions and empires. Plato's ^uialogy between the individual and the race is therefore irrelevant, as well as untrue. The fatalistic conception to which it tempts us, saying that races must die, just as iudividuals must, and that therefore it is idle to I'epine or oppose, is utterly unwarrantable, and extremely unhealthy. To take our own case, des])ite the talk a])Out our own racial decadence, our babies still come into the world fit and strong and healthy. AVe kill them in scores of thousands every year, but this infant mortality is not a sign that the race is dying, Imt a sign that even the most splendid living material can be killed or damaged, if you try hard enough. The babies do not die because races are mortal, but because individuals are — and we kill them. The babies drink poison, eat poison, and breathe poison, and in due course die. The theory of racial senihty, inap])licable everywliere because untrue, is most of all inapplicable here. If a race became infertile, Plato and Ai'istotlc would be right. There is no such instance in history apart from well-defined external, not inherent, causes, as in the case of the Tasmanians. Dismissing this analogy, we may also dismiss, as based upon nothing better, the idea that the great tragedies of history 1908] on Biology and History. 49 were necessary events at all. We must look elsewhere than amongst the inherent and necessary factors of racial life for the causes which determine these tragedies ; and we shall be entitled to assume as conceivable the proposition that, notwithstanding the consistent falJ of all our predecessors, these causes are not inevitable, but being external and environmental, may possibly be controlled. The second of the two false interpretations of history in terms of biology is still, and always has been, widely credited. It is that, in consequence of success, a people becomes idle, thoughtless, unenter- prising, luxurious ; and that these acquired characters are transmitted to succeeding generations, so that finally there is produced a degene- rate people unable to bear the burden of empire, and then the crash comes. The historian usually introduces the idea already dismissed, by saying that a " young and vigorous race " invaded the imperial territories, and so forth. The terms " young " and " old," applied to human races, usually mean nothing at all. This doctrine of the transmission to children of characters acquired by their parents, is the explanation of organic evolution advanced by Lamarck rather more than a century ago. It is employed by his- torians for the explanation of both the processes they record, progress and retrogression. Thus they suppose that for many generations a race is disciplined, and so at last there is produced a race with dis- pline in its very bone ; or for many generations a nation finds it necessary to make adventure upon the sea, and so at last there is pro- duced a generation of predestined sailors with blue water in its blood. And, in similar terms, moral and physical retrogression or degeneration are explained. Let us consider the contrast between the interpretation which accepts the Lamarckian theory of the transmission of acquired characters and that Avhich does not. Consider the babies of a new generation. According to Lamarck, they have in their blood and brain the consequences of the habits of their ancestors. If these have been idle and luxurious, the new babies are predestined to be idle and luxurious too. This, in short, is a " dying nation." But, if acquired characters are not transmitted, the new generation is, on the whole, not much better, not much worse, than its predecessors, so far as this supposed factor of change is concerned. Each generation makes a fresh start, as we see in the babies of our slums to-day. Lamarck's theory is discredited. The view of Mr. Francis Clalton is accepted, that acquired characters are not transmitted, either for good or for evil. If there are no other factors of racial degeneration or racial advance, then races do not degenerate or advance, but make a fresh start every generation, and empires rise and fall without any relation to the breed of the imperial people — an incredible proposi- tion. Certain apparent though not real exceptions exist to the denial of the Tjamarckian theory of the transmission of acquired characters. Vol. XIX. (No. 102) E 50 Dr. C. W. Saleehj [Feb. 14, These exceptions are furnished by what may be called the racial poisons. Alcohol, for instance, is a substance, certainly poisonous in all but very small doses, which is carried by the blood to every part of tlie body, and may and does injure its racial elements. Thus a true racial degeneration may be "caused. Other poisons, such as those of certain diseases, act similarly. We must therefore note, in passing, a biological factor of his- torical importance, hitherto scarcely recognised by historians. Certain of our diseases, and especially consumption or tuberculosis, are at present making history by their extermination of aboriginal races. Minute living creatures, which we call microbes, are introduced into the new and favourable environment constituted by the blood and tissues of human races hitherto unacquainted with them, and the consequences are known to all. But, further, it has lately been sug- gested as highly pro])able, by Professor Ronald Ross, that the fall of Greece, that incalculable disaster for mankind, was due to the inva- sion not of human foes, but of the humble living species wliich are responsible for the disease miscalled malaria. Malaria, like alcohol, produces true racial degeneration, its poisons affecting those racial elements of which the individual body, as biologically conceived by Weismann, is merely the ephemeral host — recalling the great line of Lucretius, " Et quasi cursores, vital lampada tradunt.'" To lame the runner is not to injure the torch he bears — acquired characters are not transmitted ; but the racial poison makes dim the lamp ere he passes it on. But, leaving poisons out of the question, races of men and animals do undergo change, progressive and retrogressive, in consequence of the action of another factor than that advanced by Lamarck ; and this is the factor of " natural selection," so termed by Charles Darwin in 1858, exactly half a century ago ; or "survival of the fittest," to use Herbert Spencer's phrase. If, of any generation, individuals of a certain kind are chosen by the environment for survival and parentage, the character of the species will change accordingly. If what we call the best are chosen, their goodness will be transmitted in some degree, and the race will advance ; if what we call the worst are chosen, their badness will be transmitted in some degree, and the race will de- generate. Now in the case of all species other than man the only possible progress is this racial or inherent progress, which is dependent upon a choice or selection of the best for parents, and is comparable in some measure, as Darwin showed, with the change similarly produced by the selective breeding, or " artificial selection," of the lower animals by man. But in the case of man himself, there is a wholly different kind of progress also attainable, which is not inherent or racial progress at all, but yet is real progress ; and which has the most important relation to the inherent or racial progress that may be achieved by the process of natural selection, or the choice of parents. The dis- 11)08] on BloJogy and History. 51 Unction between these two hinds of human ])rogress is as cardinal as it is hitherto ignored. It was said just now that acquired characters are not transmissible by heredity ; but man has learnt to circumvent the laws of heredity by transmitting his spiritual acquirements through language and art. Even before writing, there was tradition passed on from mouth to mouth. As long as man was speechless he advanced, I believe, no faster than other creatures —we know that he has an undistinguished past of some hundreds of thousands of years : but with speech and writing came the transmission of acquirements in this special sense. The past education of a mother will not enlarge her baby's brain, but she can teach her daughter what she has learnt, and so the child can, in a sense, begin where the parent left off — in analogy with what Lamarck wrongly imagined to be the case with the young giraffe, that was supposed to profit by the stretching of the parental necks. It is this transmission of spiritual acquirements — outside the germ-plasm, and notwithstanding its laws — that explains the amazing acquired progress of man in the last ten or twenty thousand years, as compared with three or perhaps five hundred thousand before them. This kind of progress is peculiar to man ; it is the gift of intelli- gence, and it may be called traditional or acquired jjroc/ress. It is an utterly different thing from inherent or racial progress, an improve- ment in the breed dependent upon the happy choice of parents. And it is surely evident that acquired progress is compatible with inherent decadence. To use Coleridge's image, a dwarf may see further than a giant if he sits on the giant's shoulders ; yet he is a dwarf, and the other a giant. Any schoolboy now knows more than Aristotle, and that is true progress of one kind, but the schoolboy may well be a dwarf compared with Aristotle, and may belong to a race degenerate when compared with his : and that would be inherent or racial deca- dence subsisting with acquired or traditioncd progress. Now whilst the accumulation of knowledge and art and inven- tion from age to age is real progress, it evidently depends for its security upon the quality of the race. If the race degenerates — whether through a racial poison, alcohol or malaria, or through, say, the selection of the worst for parentage — the time will come when its heritage is too much for it. The pearls of the ancestral art are now cast before swine, and are trampled on ; statues, temples, books, are destroyed, or burnt, or lost. If an empire has been built, the degene- rate race cannot sustain it. There is no wealth but life ; and if the inherent quality of the life fails, neither battle-ships, nor libraries, nor symphonies, nor Free Trade, nor Tariff Reform, nor anything else, will save a nation. Empires and civilisations, then, may have fallen, despite the strength and magnitude of the superstructure, because their living foundations became weak ; and the bigger and heavier the superstruc- ture, the less could it survive the failure of the foundations. If the Fiji islanders des:enerate, there is little consequence ; if the breed of i; 2 52 Dr. C. W. Saleehy [Feb. 14, Romans degenerate, all their vast mass of acquired progress and power crushes them into dramatic ruin. Acquired progress will not compensate for racial or inherent decadence. If the race is going dow^i, it will not compensate to add another dependency to your empire ; on the contrary, the bigger the empire, the stronger must be the race ; the bigger the superstructure, the stronger the founda- tions. Acquired progress is real progress, but it is always dependent for its maintenance upon racial or inherent progress— or, at least. upon racial maintenance. It is submitted that civilisations and empires have succumbed because they represented only acquired or traditional progress ; and this availed not at all when, for instance, the races that built them up began to degenerate. And, apart from the action of racial poisons, the only explanation of racial degeneration yet considered by the historians is the Lamarckian one of the transmission of ac- quired habits of luxury and idleness from parent to child : an explana- tion which the modern study of heredity empowers us to repudiate. What theory of this alleged degeneration is there to offer in its place ? and especially what theory which explains racial degeneration amongst not the conquered but the conquerors, amongst the successful, the imperial, the cultured, the leisured — the well-catered -for in all respects, bodily and mental ? Whij is it that not enslaved, hut imperial peoples deyenerate ? Why is it that nothing fails liJce success ? The true and sufficient answer has been given by no academic historian : but the clue to it was given half a century ago by the greatest historian of all time, Charles Darwin. The reason is that no race or species, vegetable or animal or human, can maintain its organic level, let alone raise it, unless its best be selected for parentage. We know that, as individuals, we must struggle or we degenerate. "Work is the law," as Ruskin said, whether for a livelihood or for enjoyment. Living things are the product of the struggle for exist- ence : we are thus evolved stragglers by constitution ; and directly we cease to struggle, we forfeit the possibilities of our birth-right. " Thou, 0 God," said Leonardo, " hast given all good things to man at the price of labour." The case is the same with races or nations. Directly the condi- tions become too easy, selection ceases : it is as successful to be incom- petent or lazy or vicious as to be worthy. The hard conditions that kept weeding out the unworthy are now relaxed, and the fine race they made goes back again. There even occurs the phenomenon of reversed selection, when it is positively fitter to be bad than good, covTardly than brave— as when religious persecution murders all who are true'^to themselves, and spares hypocrites and apostates; or when healthy children are killed in factories, or by their mother's work in factories, whilst feeble-minded children or deaf-mutts are carefully tended until maturity and then sent into the world to reproduce their maladies. Under reversed selection such results are obtained as a 1908] on Biology and History. 53 breeder of racehorses or plants would obtain if he went to work on similar lines ; the race degenerates rapidly, and if it be an imperial race its empire comes crashing down about its ears. All empires and civilisations hitherto have involved the risk of partial or complete arrest or reversal of the process of natural selection ; and. in the cases where their doom has been irretrievable, it is the racial degenera- tion so produced that has been its cause. When a race is making its early way by force, as by incessant war, selection is stringent. The weak, cowardly, diseased, stupid, are ruthlessly expunged from generation to generation. As civilisation advances, a higher ethical level is reached — all true civiHsation tend- ing to abrogate and ameliorate the struggle for existence. The diseased and weakly and feeble-minded are no longer left to pay the penalty sternly exacted by Nature for unfitness : they are allowed to survive, which is well ; and to mul iply, which is ill. A successful race can apparently afford to permit this, as a race that is fighting for its existence cannot. But in reality no race can afford this abso- lutely fatal process ; especially when unchallenged success comes, and even interferes with the natural process of selection to the extent of not merely abrogating, but actually reversing it, so that it may be more advantageous — more fit — to be a coward, or an idler, or diseased, or feeble-minded, than the reverse. The fittest survive in any case ; but fitness is not goodness. It may be, but it may be badness. Fitness is merely the capacity to fit — to fit the environment. That society in which it is fittest to be best is safe ; that society in which it is equally fit to be good, bad, or indif- ferent is doomed ; that society in which it is fittest to be worst is already damned. A nation will ascend, under the influence of selection which is such that the fittest selected are also the best ; a nation will degene- rate, under the influence of selection which is such that the fittest selected are also the worst. A nation will even degenerate if selection be merely abrogated, and universal survival or indiscriminate survival be substituted for any process of selection at all. If a nation can ascend in any sure way (its surety being dependent upon the fact that the ascent is in the very blood of the people) only when natural selection actively operates in the choice of the best for survival and parentage, then we begin to realise why it is that in the whole course of history hitherto this sure ascent has scarcely been realised. Babylon may have lasted for 4000 years, as the historians tell us, yet at last it fell. If selection had been operating in Babylon throughout that time, choosing only the best, the noblest and the wisest, conferring upon them, and npon them alone, the supreme privilege and duty of parentage, could Babylon have fallen ? Hence the explanation of the truth expressed by Gibbon, " All that is human must retrograde if it do not advance." Why should this be so ? Why should it not be possible merely to maintain a 54 Dr. G. W. SaUeby [Feb. 14, position gained ? The answer is, that the civihsation which merely maintains its position is one in which selection has ceased ; if selection had not ceased, the position would be more than maintained, there would be advance. But without selection the breed will certainly degenerate, the lower individuals multiplying more rapidly than higher ones, in accordance with Spencer's law that the higher the type of the individual the less rapidly does he multiply ; and thus the race which is not advancing is retrograding, as Gibbon declared. The selection of the best for parentage is the sole factor of in- herent or racial progress ; but the traditional or acquired progress, which we call civilisation, tends to thwart or abrograte or even invert this process. Thus the conditions necessary for the secure ascent of any race, an ascent secured in its very blood, made stable in its very bone, have not yet been achieved in history ; and this is the reason ivhy history records no enduring etnpire. It is not for a moment asserted that there are no other causes of imperial failure than the arrest or inversion of selection. But if this is not the cause, then, in the absence of the transmission of acquired characters, the race has not degenerated, and is capable of reassert- ing itself. Only l)y the arrest or inversion of selection can a race degenerate — apart from alcohol and certain diseases. If, then, a civilisation or empire has fallen through causes altogether non- biological — through carelessness, or neglect of motherhood or altera- tion of ideals — the changes in character so produced are not trans- mitted to the children, and the race is not degenerate, but merely deteriorated in each generation. For instance, we have been brought up to believe that there is no possible future for Spain — it is a dying nation, a senile individual, a people of degenerates ; it has had its day, which can never return. The historian explains this by a fallacious use of the analogy between a race and an individual, and by the false Lamarckian theory of heredity. But the biologist believes that since Spain has not been subjected — or, at any rate, not subjected long enough — to the only process which can rapidly ensure real degeneration, viz. the consistent and stringent selection of the worst, she is yet capable of regeneration. Regenera- tion is not really the word, because there has been no real de- generation, but only the successive deterioration of successive and undegenerate generations. If we took an animal species that has degenerated, such as the intestinal parasites, and endeavoured to regenerate them, we should begin to realise the magnitude of our task. That is not the task for Spain, the biologist asserts. Merely the environment must be altered — not the mountain ranges and the rivers. Buckle notwithstanding, but the really potent factors in the environment, the spiritual and psychical and social factors — and the deterioration of each new generation, inherently undegenerate, will cease. 1908] on Biology and History. 55 And the biologist is right. The "dying nation" alters its psychical environroent. It introduces the practice of education, it begins to shake off the yoke of ecclesiasticism ; and what are the consequences ? The new generation is found to be potentially little worse, and little better, than its predecessors of the sixteenth century. There has been no racial degeneration. The environment is modified for the better, i.e. so as to clioose the better, and Spain, as they say in misleading phrase, " takes on a new lease of life." But tlie historian might well write a volume upon the same thesis as appUed to China and Japan. The popular belief used to be, that China illustrated the so-called law of nations. It was the decadent, though monstrous, relic of an ancient civilisation ; it had had its day; inevitable degeneration, which must befall all peoples, had come upon it. Behold it in the paralysis which precedes death ! But in the light of the facts of Japan, and such a phrase as " the yellow peril," we have discarded our old theories. The metaphor must be changed. This is not paralysis, but merely stupor. It is suspense, not recuperation ; but assuredly it is not paralysis. Who now would dare to say that China has had its day, even if he still clings to the old fictions about Spain ? There is another factor of history to which, I believe, the biologist must attach enormous importance, but which no historian yet has adequately reckoned with. The prime assumption of this lecture from beginning to end, is that " there is no wealth but life ; " and, in the attempt to suggest interpretations of history based upon this truth, so little recked of by the historian, we have considered the life in question from the point of view of its determination by heredity, and its varying value according to the inherent and transmissible characters selected for perpetuation in each generation. But a w^ord must be said as to the other factor which, with heredity, determines the character of every individual — and that factor is the environ- ment. We must note the most important aspect of the environ- ment of human beings, and observe that historians hitherto have wholly ignored it ; yet its influence is incalculable. This is motherhood. It is man's intelligence that has made him lord of the earth ; it is qualities of intelligence that have largely determined the course of history as wrought out between human races and civilisations. Now intelligence is a limitless thing — it can learn everything ; lut, it has everything to learn. The lower animals have instincts — neither needing nor capable of education, but in order that intelligence shall be possible, instinct must make room for it. Thus, at birth we human beings have nothing ; intellect being only potential, not actual, and instinct having almost entirely lapsed. We come into 56 Dr. C. W. SaUeby [Feb. 14, the world more helpless and incompetent than the young of any other living creature ; the human baby is a fraction more helpless even than the baby ape. A later age may reveal a Newton or a Kelvin, a Shakespeare or a Goethe ; but all were helpless igno- rant babies at first, unable even to find their way to the mother's breast that was made for them. Thus motherhood, the importance of which has been steadily rising throughout the ages, and is enor- mous in all the mammals, is supremely important for the highest of the mammals, which is man. No motherhood, no intelligence. You may have the most perfect system of selection of the finest and high- est individuals for parentage ; but the babies whose potentialities — heredity gives no more — are so splendid, are always, will be always, dependent upon motherhood. What was the state of motherhood during the decline and fall of the Roman empire ? This factor counts in history ; and will always count, so long as three times in every century the only wealth of nations is reduced to dust, and begins again in helpless infancy. As to Rome we know little, what- ever may be suspected ; but we know that here, in the heart of the greatest empire in history — and it is at the heart that empires rot — thousands of mothers go out every day to tend dead machines, whilst their own flesh and blood, with whom lies the imperial destiny, are tended anyhow or not at all. To-day our historians and politicians think in terms of regiments, and tariffs, and " Dreadnoughts " ; the time will come when historians think in terms of babies and mother- hood. We must think in such terms, too, if we wish Great Britain to be much longer great. A history of motherhood is yet to seek. Meanwhile, who will not deplore the perennial slaughter of babies in this land, the deterioration of many for every one killed outright, the waste of mothers' travail and tears ? Had all Roman mothers been Cornelias, would Rome have fallen ? Consider the imitation mothers — no longer mammalia — to be found in certain classes to-day — mothers who should be ashamed to look any tabby cat in the face : consider the ignorant and downtrodden mothers amongst our lower classes ; and ask whether these things are not making history. Who will join the new party of one that calls itself maternalist ? These principles find their warrant and application in the un- exampled riddle of the persistence and success, throughout more than two thousand years and a thousand vicissitudes, of the Jewish people. It is true that we have here no exception to the apjmrent law that empires are mortal, for there never was a Jewish empire ; the Jews were never subject to tlje risk involved for racial or inherent progress, by the possession of great acquired powers leading to the arrest of strugiile and selection. But just as the fall of empires has often not been the fall of races — various races having at various times carried on the same imperial tradition — so the persistence of the Jews, as 1908] on Biology and History. 57 cuiicrasted with the impermanence of empires, has been the persistence of a race. It has been asserted that that race of people decays in which selec- tion ceases or is inverted ; that in the absence of selection of the fittest for life and parentage, no species, vegetable, animal or human, can prosper, much less progress. Now the Jews, the one human race of which we know assuredlv that it has persisted unimpaired, have been the most continuously and stringently selected of any race that can be named. Every measure of persecution and repression, practised against them by the peoples amongst whom they have lived, has directly tended towards the very end which those peoples least desired to compass. Other peoples found themselves prosperous through the efforts of their fathers ; the struggle for existence abated ; it was, so to say, as fit to be unfit as to be fit — with the inevitable result, racial decadence. But this has never been the case of the Jews. They have always had to struggle for life intensely, and their unexampled struggle has been a great source of their unexampled strength. The Jew who was a weakling or a fool had no chance at all ; the weaklings and the fools being weeded out, intensity and strength of mind became the common heritage of this amazing people. Secondly, there was everything to favour motherhood. Here reli- gious precept and ethical tradition joined with stern necessity to the same end— the end which always meant a new and strong beginning for the next generation. Even to-day all observers are agreed that infant mortality is at a minimum among the Jews ; their children are superior in height and weight and chest measurement, to Grentile children brought up amidst poverty far less intense in our own great cities— /m a belter material environment, hut a far inferior maternal environment. The Jewish mother is the mother of children innately superior, on the average, since they are the fruit of such long ages of stringent parental selection ; and she makes more of them because she fails to nurse them only in the rarest cases, when she has no choice, and because in every detail her maternal care is incomparably superior to that of her Gentile sister. Given a high standard of motherhood, in a highly selected race, what other result than that we daily witness and envy can we expect ? Thirdly, the Jews do not abuse alcohol ; and thus avoid one of the few causes of true racial degeneration, apart from arrest of selection or selection of the worst, for parentage. If these principles are vaHd, it is evident that our redemption from the fate of all our predecessors is to be found only in what Mr. Francis Galton calls eugenics— the selection of the best for parentage. The appropriateness of Mr. Galton's relation to this question is unmistake- able. As advocate of the principle of selection, he is the cousin of Charles Darwin, and he is the author of the theory that acquired characters are not transmitted, and therefore that selection alone 58 Dr. C. W. Salep^ [Feb. 14, changes races — that mere education is a Sisyphean task, which has to be done all over again from the beginning in each generation. Using the word environment in its widest sense, including, for instance, public opinion— and its use in any sense less wide is always erroneous and misleading^ — we must surely see that it is our business to provide the environment which selects the best for parentage and discourages the parentage of the worst : say, to Ijegin with, the deaf and dumb, the feeble-minded, the insane, the epileptic, the inebriate, those afflicted with hereditary disease of other kinds, and so forth. Our principles should enable us, also, to define what we mean by good environment. Comprehensive and indiscriminate charity means a good environment for many in a sense, but it may also mean the selection of the worst for parentage — e.g. the feeble-minded. This good environment, then, means the degeneration of the race. We must therefore appraise environment in terms of its selective action. A good environment is that w^hich selects the good, and the best en- vironment is that which selects the best ; discovers them, makes the utmost of them, and confers upon them the supreme privilege and duty of parentage. That, and that alone, is the best environment ; and all other moral judgments upon environment are fallacious, and will be disastrous. The new law of love need not go, the brutal struggle for existence need not be restored, we need not be damned to be saved. The unfit must survive, hut they must not multiply. We need only follow the Lancashire society Avhich now cares for the feeble-minded all their days, and thus serves the present and the future simultaneously. Eugenics, or " good breeding," is Mr. Francis Galton's name for the science of race-culture, which assumes that there is no wealth but life, and that the first duty of all governments and patriots, and good citizens is, to quote Ruskin again, " the production and recognition of human worth, the detection and extinction of human unworthiness." The idea is not new-fangled, but w^as clearly laid down by Plato, and by Theognis two centuries before him. The modern expression of it is now nearly a quarter of a century old, and it has already passed the stage of ridicule, except by the ridiculous. Eugenics is a project of the most elevated and provident morality, aiming at no object less sublime than the ennoblement of mankind ; and if one may suggest its motto, it would be, The products of progress are not jnechanisms but men. It aims at ." working out the beast." It is based upon the principle of the selection or choice of the superior for parentage, Avhich has been the essential factor of all progress in the world of life, but which all civilisations have tended, in some degree, to abrogate, or even to invert — as when the feeble-minded child is cared for till maturity, and sent out into the world to produce its like, whilst healthy children are daily destroyed by ignorance and neglect. 1908] on Biology and History. 59 " Through Nature only can we ascend," and the merit of the eugenic proposal is that it is built upon "the solid gronnd of Nature." To the economist, it declares tliat the culture of tlie racial life is the vital industry of any people. It is to work through marriage, an institution more ancient than mankind, and supremely valuable in its services to childhood — with which lies all human destiny. Neither Mr. Galton, nor the recently founded Eugenics Education Society, countenances for a moment the insane and vicious proposals which falsely assume that the methods of the stud farm are applicable to man — who is not an erected horse. Eugenics appeals to the individual, asking for a little imagina- tion— to make us realise that the future will one day be the present, and that to serve it is to serve no fiction or phantom, but a reality as real as the present generation. It teaches the responsibility of the noblest and most sacred of all professions, which is parentage, and it makes a sober and dignified claim to be regarded as a constituent of the religion of the future. It goes to the root of the matter : where the well-meaning, but short-sighted, pin their faith on the hospitals, the eugenist seeks to brand the transmission of hereditary disease as a crime, and thus literally to extirpate it altogether. That its methods are practicable is proved by the fact that it is practised — as by the northern society for the ''' permanent care of the feeble-minded," just referred to. National eugenics ofl'ers, I submit, our sole chance of escape from the fate which has overtaken all previous civilisations ; and suggests the principles of a New Imperialism. It honours men and women, by declaring that human parentage is crowned with responsibility to the unborn, and to all time coming ; and that man, the animal in body, is also a self-conscious being, " looking before and after," who is human because he is responsible ; and to whom the laws of nature have been revealed, not to satisfy an intellectual curiosity, but for the highest end conceivable — the elevation of his race. Says Wordsworth : — " Having brought the books Of modern statists to their proper test, Life, human life, with all its sacred claims ; And having thus discerned how dire a thing Is worshipped in that idol proudly named ' The Wealth of Nations ' ; where alone that wealth Is lodged, and how increased : and having gained A more judicious knowledge of the worth And dignity of individual man, 60 Biology and History. [Feb. 14, I could not but inquire Why is this glorious creature to be found One only in ten thousand ? What one is, Why may not millions be ? What bars are thrown By Nature in the way of such a hope ? " Consider how far we have come, the base degrees by which we did ascend, and answer with Shakespeare, "There are many events in the womb of Time which will be delivered." [C. W. S.] 1908] Thf Ether of Space. 61 WEP]KLY EVENING MEETING, Friday. Febniaiy 21, 1908. The Right Hon. Lord Raylei&h, O.M. P.O. M.A. D.C.L. LL.l). Sc.I). Pres.R.8.. in the Chair. Sir Oliver LodCxE, LL.D. D.Sc. F.R.S. 3LRJ. The Ether of Space. [abstract.] Thirty years ago Clerk Maxwell g-ave in this place a remarkable address on " Action at a Distance." It is reported in yonr Jonl^nal, Vol. VII., and to it I wonld direct attention. Most natural philo- sophers hold, and have held, that action at a distance across empty space is impossible ; in other words, that matter cannot act where it is not, but only where it is. The question '• where is it ? " is a further question that may demand attention and require more than a superlicial answer. For it can be argued on the hydrodynamic or vortex theory of matter, as well as on the electrical theory, that every atom of matter has a universal though nearly infinitesimal prevalence, and extends everywhere ; since there is no definite sharp laoundary or limiting periphery to the region disturbed by its existence. The lines of force of an isolated electric charge extend throughout illimitable space. And though a charge of opposite ?ign will curve and concentrate them, yet it is possible to deal with both charges, by the method of superposition, as if they each existed separately without the other. In that case, therefore, however far they reach, such nuclei clearly exert no " action at a distance " in the technical sense. Some philosophers have reason to suppose that mind can act directly on mind without intervening mechanism, and sometimes chat has been spoken of as genuine action at a distance ; but, in the first place, no proper conception or physical model can be made of such a process, nor is it clear that space and distance have any par- ticular meaning in the region of psychology. The links between mind and mind may be something quite other than physical proximity, and in denying action at a distance across empty space I am not denying telepathy or other activities of a non-physical kind : for although brain disturbance is certainly physical and is an essential 62 Sir Oliver Lodge [Feb. 21, concomitant of mental action, whether of the sending or receiving variety, yet we know from the case of heat that a material movement can be excited in one place at the expense of corresponding move- ment in another, withont any similar kind of transmission or material connection between the two places : the thing that travels across vacuum is not heat. In all cases where physical motion is involved, however, I would have a medium sought for ; it may not be matter, but it must l)e something ; there must be a connecting link of some kind, or the transference cannot occur. There can be no attraction across really empty space. And even when a material link exists, so that the connexion is obvious, the explanation is not coniplete : for when the mechanism of attraction is understood, it will be found that a l)ody really only moves because it is pushed by something from behind. The essential force in nature is the vis a tergo. So when we have found the " traces," or discovered the connecting thread, we still run up against the word " cohesion," and ought to be exercised in our minds as to its ultimate meaning. Why the whole of a rod should follow, when one end is pulled, is a matter requiring explanation ; and the only explanation that can be given involves, in some form or other, a continuous medium connecting the discrete and separated particles or atoms of matter. When a steel spring is bent or distorted, what is it that is really strained ? Not the atoms— the atoms are only displaced ; it is the connecting hnks that are strained — the connecting medium— the ether. Distortion of a spring is really distortion of the ether. All stress exists in the ether. Matter can only be moved. Contact does not exist between the atoms of matter as we know them ; it is doubtful if a piece of matter ever touches another piece, any more than a comet touches the sun when it appears to rebound from it ; but the atoms are connected, as the comet and the sun are connected, by a continuous plenum without break or discontinuity of any kind. Matter acts on matter only thi'ough the ether. But whether matter is a thing utterly distinct and separate from the ether, or whether it is a specifically modified portion of it— modified in such a way as to be susceptible' of locomotion, and yet continuous with all the rest of the ether, which can be said to extend everywhere — far beyond the bounds of the modified and tangible portion — are questions demand- ing, and I may say in process of receiving, answers. Every such aiiswer involves some view of the universal and possibly 'infinite uniform omnipresent connecting medium, the Ether of space. It has been said, somewhat sarcastically, that the ether was made in England. The statement is only an exaggeration of the truth. I might even urge that it has been largely constructed in the ^ Royal Institution ; for, I will remind you now of the chief lines of evidence un which its existence is beUeved in, an.d- our knowledge of it is 1908] on the Ether of Space. 63 based. First of all, Newton recognised the need of a medium for explaining gravitation. In his " Optical Queries " he shows that if the pressure of this medium is less in the neighbourhood of dense bodies than at great distances from them, dense bodies will be driven towards each other ; and that if the diminution of pressure is inversely as the distance from the dense bodv, the law will be that of gravitation. All that is required, therefore, to explain gravity is a diminu- tion of pressure, or increase of tension, caused by the formation of a matter unit — that is to say of an electron or corpuscle : and although we do not yet know what an electron is — whether it be a strain centre, or w^hat kind of singularity in the ether it may be— there is no difficulty in supposing that a slight, almost infinitesimal, strain or attempted rarefaction should be produced in the ether whenever an electron came into being — to be relaxed again only on its resolution and destruction. Strictly speaking it is not a real strain, but only a " stress " ; since there can be no actual yield, but only a pull or tension, extending in all directions towards infinity. The tension required per unit of matter is almost ludicrously small, and yet in the aggregate, near such a body as a planet, it becomes enormous. The force with which the moon is held in its orbit would be great enough to tear asunder a steel rod four hundred miles thick, with a tenacity of 30 tons per square inch ; so that if the moon and earth were connected by steel instead of by gravity, a forest of pillars would be necessary to whirl the system once a month round their common centre of gravity. Such a force necessarily implies enormous tension or pressure in the medium. Maxw^ell calculates that the gravitational stress near the earth, which we must suppose to exist in the invisible medium, is 3000 times greater than what the strongest steel could stand ; and near the sun it should be 2500 times as great as that. The question has arisen in my mind, whether, if the whole sensible universe —estimated by Lord Kelvin as equivalent to about a thousand million suns — were all concentrated in one body of specifiable density,* the stress would not be so great as to produce a tendency towards etherial disruption ; which would result in a disintegrating explosion, and a scattering of the particles once more as an enormous nebula and other fragments into the depths of space. For the tension would be a maximum in the interior of such amass ; and, if it rose to the value 10^^ dynes per square centimetre, something would have to happen. I do not suppose that this can be the reason, but one would think there must be some reason, for the scattered condition of gravitative matter. * On doing the arithmetic, however, I find the necessary concentration absurdly great, showing that such a mass is quite insufficient.^ See Appendix, 64 Sir Oliver Lodge [Feb. 21, Too little is known, however, about the mechanism of gravitation to enable ns to adduce it as the strongest argument in support of the existence of an ether. The oldest valid and conclusive requisition of an etherial medium depends on the wave theory of light, one of the founders of which was your Professor of Natural Philosophy at the beginning of last century, Dr. Thomas Young. No ordinary matter is capable of transmitting the undulations or tremors that we call light. The speed at which they go, the kind of undulation, and the facility with which they go through vacuum, forbid this. So clearly and universally has it been perceived that waves must be waves of something — something distinct from ordinary matter — that Lord Salisbury, in his presidential address to the British Associa- tion at Oxford, criticised the ether as little more than a nominative case to the verb to undulate. It is truly tit at, though it is also truly more than that : but to illustrate that luminif erous aspect of it, I will quote a paragraph from that lecture of Clerk Maxwell's to which T have already referred : — " The vast interplanetary and interstellar regions will no longer be regarded as waste places in the universe, which the Creator has not seen fit to fill with the symbols of the manifold order of His kingdom. We shall find them to be already full of this wonderful medium ; so full, that no human power can remove it from the smallest portion of space, or produce the slightest flaw in its infinite continuity. It extends unbroken from star to star ; and when a molecule of hy- drogen vibrates in the dog-star, the medium receives the impulses of these vibrations, and after carrying them in its immense bosom for several years, delivers them, in due course, regular order, and full tale, into the spectroscope of Mr. Huggins, at Tulse Hill." (It is pleasant to remember that those veteran investigators Sir William and Lady Huggins are still at work.) This will suffice to emphasise the fact that the eye is truly an etherial sense-organ — the only one which we possess, the only mode by which the ether is enabled to appeal to us, and that the detection of tremors in this medium — the perception of the direction in which they go, and some inference as to the quality of the object which has emitted them — cover all that we mean by " sight " and " seeing." I pass then to another function, the electric and magnetic phe- nomena displayed by the ether ; and on this I will only permit myself a very short quotation from the writings of Faraday, whose whole life may be said to have been directed towards a better understanding of these ethereous phenomena. Indeed, the statue in your entrance hall may be considered as the statue of the discoverer of the electric and magnetic properties of the Ether of space. Faraday conjectured that the same medium which is concerned in the propagation of hght might also be the agent in electromagnetic phenomena. " For my own part," he says, " considering the relation 1908] on the Ether of Space. 65 of a vacuum to the maguetic force, and the o^eneral character of magnetic phenomena external to the magnet, I am much more inclined to the notion that in the transmission of the force there is such an action, external to the magnet, than that the effects are merely attraction and repulsion at a distance. Such an action may be a function of the aether ; for it is not unlikely that, if there be an aether, it should have other uses than simply the conveyance of radiation." This conjecture has been amply strengthened by subsequent in- vestigations. One more function is now being discovered ; the ether is being found to constitute matter — an immensely interesting topic, on which there are many active workers at the present time. I will make a brief quotation from your present Professor of Natural Philosophy (J. J. Thomson), where he summarises the conclusion which we all see looming before us, though it has not yet been completely attained, and would not by all be similarly expressed : — " The ivhole mass of any body is just the mass of ether surrounding the body which is carried along by the Faraday tubes associated with the atoms of the body. In fact, all mass is mass of the ether ; all momentum, momentum of the ether ; and all kinetic energy, kinetic energy of the ether. This view, it should be said, requires the density of the ether to be immensely greater than that of any known substance." Yes, far denser — so dense that matter by comparison is like gossamer, or a filmy imperceptible mist, or a milky way. Not unreal or unimportant — a cobweb is not unreal, nor to certain creatures is it unimportant, but it cannot be said to be massive or dense ; and matter, even platinum, is not dense when compared with the ether. Not till last year, however, did I realise what the density of the ether must really be,* compared with that modification of it which appeals to our senses as matter, and which for that reason engrosses our attention. If I have time I will return to that before I have finished. Is there any other function possessed by the ether, which, though not yet discovered, may lie within the bounds of possibility for future discovery ? I believe there is, but it is too speculative to refer to, beyond saying that it has been urged as probable by the authors of " The Unseen Universe," and has been thus tentatively referred to by Clerk Maxwell :— " Whether this vast homogeneous expanse of isotropic matter is fitted not only to be a medium of physical interaction between dis- tant bodies, and to fulfil other physical functions of which, perhaps, we have as yet no conception, but also ... to constitute the material organism of beings exercising functions of life and mind as high or * See Lodge, Phil. Mag., April 1907 Vol. XIX. (No. 102) 66 Sir Oliver Lodge [Feb. 21, higher than ours are at present — is a question far transcending the Hmits of physical speculation." And there for the present I leave that aspect of the subject. I shall now attempt to illustrate some relations between ether and matter. The question is often asked, is ether material ? This is largely a question of words and convenience. Undoubtedly, the ether belongs to the material or physical universe, but it is not ordinary matter. I should prefer to say it is not " matter " at all. It may be the substance or substratum or material of which matter is composed, but it would be confusing and inconvenient not to be able to dis- criminate between matter on the one hand, and ether on the other. If you tie a knot on a bit of string, the knot is composed of string, but the string is not composed of knots. If you have a smoke or vortex-ring in the air, the vortex-ring is made of air, but the atmo- sphere is not a vortex-ring ; and it would be only confusing to say that it was. The essential distinction between matter and ether is that matter moves^ in the sense that it has the property of locomotion and can effect impact and bombardment : while ether is strained, and has the property of exerting stress and recoil. All potential energy exists in the ether. It may vibrate, and it may rotate, but as regards locomotion it is stationary — the most stationary body we know — absolutely stationary, so to speak ; our standard of rest. All that we ourselves can effect, in the material universe, is to alter the motion and configui-ation of masses of matter ; we can move matter, by our muscles, and that is all we can do directly : everything else is indirect. But now comes the question, how is it possible for matter to be composed of etlier ? How is it possible for a solid to be made out of fluid ? A solid possesses the properties of rigidity, impenetrability, elasticity, and such like ; how can these be imitated by a perfect fluid such as the ether must be ? The answer is, they can be imitated by a fluid in motion ; a statement which we make with couiidence as the result of a great part of Lord Kelvin's work. It may be illustrated by a few experiments. A wiieel of spokes, transparent or permeable when stationary, becomes opaque when revolving, so that a ball thrown ngainst it does not go through, but rebounds. The motion only affects per- meability to matter ; transparency to light is unaffected. A silk cord hanging from a pulley becomes rio:id and viscous when put into rapid motion ; and pulses or waves which may be generated on the cord travel along it with a speed equal to its own velocity, whatever that velocity may be, so that they appear to stand still. This is a case of kinetic rigidity ; and the fact that the wave-transmission velocity is equal to the rotatory speed of the material, is typical and 1908] on the Ether of Space. 67 important, for in all cases of kinetic elasticity these two velocities are of the same order of magnitude. A flexible chain, set spinning, can stand up on end while the motion continues. A jet of water at sufficient speed can be struck with a hammer, and resists being cnt with a sword. A spinning disk of paper becomes elastic like flexible metal, and can act like a circular saw. Sir William White tells me that in naval construction steel plates are cut by a rapidly revolving disk of soft iron. A vortex-riug, ejected from an elliptical orifice, oscillates about the stable circular form, as an indiarubber ring would do ; thus fur- nishing a beautiful example of kinetic elasticity, and showing us clearly a fluid displaying some of the properties of a solid. A still further example is Lord Kelvin's model of a spring balance, made of nothing but rigid bodies in spinning motion.* If the ether can be set spinning, therefore, we may have some hope of making it imitate the properties of matter, or even of con- structing matter by its aid. But how are we to spin the ether ? Matter alone seems to have no grip of it. I have spun steel disks, a yard in diameter, 4000 times a minute, have sent light round and round between them, and tested carefully for the sUghtest effect on the ether. Not the shghtest effect was perceptible. We cannot spin ether mechanically. But we can vibrate it electrically ; and every source of radiation does that. An electrified body, in sufficiently rapid vibration, is the only source of ether-waves that we know ; and if an electric charge is suddenly stopped, it generates the pulses known as X-rays, as the result of the collision. Not speed, but sudden change of speed, is the necessary condition for generating waves in the ether by electricity. We can also infer some kind of rotary motion in the ether ; though we have no such obvious means of detecting the spin as is furnished by vision for detecting some kinds of vibration. It is supposed to exist whenever we put a charge into the neighbourhood of a magnetic pole. Round the line joining the two, the ether is spinning like a top. I do not say it is spinning fast : that is a question of its density ; it is in fact spinning with excessive slowness, but it is spinning with a definite moment of momentum. J. J. Thomson's theory makes its moment of momentum exactly equal to e m, the product of charge and pole ; the charge being measured electro- statically and the pole magnetically. How can this be shown experimentally ? Suppose we had a spin- ning top enclosed in a case, so that the spin was unrecognisable by ordinary means— it could be detected by its gyrostatic behaviour to * Address to Section A of British Association at Montreal, 1884. F 2 68 Sir Oliver Lodge [Feb. 21, force. If allowed to "precess" it will respond by moving perpen- dicularly to a deflecting force. So it is with the charge and the magnetic pole. Try to move the charge suddenly, and it immediately sets off at right angles. A moving charge is a current, and the pole and the current try to revolve round one another — a true gyi'O- static action due to the otherwise unrecognisable etherial spin. The fact of such magnetic rotation was discovered by Faraday. I know that it is usually worked out in another way, in terms of lines of force and the rest of the circuit ; but I am thinking of a current as a stream of projected charges ; and no one way of regarding such a matter is likely to exhaust the truth, or to exclude other modes which are equally valid. Anyhow, in whatever way it is regarded, it is an example of the three rectangular vectors. The three vectors at right angles to each other, which may be labelled Current, Magnetism, and Motion respectively, or more generally E, H, and Y, represent the quite fundamental relation between ether and matter, and constitute the link between Electricity, Magnetism, and Mechanics. Where any two of these are present, the third is a necessary consequence. This principle is the basis of all dynamos, of electric motors, of light, of telegraphy, and of most other things. Indeed, it is a question whether it does not underlie everything that we know in the whole of the physical sciences ; and whether it is not the basis of our conception of the three dimensions of space. Lastly, we have the fundamental property of matter called inertia, which, if I had time, I would show could be explained electro- magnetically, provided the etherial density is granted as of the order 10^^ grammes per cubic centimetre. The elasticity of the ether would then have to be of the order 10^^ c.g.s. : and if this is due to intrinsic turbulence, the speed of the whirling or rotational elasticity must be of the same order as the velocity of light. This follows hydrodynamically ; in the same sort of ^ay as the speed at which a pulse travels on a flexible running endless cord, whose tension is entirely due to the centrifugal force of the motion, is precisely equal to the velocity of the cord itself. And so, on our present view, the intrinsic energy of constitution of the ether is incredibly and porten- tously great ; every cubic millimetre of space possessing what, if it were matter, would be a mass of a thousand tons, and an energy equivalent to the out-put of a million-horse-power-station for 40 mil- lion years. The universe we are living in is an extraordinary one ; and our investigation of it has only just begun. We know that matter has a psychical significance, since it can constitute Irain, which links together the physical and the psychical worlds. If anyone thinks that the ether, with all its massiveness and energy, has probably no psychical significance, I find myself unable to agree with him. 1908] on the Ether of Space. 69 Appendix I. On Gravity and Etherial Tension. Stating the law of gravitation as F = y — ^, the meaning here adopted for etherial tension at the surface of the Earth is SO that the ordinary intensity of gravity is 6?T yE 4 ^ Accordingly, near the surface of a planet the tension is Tq = g R, or for different planets is proportional to p R^. The velocity of free fall from infinity to such a planet is V(2 Tq) ; the velocity of free fall from circumference to centre, assuming uniform distribution of density, is V (Tq) ; and from infinity to centre it is V(3 Tp). Expanding all this into words : — The etherial tension near the earth's surface, required to explain gravity by its rate of variation, is of the order 6 x 10^^ cg.s. units. The tension near the sun is 2500 times as great. With different spheres in general, it is proportional to the density and to the super- ficial area. Hence, near a bullet one inch in diameter, it is of the order 10- ^ ; and near an atom or electron about 10" ^'. In order to set up a tension equal to the critical, or presumably disruptive, stress in the ether [10^^ c.g.s.], a globe of the density of the earth would have to have a radius of eight light years. In order to generate a velocity of free fall under gravity equal to the velocity of light, a globe of the earth's density would have to be equal in radius to the distance of the earth from the sun, or say 26,000 times the earth's radius. If the density were less, the superficial area would have to be increased in proportion, so as to keep p W constant. The whole visible universe within a parallax of yoW second of arc, estimated by Lord Kelvin as the equivalent of 10^ suns, would be quite incompetent to raise etherial tension to the critical point 10^^ c.g.s. unless it were concentrated to an absurd degree ; but it could generate the velocity of light with a density comparable to that of water. If the average density of the above visible universe (which may be taken as 1*6 X lO-^^ grammes per c.c.) continued without limit, a disruptive tension of the ether would be reached when the radius was comparable to 10^^ light years : and the velocity of light would 70 Sir Oliver Lodgp [Feb. 21, be generated by it when the radius was 10' light years. But hetero- geneity would enable these values to be reached more easily. It is noteworthy how exceedingly small is the average or aggregate density of matter in the visible region of space ; and Lord Kelvin has shown that throughout space in general it inust be smaller still — in fact ultimately infinitesimal. The estimated density of 10 ~^^ c.g.s. means that the visible cosmos is as much rarer than a vacuum of a hundred millionths of an atmosphere, as that vacuum is itself rarer than lead. It is, of course, because ordinary masses of matter likewise consist of separated particles, with great intervening distances in proportion to their size, that we are able to assert the minute aggregate density of ordinary stuff, such as water or lead, as compared with the con- tinuous medium of which all particles are supposed to be really composed. The fundamental medium itself must be of uniform density everywhere, whether materiahsed or free. Appendix II. Explanatory Eemarks concerning the Density of Ether. I observe that it is surmised by at least one thoughtful and friendly critic — C. W. S. in the Westminster Gazette — that in speaking of the immense density or massiveness of ether, and the absurdly small density or specific gravity of gross matter by comparison, I intended to signify that matter is a rarefaction of the ether. That, however, was not my intention. The view I advocate is that the ether is a perfect continuum^ an absolute 7;/^?^/??/, and that therefore iio rarefac- tion is possible. The ether inside matter is just as dense as the ether outside, and no denser. A material unit — say an electron — is only a peculiarity or singularity of some kind in the ether itself, which is of perfectly uniform density everywhere. What we sense as matter is an aggregate or grouping of an enormous number of such units. How then can we say that matter is millions of times rarer or less substantial than the ether of which it is essentially composed ? Those who feel any difficulty here, should bethink themselves of what they mean by the average or aggregate density of any discontinuous system, such as a powder, or a gas, or a precipitate, or a snowstorm, or a cloud, or a milky way. If it be urged that it is unfair to compare an obviously discrete assemblage like the stars, with an apparently continuous substance like air or lead, the answer is that it is entirely and accurately fair ; since air, and every other known form of matter, is essentially an aggregate of particles, and since it is always their average density that we mean. We do not even know for certain their individual atomic density. The phrase " specific gravity or density of a powder " is aml)igu- 1908] on the Ether of Space. 71 ous. It may mean tlie specific gravity of the dry powder as it lies, like snow ; or it may mean the specific gravity of the particles of which it is composed, like ice. So also with regard to the density of matter, we miglit mean the density of the fundamental material of which its units are made — which would be ether ; or we might, and in practice do, mean the density of the aggregate lump which we can see and handle ; that is to say, of water or iron or lead, as the case may be. In saying that the density of matter is small, I mean, of course, in the last, tbe usual, sense. In saying that the density of ether is great, I mean that the actual stuff of which these highly porous aggregates are couiposed is of immense, of well-nigh incredible, density. It is only another way of saying tliat the ultimate units of matter are few and far between — i.e. that they are excessively small as compared with the distances between them ; just as the planets of tlie solar system, or worlds in the sky, are few and far between — the inter- vening distances beiug enormous as compared with the portions of space actually occupied by lumps of matter. Here it may be noted that it is possible to argue that the density of a continuum is necessarily greater than the density of any discon- nected aggregate : certainly of any assemblage whose particles are actually composed of the material of the continuum. Because the former is " all there," everywhere, without break or intermittence of any kind ; while the latter has gaps in it — it is here, and there, but not everywhere. Indeed, this very argument was used long ago by that notable genius Robert Hooke, and I quote a passage which Professor Poynting has discovered in his collected posthumous works, and kindly copied out for me : — " As for matter, that I conceive in its essence to be immutable, and its essence being expatiation determinate, it cannot be altered in its quantity, either by condensation or rarefaction ; that is, there cannot be more or less of that power or reality, whatever it be, within the same expatiation or content ; but every equal expatiation contains, is filled, or is an equal quantity of ?nateria ; and the densest or heaviest, or most powerful body in the world contains no more materia than that which we conceive to be the rarest, thinnest, lightest, or least powerful body of all ; as gold for instance, and CBther, or the substance that fills the cavity of an exhausted vessel, or cavity of the glass of a barometer above the quicksilver. Nay, as I shall afterwards prove, this cavity is more full, or a more dense body of aether, in the common seuse or acceptation of the word, than gold is of gold, bulk for bulk ; and that because the one, viz., the mass of ffither, is all aether : but the mass of gold, w^hich we conceive, is not all gold ; but there is an intermixture, and that vastly more than is commonly supposed, of aether with it ; so that vacuity, as it is com- monly thought, or erroneously supposed, is a more dense body than 72 The. Ether of Space. [Feb. 21, the gold as gold. But if we consider the whole content of the one with that of the other, within the same or equal quantity of expatia- tion, then are they both equally containing the materia or body." [_From the Posthumous Works of Robert Hooke, M.D., F.B.S., 1705, 2)}?. 171-2 (as copied in Memoir of Dalton, by Angus Smith). Newton's contemporaries did not excel in power of clear expression, as he himself did, but Professor Pojnting interprets this singular attempt at utterance thus : " All space is filled with equally dense materia. Gold fills only a small fraction of the space assigned to it, and yet has a big mass. How much greater mast be the total mass filling that space." The tacit assumption here made is that tne particles of the aggre- gate are all composed of one and the same continuous substance, practically that matter is made of ether ; and that assumption, in Hooke's day, must have been only a speculation. But it is the kind of speculation which time is justifying, it is the kind of truth which we all feel to be in process of establishment now. AYe do not depend on that sort of argument however ; what we depend on is experimental measure of the mass, and mathematical estimate of the volume, of the electron. For calculation shows that however the mass be accounted for, whether electrostatically or mag- netically, or hydrodynamically, the estimate of ratio of mass to effect- ive volume can differ only in a numerical coefficient, and cannot differ as regards order of magnitude. The only way out of this conclusion would be the discovery that the negative electron is not the real or the main matter-unit, but is only a subsidiary ingredient, whereas the main mass is the more bulky positive charge. That last hypo- thesis however is at present too vague to be useful. Moreover, the mass of such a charge would in that case be unexplained, and would need a further step, which would probably land us in much the same sort of etherial density as is involved in the estimate which I have based on the more familiar and tractable negative electron. It may be said why assume any finite density for the ether at all- ? Why not assume that, as it is infinitely continuous, so it is infinitely dense — whatever that may mean — and that all its properties are infinite ? This might be possible were it not for the velocity of light. By transmitting waves at a finite and measurable speed, the ether has given itself away, and has let in all the possibilities of calculation and numerical statement. Its properties are thereby exhibited as essentially finite — however infinite the whole extent of it may turn out to be. [O. L.] 1908] Explosive Combustioii. WEEKLY EVENING MEETING Friday, February 2^^ + ^H-i, would at once raise serious difficulties. It therefore remained to consider whether the solution of the 1908] on Explosive Oombustmi. 77 problem might not lie in the assumption of an initial association of the hydrocarbon and oxygen forming an unstable "oxygenated" molecule, which subsequently rapidly decomposes. Thus, for example, the changes involved in the explosive combustion of an equimolecular mixture of ethylene and oxygen might conceivably be represented somewhat as foUow^s : — C2H4 + Oo = [C2H4O2] = 2C0 + 2H2 unstable Many years ago, indeed. Professor H. E, Armstrong, suggested that the combustion of a hydrocarbon takes place under the conjoint influence of water and oxygen, and involves the successive formation of intermediate ^^ hydroxi/latecV' molecules, which at high tempera- tures rapidly decompose into simpler products. Little notice was taken of his suggestion at the time, but recent researches have shown that " hydroxylated " molecules are probably formed, even in flames, although I think it doubtful whether water vapour is an essential factor in the process. The researches recently carried out at the Manchester University, have covered the entire range of conditions under which hydro- carbons can be burned, from the slow flameless combustion dis- covered by Davy, right up to the extreme conditions of detonation. An exhaustive study of the slow combustion of methane, ethane, ethylene, and acetylene, at temperatures between 250° and 400° C, afforded decisive evidence against the preferential burning, whether of carbon or of hydrogen. Large quantities of aldehydic intermediate products were isolated, and the balance of evidence was decidedly in favour of the " liydroxylatioa " theory, with the proviso, however, that the oxygen is directly active. Finally, the following scheme was put forward for the slow combustion of ethane, and ethylene at 250° to 850^ C. CH:i.CH3 -> CH3.CH.2OH -> CH3.CH(0H)2 -^ CO +_H20 + H.CHO -> H.COOH -^ C0(0H)2 . — -^ ForTnaldehyde Formic Carbonic Ethane Ethyl Alcohol HoO + CH3.CHO— i Acid Acid I Acttaldthyde . ' , — — ■ ^ CO + H2O CO2 + H2O. CHgrCHg. ^H2C:CH(0H) ->- (HO)CH:CH(OH) ^ H.COOH ^ C0(0H)2 ,— — ' — -^ Formic Acid Carbonic Acid Ethylene 2 H.CHO , ■ — -, , ' Formaldehyde ' CO + H2O COo + H2O Translated into words, this means that, in the case of ethane, the initial oxidation product is probably ethyl alcohol C2H5.OH. The alcohol has not, indeed, been actually isolated during the slow com- bustion at 300^ 0., chiefly because it is much more rapidly oxidised 78 Professor William Arthur Bone [Feb. 28, under these conditions than is ethane itself : it is, however, formed in quantity when ethane is oxidised by means of ozone at 100° C. The second stage involves the rapid oxidation of the alcohol to the un- stable CHg . CH(0H)2, which at once decomposes into steam and acetaldehyde. The acetaldehyde is in turn burnt to carbonic oxide, steam, smd formaldehyde /possibly through the unstable ho.c.h\ ^nd \ ho. 0:0/ finally the formaldehyde is burnt to steam and oxides of carbon, probably through formic acid and carbonic acid. As the temperature rises, the intermediate products become more and more unstable, and to an increasing extent decompose into simpler products, which then undergo independent oxida- tion. Thus ethyl alcohol decomposes into ethylene and steam, acetaldehyde either into methane and carbon monoxide, or into carbon, hydrogen, methane, and carbon monoxide, according to the tempera- ture, and formaldehyde is resolved into carbon monoxide'' and hydrogen, as follows : — Etlnjl Alcohol Acetaldehyde Formaldehyde an^oH. CH3.CH0 H.cHo OhT+IU) . J ' CH, + C0~^ ( CO +I12 \C + 2H2 + CO/ With the extension of the research to the conditions existing in hydrocarbon flames and explosions, it became increasingly evident that the mechanism of combustion is essentially the same above as below the ignition point. I do not mean, of course, that the phenomena observed at low temperatures, in slow combustion, are exactly reproduced in flames, but rather that the result of the initial molecular encounter between the hydrocarbon and oxygen is probably much the same in the two cases, namely, the formation of an " oxygenated " molecule. At the higher temperatures of flames, secondary thermal decompositions undoubtedly come into operation at an earlier stage, and play a more important role than in slow combustion, but they do not precede the onslaught of the oxygen upon the hydrocarbon, but arise in consequence of it. I am aware that there are eminent critics who, whilst admitting the validity of these views as applied to slow comlmstion, hesitate to accept entirely their extension to explosive combustion. They find it difiicult to believe that such compounds as ethyl alcohol, acetaldehyde, formalde- hyde, and the like, which are undoubtedly very unstable at liigh temperatures, can possibly be formed in flames. But surely this objection involves some confusion of thought as to the factors which govern .the formation and stability of chemical compounds ; the fact that a substance cannot permanently exist at a given temperature 1908] on ETplosivp, Gomlustlon. 79 does not justify the assertion that it cannot be formed at that tem- perature by the operation of factors which are not concerned in its decomposition. Therefore, I am not prepared to admit that because the acetaldehyde molecule does not long rcjmain intact at high tem- peratures, it necessarily follows that it cannot be brought into actual existence as the result of the interaction of ethane and oxygen in flames. Professor Smithells, in his recent presidential address to the chemical section at the British Association (1907), expressed his dissent from my views, as applied to flames, on the ground that " The isolation of an intermediate product under one set of circum- stances is in itself no proof that this product is transitorily formed when the reaction is proceeding under another set of circumstances. ..." To this I would reply, that whilst the isolation of (say) acetaldehyde in the slow oxidation of ethane is not hy itself sufficient proof of its transitory formation in the explosive combustion of the hydrocarbon, yet if it can be demonstrated, not only that the facts of explosive combustion can be best interpreted on the assumption of its formation, but that, so far as can be judged at present, no other interpretation can be advanced, and, moreover, that aldehydes are actually produced in flames, then it may be justly claimed that the assumption is well founded, and that the onus of its experi-. mental disproof rests with the sceptics. Having thus, I hope, explained the main issues involved in the controversy, I shall now proceed to perform a series of experiments on the explosive combustion of acetylene, ethylene, and ethane, some of wln'ch are crucial as regards the rival theories under discussion. Experiment II. — I have here three cyUndrical bulbs of stout boro- silicate glass (capacity = about 60 c.c), fitted with firing wires, her- metically sealed, and containing respectively equimolecular mixtures of each of the three hydrocarbons with oxygen, that is to say, mix- tures corresponding to C2H2 -f- Oo, C2H4 + Oo, and CoHg + 0.,, respectively. Now, according to the theory of the preferential combustion of carbon, these mixtures should on explosion, yield nothing but car- bonic oxide and hydrogen, without any separation of carbon, or formation of steam, as follows : — (a) C..H., + O., = 2C0 + H2 1-5 (6) dn; + 0: = 2C0 + 2H. 2-0 (c) G^He + Ol = 2G0 + SKl 2-5 * The symbols p^ and p.,, used in this and subsequent tables, denote the initial and final pressures of the cold original mixture and gaseous products (dry) at constant volume and at the same temperature, 80 Professor William Arthur Bone [Feb. 28, Oil firing tlie mixtures, it is at once evident that something very like this does happen in the cases of {a) and {!)). There is absohitely no deposition of carbon, and no appreciable condensation of steam in the cold products. Far otherwise is it, however, in the case of the bulb containing the mixture CoHg-t- O2. A lurid flame Alls the vessel, accompanied by a black cloud of carbon particles, and a close inspection of the cold bulb will reveal a considerable conden- sation of water. The pressure ratio 'p2l'Pi is approximately 1 ' 5, and an analysis of the gaseous products would prove the presence of about 10 per cent, of methane. The bulb will. now be opened, rinsed out with water, and the formation of aldehydic products demon- strated by means of SchifP's reagent. It is clear that these results are wholly inconsistent with the theory of the preferential burning of carbon. As it is obviously impracticable forme to complete the experiment by analysing the gaseous products before you, I will draw your attention to the following tabulated results of three similar experi- ments carried out some time a^'o. Table I. -Results of Experiments on Inflammation in Sealed Glass Bulbs. Original Mixture. C, H., + J., c. i5 mn 0-2 GJl, + 0., P\ 352 mm 5 1. 746 mm. p.. 508 „ 1053 „ 1148 „ P-2/Pl 1-44 1-93 1-54 = CO., 0-75 0-30 4-20 111 CO 67-10 50-00 33-55 CH^ + C^H, ml nil 2-75 ^==s CH, 1-55 1-70 10-85 i" H, 30-60 48-00 48-60 C H 1 0 C H 0 C H 0 Units in original | mixture . . . | 352 176 176 545 545 272 746 1119 376 Units in gaseous \ products ... 1 352 171 175 547 541 267 621- 854 241 DifEerence . Practically nil. Practically nil. 125 265 135 Did time permit, I could easily demonstrate to you by other similar experiments, that the outward difference here revealed between the burning of ethylene and that of ethane extends to all the other gaseous olefines and paraffins : that is to say, whereas mixtures of olefines and oxygen corresponding to CnH2n + ^ O2 on explosion id 1908] on Explosive Combustion. 81 yield mainly carbonic oxide and hydrogen, without separation of car- bon, mixtures of paraffin and oxygen corresponding to (^J^^n + 2 + ^ O2 yield carbon, oxides of carbon, methane, hydrogen, and steam, all in considerable quantities. Are we then to conclude that there is some peculiarity about the constitution or combustion of an define which induces a preferential burning of its carbon, whilst the corre- sponding paraffin is burnt in an entirely different way ? The following experiment will show that such a view cannot for a moment be enter- tained. Experiment III. — I will now fire a bulb containing a mixture of GO per cent, of ethylene and 40 per cent, of oxygen (i.e. 3C2H4 + 20.3). xis might be expected, the flame is accompanied by a large deposition of carbon, but what is of greater importance still is the fact that a considerable amount of water is also formed. The full significance of this experiment may be gathered from the following data. Original mixture C,.H, = 59-65 per cent. l\ = 562 mm 0, = 40-35 P, = 81Q „ PJPl Gaseous products CO, = 2-5, CO = 37-2, C,H,, + C„H, = 6-4, CH, H2 = 47 • 4 per cent. 1-45 6-5, Units in original mixture Units in gaseous products Difference . c H 0 670 482 670 572 227 172 188 98 aa I think it will be now admitted that such an experiment as this completely destroys the foundations of the theory of the preferential burning of carbon. As I have already stated, the original experi- mental basis of the theory, was the behaviour of an equimolecular mixture of ethylene and oxygen, yet here is proof that on closer examination the behaviour of ethylene is inconsistent with the theory. I would therefore say to those who may be inclined to cavil at my views as to the mechanism of combustion, that what- ever may l3e the final issue of the controversy, this fact, amongst others, must be explained, namely, that whereas a mixture of an ole- fine and oxygen corresponding to C^Hg^ f ^^ O2, yields mainly car- bonic oxide and hydrogen on explosion, in harmony with the equa- tion— Vol. XIX. (No. 102) G 82 Professor WiUiam Arthur Bone [Feb. 28, C„H9„ + " Oo = nCO + nE,, a diminution of the oxygen below this Hmit at once gives rise to steam formation. Experiment /F. — The next experiment is designed to ihustrate the infinitely greater affinity of acetylene and ethylene as compared with that of hydrogen for oxygen at the high temperatures of flames. I have here two bulbs containing mixtures of each of these hydrocarbons with hydrogen and oxygen corresponding to C2H2 + 2H2 + O2 and C2H4 + Ho + O2, respectively, and I will ask you to contrast the be- haviour of these with that of the equimolecular mixture of ethane and oxygen, C2H6 + O2, which was exploded a few^ minutes ago. It should be noted that whilst all three mixtures contain the same relative pro- portions of carbon, hydrogen and oxygen, they differ in respect of the proportions between the combined carbon and hydrogen. Asking you to bear in mind how the equimolecular mixture of ethane and oxygen on explosion gave rise to a black cloud of carbon and a considerable formation of water, I will now fire the other two mixtures. You will observe that in neither case has there been any deposition of carbon, and an inspection of the cold bulbs will show that little or no steam formation has occurred. In fact, the hydrocarbon has been burnt to carbonic oxide and hydrogen, leaving the hydrogen absolutely untouched by the oxygen, as the following detailed results show (Table II.). These experiments have an important bearing on the chemistry of flames. Hydrogen is usually considered as one of the most com- bustible of gases, but here we see it pushed to one side by the all- powerful hydrocarbon, as though it were so much inert nitrogen. This at once raises another question which has lately been occupying my attention. Ever since Davy's experiments on flame, the com- bustibility of hydrogen has been considered to be superior to that of methane ; this, however, cannot be true in regard to slow combustion, since it can be easily proved that between ^00° and 400° C. methane is oxidised at a far faster rate than hydrogen. Nevertheless, I have recently observed facts which incline me to think that possibly it may be true in regard to flames. If further investigation confirms this opinion, it will be necessary to enquire into tlie cause of the peculiar relative inertness and stability of methane as compared with other gaseous hydrocarbons when subjected to the action of oxygen at high temperatures. It does not I think impose too great a strain on the imagination to picture the probable mechanism of combustion in hydrocarbon flames, and for this purpose ethylene and ethane may be taken as typical examples. It may be assumed that, with the possible excep- tion of methane, the affinity of a hydrocarbon for oxygen is so great at high temperatures that the initial stage of its combustion takes 1908] on Explosive Comhiistion. 83 Table II.— Experiments on Inflammation in Sealed Glass Bulbs. 0 riginal Mixture. C.,H 4 + H., + 0., CoH., + 2H., + 0., Vi 303 mm. 534 mm. P2 750 „ 653 „ Ih/lpl 1-49 1-22 O 03 CO., 0-35 0-2 ~o% CO' 39-60 39-8 ^^t C..H., + C.,H, 1-25 nil iU " CH, ' 3-65 0-2 H., 55-15 59-8 C H 0 C H 0 Original mixture . 341 505 168 267 400 133 (laseous products . 346 478 151 262 394 131 Difference . — 27 17 Negligible precedence of all other chemical phenomeua in flames. This is pro- bably true of the propagation of flame through explosive mixtures of hydrocarbons and oxygen. In the special case of a stream of a hydro- carbon burning in air, partial decomposition may occur in the inner- most regions of the flame, where the supply of oxygen is very limited, before combustion begins. But, in general, whenever the hydrocarbon and oxygen are brought together at high temperatures, their mutual affinities will prove superior to any disruptive forces wliich would otherwise break down the hydrocarbon. It is probably not so much the original hydrocarbon as its hydroxylated molecule which decom- poses in flames ; the sudden increase in the internal energy of the hydrocarbon molecule, consequent upon its initial association with oxygen, would render the resulting hydroxylated molecule extremely unstable, and, in default of its immediate further oxidation, it would speedily decompose. The explosive combustion of ethylene may, therefore, be represented by the following scheme — 0 H..C : CH., HO . CH : CH., - /CoH/+H„0^ \ 20 + H., + H,0 f HO . CH CH . OH 2CHoO = 2C0 + 2H., In a sufficient supply of oxygen, the transition from the original hydrocarbon to the dihydroxy state is probably so rapid that no breaking down of the ethylenic structure occurs in passing through the initial momhydroxy stage. Indeed^ it is conceivable that under 84 Professor William Arthur Bonp [FeT). 28, the extreme conditions of detonation the passage from 0 to 2 maybe effected in a single molecular impact. The dihydroxy derivative would at once break down into carbon monoxide and hydrogen, via formaldehyde. But when the oxygen supply is reduced below the equimolecular proportion, it is evident that the initial monohydroxy derivative can- not all be oxidised to the dihydroxy stage ; some of it would, there- fore decompose, partly into acetylene and steam, and partly also into carbon, hydrogen, and steam, together with some methane. In a similar manner, the combustion of ethane would involve the rapid passage through ethyl alcohol to acetaldehyde and steam, with subsequent decomposition of the aldehyde into carbon, hydrogen, methane, and carbonic oxide, with the proviso that a reduction of the oxygen supply below the equimolecular proportion, would bring about in some measure the decomposition of the alcohol into ethylene and steam, etc., at stage 1. 2 CH3 . CH (0H)o OhT+^H^ I CH7rCH0'+H.,0 \G + 2H„ + CO/ But the cases of ethane and ethylene are typical of all other hydrocarbons, so that it may be said that, in general, the mechanism of explosive combustion involves, (1) the initial formation and subse- quent decomposition of hydroxylated (or " oxygenated ") molecules ; (2) in a sufficient supply of oxygen, the independent oxidation of the decomposition products ; (3) in an insufficient oxygen supply, the subsequent breaking down of unsaturated hydrocarbons, interactions between carbon and steam, or between oxides of carbon, hydrogen, and steam, the final system depending on the amount of available oxygen, the temperature of the flame, and the rate of cooling. Experiment V. — The influence of different rates of cooling of the flame on the final system may be illustrated by firing an equimole- cular mixture of ethane and oxygen in two glass vessels, having approximately the same volume, but widely different surface areas. For this purpose I have selected (1) a tube about 1 metre long and 2 cm. internal diameter, and (2) a globe of 8*5 cm. internal diameter. Both these vessels have the same volume (about 300 c.c), but the surface area of the tube is very nearly 3 times that of the globe. It is therefore to be expected that, in consequence of tlie more rapid cooling of the flame, there will be a greater accumulation of the primary combustion products in the case of the tube experi- ment. On comparing the results of the two explosions, it is at once evident that more water and less carbon have been produced in the case of the tube ; moreover, the pressure ratio j^a/j^j, is 1*45 as com- 1908] on Explosive Gomhustion. 85 pared with about 1 ' 75 in the globe experiment, and an examination of the products would show that the lower ratio is accounted for by the much greater survival of acetylene, ethylene, and aldehydic pro- ducts in the tube experiment. These facts, which are set forth in the following table, are in complete harmony Avitli the hydroxylation theory. Table III. — Inflammation of an Equimolecular Mixture of Ethane and Oxygen. A. In Long Tube. B. In Large Globe. V2/P1 701 mm. 1018 „ 1-45 685 mm. 1187 „ 1-73 all a,. C0„ GO" Ha 4-20 34-80 5-OOi r, rK 2-65} '-^^ 8-85 44-50 3-40 36-10 1 0-15 7-25 53-05 Original mixture . Gaseous products . C 694 643 H 1041 738 0 354 220 0 678 558 H 1017 805 0 346 255 Difierence . 51 303 134 120 212 91 % Difierence 7-6 29 37-8 18 20 27-5 Experiment VI. — The experiments I have so far shown you, refer more particularly to the initial period of " inflammation " in explosive combustion, that is to say, to the conditions ordinarily prevailing in hydrocarbon flames. The question may be asked whether or not the views I have advanced are applical)le to the extreme conditions of " detonation " or of explosions under high initial pressures. The question may be put in the following form : Is there any experimental evidence of discontinuity between " inflam- mation^' and 'Uieto nation'' as regards the nature and sequence of the chemical changes involved ? or. Is the hydrocarbon attacked by oxygen in an entirely different way in explosive combustion at high pressures, or in the explosion wave, to what it is in ordinary flames ? This question can, I think, best be answered by a consideration of the behaviour of an equimolecular mixture of ethane and oxygen under these extreme conditions. It is difficult to set up detonation in this mixture ; the gases 86 Professor William Arthur Bom [Feb. 28, must be tired at an initial pressure of about 1| atmosphere in a stout leaden coil of about 1 inch internal diameter. Even then, it is necessary to start the explosion wave in a special firing piece containing electrolytic gas under pressure. I therefore regret that, owing to the special arrangements requisite for success, it is not possible to make the experiment to-night. I will, however, give you the results obtained on detonating the mixture in my laboratory, but before doing so, I will carry out an experiment on the explosion of the gases at an initial pressure of 15 atmospheres. The cylindrical steel bomb on the table is part of an apparatus recently installed in the Fuel and Metallurgical Laboratories of the University of Leeds for investigations on gaseous explosions under high pressures. The bomb is about a foot long with an external diameter of 4 inches, and the central cylindrical explosion chamber is 8 inches long by 1 inch in diameter. It has been tested by hydraulic pressure up to 2000 atmospheres, and has been repeatedly used for experiments with mixtures of hydrocarbons and oxygen at initial pressures of as much as 40 atmospheres. The bomb is now connected, through a valve at the top, with a standard Bourdon gauge, and contains an equimolecular mixture of ethane and oxygen at a pressure of 15*8 atmospheres. The valve will now be closed, and the mixture fired by means of an electrical arrangement in the special firing piece. All that is audible of the explosion is a sharp click, and on open- ing the valve connecting with the gauge again, the final pressure of the cold products of explosion is recorded. After applying the necessary correction for the '' dead space " in the gauge connections, but the final "corrected" pressure is as nearly as possible 30*8 atmospheres, corresponding to a ratio p^lVi = 1'93. I would now direct your attention to the tabulated results of a similar bomb experiment carried out a few weeks ago at Leeds at an initial pressure of 25 atmospheres, and also at the same time to those of another experiment in which the gases were detonated in a lead coil at an initial pressure of 1| atmosphere. In both these experiments carbon was deposited, and it is evident also, that steam was formed. The ratio ^a/Pi? ^^s ^^ nearly as pos- sible 2*0 instead of the 2*5 required by the theory of the preferential combustion of carbon. Moreover, a notable feature of the results is the presence of as much as 7 per cent, of methane among the products of the experiment at 25 atmospheres ; the fact that so much methane survived when all other hydrocarbons were battered to pieces during the explosion (no traces of either acetylene or ethylene being found in the products) is a remarkable testimony to its relatively great stability at the highest temperatures of explosion flames. There is no evidence in these experiments, of any real discontinuity between the chemical phenomena of ordinary " infiammatimi " and those of " deto- nationy The higher temperatures, and more violent conditions in 1908] on Explosive Combustion. S7 Table IV. — Results of Explosion of an Equimoleculae Mixtuee Ethane and Oxygen undee High Peessuees. A. E Detonation in Lead Coil. EspU jsion in Steel Bomb. Pi 1180 mm. 25-2 atms. V2 2240 „ 51-7 P2/P1 1-90 2-05 oo„ 1-80 2-6 r§.- CO 39-10 37-2 C2H2 0-50| 1 ^^ } nil OH, 7-70 7-0 ^ H. 50-00 52-2 G H 0 G H 0 Original mixture . . . 1186 1779 587 mm. 25-35 38-0 12 -55 atms. Gaseous products . 1151 1507 488 „ 24-50 34-6 11-05 „ Difierence . 35 272 99 „ 0-85 3-4 1-5 % Difference . . 3 15 17 3-4 9 12-0 ^^ detonation^'' are responsible for the more complete breaking down of unsaturated hydrocarbons, and a greater " unburning " of steam by carbon, but there is probably no difference as regards the mode in which the hydrocarbon is attacked by the oxygen in the two cases. I therefore believe, that, so far as our pi-esent knowledge goes, the views I have put forward, afford a simple and consistent interpreta- tion of hydrocarbon combustion, whether it be the slow flameless kind discovered by Davy, or the more complex phenomena of ordinary flames so wonderfully expounded by him, or linally the extreme con- ditions characteristic of the explosion wave.* * I desire to acknowledge the devoted help rendered to me in the conduct of these investigations by the following research students of the Manchester University : Messrs. R. V. Wheeler, W. E, Stockings, G. W. Andrew, Julien Drugman, and H, Henstock. [W. A. B.] General Monthly Meeting. [March 2, GENERAL MONTHLY MEETINCx, Monday, March 2, 1908. Sir James Ceichton-Browne, M.D. LL.D. F.R.S., Treasurer and Vice-President, in the Chair. Colonel David Bruce, C.B. D.Sc. F.R.S. Miss Dorothy Deane Butcher, Miss Louisa Dawson Cleghorn, Mrs. Margaret Hannay Clerk, Vivian Gordon, Esq. James Hunter Gray, Esq. Miss Catherine Hassard, William Preece, Esq. Caleb Williams Saleeby, Esq., M.D. F.R.S.E. Hans Saner, Esq., M.D. Mrs. Virginia Schilizzi, Miss Helena Stefanovich Schilizzi, Harold Albert Wilson, Esq., M.A. D.Sc. F.R.S. Charles Edward Wurtzburg, Esq. were elected Members of the Royal Institution. The Special Thanks of the Members were returned to Sir Andrew Noble, Bart., K.C.B., for his Donation of £100 to the Fund for the Promotion of Experimental Research at Low Temperatures, and to Mr. Shelford Bidwell for his Donation of £5 5s. to the General Fund. Also to Mr. W. Hugh Spottiswoode for his present of a Manu- script Record containing the early Laboratory Experiments of the late John Peter Gassiot, F.R.S., who was formerly a Manager and Benefactor of the Institution. Also to Mrs. Kemp for her gift of a portrait of the late Sir Benjamin Baker, K.C.B. F.R.S., a Vice-President of the Royal Institution. The Presents received since the last Meeting were laid on the table, and the thanks of the Members returned for the same, viz. : — PROM Secretary of State for India — Agricultural Journal of India, Vol. II. Part 4. 8vo. 1907. Linguistic Survey of India^ Vol. IX. Part 3. 4to. 1907. Trigonometrical Survey of India, Vol. XVIII. 4to. 1906. Geological Survey : Records, Vol. XXXII. Part 2. 8vo. 1907. 1908.] General Monthly Meeting. 89 British Museum Trustees — Guide to the Great Game Animals. 8vo. 1907. Guide to the Fossil Invertebrate Animals. 8vo. 1907. List of British Seed Plants and Ferns. 8vo. 1907. Special Guides, No. 3, Memorials of Linnseus. Svo. 1907. Accademia clei Lincei, Bcale, Roma — Classe di Scienze Fisiche, Mathematiche e Natural!. Atti, Serie Quinta : Rendiconti. Vol. XVII. 1^ Semestre, Fasc. 2. Svo. 1908. Allegheny Observatory — Publications, Vol. I. No. 2. 4to. 1907. American Geographical Society — Bulletin, Vol. XL. No. 1. 8vo. 1908. American Philosojjhical Society — Transactions, Vol. XXI. Part 5. 4to. 1907. Astronomical Society, Royal — Monthly Notices, Vol. LXVIII. No. 3. 8vo. 1908. Automobile Club — Journal for February, 1908. Boston Public Library — Monthly Bulletin for February, 1908. 8vo. British Architects, Royal Institute of — Journal, Third Series, Vol. XV. Nos. 7-8. 4to. 1908. British Astronomical Association — Journal, Vol. XVIII. No. 4. 8vo. 1908. Brooklyn Institute of Arts and Sciences — Science Bulletin, Vol. I. No. 2. 8vo. 1907. Canada, Department of Agriculture — Farm Weeds of Canada. By G. H. Clark and J. Fletcher. lUust. N. Criddle. 4to. 1900. Canada, Geological 5 ?«xy'?/— Reports, Nos. 958, 968, 1017. 8vo. 1906-8. Carnegie Foundation — Second Annual Report, 1907. 8vo. Chemical Industry, Society o/— Journal, Vol. XXVII. Nos. 2-3. 8vo. 1908. Chemical ,Socie^?/— Proceedings, Vol. XXIV. Nos. 386, 337. 8vo. 1908. Journal for February, 1908. 8vo. Civil Engineers, Institution of — Proceedings, Vol. CLXX. 8vo. 1907. Editors — Agricultural Economist for March, 1908. 4to. American Journal of Science for February, 1908. 8vo. Analyst for February, 1908. 8vo. Astrophysical Journal for January, 1908. 8vo. Athenaeum for February, 1908. 4to. Author for February, 1908. 8vo. British Homoeopathic Review for February, 1908. 8vo. Chemical News for February, 1908. 4to. Chemist and Druggist for February, 1908. 8vo. Dioptric Review for February, 1908. 8vo. Dyer and Calico Printer for February, 1908. 4to. Electrical Contractor for February, 1908. 8vo. Electrical Engineer for February, 1908. 4to. Electrical Engineering for February, 1908. 4to. Electrical Review for February, 1908. 4to. Electrical Times for February, 1908. 4to. Electricity for February, 1908. 8vo. Engineer for February, 1908. fol. Engineering for February, 1908. fol. Horological Journal for February, 1908. 8vo. Illuminating Engineer for February, 1908. 8vo. Journal of the British Dental Association for February, 1908. 8vo. Journal of State Medicine for February, 1908. 8vo. Law Journal for February, 1908. 4to. London University Gazette for February, 1908. 4to. Model Engineer for February, 1908. 8vo. Motor Car Journal for February, 1908. 8vo. Musical Times for February, 1908. 8vo. Nature for February, 1908. 4to. New Church Magazine for March, 1908. 8vo. Page's Weekly for February, 1908. 8vo. Photographic News for February, 1908. 8vo. 90 Gen&ral Monthly Meeting. [March 2, Editors — continued. Science Abstracts for January, 1908. 8vo. World of Travel for February, 1908, 8vo. Zoophilist for Jan.-Feb., 1908. 8vo. Franklin Institute— J omnal, Vol. CLXV. No. 2. 8vo. 1908. Geographical Society, Boy al— J ouvn&\, Vol. XXXI. No. 2. 8vo. 1908. Geological Society — Abstracts of Proceedings, No. 855. 8vo. 1908. Gottingen, Royal Society of Sciejices— Nachrichten, 1907, Mat.-Phys. Klasse, Heft 5 ; Geschaftliche Mitteilungen, Heft 2. 8vo. 1907. Harle^n, Societe Hollandaise des Sciences — Archives Neerlandaises, Ser. II. Tome XIII. Livr. 1-2. 8vo. 1908. Leeds Philosophical Society — Eighty-sixth and Eighty-seventh Annual Reports, 1905-7. 8vo. 1905-7. Levy, Bev. S., M.A. {the Author) —Anglo-Jevfish Historiography. 8vo. 1908. Literature, Royal Society o/— Transactions, Vol. XXVIII. Part 1. 8vo. 1908. London County Cotmcil — Gazette for February, 1908 4to. Manchester Literary and Philosophical Society — Proceedings, Vo.. LII. Part 1. 8vo. 1908. Meteorological Office — Observations at Stations of the Second Order, 1903. 4to. 1908. Meteorological Society, Royal — Joiu-nal, Vol. XXXIII. No. 145. 8vo. 1908. Record, Vol. XXVII. No. 105. 8vo. 1908. Mexico — Anales de la Secretaria de Comunicaciones, No. 17. 8vo. 1907. Microscopical Society, i?oi/aZ— Journal, 1908, Part I. 8vo. Mitchell, Messrs. C. & Co. {the Publishers) — Newspaper Press Directory, 1908. 8vo. Monaco, Uhistitut Oceanographique — Bulletin, Nos. 109-110. 8vo. 1908. Moscoiv University — Le Physiologiste Russe, Vol. V. Nos. 81-85. 8vo. 1907. National Church League — Gazette for February, 1908. 8vo. Navy League — Journal for February, 1908. 8vo. New York, Society for Experimental Biology — Proceedings, Vol. V. No. 2. 8vo. 1908. New Zealand, Agent-General — Official Year Book, 1907. 8vo. North of England Institute of Mining .E?i^inecrs— Transactions, Vol. LVIII. Part 2. 8vo. 1908. Paris, Societe d' Encouragement pour VIndustrie Nationale — Bulletin for January, 1908. 4to. Paris, Sociite Francaise de Physique — Bulletin, 1907, Fasc. 3. 8vo. Pennsylvania, University o/— Publications, Astronomical Series, Vol. III. Part 3. 4to. 1907. Pharmaceutical Society of Great Britain — Journal for February, 1908. 8vo. Photographic Society, Royal— JoumdA, Vol. XLVIII. No. 2. 8vo. 1908. Physical Society — Proceedings, Vol. XX. Part 6. 8vo. 1907. Radcliffe Library— C&taAogue of Books, 1907. 4to. 1908. Royal Engineers Institute— J omnal, Vol. VII. No. 3. 8vo. 1908. Royal Society of Arts — Journal for February, 1908. 8vo. Royal Irisli Academy— Fioceedings, Vol. XXVII. Section C, Nos. 1-3. 8vo. 1908. Royal Society of London — Philosophical Transactions, A, Vol. CCVII. No. 425 ; B, Vol. CXCIX. No. 259. 4to. 1908. Proceedings, Vol. LXXX. A, No. 536 ; B, No. 536. 8vo. 1908. St. Petersburg, Chambre des Poids et Mesures—Memoues, No. 8. 8vo. 1907. St. Petersburg, Imperial Academy of Sciencgs— Bulletin, 1908, Nos. 2-3. 8vo. Sanitary Institute, i?ot/aZ— Journal, Vol. XXIX. No. 1. 8vo. 1908. Selborne Society — Nature Notes for February, 1908. 8vo. S^nith, B. Leigh, Esq., M.R.I. — The Scottish Geographical Magazine, Vol. XXIV. No. 2. 8vo. 1908. Smithsonian Ins^if^^fio?i— Miscellaneous Collections: Quarterly Issue, Vol. IV. Part 3. 8vo. 1907. 1908.] General Monthly Meetmg. 91 Smithsonian Institution — contiriued. Contributions to Knowledge, Vol. XXXIV. No. 1692 ; Vol. XXXV. No. 1723. 4to. 1907. Annual Eeport on U.S. National Museum, 1907. 8vo. 1907. Societa degli Spettroscopisti Italiani—Memovie, Vol. XXXVIII. Disp. 1. 4to. 1908. Toronto University— Studies : Chemical, Nos. 66-72; Physical, Nos. 20-21 ; Biological, No. 6 ; Psychological, Vol. II. No. 4. Svo. 1907. Transvaal Department of Agriculture — Journal, Vol. VI. January, 1908. Svo. United Service Institution, Boyal — Journal for February, 1908. 8vo. United States Department of Commerce and Labour — Bulletin of the Bureau of Standards, Vol. IV. No. 2. 8vo. 1908. United States Patent Office— Gazette, Vol. CXXXII. Nos. 4-7. 4to. 1908. Verein zur Beforderung des Geivej-bfleisses—Y evh&ndlungen, 1908, Heft 2. 4to. Wellco7ne Chemical Research Laboratories — Publications, Nos. 70-6. 8vo. 1907. 92 Professor A. E. H. Love [March 6, WEEKLY EVENING MEETING, Friday, March 6, 1908. Donald W. C. Hood, Esq., C.V.O. M.D. F.R.C.P., Vice-President, in the Chair. Professor A. E. H. Love, M.A. D.Sc. F.R.S. The Figure and Constitution of the Earth. The subject of this lecture is the figure and constitution of the Earth. I have chosen this title in order to draw attention to the theory which asserts that the shape of the earth is an outward and visible sign of its inward structure. We know that the shape of the earth is a very good sphere. It would be difficult to make so exact a sphere. If we could make a model 25 feet in diameter the inequality of the surface would have to amount to no more than one inch. That is to say, the longest diameter of the model would have to exceed the shortest by one inch. Tlie inequalities of the surface, trifling as they are in comparison with the dimensions of the earth, are very important to mankind, and we try to understand how they came to be what they are. The greatest interest attaches to those inequalities which are con- cerned in the distribution of continent and ocean ; but, before passing to the consideration of these, I must advert to that inequality which, although it is the greatest of all, has hardly any influence upon this distribution. A rotating body of planetary dimensions cannot be a perfect sphere ; but, owing to the rotation, the equatorial parts must be driven outwards from the axis, and the formation of the equatorial protuberance must be compensated by the flattening of the parts near the axis. Newton determined the shape as an oUate spheroid, the figure formed by the revolution of an ellipse about its shortest diameter. The relative situation of an oblate spheroid of small ellipticity and a sphere of equal volume may be illustrated by an ellipse and a concentric circle, adjusted so that the diameter of the circle exceeds the shortest diameter of the ellipse by twice as much as the longest diameter of the ellipse exceeds the diameter of the circle. [The figure was sliown on a lantern slide.] In the case of the earth, the elevation all round the equator is about 4^ miles, the depression at either pole about 8f miles. The result that there is equatorial protuberance as well as polar flattening, and that the one is half as great as the other, is as much a part of the theory, and is as well 190S] on the Figure, and Constitution of the Earth. 08 verified by observation, as the result that there is polar flattening. The inequality is named eUiiMcity of the meridians. The existence of this inequality has often been supposed to prove that the interior of the earth is fluid, or that, if not fluid now, it was so once. The actual amount of the inequality, as specified by the excess of the equatorial diameters above the polar diameter, is about 26 miles. Newton computed it on the hypothesis that the earth is composed of homogeneous incompressible fiuid, and found that with that constitution the amount of the inequality would be about 38 miles. Many years ago, Lord Kelvin pointed out that the earth would have elliptic meridians if the matter of which it is composed were as rigid as steel, and he showed that, if the substance were homo- geneous and incompressible, and had this degree of rigidity, the amount of the inequality would be about 11 miles. [The numbers were thrown on the screen.] As the substance is neither homo- geneous nor incompressible, these results do not decide the question of internal fluidity. 8o far it has not been possible to take account theoretically of the compressibiUty or of the heterogeneity, but it is probable that both would increase the computed ellipticity. If this could be proved, the actual amount of the inequality would show that the interior of the earth has a high degree of rigidity. Rigidity of a substance may be defined qualitatively as capacity to stand in a shape, or in a state, which requires the existence, within the substance, of difi^erent pressures in different directions. There is a corresponding quantitative definition in terms of the amount of force required to produce a given change of shape. Substance. Rigidity. Water Sandstone .... Glass Granite Copper Steel Earth as a whole . '. 0 0-15 0-29 0-38 0-55 1-0 1-G6 This table [thrown on the screen] shows the rigidities of some sub- stances, steel being regarded as a standard. The last entry in the table is the average rigidity of the materials of the earth, as deter- mined by the rate of transmission of earthquake shocks to great dis- tances. The conclusion that the earth is a very rigid body was reached by Lord Kelvin, by investigations on the tides, and by Sir George Darwin, by investigations concerning the stress produced in the interior by the weight of continents and mountains, and it has been confirmed in a very striking way by recent investigations in 94 Professor A. E. H. Love [March 6, seismology. The very great rigidity of the matter within the earth is doubtless due to the very great pressure to which this matter is subjected. The detection of the ellipticity of the meridians requires rather refined means of observation, because it is very nearly the same for the general mass of the earth as it is for the waters of the ocean; but there are other inequalities of the surface, manifested by the elevation of the continents and the depression of the ocean basins, which are much more obvious. For information in regard to them we have re- course to maps, to observations of the heights of places above sea level, and to soundings. [A map of the world on Mercator's projec- tion was shown and reasons for using other projections indicated.] In order to reduce to a mathematical theory the inequalities in ques- tion, we must begin by getting an arithmetical acquaintance with the facts. Our first question must be as to the sizes of the inequalities. The height of the highest mountain is between five and six miles, the greatest depth yet sounded anywhere in the ocean is less than six miles. Thus the amounts of these inequalities are less than those answering to ellipticity of the meridians. But the corresponding gradients are steeper. On very many coasts the gradient from the shore to very deep water (2000 fathoms) is about 1 in 150. The ellipticity of the meridians gives a maximum gradient, estimated by rate of descent towards the centre, of 1 in 800. Our next question must be as to the sizes of the depressed and elevated portions of the surface. A map on an equal area projection shows tliat much the greater portion of the surface is covered by water. [Maps of two separate hemispheres, each true in area, were shown by slides.] The great expanse of the ocean hides from us many of those features of the somewhat irregular surface of the earth which are partially mani- fested in the continental elevations and oceanic depressions. This surface projects beyond the spheroid appropriate to the rotation in some places, in others it runs inside it. AVhere it projects we say there is elevation ; where it runs inside we say there is depression. Depression does not imply concavity. The surface is almost every- where convex, thougli it is flattpr in some parts than in others. The oceans rest on the depressions and extend upwards over parts of the elevations, and it is the shape of the parts that are covered by water, much more than the shape of the mountainous continental surface, that really determines the shape of the earth. Our next question must be as to the amounts of the area of the surface of the earth which are at various heights above or depths below the level of the sea. The most important information is summarised in this table (p. 95). [Thrown on screen.] Since only about 2 per cent, of the total surface is more than 6000 feet above the level of the sea we need not pay much attention to mountains, but we must pay great attention to the depth of the sea in different parts. It is remarkable that although the depth exceeds 1908] on the Figure and Constitution of the Earth. 05 2000 fathoms over considerably more than half of the oceanic area, yet the areas over which the depth exceeds 3000 fathoms amount in the aggregate to only about 3 per cent, of the total surface, and these areas, 40 or more in number, are scattered irregularly over the globe. Total area j 100 More than 6000 feet above sea level ... 2 Above sea level 28 Below sea level 72 More than 6,000 feet below sea level . . 57 12,000 „ „ ... 43 18,000 ,, 3 In seeking to appreciate the general features of the shape of the earth we may disregard these " deeps," just as we disregard mountains. Except in certain deeps, the surface of the earth beneath the sea is everywhere convex. The most important data for determining the shape of the earth are the coast line and the contour lines at 1000 and 2000 fathoms depth. If on a map of the world we draw the contour line at 1000 fathoms depth, we find that the continents are not only widened on all sides, but that, with the exception of the Antarctic continent, they form a single continuous region of elevation. At this depth the Antarctic regions become a continuous region of elevation nearly as far north as the 60th parallel all round. The xerotic Ocean is reduced to two enclosed patches of deep water, one to the north of G-reat Britain, the other to the north of Russia and Siberia. South America does not taper to the south, but spreads out to the south-east. The ridge joining Xorthand South America is widened out across the West Indies, and the Caribbean Sea and Gulf of Mexico are reduced to a few enclosed patches of deep water. North America is joined on the northern side to Europe and to Asia. The Mediterranean and adjacent seas are represented by a few patches of deep water. Asia is joined to Australia by way of Borneo and New Guinea, and Australia extends southwards over Tasmania and south-eastwards over New Zealand. If we proceed to draw the contour line at 2000 fathoms depth we find that the continents are further widened, and such seas as the Arctic Ocean, the Caribbean and the Mediterranean, almost entirely disappear ; but the most important fact is that at this depth the Antarctic continent is not detached, but is united both to South America and to Australia. [Maps of the world in hemisplieres with the contour lines at 1000 fathoms and 2000 fathoms depth were shown by slides.] Such maps teach us that the continents are to be regarded as one continuous region of elevation. If we neglect small isolated areas of depression and elevation, we can draw between the 1000-fathoms line and the 2000-fathoms line a curve which divides 9fi Professor A. E. H. Love [March 6, the surface of the globe into two regions of equal area : the conti- nental region and the oceanic region. [A slide was shown of a map of the world, true in area, spread out on a rectangle, with the curve drawn.] The continental region is continuous and contains all the continents. The oceanic region consists of two separate portions : the basin of the Pacific Ocean, and the basin of the Atlantic and Indian Oceans. This curve may be called the lioundary of tlie continental region. It is a cardinal feature in any geometrical description of the earth's surface. The gravitational theory of the figure of the earth asserts that the cause of the inequalities expressed by continental elevation and oceanic depression is deep-seated. It is sometimes abbreviated into the formula " heavier matter under the oceans." The average density of surface rocks is 2*8 times the density of water. The average density of the earth as a whole is 5 • 5 times the density of water. [The numbers were thrown on the screen.] The formula does not mean that the surface rock of density 2 • 8 has been stripped off the parts where the oceans are, but it means that the denser matter lies rather nearer the surface under the oceans, rather deeper down under the continents. The fact that the figure of the earth is a very good sphere shows that the inequalities in the arrangement of the denser and rarer matter are small, or that the distribution of mass is very nearly symmetrical about a centre. If it were exactly sym- metrical, specimens of the material brought from different parts of any spherical surface described around the centre would all have the same density. The spherical surface would be described as a surface of equal density. The notion of surfaces of equal density is important in the description of unsymmetrical arrangements as well as sym- metrical ones. If on any section of the earth, cut right through the middle, tlie points at which a particular density exists could be joined up, a curve would be formed. The different curves answering to different densities would lie one inside another, like isobars on a weather chart. The density at any point inside a particular curve would be greater than the density at any point on the curve, the density at any point outside it would be less. To join up all the points where the same density is found in the cubic space within the earth would require a surface, just as to join up points in a plane section requires a curve. The surface is a surface of equal density. The series of surfaces of equal density within the earth resemble the coats of an onion, but with the differences that arise from the distinc- tion between a geometrical surface and a thin sheet of matter. The thing we know about these surfaces is that they are nearly spherical and nearly concentric. The surface of water resting on the earth must be everywhere at right angles to the direction of gravity. If the surfaces of equal density were concentric spheres, the surface of the ocean would be a sphere concentric with them, and the whole earth would be covered by water. If the surfaces of equal density 1908] on the Figure and Constitution of the Earth. 97 are only nearly spherical, or nearly concentric, the surface of the ocean must have inequalities of the nature of a heaping up of the waters over areas of oceanic dimensions. The inequalities of the sur- faces of equal density determine those of the surface of the ocean, and have a decided influence upon those of the surface of the earth. In the simplest imaginable case the surfaces of equal density Avould be accurately spherical but not accurately concentric, crowded together on one side, spaced out on the opposite side. This arrangement may be illustrated by a diagram of a system of circles one inside another, with their centres in a straight line. [Shown by a slide.] The surface of water resting on a body with such a distribution of mass would be a sphere with its centre at, or very near to, the centre of gravity of the body. [Shown by a slide.] It would cut the surface of the body so as to yield a land hemisphere and a water hemisphere. A map of one hemisphere of the earth, with its centre about the middle of France contains all the continents except the southern part of South America, the Antarctic continent, Australia ; the other hemisphere is nearly covered by water. [Stereographic maps of these two hemi- spheres were shown by slides.] It is certain that the distribution of mass within the earth has an inequality of the type considered — the type characterised by eccentric position of the centre of gravity. This is the simplest kind of inequality which a nearly spherical and symmetrical body can have. There is a mathematical theory by which we can connect the inequalities of the surface with the distribution of density. The standard patterns of inequalities are called spherical harmonics. The kind of inequality which we have been considering is specified by a spherical harmonic of the^rs^ degree. It is as if the earth were drawn up out of the sea towards one side, the effect being produced by gravity acting unsymmetrically, and drawing the sea to one side of the earth. A\\ inequ^jlity of density specified by a spherical harmonic of the first degree, means that the surfaces of equal density are crowded to one side without change of shape. Inequalities of density specified by spherical harmonics of higher degrees, mean that the surfaces of equal density are distorted according to one or more of the standard patterns. If this were the case in the earth, the surface of the earth, and the surface of the sea, would be distorted according to the same pattern, but the amounts of distortion would be different for the two surfaces. This was exemplified in the case of the body with non- concentric spherical surfaces of equal density, where the distortion is replaced by a shifting to one side, and the surface of the body was shifted to one side, the surface of the ocean to the other side. The defects of the arrangement of land and water on the earth, as a land hemisphere and a water hemisphere, enable us to detect other in- equalities of the surface specified by spherical harmonics of higher degrees. The defects are best shown by means of a map of the two hemispheres drawn one on the top of the other. Thus, we may draw YoL, XIX, (No. 102) ^ II 98 Professor A. E. H. Love [March 6, a map of one hemisphere with its centre in the middle of France, and, over this map, a map of the other hemisphere turned upside doiun, so that any point of the second map coincides with its antipodes in the first. [Shown by a sHde in which the outhnes of the two maps were coloured differently.] The combined map shows oceans nearly every- wdiere at the antipodes of continents. But it shows Borneo and some adjacent islands at the antipodes of parts of South America ; it shows the southern extremity of South America antipodal to a part of Asia, and it shows the Antarctic region of elevation at the anti- podes of the Arctic one. Thus certain parts of the continental region of elevation are antipodal to certain others. Now this ar- rangement assures us that the surface is somewhat ellipsoidal, or that it has an inequality specified by a spherical harmonic of the second degree. You know that an ellipsoid is a surface specified by means of three principal directions, which I may refer to as right and left, back and front, up and down. In one of these, say the right and left direction, the ellipsoid projects beyond a sphere of the same volume ; in the second, back and front, it runs inside the sphere ; in the third, up and down, it may project beyond or run inside according to circumstances. The right and left direction obviously corresponds with the diameter from Borneo to the north-east corner of Brazil ; the up and down with the earth's axis. The main feature of a nearly spherical ellipsoid is the existence of two great areas of depression, antipodal to each other, corresponding with the parts where the eUipsoid runs inside the sphere. I make out that the best fit is obtained by fixing one of these so as to coincide nearly with the basin of the Pacific Ocean. The antipodal depression must then contain Africa, the Mediterranean, some neighbouring countries, and parts of the Atlantic and Indian Oceans. It appears that the ellipsoidal inequality, though it certainly exists, is less important than the inequality of the first degree. [Slides were shown of maps of two hemispheres with the two areas of depression marked.] Now we go back to our double map and observe that Australia is antipodal to the central part of the Atlantic Ocean. [Double map with centre of one hemisphere in Australia shown by slide.] Near the middle of the w^ater hemisphere we have a continent surrounded by ocean. Near the middle of the land hemisphere we have an ocean almost surrounded by continents. This arrangement cannot be expressed by the harmonic of the first degree, or by that of the second degree, or by any combination of the two. It shows to a mathematical eye that there must be an inequality specified by a spherical harmonic of the third degree. The simplest kind of defor- mation of a sphere which can be expressed by a spherical harmonic of the third degree is shown in Fig. 1, p. 99, where the dotted circle repre- sents the sphere. [Shown by slide.] The figure has been described as pear-shaped. Beginning at the top we see the elevated stalky the depressed waist, the protuberant ring, and the flattened croivn. A 1008] on the Figure and Constitution of the Earth. 99 sphere with an inequality expressed by this harmonic would show in one hemisphere a central elevation surrounded by a zone of depres- sion, in the other a central depression surrounded by a ring of eleva- tion. [Shown by slide.] This is something like what we observed in the case of Australia in one hemisphere and the central Atlantic in the other, but it is much too symmetrical. A more general type Fig. 1. of spherical harmonics of the third degree gives us an unsymmetrical pear-shaped figure (Fig. 2) ; it is more like a natural pear than the other. [Shown by slide.] The stalk is rather to one side, the waist is higher on one side tlian the otlier, so is the protuberant ring, and the crown is askew. When it is said, as it is sometimes, that the figure of the earth is pear-shaped, it ought to be meant that the sur- face has an inequality of this type. This figure is obtained by com- bining the inequality which we examined just now with another (Fig. ;3), which represents another special type of spherical harmonics of the third degree. [Shown by slide.] Here we have, on one side, elevation above and below and a central depression ; on the other side, depression above and below, and a central elevation. A sphere with an inequality expressed by this harmonic would show in either hemisphere a circle surrounded by a ring ; half of the circle and the alternate half of the ring are elevated, the other halves are depressed. [Shown by slide.] Seen from a different point of view it would show in one hemisphere a central band of elevation bordered by H 2 100 Professor A. E. H. Love [March 6, semicircular caps of depression, in the antipodal hemisphere a central band of depression bordered by semicircular caps of elevation. [Shown by slide.] A map of one hemisphere with its centre in latitude 15° N. and longitude 80° W., shows the Arctic and xitlantic oceans as a somewhat irregular central band of depiession, with regions of eleva- tion on either side of it. [Map shown by slide.] Australia would Fig. 2. be near the middle of the antipodal band of elevation. Our unsym- metrical pear-shaped figure was obtained by one way of combining the two types of spherical harmonics of the thkd degree. Many other figures can be so obtained. The most important are these : A division of the sphere into octants alternately depressed and ele- vated, and a division of the sphere into six equal sectors alternately depressed and elevated. [The mode of generation of these figures was shown by slides.] Traces of both can be found on the earth. A map of the world spread out on a rectangle, and divided into eight equal parts by the equator and the meridians of longitude 5° E., 95° E., 175'^ W., 85° W., shows four northern octants roughly co- inciding with North America, the Northern Atlantic, Asia, the Northern Pacific, and the four corresponding southern octants roughly coincid- ing with the Southern Pacific, South America, the Indian Ocean, Australasia. [Map shown by slide.] A map of the southern hemi- sphere shows three separate continental masses, South America, Africa, Australasia, running out towards the equator, arranged with 1008] on the Figure and Gonstitution of the Earth. 101 some approach to symmetry, and on the whole widening as they go. [Map shown by slide.] From this discussion we conckide that the surface of the earth presents all the types of inequalities which can be specified by spherical harmonics of the third degree or represented by pear-shaped figures. Since each of the types gave us elevation in Australia and antipodal depression in the central Atlantic, we must Fig. 3. not entertain a prejudice in favour of Australia as a sort of stalk for a pear-shaped figure. We shall find that it is better to regard it as a part of the protuberant ring of such a figure. I will not proceed to describe the spherical harmonics of the fourth and higher degrees, because it is possible to go some way towards accounting theoretically for the existence of inequalities of the first three degrees, but not for those of higher degrees, and, if we found these to exist, we should have to infer that they are not due to gravi- tational causes, but to local tectonic accidents. We know that the actual shape, whatever it may be, can be reproduced by combining harmonics of all degrees ; but, if we find that a fair approximation to the actual shape can be obtained by taking those of the first three degrees only, we may conclude that the main features of the shape are due to gravitational causes. If the depth of the sea, or height of the land, at every point were accurately known, we could use a definite, straightforward and very laborious, mathematical process to determine the proportions in which the various harmonics must be combined in 102 Professor A. E. H. Love [March 6, order to reproduce the actual shape. As the heights and depths are not known everywhere, we use the same process in a rough kind of way, by treating all the land as at one height, the parts of the sea that are less than 1000 fathoms deep as at one depth, those that are between 1000 and 2000 fathoms deep as at a second depth, those that are more than 8000 fathoms deep as at a third depth. By this rough process we can get a suggestion as to the best kind of combination, and tlien we can modify it so as to get a better fit. The first harmonic gives us elevation over one hemispliere, depres- sion in the other. In the best fit I have found, the centre of the ele- vated hemisphere is in the Sudan, not far from Wady Haifa. The hemisphere includes practically the whole of the Arctic, Atlantic and Indian Oceans, Europe, Asia and Africa. Its boundary runs just north of Bering's Strait, cuts across North America to a point near Cape Hatteras, and cuts across South America from a point near the mouth of the Amazon to a point near the mouth of the Rio de la Plata. The depressed hemisphere includes practically the whole of the Pacific Ocean, the greater part of North and of South America, Central America and the West Indies, the Antarctic continent, Aus- tralia and New Guinea. [Maps of these hemispheres were shown by slides.] I described earlier the situation of the elevations and depres- sions yielded by the second harmonic according to the best fit that I have found. The third harmonic gives us a central region of eleva- tion of an oval shape, occupying parts of Europe, Asia and Africa, a sort of stalk of an unsyinmetrical pear-shaped figure. This is sur- rounded on all sides by a zone, in which the third harmonic gives us depression — a sort of waist for the pear. The Arctic, Atlantic, and Indian Oceans are in the waist, and so also are the southern and western extremities of Africa, northern and western Europe, and a great part of Asia. The crown of the pear is in the south-western Pacific, and the protuberant ring contains all but the most north- easterly parts of North America, all South America, except the eastern extremity of Brazil, the Antarctic continent, all Australia except the most westerly part, and New Guinea. The boundary between the waist and the protuberant ring of the pear runs near to the boundary between the elevated and depressed hemispheres of the first harmonic. [Maps illustrating the position of the stalk, waist, etc., of the pear- shaped figure were shown by slides.] Any one of the harmonics by itself gives depression in some wide tract of actual continent and elevation in some large ocean, and the same is true of any combination of two. When the three are com- bined it is found that almost every bit of actual continent is included in the region of computed elevation, and that the boundary of this region runs everywhere near to the actual boundary of the continental region. The computed elevation is found to exceed 10 per cent, of its maximum value in three regions, which coincide roughly with (i) Europe, Asia and Africa, (ii) North and South America, (iii) Parts of 1908] on the Figure and Constitution of the Earth. 103 Australia and the Antarctic continent. The defects of the computed map admit of an interpretation connecting them with geological events. The conclusion appears to be warranted that the main features of the shape of the earth can be regarded as due to the causes which would give rise to inequalities expressed by spherical harmonics of the first, second, and third degrees. [Statement illus- trated by four maps shown as slides.] I proceed to explain how the three inequalities are accounted for, and I take first the harmonic of the second degree, characterised by ellipsoidal figure and antipodal continents. [A table showing the characters of the harmonics was thrown on the screen]. The ellip- soidal figure means that there is ellipticity of the equator as well as ellipticity of the meridians. The ellipticity of the meridians is due to the rotation ; and the fact that both the Arctic and the Antarctic regions are parts of the continental region, shows that the ellipticity is rather greater for the mobile waters of the ocean than it is for the very rigid earth, as we should expect. The ellipticity of the equator is more difficult to account for. It has been suggested that it may be a survival from the state of the earth at the time when the moon had but recently broken away. If the inequality of the first degree, characterised by the eccentric position of the centre of gravity, could be accounted for, it would be easy to account for the inequality of the third degree, answering to the pear-shaped figure, by the interaction of the causes which give rise to harmonics of the first and second degrees. A rotating body with its centre of gravity at a distance from its centre of figure would have its surface deformed in an unsym- metrical way. The denser parts would recede from the axis more than the rarer parts, and the surface would get an inequality specified by a spherical harmonic of the third degree, or it would become pear- shaped. It remains to account for the eccentric position of the centre of gravity. The only dynamical theory which has been put forward to account for this is the theory of gravitational instability. Accord- ing to this theory the earth was once, when it was less compact than it is now, what may be called too heavy for its strength. If this were the case it would sway to one side, just as a plank, set up on end, and held fast at the bottom, may be too long to stand straight up, and then it bends over to one side. It has been shown to be probable that this condition of things would arise if a certain fraction, here denoted by p/e, approaches a certain critical value. The heaviness of the planet is specified appropriately by the pressure that would be exerted at its centre by the superincumbent material if the density were the same all through. This pressure is denoted by p. In the case of the earth, jt? is about one and three quarter millions of atmospheres. The appropriate measure of the strength is the elastic resistance called into play when waves of compression travel through the substance. This elastic resistance is denoted by e. [Definitions of p and e were thrown on the screen.] If the substance were granite, in the same condition 104 Professor A. E. H. Love [March 6, as we have it at the earth's surface, e would be about five hundred thousand atmospheres. Owing to the great pressures in the interior, the strength of the materials of the earth is on the average much greater than the strength of granite at the surface. The critical value of the fraction ^?/e is about ;V5. The value for the earth in its present state is about 0'81, which is far removed from the critical value. The value for the earth if its strength all through were that of granite is about ;^-5. If it were bigger and less compact, so that its average density was :> ' o instead of 5 • 5, and its strength all through were that of granite, the value would be about 1'75-. but, if the strength were that of sandstone, it would be about 3 "2. It seems quite probable that if the earth was once less compact, and conse- quently less strong, than it is now, its condition might have been critical, and that the centre of gravity might then have taken up an eccentric position. It is natural to examine other planets from the same point of view. If Mars with his actual density had a strength all through equal to that of granite, the value of p/e for him would be very small (0*03). This result suggests that any elevations and depressions which may exist on the surface of Mars are not due to eccentric position of the centre of gravity. [The numbers were thrown on the screen.] We conclude that the eccentric position of the earth's centre of gravity, like the ellipticity of the equator, may be a survival from a past state in which this inequality was greater than it is now. The pear-shaped figure has been traced to the interaction of two sorts of causes : the eccentric position of the centre of gravity and the causes which give rise to the ellipsoidal figure, among them the rotation. The inequality specified by harmonics of the third degree must there- fore have been at one time less prominent than it is now, in compari- son with the inequalities specified by harmonics of the first and second degrees. In attempting to trace the general effects of this change in the relative prominence of the various inequalities, we must observe in the first place that the ellipticity of the meridians, which is one of the characters of the harmonic of the second degree, is subject to fluctuations owing to the diminishing speed of the earth's rotation. As the speed of the rotation diminishes the equatorial protuberance of the surface of the ocean diminishes, and so does the equatorial protuberance of the surface of the earth. The equatorial protuber- ance is greater for the ocean, and the excess tends to diminish, so that there is a constant tendency for the ocean to inundate the Arctic and Antarctic regions ; but this tendency must be checked from time to time by subsidences in equatorial regions, for the equatorial pro- tuberance of the earth's actual figure must be progressively diminished. The changes that have taken place in the shape and size of the ellip- soidal inequality are therefore of great complexity, but fortunately the actual influence of this inequality upon the distribution of continent and ocean is not very great, and we ca-u form a fairly satisfactory notion 190.S] 0)1 the Figure and Gonditution of the Earth. 105 of some of the most important changes that can have been produced by g-ravitational causes, by leaving this iuequaHty out of account. We seek then the changes that can have been produced by the actual diminution of the inequality of the first degree, resulting in an increase of the relative prominence of the inequality of the third degree. The changes, being of the nature of the relief of strain, must take place somewhat spasmodically, l)ut at any one place they would be progressive, not fluctuating, and we should expect that the actual reduction in the inequality of the first degree would be greatest where the inequality is greatest, that is near the centres of the two hemi- spheres, where it gives us elevation and depression respectively. The regions where the computed elevation is greatest contains the Mediterranean and adjacent seas. The idea of a progressive diminution in the amount of the first harmonic suggests, that the formation of these seas, and of the neighbouring mountain ranges, is not to be ascribed entirely to a series of tectonic accidents, but that these move- ments were at least in part conditioned by a gravitational change. The increase in the relative prominence of the third harmonic would bring it about that where the first harmonic gives us elevation and the third depression oceans might be formed, and, if formed, they would get wider and deeper with the lapse of time. This state of things is found in the Arctic, Atlantic and Indian oceans. Where ancient con- tinents are destroyed by inundation we should expect that some rem- nants would survive to mark the ancient sites. In such places the computed elevation would be apt to be too small. This is the case, for example, in South Africa, West Africa, Brazil and the north- eastern part of North America. On the other hand, where the first harmonic gives us depression and the third elevation, there would be a tendency for the continental region to encroach upon the oceanic. This state of things is found around the shores of the Pacific, espe- cially on the American side, and on the greater part of the coast of Australia. Where an ancient ocean is contracted by retreat of the sea, we should expect to find that in some parts the new elevation would fail to be formed and the sea would retain its mastery. In such places the computed elevation w^ould be apt to be too great. This is the case for example, between Australia and the Antarctic continent and to the west of Central and South America. It appears that a change in the actual amount of the inequality answering to the first harmonic, combined with an increase in the relative prominence of the inequality answering to the third harmonic, accounts foi* most of the defects of the theoretical map obtained by combining harmonics. [The statement was illustrated by two maps shown as slides.] The conclusion that the Atlantic and Indian Oceans are modern in com- parison with the Pacific, is one to Avhich geologists have been led by independent evidence, and the differing characters of the coasts around the two great ocean basins has been especially emphasised by Suess. The difference consists in the relations of the coasts to the mountains. 106 Figure and Comtitiition of the Earth. [Marcli 6, Around the margin of the Pacific the mountain chains generally run parallel to the coasts, as if their formation had been the result of a series of incidents in the advance of the continent to enroach upon the ocean. Around the margin of the Atlantic and Indian Oceans the coast generally cuts across the strike of the mountains, as if the sea had advanced to inundate previously existing continents. The changes that have taken place in the face of the earth have been ascribed to two kinds of causes : gravitational and tectonic. The gravitational effects are due to changes in the distribution of the earth's mass, producing a shift of position of the oceans. The tectonic changes consist in the formation of mountains, and, possibly, of deeps. Except in so far as they may be incidents accompanying spasmodic but progressive gravitational changes, they are usually associated with the contraction of the earth as it parts with its internal heat, and consequently they are outside the purview of the theory which I have been trying to explain. The gravitational changes have been regarded as a mystery. I hope that this theory may prove to contain the key of the mystery. [A. E. H. L.] 1908.] Transatlantic Wireless Telegraphy. 107 WEEKLY EVENING MEETING, Friday, March 13, I'JOS. Sir William Crookes, D.Sc. F.R.S., Honorary Secretary and y ice-President, in the Chair. CoMMENDATORE G. Marcoxi, LL.D. D.Sc. M.R.I, Transatlantic Wireless Telegraphy. Before I go into my subject, it mi.s^ht interest you to know that the invitation from the Royal Institution to dehver this lecture was sent to me by transatlantic wireless telegraphy on October 19, when I was in Canada. The following is the text of the message : — " Marcoiti, Glace Bay. " Hearty congratulations on behalf of Royal Institution, the home of Faraday. We invite you to give first Friday evening discourse on January 17 next. Please reply by wireless. " Sir William Crookes, " Royal Institution, London." To which I replied, also by wireless : — " By means of ether waves across Atlantic I thank you for honour invitation to lecture at Royal Institution. Owing uncertainty my future plans greatly obliged if you will permit me postpone acceptance until I return to London. " Marconi." I have had the honour on previous occasions of describing before this Institution some of the stages through which the application of electric waves to telegraphy through space has passed. This evening I propose to confine myself chiefly to describing the results and observations recorded during the numerous tests and experiments which I and my collaborators have been carrying out with the object of proving that wireless telegraphy across the Atlantic was possible, not merely as an experimental feat, but as a new and practical means for commercial communication.* * Journ. Inst. Elec. Eng., xxviii. 1899, p. 291. 108 Commendatore G. 31arconi [March 13, In March, 1899, communication was estabUshed by means of my system of wireless telegraphy across the Channel between Eugland and France (see Fig. 1), and the Times of March 29 of that year pubHshed the first press telegram ever transmitted to England from abroad by means of electric wave telegraphy. At that time a considerable discussion took place in the Press as to whether or not wireless telegraphy would be practicable for much longer distances than those then covered, and a general opinion pre- vailed that the curvature of the earth would be an insurmountable obstacle to long-distance transmissions, in the same way as it was, and FIC.l CHART or r.c STRAITS » OOVtR •name wacoM nwuis mxxMfo n SOUTH FORELAND «oWIMEREUX 1899 UX> is, an obstacle to signalling over considerable distances by means of optical signals such as flashlights, the heliograph, or the semaphore. Othei" difficulties were anticipated as to the possibility of being able practically to employ and control a transmitter capable of radiat- ing an amount of electrical energy large enough to actuate a receiver at really great distances, and, granting the possibility of this, whether such a powerful radiator would not interfere with the working of all other wireless stations Avhich might be estabHshed on shore or ships within the sphere of influence of the long-distance sender. AVhat so often occurs in most pioneer work has repeated itself in the case of long-distance wireless telegraphy — the anticipated obstacles and difficulties were either imaginary or else easily surmountable ; but 1908.] on Transatlantic Wireless Telegra]ohy. 109 in their place unexpected barriers manifested themselves, and my efforts and those of my collaborators have been mainly directed to the solution of problems presented by difficulties which were not antici- pated when the tests over long distances were first initiated. In January 1901, wireless communication was established between St. Catherine's Point in the Isle of Wight and Lizard in Cornwall, over a distance of 186 miles. The height of these stations above the sea level did not exceed 300 feet (100 metres), whereas to clear the curvature of the earth a height of more than a mile at each end would have been necessary. The result of these tests went far to convince me that electric waves produced in the manner I had adopted were able to make their way round the curvature of the earth, and that therefore it was not likely that this factor would constitute a barrier to the transmission FIC.2 CHART or THE CNCL I SH CH ANNEIL SHOWINC MARCONI WIRELESS, TELEGRAPH STATIONS AT H I TON(lSLE or MIGHT) AND THE L I Z ARO of waves over greater distances. At this time I had achieved a con- siderable measure of success, by means of syntonic or tuning devices, in preventing mutual interference between stations, and Professor Fleming described, in a letter to the Times dated October 4, 1900, the results obtained, and which he and others had witnessed.* The principle on which the transmitters and receivers at St. Catherine's Point and the Lizard were worked is shown in diagrams ?i and 4. At the transmitting end a condenser, usually taking the form of a battery of Leyden jars, Imd one terminal connected to one spark-ball of an induction coil or transformer, and the other to the primary circuit of an oscillation transformer. The opposite terminal of this transformer circuit was joined to the second spark-ball. The con- denser was charged to the potential necessary to produce a suitable Jouru. Soc. Arts, xlix. No. 2530, 1901. 110 Commendatore G, Marconi [March 13, spark by means of an induction coil. The secondary circuit of the oscillation transformer was inserted between the vertical conductor or aerial wire, and earth, and an adjustable inductance coil included in the circuit. The circuits, consisting of the oscillating circuit and radiating circuit, were more or less closely " coupled " by varying the distance between the primary and secondary of the oscillation transformer. By the adjustment of the inductance inserted between the elevated conductor and earth, and by the variation of the capacity of the primary circuit of the oscillation transformer, the two circuits of the FIC.JJ FiC.4 '•-^^ transmitter could be l)rought into resonance, a condition which I first found was absolutely necessary in order to obtain efficient radiation. The receiver consisted also of a vertical conductor or aerial con- nected to earth through the primary of an oscillation transformer,' the secondary of which included a condenser and a coherer, or other suitable detector, it being necessary that the circuit containing the aerial and the circuit containing the detector should be in resonance with each other, and also in tune with the periodicity of the oscilla- tions transmitted from the sending station. The energy employed to signal over a distance of 186 miles could be brought as low as 150 watts, and even less if a higher or larger aerial had been used. 1908.] on Transatlantic Wireless Telegraphy. Ill The facility with which distances of over 100 miles could be covered prior to 1900, and the success of the methods for preventing mutual interferences,* led me to advise that two large power stations be constructed, one in Cornwall and the other in North America, in order to test whether it was possible to transmit messages across the Atlantic Ocean. I have often been asked why I did not first endeavour to establish commercial communication between places situated at a shorter dis- tance. The answer is very simple. The cables which connect England to the Continent, and between most Continental nations, are Govern- ment-owned, and these Governments would not, and will not, allow the establishment of any system, wireless or otherwise, which might in any way tamper with the revenue derived from these cables. As regards transatlantic communication, however, the conditions were different. There was no law either here, in Canada, or in the United States, to impede the working of wireless telegraphy across the Atlantic. A further potent reason, moreover, an economical reason, prompted me to attempt communication with America. Notwithstanding the cost of high-power stations, I am convinced that it is more profitable to transmit messages at 0^^. a word to America than at, say, \d. a word across the Channel, and that the economical advantage of wireless over cables and land-lines increases instead of diminishing with the distance. A site suitable for a long-distance station was chosen at Poldhu, in Cornwall, and here in 1900 work w^as commenced in earnest — work in which I was ably assisted by Professor J. A. Fleming, of the University of London. The transmitter at Poldhu was similar in principle to the one I have already described, but it is obvious that the considerable distance over which it was proposed to transmit signals necessitated the employment of more powerful electro-magnetic waves than those ever previously used. These were obtained by means of a generating plant consisting of an alternator capable of an output of about 25 kilowatts, which, through suitable transformers, charged a condenser having a glass dielectric of great strength. Time does not permit me to describe in detail all the engineering difficulties which were encountered in controlling electrical oscilla- tions of a power which at that time was certainly unprecedented, and as the tests were made possible by commercial organisation, the objects of which do not consist solely in the advancement of science, you will understand that a detailed description of the plant used at the transatlantic stations cannot, for the present at least, be made public. * Journ. Soc. Arts, xlix. No. 2530, 1901. 112 Commendatore G. Marconi [March 13, My early tests on wireless transmission by means of the elevated capacity method had convinced me that when endeavouring to extend the distance of communication it was of little utility merely to increase the power of the electrical energy applied to the transmitting circuits, but that it was also necessary to increase the area or height of the transmitting and receiving elevated conductors. As it was economically impracticable to use verticable wires of very great height, the only alternative was to increase their size or capacity, which, in view of the facts I had first noticed in 1^] on Recent Earthquakes. 189 lamp moved about outside the box produced no effect upon the paper inside. A self-recording thermometer and a hygrometer showed that the temperature and the moisture in the chamber were practically constant. A similar piece of apparatus was installed at a depth of 160 feet, in the King Edward Mine, Camborne, Cornwall. These experiments were commenced at Pan Chalk Pit in February 19 Go, and were continued for four months. They were taken up again in the middle of August 1906, and lasted eight months. A sheet of paper on development was frequently quite clear, but at times it was partly or entirely marked with dark bands, black lines, round black spots, or semi-circular spots along the lower edges. At Shide, the dark bands have not been numerous, but they occurred on nearly all the sheets from Camborne. In certain cases we appear to have three bands, the positions of which apparently coincide with the three holes in the zinc plate. In some of these bands there are hard black lines broken along their length and made up of black spots. The black spots vary in diameter from a fraction of a millimetre to 8 millimetres. In the centres of some of these there is a small white or brownish spot. As pointed out by Mr. W. H. Bullock, of Newport, these closely resemble spots which can be produced on bro- mide paper by a tiny electric spark. During a week we may have either no spots, one spot, or a hundred spots. The semicircular spots which I have called singeings, are found on the lower edge of the paper where the brass cylinder joins the aluminium rim. There may be two or three of these per week, whilst at other times they occur at intervals of about half-an-hour. As only ten black spots occurred at the time of large earthquakes we can only regard these as coincidences. Neither dark bands, spots nor singeings appear to be connected beyond what I have mentioned with any particular meteorological conditions. Neither is there any reason for supposing that these effects are due to radio-activity. If a piece of bromide paper is sealed up in a black envelope and another piece is placed in a black envelope, which has a thin glass window, and these are laid on a surface of chalk, the glass window touching the same, say for a period of several days, it was found after development that one piece of paper showed the image of the window, whilst the other had only stains which might be attributed to dampness. With the object of determining whether micro- organisms played any part in the phenomena observed, my friend. Dr. R. C. Brown, M.D., of Parkhurst, has made cultures from scrapings from the surface of the chalk before which my cylinder was exposed. Cultures were also made from scrapings taken from the open chalk. Micro-organisms were found in both. These have been exposed to a moving photographic surface similar to that used in the pit, but they gave no evidence of luminosity. The conclusion for the present is that the luminosity occasionally seen at Pan Pit may result from a very feeble brush or glow-like electrical discharge. If this be the case it would also account for the bands on the photo- graphic paper, the other markings being due to minute sparks. 140 Mr. John Milne [March 20, Moreover, if this is so, and we assume that silent electrical adjust- ments have a real existence, it is difficult to escape the conclusion that these must have an effect on what we call "climate," and hence upon everything that lives upon the surface of the globe. We have many instances of places only separated by a few miles, as for example, Newport and Sandown in the Isle of AVight, or Bournemouth and Swanage, the climates of which are said to be very different. The thermometer, barometer, and hygrometer do not explain these differences, the only apparent difference between such places appears to be one of soil and the moisture in the same. Inasmuch as we lind great differences in the emanations from granite, clayslate, and chalk, it would seem extremely probable that we should find differences in the relative electrical conditions of different soils. To determine whether earthquakes are increasing or decreasing, it is not only necessary to turn over the pages of many histories, but also to consult the geologist. Jules Verne might perhaps have dipped deeper into time than a geologist or physicist, and drawn pictures of the reactionary effect which might accompany the collision of one world with another, bombardments of great meteorites, a click that announced the birth of our moon, the sudden yieldings of a primitive crust covering an ocean of molten rock, and of many other things that float through the brains of those who entertain us with the results of their imaginations. The greater number of earthquakes, and certainly all that are large, originate from the formation or extension of faults. These operations have been most marked when secular movement amongst rock masses is in progress, as, for example, during the growth of mountains. Should this be in operation near large bodies of waters, volcanoes and earthquakes are found in the same region. If, therefore, we wish to know when earthquake fre- quency and intensity was at a maximum, we turn to those periods in geological history when mountain ranges were built, when volcanic activity was pronounced, and when great faults were made. The first of these periods would be coincident with the creation of the Urals, the Grampians and other ancient mountain ranges. This took place in Palaeozoic times. Another period of mountain formation was in early Tertiary times, when the Himalayas and the Alps were slowly, but intermittently brought into existence. In both these periods volcanic activity was pronounced and beds of coal were formed. When the crust of the earth was crumbhng, mountains grew spasmodically, faults gave rise to earthquakes, volcanic forces found their vents, and conditions existed which gave rise to the accumulation of materials to form coal. In quite recent times, many large faults have been created at the time of earthquakes. In 1