SOCIOLOGY

no comprehensive presentment of social science having, as yet, obtained general recognition, a detached survey of the sociological field must needs follow the lines of the leading schools, and of individual writers most widely influential or significant. the several schools of thought up to 1914 the two most representative schools were (a) of durkheim, essentially following the tradition of auguste comte, who founded sociology by the publication of his philosophie positive during the years 1830-42; and (6) of de tourville and demolins, following the tradition of frederic le play, who, independently of comte, and without reference to his work, founded the more concrete and observational side of sociology, especially by monographic publication of his les ouvriers euro- peens, from 1855 onwards. durkheim.—both these schools suffered an arrest during the world war; but the organ of the durkheim school, 1’ annee sociologique recommenced publication in 1925, and on the same plan as previously, but edited by marcel mauss in place of durk- heim, who died in 1917. the scheme of the annee is to publish each year a series of studies by members of the school, and also an analysis and epitome of the more important writings produced in general sociology and in each of the main specialisms within the sociological field. the aunee selects and epitomises relevant advances in economics, political philosophy, ethics, jurisprudence, criminology, social geography, anthropology, social psychology, demography, comparative religion, aesthetics, etc. this com- prehensive survey and abstract makes a file of the aznee an in- valuable requisite of the serious student, whether of general or specialised interest. le play.—the organ of the le play school (la science sociale) had a different purpose. while the approach of comte was primarily logico-mathematical, biological, historical and inter- pretative, that of le play was from physical science and industry, with clirect observation, especially through travel, first of repre- sentative working-class families, by means of family budgets, and next of their actual living communities: and especially of the fundamental nature occupations; all studied at first hand jn their environment, and in their resulting social organisation, with its characteristic ideas and ideals. hence have been published in za science sociale a long series of social monographs, in contribution to the geographico-social study of communities as they develop from their simple origins and isolated situations towards com- plex cultures interacting to form our historic civilisations. this line of treatment has been more akin to the naturalistic and de- scriptive attitude of balzac and later realist french literature than to the abstractly philosophic, or the strictly anthropological, historical, or psychologic treatments of other schools, and so has elicited, as yet, too little appreciation in the run of current sociology. a third group of active sociologists in france is that associated with the institut international de sociologie, with its periodic congresses and its revue internationale de soctologie, ably edited by rene worms until his death in 1926. the two formative french schools, continuing and developing the initial impulses of their respective founders, are manifestly complementary. but owing to the sharp division in france be- tween the traditions of the revolution and of the counter-revolu- tion, to which the doctrines of comte and of le play respectively first appealed, these have, unfortunately for the progress of science, run independent courses, with little or no inter-pene- tration. except fora book by paul bureau (ntreduction a la methode sociologique, paris, 1923), no serious attempt seems as yet to have been made in france to integrate their respective methods and products. the work of geddes.—but a third school, initiated in edin- burgh about 1890 by patrick geddes has laboured continuously towards uniting and developing both these main french tradi- tions, view-points and methods; more especially by applying the characteristic methods of each towards studying the evolution of cities and their regions. for this school it is living cities and their regions which most fully offer to the scientific student, as well as to the plain man, the directly observable aspects of civilisation. and if, along with direct observation, there is afforded, as by this synthetic school, a historic and contemporary interpretation which utilises the available specialised knowledge, then does the student of cities attain towards that complex unity of present- ment which sociology demands. to this end has been developed, and largely in harmony with the le play school, the character- istic method now widely known as regional and civic survey; such surveys emanating from this group, with their pragmatic motto of “ vivendo discimus,”’ have been experimentally applied in great britain, france, india, palestine, etc., towards regional improvement and in city and university design. with these 575 practical endeavours should also be appreciated the advances made by social workers in almost all countries, for their labours contribute, if not always immediately, yet indirectly, to the progress of social science. this survey method is being increasingly applied as the pre- liminary inquiry requisite for town-planning, in its later develop- ments known as regional. it is also being adopted in schools as an introduction to social studies made by direct observation in the open air along with nature studies, or as sequels to these. but these educational and civic applications alike too often lack the systematic and synthetic character essential to a scientific handling of sociological issues.1 importance of interconnection.—from the unified standpoint of the preceding schools the most generalised conception for the upbuilding of a science of sociology is that of the essential inter- connection of all main aspects of any given community and its civilisation. its situation in place, its actual industries anc evervday work, and its people of all classes, with their common sense and experience, their ordinary feelings of selves and family, are all intimately connected with their ideas, social and political, with their scientific interests and aesthetic preferences and even with the religion and the philosophy of their own times as well as of carlier phases. but this view of social interaction is not to be confused with the too simple ‘‘ economic determina- tion of history” se emphasised by and since marx; for the eco- nomic processes of each place and age are seen by the sociologist to be deeply influenced, often even determined, by preceding as well as current ideas and ideals; so that constant interaction 1s ever going on between the “‘ temporal and spiritual ” forces in every society. the actions and reactions of all these social factors in functional interplay thus produce the general and working ‘“ consensus ”’ essential to each given community, in its character- istic phase and main level of civilisation; with its current and predominant “ representation of life” accordingly. the social heritage-—-changes in all these aspects of a civill- sation, however, arise, even from generation to generation (especially when stimulated by great events), and still more from age to age, with their correspondingly fresh phases, and with variations, both objective and subjective, each modifying the other. yet despite all such changes of the social consensus in its functionings and institutions and of representation of life accord- ingly, there is always traceable a definite continuity, even of “ filiation,” with the preceding phases, however great the scem- ing contrast. ‘the outcome of these complex interactions is an unmistakable social inheritance. above and beyond biological heredity there exists therefore a characteristic social heritage (and its associated burden of evil) which, by differentiating hu- man from animal societies, constitutes the essential subject matter of sociology. and of this heritage, cities and their regions are more than the repositories. they are essentially concerned in transmitting it from generation to gencration, and in modify- ing, for better or worse, its volume, character and purpose. it follows that the regional and civic survey, as a means of scientific advance, must develop a technique for study, at once obser- vational and systematic, of the social heritage, in its past, present and incipient phases.? 1for the principles requisite to a systcmatic presentation see papers by geddes, in sociological papers, vol. 1, 2, 3 and in the sociological review of 1925 (le play house press, 65 belgrave road, london). for an elementary account, prepared for social workers and studious citizens, see introduction to regional surveys, by sybella branford and alexander farquharson (le play house press). later developments of the method, and many applications to theoretical studies and practical questions, will be found in the sociological review, the organ of the (british) sociological society. amongst characteristic books of the same school, but of more gen- eral treatment, may be mentioned the coming polity (revised edition 1919), and our social inheritance (1919), both by v. branford and p. geddes, and cities in evolution (1915), by p. geddes and science and sanctity (1923), by v. branford. for the relation of sociology to biology, as viewed by this school, see, biology py geddes and j. a. thomson in the home university library, london. 2for a set of formulae adjusted to this purpose see, in addition to the papers by geddes already mentioned, our social inheritance by branford and geddes, part i. sociology the preceding outline indicates the needed and practical utilisation alike of le play’s teaching and comte’s, along with that of other writers, respectively observant and interpretative, concrete or abstract. all are needed, and all require fuller co- ordination; and for this purpose, no doubt, revision. thus comte’s classification of the sciences as essentially physical, bio- logical and social, and his famous “ law of the three states ”’ (as successively theological and military, metaphysical and political, positive and industrial; or, as john stuart mill summed them, volitional, abstractional and scientific), have been absorbed into the body of social thought more fully than is commonly realised; yet each of these master concepts demands fuller inquiry, with consequent restatement. so too le i'lay’s essential formula of “‘ place, work and folk,” though necessary for the correlation of geographic, economic, anthropological and social inquiries, calls for elaboration. the other basal contribution of le play and his continuators comes from their insistence on, and treatment of, the primary occupa- tions. gathering and hunting, herding and cultivating, mining, woodcraft and fishing —all these are viewed as elemental types of adaptation between man and nature, each definitely related to given environments, and together in their unity composing a rich rural matrix, from which urban civilisations have issued, and are perennially renewed, developed, arrested or degraded, according as, under more or less urbanised conditions, the char- acteristic traits and dispositions of the original rural types per- sist and undergo modifications towards progress, reversion or perversion. from this presentment of elemental social types and their interplay for good and evil, arises a “‘ natural history ”’ of civilisa- tions, which goes far beyond the superficial handling of the funda- mental occupations by early economists and anthropologists. yet, mainly perhaps by lack of detailed reference and specific instance, this le play doctrine of social evolution and regression has, so far, failed to win recognition from the specialised investi- gators of current economics and anthropology. place, work, folk.—the three primary social factors of place, work, folk, so insisted on by the le play school, correspond, term for term, with the primary biological concepts of environment, function, organism. hence the possibility of a sociology con- centrated on the social heritage and its progress, arrest or per- version, in social life, yet definitely correlated with biology and presenting the social process as not only continuous with the organic and individual life-processes, but increasingly transcend- ing these. in all human communities, progress is thus seen to consist essentially in an orderly and rational modification and even transformation, of environment, through those kinds of work, z.e., occupation up to its widest sense, which give expression to composite ideals at once social and individual, rural and urban. amongst various endeavours towards such a sociology, 2z.e., continuous with biology but utilising as fully as may be the re- sources of philosophy, of psychology, history and all other relevant specialisms, that of geddes and his fellow-workers starts from the more naturalistic and geographical approach; and that of l. t. hobhouse sets out froma more strictly humanistic stand- point, psychologic and philosophic. hobhouse’s main works are mind in evolution (1915); morals in evolution (1923); and the following four books, together constituting the author’s prin- ciples of sociology, viz.: metaphysical theory of the state (1918); the rational geod (1921); the elements of social justice (1921); and secial development (1923). specialised approaches.—as a notable instance of the many contributions towards a general sociology, at once natural- istic and humanistic, starting from anthropology, may be espe- cially mentioned the works of professor westermarck. his classic history of human marriage, many times revised, was followed by origin and development of moral ideas (2nd ed., 1917), and other works. amongst other advances in england from anthro- pology towards sociology may be cited those of rivers, haddon, marett, myers, peake, fleure, seligman, crawford, elliot smith, perry and malinowski. a similar list could be compiled, for other countries, of anthropologists moving, deliberately or uncon- soda fountain—soderblom sciously, towards a general sociology. and the same, in less de- gree, is true of psychologists, economists, historians, geographers and other specialised groups. but all these regiments of sociolo- gists, actual or would-be, are too inclined to march independ- ently of each other, and without guidance from the synthetic concepts and co-ordinating methods grown up in the central tradition of the main science. work in various countries united states —in contrast to the surviving indifference to sociology on the part of british universities (with the conspicuous exception of london), those of the united states have mostly established chairs, sometimes even departments. from this american source issues a copious stream of literature, mainly text books for students, but also more considerable works, both methodological and ‘of comprehensive range. lester ward, the american pioneer of sociology before its academic adoption, giddings, albion small, e. a. ross, ellwood, vincent, cooley, barnes and many younger writers have produced notable works. yet american sociology suffers from inadequate relation to the twofold french beginnings of the science and to the develop- ments which have grown up out of these historic initiatives. this lack of continuity makes difficult the correlation of the american output with the main european lines of thought and research. indeed, an increasing tendency has shown itself in american sociology to abandon the traditional endeavour to unify the whole body of relevant social studies, specialised and general, and to organise their essential product into an integrated doctrine in line with biology and the other “‘ preliminary ” sciences. this tendency, narrowing, yet in a sense progressive, has been stimu- lated by the remarkable advance of psychology in america, and also more or less by le bon and his many successors in the study of the group mind. its main effort has been towards the psy- chology of groups and their interaction. in other words, american sociology has been especially concentrating on social psychology. the american journal of sociology, founded by albion small in 1895 markedly reflects this specialising tendency in its later issues. two companion periodicals (social forces and the journal of a pplied sociology) attest the abundance and vitality of american sociology. germany.—a notable post-war movement in sociology has arisen in germany, where, before the world war the subject as such was hardly recognised in the universities, notwithstanding the sustained efforts of simmel, ratzenhofer, barth, tennies and others. but an inquiry made in 1925 by leopold von wiese showed that in nearly every university of the german-speaking world the study of sociology was being more or less organised. institutes and societies have been established for promoting sociological studies and research, whence emerges a growing out- put of periodical and other literature. in addition to the older archiv fiir sozialwissenschaft und sozial politik there are now many periodicals in this field. first after the war came the kelner vierteljahrschrift fiir soziologie (started in 1920 by von wiese), which gives admirable surveys of current literature in addition to original articles. the jahrbuch fiir soziologic; ethos: vierteljahrschrift fity sosiologie, geschichte und kultur-philoso phie; and the zeitschrift fiir v dlkerpsychologie und sosiologic, all began publication in 1925. there has also been a considerable output of books on sociology in germany since the war, but these, like most teaching in german universities, appear to emanate either from some single and specialised field or from a general phil- osophy of social life; and so in either case are inadequately related or in comprehensive indifference to the originative and funda- mental traditions. other countries—in italy, belgium, spain, holland, switzer- land and the scandinavian countries, few signs of progress are discernible in general sociology, apart from sporadic advances of the specialisms within the sociological field. true, the institut de sociologie in brussels has enlarged and improved its journal (revue de pinstitut de sociologie) since the war; but in italy the rivista tialiana sociologica has ceased publication. in czecho- slovakia and poland a definitely sociological movement, with 379 institutes and prospect of publications, has arisen. also in japan there was launched in 1925 a sociological society which pub- lishes a monthly journal. the future of soctology—new growths in general sociology are seriously handicapped by the obstacles that have impeded, or even arrested, the progress of the science during the past two generations. these obstacles, indicated above, need candid recog- nition and discussion if they are to be overcome, and so make way for that ever-developing inhcritance of svstematised knowl- edge which, essential to the continuing growth of every science, is supremely required for the complex issues of sociology. that neglect of the two originative i'rench traditions, which was so marked in herbert spencer's principles of sectology and in his systematic tudbles, has been too much continued by most later sociologists, and has become well nigh a dumnosa hacreditus. but a prior obstacle lies at the very foundation of the science. the failure of both comte and le play adequately to organise their respective doctrines and incorporate therein the relevant specialisms of their day, has been aggravated by the unsystema- tised progress of those detailed advances and by the multiplica- tion of new minor specialisms taken up in disregard of their place in general sociology. and the few synthetic workers, who have laboured to unite and develop the two initiative french tradi- tions into a body of doctrine incorporating the relevant special- isms, have so far, achieved but little success in the leavening of academic institutes and official organisations. yet, in spite of these many disabilities under which the synthetic movement labours, its progress towards unity and clearness is none the less advancing. (see anthropology; biology; human geography.) (v. b.) soda fountain: see food servicy. soddy, frederick (1877- ), british scientist, was born at eastbourne, sussex, on sept. 2 1877, and was educated at eastbourne college, the university college of wales, abery- stwyth and merton college, oxford. from 1900-2 he held the post of demonstrator of chemistry at the mcgill university, montreal, where he carried out research work on radioactivity with sir e. rutherford, and for the next two years he worked under ramsay at university college, london, becoming in 1904 lecturer in physical chemistry and radioactivity at the university of glasgow. ten years later he went to aberdeen university as professor of chemistry, but he left there in 1919 to become lee’s professor of inorganic and physical chemistry in the university of oxford. he made many valuable contributions to the science of radioactivity, and will be particularly remembered for his work on the nature of isotopes, for which he was awarded the nobel prize for chemistry in 1921. he was elected f.r.s. in roto and was a member of many british and foreign scientific so- cleties, being president of the rentgen society 1905-6. (see rays.) hlis numerous scientific publications, chiefly on radioactivity, include radioactivity (1904), the interpretation of radium (1909, revised and enlarged by a section on the “structure of the atom” (1920). chemistry of the radioactive elements (part i., 1920; part i1., 1914); afatier and energy (1912); science and life (1920); cartesian economics (1922), inversion of science (1924). soden, hermann, freeiherr von (1852-1914), german biblical scholar (see 25.339), died in berlin jan. 15 1914. soderblom, nathan (1866- ), swedish ecclesiastic, was born in trene jan. 15 1866 and educated at the university of upsala. in 1894 he became chaplain to the swedish legation in paris and in rgot took a theological degree at the sorbonne for his thesis la rie future d'apres le maszdeisme. he was professor of the history of religion at the university of upsala from 1901-4 and also at leipzig from 1912-4 and gained a wide reputation as one of the foremost contemporary investigators in this field and also for his studies of persian religion and theocracy. in 1914 he became archbishop of upsala. in the negotiations after the lambeth conference in 1908, which led to an official understanding between the swedish and english churches, he took an enthusiastic part. having extensive inter- national relations, sederblom worked with success for an ap- proach to “ evangelical catholicity ’’ among various christian societies, and played an important part in the preparations for 580 the universal christian conference on life and work held at stockholm in aug. 1925, in which he was one of the leaders. soissons-reims, battle of: see german offensive. sokolnikov, gregory yakovlevich § (1888-— ) russian communist and financial expert, was the son of a doctor. he studied in moscow and at the university of paris. he lived in exile until the revolution of feb. 1917, when he returned to russia and entered politics and journalism. after the nov. revolution, sokolnikov at first worked in the soviet finance department (for nationalisation of banks), but later took part in the civil war, holding the highest military commands in thie revolutionary army in turkistan. at the end of 1921, immedi- ately after the proclamation of the new economic policy, sokolnikov was appointed to the committee of the people’s commissariat of finance; at the beginning of 1922 he held the post of deputy people’s commissar of finance, becoming com- missar soon after. at this time the tinances of soviet russia were completely disorganised. only 10% of the government expenditure was covered by taxation, if one excepts the taxes in kind on natural products which formed the whole basis of the government’s finances. the daily expenditure could practically only be covered by continual issues of worthless currency. in the course of four years (1922-5) the system of taxes was restored to order, the government undertakings began to yield a profit, the budget was put in order, the deficit being reduced to neg- ligible quantities; the most important reform being the reform of the currency. this was begun at the end of 1922 and the new state bank was given the right of issuing notes; it was completed in 1924 with the reorganisation of the treasury bills and the stabilisation of the soviet currency. in 1923-5, which period comprised the chief reforms, the financial department played the most im- portant part in the government of soviet russia, and sokol- nikov enjoyed great political influence. he succeeded in col- lecting in the finance commissariat a considerable number of energetic young members of the communist party and talented non-party specialists. at the end of 1925, when great dissen- sions arose in the communist party on the economic-political question, sokolnikov went over to the opposition, joining the group which included zinoviev, kamenev, etc. after the 14th congress of the communist party in jan. 1926 he was removed from the post of commissar of finance and appointed deputy president of the ‘ gosplan,” or state-planning commission. (lae ¥:) solar energy.—the sun radiates out energy at a rate which varies at most only slightly from day to day or from year to year. so far as is known, the rate of radiation is approximately the same for all directions in space. only a tiny fraction of this radiation, less than one part in two thousand millions, falls on our earth, but from observations on the amount of this it is possible to estimate the total output of solar energy. the solar constant is defined as the quantity of radiation which woulk! fall per minute on an area of one square centimetre at the earth’s surface, placed so as to face directly toward the sun, if the earth’s atmosphere were absent, the earth being at its mean dis- tance from the sun. the best determination of the solar con- stant, that of abbot and fowle, gives its value as 1-93 calories. the mean distance of the earth from the sun, 92,800,000 m., is approximately 215 times the sun’s radius, so that the energy emitted per minute by a square centimetre of the sun’s surface must be (215)?x1-93 calories, or about 89,c00 calories. in terms of energy each square centimetre of the sun’s surface has an output of energy equal to that of an engine of 8-4 ii.p. this represents a more concentrated output of racliation than can be produced in the laboratory. the output of energy from the carbons of an electric arc is something under two horse-power per square centimetre, so that the sun’s surface must be at a temperature substantially higher than that of the electric arc, which is about 3,700°. the energy emitted from a perfect radiator at absolute temperature t is ot‘ per sq. centimetre, where o is stefan’s constant. on the supposition that the sun’s | surface behaves like a perfect radiator, calculation shows that t soissons-reims, battle of—solar energy the “‘ effective temperature ” of the sun’s surface is about 5,740° absolute, or 5,470° centigrade. knowing the area of the sun’s surface (5-9 x 10” sq. cm.) and the output of radiation per sq. centimetre, we can calculate that the sun’s total radiation must be about 5:4 x 10? calories per minute, the equivalent in energy to the output of an engine of 5 x 10% horse-power. even this colossal figure represents a rather low output of energy for a star; the star v puppis is known to be radiating at. fully 10,000 times this rate, while the giant star bd 6° 1309 recently studied by plaskett is probably emitting some 30,c00 times as much energy as the sun. from quite early times scientific curiosity has, naturally enough, been concerned as to the source of this treme dous outpouring of energy. early speculations that the sun was mere- ly radiating away an unreplenished store of heat, like a red-hot cannonball suspended in space, were soon found to allot it an inadequate span of life. ‘the further conjecture that the sun’s heat might be maintained by a sort of combustion of its whole mass did not meet with much better success; it was calculated that if the sun’s whole mass were solid coal, and if this coal were burned in pure oxygen, the resulting heat would only suffice to maintain the sun’s radiation at its present rate for about 6,000 years. : | mayer’s hvpothesis.—the first hypothesis to provide anything in the least approaching to an adequate supply of heat was that of robert maver. according to his hypothesis, the energy of the sun’s radiation was provided bya continuous fall of meteorites anc other small bodies into the sun. a meteorite starting with a small velocity at the confines of the solar system and falling under the sun’s gravitational attraction would have acquired a velocity of about 400 km. a second by the time it reached the sun’s surface. as the meteorite was brought to rest the energy of its motion would be transformed into heat, precisely as the energy of a bullet is transformed into heat when it strikes the target. mayer calculated that a shower of meteorites of total mass equal to that of the earth would provide heat equal to that radiated away by the sun in rather over 95 years. thus the sun’s radiation could be accounted for if we were free to suppose that meteors of total mass rather less than that of our moon fell into the sun every year. the hypothesis required the sun to be continually increasing in mass at a rate equal to about one moon per annum, so that the present mass of the sun fixed a limit to the total amount of radiation that could have been emitted by the sun. it was found that the infall of metcorites could not have provided radiation at the present rate for more than 18,000,000 years. there is in any case no reason for thinking that meteorites are distributed in space as freely as is required by this hypothesis, and indeed every reason for thinking the contrary, for, 1f meteo- rites were distributed to the extent required, so many would fall on our earth as to keep its temperature at a point at which it would be uninhabitable (cf. grolocy). helmholtz’? hypothesis—in 1853 helmholtz propounded an alternative hypothesis which provided for the same total radia- tion as the hypothesis of mayer, without its objections. helm- holtz supposed the sun’s radiation to be provided, not by the spasmodic infall of meteorites, but by a gradual and regular infall of the sun’s mass as he contracted in consequence of his radiation. the loss of energy resultant on radiation caused the sun to shrink; as this shrinkage took place each particle of the sun’s mass moved to positions ever nearer to his centre; the energy set free by this gradual fall provided for more radiation, more shrinkage and so on. on this hypothesis the total heat radiated by the sun since his birth was equal to the total loss of potential energy in the sun’s present configuration minus a certain allowance for the heat at present imprisoned in his mass. it was also equal to the heat which would have been radiated if the sun had been formed entirely by an agglomeration of infalling meteorites. thus the limit set to the sun’s total past radiation by this hypothesis was the same as that set by the meteoric theory of mayer, namely a total past radiation equal to about 18,000,000 years of radiation at the present rate. solar energy discovery of radioactivity.— until quite recently no theory of the origin of the sun’s heat allotted him a longer life than this. it is true that, in the excitement which first followed the dis- covery of radioactivity (g. v.), it was thought that the properties of radioactive substances permitted of an almost unlimited ex- tension to the sun’s past age and future life, but the various con- jectures then made speedily proved to be false. a gramme of radium emits heat at the rate of about 138 calories per hour or, measured as energy, at the rate of about 1,600,000 ergs a second, whereas the sun’s radiation represents an emission of only about two ergs a second from each gramme of his mass. it would at first sight appear that the supposition that even a small fraction of the sun’s mass is radium would amply account for the sun’s radiation, past, present and future. this view is fallacious on account of the fact that radium (q.z.) does not last for anything like the time throughout which thesun’s radiation must besupposed to have lasted; it is reduced to half strength, in about 1,760 years. to allot the maximum possible life to the sun we should have to suppose his whole mass to have consisted originally of pure uranium, the parent radioactive substance out of which all others are formed. rutherford has, however, calculated that this supposition would add at most 5,000,000 years to the sun’s life, radiation being assumed to be at the present rate. thus all the sources of energy which have so far been mentioned, acting in conjunction, could at most provide for radiation for about 23,000,000 years at the present rate of radiation. geological estimates of earth—keven before helmholtz pro- pounded his contraction hypothesis, geologists had estimated the earth’s age in hundreds of millions of years, basing their figures on the observed rates of denudation and sedimentation. the discovery of radioactivity provided a better and simpler means of judging this age. a special kind of lead, characterised by having atomic weight 206-0, is produced by the breaking up of atoms of uranium. now the process of breaking up is a purely spontaneous one proceeding always at the same rate whatever the physical condition of the uranium may be. the constant rate is such that one out of every seven thousand million atoms of uranium breaks up each year. hence in a mixture of uranium and lead a comparison of the relative amounts of the two sub-: stances enables us to estimate the time which has elapsed since the lead first commenced to form. using this method, geologists are convinced that certain canadian rocks are at least 1,400 million years old, and as it is generally accepted that the earth originally formed part of the sun it follows that the sun must be older still. (see geolocy.) astronomical arguments.—as will be explained later, astro- nomical arguments indicate that the period of 1,400 million years, which geologists assign as a lower limit to the age of the earth, is at most only a tiny fraction of the age of the sun. while the geologist has been increasing his estimate of the earth’s age up to 1,400 million years or more, astronomical! research has been moving in the direction of asking for at least 1,000 times this period for the sun and the stars in general. no doubt a distinction must be drawn between the age of a star and the period during which it has been emitting radiation, but the difference between the two periods is less than might at first be thought. the observed velocities of the stars give some indication as to the intensity of the gravitational field in which they move, and hence of the density of gravitating matter in the universe. it is found that the visible stars account for something like a quarter of this density, and probably for more. thus it is fairly safe to state that a quarter of the whole matter in the universe, or at least in our part of the universe, is shining, and so to conclude that the period of a star’s radiation must be comparable with his total age. further than this, modern theories of stellar evolution suppose that a star shines most brightly in his early days, then less brightly, and finally ends his days in darkness. thus if astronomy indicates an age of millions of millions of years for our sun, we are safe 1n supposing that his total radiation since birth has been greater than the same number of millions of millions of years of radiation at his present rate. it is in any case abundantly clear, and with a very wide margin 581 to spare, that our sun, and consequently the other stars also, must have some source of energy beyond those already mentioned. theory of relativity —in 1905 einstein propounded his theory of relativity (g.v.), which requires that any increase in the energy of a body is necessarily accompanied by an increase in its mass, and vice versa. the standard illustration is provided by the changes which are observed to occur in the mass of a rapidly moving electron as its velocity varies. under more usual condi- tions the change in a body’s mass is so slight as to escape detec- tion; thus the “‘ mauretania’ when at full speed increased her mass by only -oo004 grammes. it is at once evident that if the actual matter in any body could be annihilated, an enormous amount of energy would be set free. in 1904, before the appearance of ejinstein’s theory of relativity, the annihilation of matter had been suggested as a possible source of energy by j. h. jeans, who further calculated in 1917 that the annihilation of 1% of the sun’s mass would set free sufficient energy to maintain the sun’s radiation at its present rate for 150,000 million years. this calculation is wholly independent of any conjectures or assumptions as to the mecha- nism by which mass is transformed into radiation. perhaps the most plausible conjecture is that the positive and negative charges of which matter is made fall into one another and mutually annihilate one another in so doing. but, quite apart from this or any other conjectures, the theory of relativity pro- vides the quite general theorem that the annihilation of a mass m in any way whatsoever sets free an amount of energy mc?, where c is the velocity of light; this is all that is essential to the calculation. the life of a star —obviously the suggestion underlying this calculation provided a quite simple source of energy for the sun’s radiation; the only outstanding question was whether the radiation was in actual fact provided from this source or from some other still unconjectured source. according to generally accepted schemes of stellar evolution a star begins its life as a “‘ giant ’’? star—a sphere of gas of enormous size, low density and very high luminosity. gradually it changes into a “ dwarf” of comparatively small size, high density and low luminosity. our sun, now a fairly typical dwarf, must have passed through a giant stage in which it radiated far more energy than now, and subsequently experienced a gradual diminution in size and luminosity. it has gradually emerged that the giant stars are of greater mass than the dwarfs, and that, in general, lower luminosity is associated with smaller mass. the close correlation between luminosity and mass was investigated by hertzsprung, by adams and joy, and others, the most noteworthy contribution being made by eddington, who showed in 1924 that visible stars of a given mass all lay within a comparatively small range of luminosities, the luminosity varying with the mass according to an assigned law. it at once became clear that if our sun had followed the normal evolutionary course, its mass in the past must have been far greater than its present mass. also, since the rate of radiation corresponding to each mass was known, it became possible to calculate the time interval between any two assigned masses on the supposition that the energy of radiation was derived from loss of mass alone. in this way jeans calculated in 1924 that the time since our sun was a giant star must be of the order of seven million million years. it is hardly necessary to specify exactly what precise point in the giant state is taken as the starting point in this calculation, for, on account of their very high rate of radiation of energy in the giant state, stars run through this stage of their careers with extreme rapidity. now the various astronomical arguments to which reference has already been made agree in indicating a period of just about this magnitude as the most probable age of stars in the condition of our sun. binary stars.—-perhaps the most satisfactory estimates are those obtained from a study of binary stars which have broken up by fission. the two constituents of such a system commence life by describing about one another orbits of almost circular shape and of dimensions so small that the two stars are almost in contact. with advancing age both the dimensions and the 582 eccentricities of their orbits increase, and a purely dynamical calculation indicates that binaries whose constituents are in about the stage of development of our sun must have lived for millions of millions of years. an interesting check is provided by a study of the ratios of the masses of the two constituents of binary stars. the radiation from a massive star is not only ab- solutely greater than that from a less massive star, but is also relatively greater; the more massive a star, the more radiation it emits per unit mass. as a consequence of this, the masses of the two constituents of a binary must continually approximate to equality as the star grows older, and it is possible to calculate the rate at which this equalisation of mass should take place. ob- servations collected by r. g. aitken show that the predicted approach to equality of mass actually occurs, and also make it possible to estimate the ages of binaries of various types. calculations based on these data give an age of 4-5 million million years for binaries of spectral types f to g, a figure which is in quite good agreement with the estimate of seven million million years for our somewhat older sun, which is obtained on the hypothesis that the sun’s radiation is due entirely to anni- hilation of its mass. source of solar energy—these and similar considerations indicate that our sun’s loss of mass in the last seven million million years is just about represented by the total radiation which it is believed to have emitted in that time. if so, there would seem to be little room for doubt that a solution has been obtained to the long-standing problem of the origin of solar energy and of stellar energy in general. the answer to the puzzle proves to be the quite simple one that the sun’s energy is derived by annihilation of the sun’s mass. the electrons and protons which form this mass constitute bottled up stores of energy; the breaking of these bottles of energy and the setting free of the imprisoned energy as radiation is at present proceeding at a rate of rather over 4,000,000 tons a second, and has been proceeding at this or a greater rate for the past seven million million years. in the same way in which it has proved possible to trace the sun’s history back into the past, we can look forward into the future and watch the sun continually decreasing in mass and juminosity. all normal stars appear to follow a single clearly defined evolutionary sequence, and just as any normal star of greater mass than our sun provides us with a picture of what he must have been at some past time, so any normal star of mass less than that of our sun gives a picture of some epoch of his future. to peer further and further into the future of our sun we must look at stars of smaller and smaller mass and so of ever lower luminosity. the faintest known star, proxima centauri, which happens to be also the nearest, has a luminosity only one twelve-thousandth of that of our sun, but there is some room for doubt whether this is a normal star, and its mass is at present unknown. of the stars whose masses are known with fair cer- tainty, the smallest masses must be attributed to the two com- ponents of 60 kruger. aitken’s determination (1925) assigns to them masses of approximately one-fourth and one-fifth of our sun, their luminosities being about a hundredth and a two- hundredth of that of our sun. these stars enable us to visualise what will be the state of our sun after an interval of about a hundred million million years. rates of radiation —while our sun emits energy at the rate of two ergs a second per gramme of his mass, plaskett’s star (b.d. 6°, 1309) already mentioned is radiating about 1,000 ergs a second per gramme. at the other end of the chain the fainter component of 60 kruger radiates only a twentieth of an erg a second per gramme. as a general rule the farther advanced a star is the less its radiation per gramme. this suggests that a newly born star consists largely of types of matter which trans- form themselves fairly rapidly into radiation; as the star ages, these easily transformable types soon get used up, so that the older stars consist solely of less transformable types. it is likely that there must finally remain a residuum of mass consisting of types of matter which either do not transform into radiation at all or at best transform themselves with extreme slowness. if the earth is at present transforming any of its mass into radiation, sologub—somaliland this must be at most at the rate of a ten-thousandth of an erga second per gramme of its mass, since any higher rate would be inconsistent with the actual temperature of the earth’s surface. thus the various chemical elements known on earth are probably of the non-transformable type. if so, the sun and the younger stars must be supposed to consist, in part at least, of chemical elements unknown to us on earth, which have the capacity of transforming their mass fairly rapidly into radiation. these un- known elements are probably of higher atomic weight than our terrestrial elements, although possibly our radioactive elements (uranium, radium, etc.) represent a last vestige, appearing even now only in infinitesimal quantities and destined ere long to dis- appear altogether. (see also radiation.) (j. h. je) sologub, fedor, pen name of fedor kuzmich teternikov (1863- ), russian man of letters, was born feb. 17 1863 in st. petersburg (leningrad), the son of a tailor. on the latter’s death, his mother became a domestic servant and the son was brought up by her employers. he studied at the teacher’s institute in st. petersburg and was a schoolmaster for 25 years, retiring in 1907. in 1897 he published his first volume of poetry and also some short stories. he is considered the greatest figure of the symbolists in prose and poetry. his best novel is the little demon (1907), in which he has created a universal type of evil in the central figure, the schoolmaster, peredonov. he also wrote several plays. his other works include the sorcery of death (a series composed of the created legend, drops of blood, queen ortruda, and smoke and ashes). the little demon, the created legend, the old house and other tales have been translated into english.