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unit of length is taken as a kilometer, then the unit of time is 1/300,000 of a second.

3. In classical mechanics for a central force

r2(02 + sin2042) of attraction f(r) the equations are

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where h and E are constants. For planetary motion about the sun, whose mass in gravitational units is denoted by m, equation (9) assumes the form

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where a is the semi-major axis. For the solar system m/a and m/r are of the order of 10-9, for the units previously defined. Thus if we identify A21 in (6) with -m/a in (10), A 1 = 108 approximately. Then from

dt

ds

(4), = 1 + 3/2 10- approximately, which shows the order of discrepancy so far as the solar system is concerned in interpreting ds and dt as the same in (5), (6), (8) and (9) (cf. Eddington, Report, p. 50).

It is well-known that it is the term 2mh2/r3 in (6) which accounts for the motion of the perihelion of Mercury. Comparing (6) and (9), we see that from the point of view of action at a distance this is accounted for if we

for the equations of a world-line of a particle in the gravitational field.

When I = 0, the integral (3) is stationary and the corresponding world-lines are those of light in accordance with the Einstein theory. Their equations are (4), (5) and

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ds

=

ds'

Some writers have obtained these equations by solving I 0 for dt and expressing the condition that dt be stationary, in accordance with the Fermat principle. The above method was given by Professor Veblen in his lectures, and appears also in Laue, Die Relativitätstheorie, Vol. 2, p. 225. Putting I = 0 in (2), we see that the units are such that the velocity of light is unity for rco, and that it diminishes as the light approaches the sun. If the

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chosen. If we denote it by e in any system of units, we may formulate the law as follows:

Two bodies attract one another inversely as the square of their distance and directly as the product of their masses and (1 + 3v2/c2), where v is the component of their relative velocity perpendicular to the line joining the bodies.

The form (1) is obtained from the Einstein theory on the hypothesis that the planet is small in comparison with the sun. It may be that the above law applies only to this case. However, it may be that the law would work if the bodies were approximately of the same As formulated the law enables one to set up the differential equations of n bodies in a manner analogous to the classical theory. It would be interesting to know whether known discrepancies in the motion of the moon would be overcome by the use of this law.

mass.

Although the term 3v2/c2 produces an observable effect only in the case of Mercury, it may produce a significant effect in molecular motion.

• 4. When in like manner equation (7) is compared with (9) we find that for a ray of light the attraction is

(14)

3mw2

would not be accurate for two or more bodies of relatively the same mass, but it may lead to a sufficiently close approximation.1

LUTHER PFAHLER EISENHART PRINCETON UNIVERSITY

THE AMERICAN ASSOCIATION FOR
THE ADVANCEMENT OF SCIENCE
SECTION F-ZOOLOGICAL SCIENCES AND
ASSOCIATED SOCIETIES

AT the Toronto meeting of the American Association for the Advancement of Science, December 27-31, 1921, Section F (Zoology) offered no separate program, but met jointly with the American Society of Zoologists. The program was arranged by the latter society.

Six joint sessions were held, the program including 101 titles distributed by subject as follows: embryology, 4; cytology, 8; comparative anatomy, 7; evolution and genetics, 24; ecology and zoogeography (with the Ecological Society of America), 13; general zoology, 2; protozoology, 2; parasitology, 22; comparative and general physiology, 17; unclassified, 2.

The session of Friday afternoon, December 30, was devoted to a symposium on orthogenesis. A biologists' smoker was held Wednes

dinner Friday evening, December 30.

The business meeting of Section F took place at the morning session on December 29, with Vice-president Kofoid acting as chairman. M. M. Metcalf is vice-president for Section F for 1922. J. A. Detlefsen was elected a member of the section committee for four years in place of the retiring member, A. M. Reese.

where may be interpreted as the angular day evening, December 28, and the zoologists' velocity of the light about the sun. Thus it is the term 3m2 in (13) which accounts for the deflection of light, and the term m/r2 does not enter. Einstein and his followers have calculated the deviation of light by noting that the velocity changes in a manner analogous to that of a refracting medium, and by applying Huygen's principle. Since the same term appears in the attraction of a planet, it may very well be that the sun affects the medium through which both the light and planets pass, and that the difference between Newton's law and (13) is due to this situation. From this point of view one would expect that the law

1 I have just found that A. V. Bäcklund in the Arkiv för Matematik, Astronomioch Fysik, Vols. 14 and 15 (just received) has made an extensive study of the relation between classical dynamics and the Einstein theory of gravitation. In the course of his three articles he obtains equation (11) and one similar to (13).

F. R. Lillie presented the following resolutions drawn up by a conference of representatives of the biological societies in regard to a proposed federation of biological societies:

RESOLVED: 1. That it is the sense of this conference that an inter-society conference should be called to study and report upon the feasibility of federation of the biological societies and to develop plans for the said federation.

2. That for the purpose of effecting such an organization, each society, and Sections F and G of the American Association for the Advancement of Science, be requested to designate its president and secretary as members of an inter

society council which shall be authorized (1) to deal with all matters of common interest, such as pooling of programs, that are consistent with the existing regulations of the constituent societies, and (2) to draw up proposals for a constitution and by-laws of a federation of the societies in question, and to present them for action at the next annual meeting.

The Section voted that the resolutions of the conference be adopted.

Independent programs were arranged by the following societies affiliated with Section FThe Entomological Society of America, The American Association of Economic Entomologists; and by the following societies affiliated with Sections F and G jointly-The American Society of Naturalists, The Ecological Society of America, The American Microscopical Society (business meeting only), The American Nature-Study Society.

HERBERT W. RAND, Secretary, Section F

SECTION G-BOTANICAL SCIENCES AND ASSOCIATED SOCIETIES

SECTION G held its session on Wednesday afternoon, December 28, 1921, in conjunction with the Botanical Society of America and the American Phytopathological Society. There was a large attendance at this meeting, and the symposium, though involving several papers, was not unduly long. Professor Rodney H. True, retiring vice-president for Section G, delivered his address on "The physiological significance of calcium for higher green plants," which has been published in SCIENCE, Vol. LV, p. 1, January 6, 1922. The vice-presidential address was followed by a symposium on "The Species Concept," at which the following papers were read: (1) "From the viewpoint of the systematist," Charles F. Millspaugh; (2) "From the viewpoint of the geneticist," George H. Shull; (3) "From the viewpoint of the morphologist," R. A. Harper; (4) "From the viewpoint of the bacteriologist and physiologist," Guilford B. Reed; (5) "From the viewpoint of the pathologist," E. C. Stakman. The writers of these papers cooperated splendidly, both in division of subject matter and in time of presentation. The results seem to confirm the expressed belief of many botanists

that a symposium of general interest, making appeal to workers in all the principal fields, is well worth while.

At the business session of Section G, John T. Buchholz, of the University of Arkansas, was elected to be a member of the section committee, his term of office to end January 1, 1926. Professor F. E. Lloyd of McGill University, was selected as vice-president for Section G for 1922.

Botanical Society of America. This society held sessions beginning Wednesday morning, December 28, 1921, and continuing through Friday. On Thursday afternoon the Mycological Section held a joint session with the American Phytopathological Society, and on Thursday afternoon the Physiological Section met in conjunction with the American Society for Horticultural Science and the Ecological Society of America. At the sessions of the Botanical Society of America, eighty-seven scientific contributions were read. The dinner for all botanists was held on Friday evening. After the dinner Dr. Marshall Howe read "A Communication from the Retiring Vice-president," Dr. N. L. Britton.

American Phytopathological Society.-Sessions of this society were begun on Wednesday morning, December 28, and continued until Saturday morning. At the business sessions of this society the following officers were elected: President, E. C. Stakman, University of Minnesota, St. Paul, Minn.; vice-president, N. J. Giddings, University of West Virginia, Morgantown, W. Va.; secretary and treasurer, G. R. Lyman, Bureau of Plant Industry, Washington, D. C. One hundred and seven scientific contributions were read during the sessions. The Phytopathologists' dinner was held on Thursday evening, the dinner being followed by a discussion of important topics, and a short business session.

Board of Control of Botanical Abstracts.Business meetings of the Board of Control were held on Tuesday, Wednesday and Thursday. During these meetings various matters were given attention including the election of editors and various considerations in connection with the publication, financial support, and circulation of Botanical Abstracts.

The Toronto meeting, from the viewpoint of the botanists, was a very successful gathering, and the attendance of plant workers was greater than had been anticipated.

ROBERT B. WYLIE,

Secretary

SECTION I-PSYCHOLOGY

THE meeting of Section I (Psychology) at Toronto was a very successful one. Although the affiliated society was meeting elsewhere, a considerable number of American psychologists attended the sessions, and to these were added several Canadian psychologists and a good many professional men and women who are interested in psychology from the point of view of its practical applications to education, business, criminology and related fields. The program was enriched by contributions from a number of men who represented these interests. The discussion of the papers was lively and in some sessions had to be limited for lack of time. The attendance at the meetings averaged about 25 and reached 125 at one session.

As is usual, there was at the Toronto meeting an intimate relation between the sessions of Sections I and Q (Education). Sessions were held conveniently in the same building, and two were joint sessions. The papers in these sessions dealt with mental tests or with psychological studies in education. There was apparent in the discussions of mental tests a disposition to examine somewhat more critically the conclusions to be drawn from the results of mental tests than has prevailed in the past. Of the other papers special mention may be made of one by Professor Thorndike in which he distinguished two types of equation-the equation for solution and the equation which expresses relationship—and advised that special care be taken to avoid confusion between the two.

The first session was devoted to general papers. Professor Dale discussed the place of psychology in university curricula, emphasizing the need of giving it reality by relating it to the practical problems of life. Professors Brett and Pillsbury discussed a number of the important issues on which modern psychologists differ, and Professor Weiss discussed

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One morning session was devoted to applied psychology. The problems in this field were discussed from the point of view of employment relations, of job analysis, and of dealing with the handicapped in occupation, by Mr. George W. Allen, Professor E. K. Strong, Jr., and Mr. Norman L. Burnett, respectively. Dr. Alfred E. Lavell, chief parole officer of Ontario, described the beneficial effects of supervised employment upon paroled prisoners.

The last session opened with two general papers on mental tests and their significance. Professor William D. Tait argued that education should be highly selective and adapted to intellectual capacity. Dr. R. M. Yerkes emphasized the need of other types of mental examination in addition to intelligence tests. The results of psychiatric and intellectual examination of Illinois prisoners were presented by Dr. Herman M. Adler. In agreement with the results of an Ohio study, his examination showed that prisoners are not a select group intellectually. He indicated, however, that they do exhibit anomalies of behavior. Psychiatry in the public schools was discussed by Dr. Eric K. Clarke. A study of the divergence between the color preferences of Indians and whites was reported by Professor T. R. Garth.

The address of the retiring vice-president, Professor E. K. Strong, Jr., dealt with the problem of propaganda. He discussed and illustrated propaganda in business, politics, and social reform (or pseudo-reform), and raised the question whether it is possible to control it or neutralize its effects. Control he recognized as very difficult, but suggested that it might be necessary to modify the legal theory of refraining from interference until propaganda could be shown to issue in overt

acts. The essential nature of propaganda is appeal to the emotions, and this makes control useless unless it takes effect when the general emotional foundation for overt action is being laid. The emotional character of propaganda also makes difficult its control through merely intellectual illumination.

A joint dinner and smoker with Section Q

was held on Wednesday evening at which short speeches were made by Dr. R. M. Yerkes and Dr. H. Addington Bruce.

The vice-president of the section for next year's meeting, at Boston, is Professor Raymond Dodge, and the new section committeeman is Dr. Yerkes.

FRANK N. FREEMAN Secretary, Section I

SECTION O-AGRICULTURE AND ASSO

CIATED SOCIETIES

SECTION O met on Wednesday afternoon, December 28, 1921, with six associated societies. The program of the meeting consisted of a symposium on "The Cooperation of Canada and the United States in the Field of Agriculture." Dr. E. W. Allen, of Washington, delivered the retiring vice-presidential address on "The Method of Science in Agriculture," calling attention to the importance of the utilization of the most accurate scientific methods in agricultural investigations, pointing out ways in which certain lines of study now under way may be made more comprehensive and urging that attention be given constantly to the improvement of methods and that the interpretaion of all results be based more directly upon the methods employed in the work.

Following the vice-presidential address, the following papers were read:

Marketing Conditions in Canada: ARCHIE LEITCH, Ontario Agricultural College, Guelph, Canada.

Organization for research in the United States: L. R. JONES, chairman, Division of Biology and Agriculture, National Research Council.

Cooperation in research: J. H. GRISDALE, deputy minister of agriculture, Ottawa, Canada.

Some economic aspects of the wheat situation: (Illustrated with lantern slides): CARLETON R. Ball, Bureau of Plant Industry, Washington, D. C.

History and development of the Canadian Society of Technical Agronomists: F. H. GRINDLEY, Gardenvale, P. Q., Canada.

The attendance at the meeting was very gratifying, over 50 persons being present. The addresses which were given were extremely interesting, and each was followed by considerable discussion. Particular interest was evi

denced in the suggestions regarding organized research and greater cooperation between the United States and Canada in the development of research activities.

At the business session of the section, R. W. Thatcher, of the New York Agricultural Experiment Station, Geneva, N. Y., was elected vice-president, and E. W Allen, of the United States Department of Agriculture, Washington, D. C., was elected a member of the section committee, his term of office to end January 1, 1926.

At the conclusion of the meeting a dinner was held at Queen's Hall; a large number of the members of the section were in attendance. This proved to be a most enjoyable occasion, and it is hoped that a dinner for Section O and all associated societies may be arranged at subsequent meetings of the association.

The meeting and dinner of Section O were highly successful in every way, and all those in attendance were enthusiastically in favor of having similar arrangements made for later meetings. The associated societies all have their programs; it is conceded that Section O should give a more general, somewhat introductory, program and one which will be of interest to all agricultural organizations. This feature of the program at Toronto was particularly successful, the dinner being an innovation which everyone felt had added materially to the success of the meeting.

Matters

The American Society of Agronomy.-This society held a meeting on Thursday, December 29, 1921, at which a general program of agronomic interest was prepared. Ten .scientific contributions were presented; each was followed by considerable discussion. About 40 agronomists from Canada and the United States were in attendance, and the meeting was a most successful one in every way. of general interest to both crops and soils men were discussed, and the exchange of ideas between the Canadian and United States investigators was particularly valuable. Since this was not the annual meeting of the society, no business was transacted. Resolutions were adopted, however, urging the continuation of the publication of the Experiment Station Record and the Journal of Agricultural Re

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