摘要:

The American Geophysical Union is the American National Committee of the International Union of Geodesy and Geophysics, and the Executive Committee of the American Geophysical Union is the Committee on Geophysics of the National Research Council. The objects of the Union are to promote the study of problems concerned with the figure and physics of the Earth, to initiate and coordinate researches which depend upon international and national cooperation, and to provide for their scientific discussion and publication. In the accomplishment of these objects, the Union is divided into sections following the plan of organization of the International Union of Geodesy and Geophysics. There are now seven sections, namely, (a) Geodesy, (b) Seismology, (c) Meteorology, (d) Terrestrial Magnetism and Electricity, (e) Oceanography, (f) Volcanology, and (g) Hydrology. A Section of Geophysical Chemistry was discontinued May 31, 1924, as the International Union had failed to provide such a Section; the Section of Hydrology was established November 15, 1930—matters pertaining to scientific hydrology referred to the American Geophysical Union had been previously looked after by special committees on hydrolog

ISSN:0002-8606    

DOI:10.1029/TR012i001p00005

年代:1931

数据来源: WILEY

摘要:

WHEREAS, The United States Navy Department, in cooperation with the Carnegie Institution of Washington, conducted a gravity‐campaign in 1928, during which observations were made under the' direction of Dr. P. A. Vening‐Meinesz, Member of the Dutch Geodetic Commission, at many points in the Caribbean Sea, the Gulf of Mexico, and the Atlantic Ocean to the northward of Porto Rico, thus adding materially to the knowledge of the crust of the Earth in the regions covered, and furnishing data for the figure of the Earth, andWHEREAS, Much additional information about gravity at sea should be secured to supplement the work already done in the Gulf of Mexico, Caribbean Sea, and West Indian waters, andWHEREAS, It is only on a submarine that such observations can be made, therefore be itRESOLVED, That the American Geophysical Union of the National Research Council recommends to the Navy Department that it give thought to the question of continuing its work on gravity at sea and of securing the necessary soundings to supplement such work, especially in the waters of the West Indies including the Caribbean Sea, and be it furtherRESOLVED, That a copy of this resolution be forwarded to the Secretary of the United States N

ISSN:0002-8606    

DOI:10.1029/TR012i001p00009

年代:1931

数据来源: WILEY

摘要:

The Fourth Assembly of the International Union of Geodesy and Geophysics held at Stockholm, Sweden, August 14–23, 1930, was attended by some 302 delegates and guests from 36 countries. Countries not yet adhering to the International Union having representation through invited guests were Austria, China, Esthonia, Germany, Union of Socialistic Soviet Republics, and Venezuela. A total of 27 persons, including 14 official delegates, represented the United States and took a leading part in bringing about the good‐will reflected in the attendance of guests from Germany and Austria. The principal activity related to the unanimous adoption of the new Statutes. These Statutes call for the designation of the international sections hereafter as associations and effect a greater decentralization of the Union's own tasks so as to make its associations practically autonomous. The unit of contribution was increased so that the annual contribution from the United States will hereafter be about $3,100. Other important.actions included the approval of the proposed Jubilee International Polar Year in 1932–33, an agreement to promote cooperation of the International Research Council and its unions with societies, organisations, or institutions engaged in work extending beyond national lines, and consideration of means to more effectively distribute publications of the International Union and of its associations. The meeting place for the Fifth General Assembly of the union in 1933 was designated to be Lisbon. Portugal. Dre Lai lemand was reelected President of the Union and Brigadier Winterbotham was elected General Secretary. The following Americans are officers of the international associations: Geodesy, William Bowie, President; Seismology, H. F. Reid, Vice‐President; Terrestrial Magnetism and Electricity, J. A. Fleming, President; Oceanography, G. W. Littlehales, Vice‐President; Volcanology, H. S. Washington, Vice

ISSN:0002-8606    

DOI:10.1029/TR012i001p00010

年代:1931

数据来源: WILEY

摘要:

I am carrying coal to Cardiff when I address this assembly on the subject of the Time‐Service.Before discussing the Naval Observatory Time‐Service, a brief history of the Observatory may be of interest. An amateur astronomer, William Lambert, presented a memorial to Congress in 1809, recommending the establishment of a First Meridian in the United States at the permanent, seat of Government. Lambert had previously determined the longitude of Washington and submitted his calculations with his memor

ISSN:0002-8606    

DOI:10.1029/TR012i001p00013

年代:1931

数据来源: WILEY

摘要:

In different problems in physical and electrical measurements, one of the most serious problems is that of securing reliable and frequent time‐signals. While the rates of good clocks and chronometers can be determined from the Arlington signals as supplied by the Naval Observatory to the required accuracy, the second or half‐second signals obtained from them are not sufficiently reliable and in some cases not of sufficient frequency to meet the needs. For some of these problems, what is needed is 20 and preferably 100 or 1,000 signals per second uniformly spaced over each second to a 0.0001 second or, better, and uniform over periods of an hour or mora to a part in a million or better. Second‐to‐second tests of the signals obtained from the Bureau of Standards Riefler clock through the contact supplied with it and relays show a dispersion of 0.01 second and more, so it would not meet the requirements even if the signals were of sufficient frequency. Figure 1 shows a record of the signals from the Riefler clock as well as from a chronometer. The missing signals are at the 59th seconds of alternate minutes. The more uniform signals are from the chronometer, and these serve to show that the scattering of the signals from the Riefler clock are not to be attributed to the recording‐

ISSN:0002-8606    

DOI:10.1029/TR012i001p00021

年代:1931

数据来源: WILEY

摘要:

Radio time‐signals are used by the Coast and Geodetic Survey in carrying on the field‐operations in (1) longitude‐determination, (2) gravity‐determination, and (3) azimuth‐measurement. A brief description will be given of the present methods employed on these phases of the geodetic operations and the, advantages which would be realized from more frequent signal‐broadcasts wil

ISSN:0002-8606    

DOI:10.1029/TR012i001p00023

年代:1931

数据来源: WILEY

摘要:

James B. MaceIwane, S.J., Director, Department of Geophysics, Saint Louis University, Saint Louis, Missouri (April 14, 1931)—I regret very much that my illness and a comparatively slow recovery with the consequent interruption of classes has made it impossible for me to prepare a paper or to get away from the University for the meeting of the Union. I should have liked very much to be present and to take part in the discussion, particularly of the project of more frequent broadcasting of time‐signals for seismographic records. The difficulties in the way of reception and the comparatively large cost might prove insuperable obstacles to routine broadcasting of minute‐to‐minute signals. If the difficulties could be overcome minute‐to‐minute signals would be the ideal. It would be a great step forward if we could have hourly time‐signals of precise character. Cost of these would not be so great and it would permit the placing of a sufficient number of precise time‐marks on each record to permit the construction of a comparatively exact correction‐curve and would synchronize rather effectively all the records

ISSN:0002-8606    

DOI:10.1029/TR012i001p00025

年代:1931

数据来源: WILEY

摘要:

The following signal time‐service is offered for the consideration of the Union as a basis for the establishment of a system of international or world‐time, the important need for which is daily becoming increasingly evident.That our basis of physical measurement rests upon determination of mass, space, and time is idiomatic. Standard units of mass and space may be made available and compared without much effort—witness our standardization‐laboratories. In many physical measurements, however, a standard unit of time which in three‐dimensional space cannot be carried about as a standard gram or centimeter is of utmost importance. Synchronous observations at widely separated points under the present system are not practical and cannot be made except at great expense. A zero‐line so to speak from which to measure time everywhere at the same unit‐intervals does not exist. Phenomena under present conditions which require synchronous observations are also difficult to make with a high degree of accuracy. The second, which once was thought to meet our needs as the smallest unit of time, has become an inordinately long interval for many physical measurements and one‐millionth of a second or microsecond now often proves a more convenient unit. “Simultaneous‐time” observations to an accuracy of at least one micro‐second would be very acceptable at the present moment in

ISSN:0002-8606    

DOI:10.1029/TR012i001p00026

年代:1931

数据来源: WILEY

摘要:

This paper sets forth the possibilities of standard‐frequency radio transmissions in connection with time‐standards. The subject is approached from the radio viewpoint but the usefulness of the transmissions to certain classes of needs for time‐service is apparent. A clear distinction should be understood at the outset, that between calendar time, on the one hand, and time‐intervals or rates, on the other. There is no known method by which calendar time can be given other than by the furnishing of time‐signals, of which the United States Naval Observatory time‐signals are the outstanding example. As for the second class of service, it is abundantly evident that time‐signals destined for the first purpose could never be given at sufficiently frequent intervals to serve all the needs for accurate standards of time‐diffe

ISSN:0002-8606    

DOI:10.1029/TR012i001p00027

年代:1931

数据来源: WILEY

摘要:

The problem of maintaining a frequency‐standard resolves Itself into two main parts. First, we must have an oscillating system which maintains a frequency sufficiently steady so that its fluctuations are negligible in comparison with the errors of measurements made against it. Second, we must have some way of finding out how constant the frequency is, and what is its absolute valu

ISSN:0002-8606    

DOI:10.1029/TR012i001p00029

年代:1931

数据来源: WILEY