摘要:

The American Geophysical Union was established in 1919 as the American Committee of the International Union of Geodesy and Geophysics, and its Executive Committee 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/TR017i001p00003

年代:1936

数据来源: WILEY

摘要:

The practical and scientific phases of geodesy are so intimately entwined that I shall not in this short paper try to treat them separately. What is of scientific value today may be of immense practical value tomorrow and, conversely, work done in the field of geodesy as an engineering operation may later have great scientific value.Until recently, geodesy was looked upon merely as a scientific subject involving the determination of the shape and size of the Earth, but it has expanded greatly from this early objective. We now not only use geodetic observations to obtain the dimensions of the Earth, but we are trying to determine the undulations of the surface of the geoid. we have learned that mean sea‐level is not an equipotential surfac

ISSN:0002-8606    

DOI:10.1029/TR017i001p00015

年代:1936

数据来源: WILEY

摘要:

The history of the application of geophysical methods to the study of oceanic basins and their margins shows an encouraging acceleration of activity since the last meeting of the American Geophysical Union. The determination of gravity at sea has been continued by Holland, Italy, France, and Japan, with the help of their respective navies. Outstanding in marine gravimetric surveys has been the recent comprehensive and arduous expedition of Dr. F. Venlng Meinesz, not only the pioneer but still the most active exponent of this type of research.

ISSN:0002-8606    

DOI:10.1029/TR017i001p00020

年代:1936

数据来源: WILEY

摘要:

A survey of the field of modern research in seismology will reveal a surprising activity in three distinct fields: The field of pure seismology; the field of engineering seismology or of seismological engineering; and the field of applied seismology or of seismic prospecting. We may consider these briefly in succession.In pure seismology emphasis is shifting from average results and statistical studies to the intensive investigation of individual regions and of individual earthquakes. Even in those cases in which genuine contributions have been made along statistical lines, as, for example, in the exhaustive paper by Jeffreys and Bullen “On the times of transmission of earthquake‐waves” (Bur. Central Séeis. Pub., A, Travaux Scientifiques, No. 11, 1935), the material has been sifted in such a manner as to bring out the distinguishing characteristics of earthquakes by means of particular constants. Also, in the three papers “On seismic waves” by Gutenberg and Richter (Beitr. Geophysik, v. 43, pp. 56–133, 1934; v. 45, pp. 280–360, 1935; v. 47, pp. 73–131, 1936) individual earthquakes are discussed. At the Fourth General Assembly of the International Union of Geodesy and Geophysics at Stockholm and again in the Fifth Assembly at Lisbon, the pressing need for the intensive study of individual earth

ISSN:0002-8606    

DOI:10.1029/TR017i001p00023

年代:1936

数据来源: WILEY

摘要:

Meteorological research is not characterized, to as great an extent as are many other fields of science, by prominent trends; that is, current meteorological literature is not in general dominated by discussions of any one particular topic or problem, but rather many widely different problems are constantly being subjected to investigations that are comparable in extent and that result in steady, even if not spectacular, progress throughout the field of meteorology. It occasionally happens, however, that for one reason or another an especially significant development takes place in connection with some particular problem, and for a time commands unusual attention. As past examples, there may be cited the striking development of the theory of turbulent motion in the lower atmosphere and its application to the explanation of a wide range of meteorological phenomena, which began with the work of G. I. Taylor in 1915; and the extensive work on the polar‐front theory of atmospheric circulations, initiated by the Norwegian meteorologists about 191

ISSN:0002-8606    

DOI:10.1029/TR017i001p00025

年代:1936

数据来源: WILEY

摘要:

During the fall of 1933 the Coast and Geodetic Survey initiated a project in each State under the Civil Works Administration for the establishment of lines of surveying monuments at a closer spacing than pertains to the regular program of surveys conducted with its own field force. These surveying monuments are located geodetically and serve as control‐stations for mapping and local surveying uses. Any maps or surveys adequately tied into such control‐survey monuments will bear a true relationship to each ot

ISSN:0002-8606    

DOI:10.1029/TR017i001p00036

年代:1936

数据来源: WILEY

摘要:

In September, 1821, the Spanish Colony now known as Central America declared its independence from Spain and formed the republics of Guatemala, El Salvador, Honduras, Nicaragua, and Costa Rica. The area, was largely an unexplored jungle and included only a few isolated and scattered settlements. The boundaries and limits were very vague, as the prime purpose was independence from Spain. In a short time the natural resources of the republics resulted in a large number of settlements. When settlements became numerous and many valuable minerals were found, boundary‐disputes arose between adjacent countries. These led to litigation and resulted in much confusion and expenditure of mone

ISSN:0002-8606    

DOI:10.1029/TR017i001p00038

年代:1936

数据来源: WILEY

摘要:

For several years the United States Coast and Geodetic Survey has carried on intermittently a series of experiments with color‐filters on first‐ and second‐order theodolites and first‐order levels in an attempt to improve the appearance of the object pointed upon by eliminating as far as possible the disturbances caused by heat‐radiation and scattering light. It is consistent with Huyghen's theory that the red and yellow filters are found to be the best for absorbing the disturbing lights of the short‐wave length, namely, those approaching the ultra‐violet part of

ISSN:0002-8606    

DOI:10.1029/TR017i001p00041

年代:1936

数据来源: WILEY

摘要:

In addition to reporting the progress made during the past year on the determination of the absolute value of gravity at Washington, the author of this paper discussed the desirability of having absolute determinations made in other countries, as outlined in the following proposed item for the agenda of the Edinburgh meeting of the International Association of Geodesy:“It is desirable that the absolute value of gravity be determined in as many places as possible and that adequate gravity‐connections between these places be established.“Note—The determination of the absolute value of gravity is of considerable importance to physicists but requires a long series of carefully planned experiments. The most recent determinations fail to agree with one another within desired limits, so that further study of this problem should be encouraged. Geodesists should cooperate with physicists by establishing strong connections by means of relative determinations of gravity at places where absolute determinations have been made, since without such connections the various absolute determinations are not comparable, and for the furtherance of their own science they should strengthen the gravity‐net of regional and national base

ISSN:0002-8606    

DOI:10.1029/TR017i001p00043

年代:1936

数据来源: WILEY

摘要:

A few years ago a gravity‐anomaly was something which a specialized scientist used in determining the size and shape of the Earth and in related studies, but today it has become one of the most useful tools in geophysical prospecting and in geological studies. A demand has thus been created for many additional gravity‐stations throughout the world and practically every major nation on the globe is today making gravity‐observations and doing research to perfect instruments that will give more accurate results and at the same time do more rapid work. The United States Coast and Geodetic Survey made a big step forward in 1932 when the new Brown instrument was put into operation. During the past year two new instruments of this type have been constructed and will be available for field‐work in the near future. Considerable research has also been done to increase the accuracy of our recording devices, so that a shorter time‐interval might be used in making an observation. At the present time the pendulum is swung at each new station for a period of six hours, which gives a value of gravity with an accuracy of about one part in

ISSN:0002-8606    

DOI:10.1029/TR017i001p00044

年代:1936

数据来源: WILEY