摘要:

The Hawaiian Islands form a chain of volcanic mounds on a fairly level ocean‐floor. The largest and most recent are at the southeast end of the chain. There are still several active volcanoes on Hawaii, the largest island of the group. The Coast and Geodetic Survey has 19 astronomical latitude‐observations and 15 gravity‐determinations on the larger islands of the Hawaiian group. The large positive isostatic gravity‐anomalies and the isostatic deflections in the meridian indicate very definitely that the Hawaiian Islands are by no means isostatically compensated. Major William Bowie and C. H. Swick have frequently called attention to the large positive gravity‐anomalies indicating the uncompensated island‐masses. In 1924, Mr. Swick computed the density of the island‐blocks of Hawaii and Oahu from the gravity‐anomalies at Mauna Kea and Honolulu, respectively, assuming the extra mass to be in the island‐blocks. The islands were assumed to be compensated. He arrived at a density of 3.62 for Hawaii and 3.34 for Oahu. In his studies of the gravity‐anomalies in the Hawaiian Islands, Roy W. Goranson [The density of the Island of Hawaii and density distribution in the Earth's crust, Amer. J. Sci., v. 16, pp. 90–120, August 1928] comes to this conclusion: “The inference is, too, that the volcanic islands of the Pacific are essentially uncompensated (sinking) loads on

ISSN:0002-8606    

DOI:10.1029/TR024i001p00034

年代:1943

数据来源: WILEY

摘要:

In view of the paper which was given at this meeting last year by Mr. Samuels of the Hydrographic Office, I do not propose to go into a minute discussion of the prismatic astrolabe or the theory of its operation. However, to recapitulate briefly, the prismatic astrolabe was invented by Monsieur A. Claude, of the French Bureau of Longitudes, and Monsieur L. Driencourt, the Chief Engineer of the Hydrographic Office of the French Admiralty.

ISSN:0002-8606    

DOI:10.1029/TR024i001p00039

年代:1943

数据来源: WILEY

摘要:

The National Research Council Committee on Fundamental Physical Constants recently appointed a Subcommittee on Gravity to study the various determinations of the absolute value of gravity and to recommend a “best” value. This Committee consists of E. A. Eckhardt, W. D. Lambert, A. H. Miller, A. Romberg, and the aut

ISSN:0002-8606    

DOI:10.1029/TR024i001p00042

年代:1943

数据来源: WILEY

摘要:

During the past year, the field‐survey work of the Division of Geodesy has been accomplished entirely for the military forces. Most of the surveys executed are to locate monuments to serve as control‐points for the mapping being accomplished in certain strategic areas in connection with the War Department mapping program. We have also provided the control for surveying and mapping at several of the outlying bases recently acquired by the United States. Control has also been established for the Coast Artillery Corps of the Army at a number of their posts located along the co

ISSN:0002-8606    

DOI:10.1029/TR024i001p00043

年代:1943

数据来源: WILEY

摘要:

(I) TriangulationsFour geodetic nets were developed in 1942:(a) The triangulation of the State of Jalisco(b) The triangulation of the Laguna (Durango‐Coahuila)(c) The connection of the triangulations of the State of Zacatecas and those of the Laguna(d) The triangulation of the Valley of Guadalajara.The triangulation of Jalisco (see Fig. 1) covers an area of 28,874 square kilometers and consists of 18 geodetic points at which the angles were measured with a “Wild” precise theodolite. This triangulation is the geodetic net on which the topographical surveys in the State of Jalisco are being based. It consists of six primary triangulations tied‐in on the Lerma and Santiago River triangulations, by means of the lateral sides Jamay‐Cerro Viejo and Llorón‐Reventón, and on a base‐line eight kilometers long situated in the vicinity of the City

ISSN:0002-8606    

DOI:10.1029/TR024i001p00049

年代:1943

数据来源: WILEY

摘要:

For some years seismologists have been collecting data relative to the existence of high‐speed surface‐waves over Atlantic paths similar to those which have been observed over Pacific paths. In the Atlantic Ocean there has been difficulty in obtaining all ocean paths of sufficient length so that identification of the wave‐groups could be accomplished without confusion. The Meteorlogical Service at Bermuda (M. A. Macky in charge), the Woods Hole Oceanographic Institution, and the United States Coast and Geodetic Survey arranged jointly to have a seismograph installed at St. Georges, Bermuda, in 1939. This was done with the hope that enough data might be accumulated so that more definite conclusions might be drawn. The earthquakes of November 10 and 28, 1942 (see Fig. 1), gave good results in that the high‐speed (Love) waves are clear and well defined for an Atlantic path. They indicate an average speed of about 4.5

ISSN:0002-8606    

DOI:10.1029/TR024i001p00057

年代:1943

数据来源: WILEY

摘要:

Uncertainty affecting the estimation of prior probabilities has led to the growth of a school which evades the difficulty by setting up a definition of the class of “significant” observations is which the prior probability does not appear.The purpose of this paper is to state one of the objections to this method. For concreteness let the likelihood or inverse probability p of an observation be defined on a three‐dimensional space. We seek to define a surface which shall divide the points of this space into two subclass the significant and the insignificant. Part of the definition of the surface is that the integral of p over the significant points shall have a prescribed value, P; we therefore call the surface an iso‐P

ISSN:0002-8606    

DOI:10.1029/TR024i001p00060

年代:1943

数据来源: WILEY

摘要:

The purpose of this paper, as its title indicates, is to show a possible application of the newly developed exponential formula of gravitation to the solution of certain geophysical problems. Among these problems are those dealing with the epeirogenic and orogenic movements of the Earth s crust in general, together with several particular aspects of these two great phenomena, for example, periodicity of mountain‐building, parallelism in oppositely situated coasts, “swelling” of ocean‐beds, concentration of earthquake occurrences in the regions of recent and present‐day mountain development, glacial periods, and also an allied astronomical problem—the explanation of the variations in the length

ISSN:0002-8606    

DOI:10.1029/TR024i001p00061

年代:1943

数据来源: WILEY

摘要:

The seismological work of the Coast and Geodetic Survey continued with little interruption during the period covered by this report in spite of some curtailment in personnel and other unfavorable conditions resulting from the war effort. Some major difficulties, however, such as the procurement of recording film, may at any time impose serious restrictions on the current program.Teleseismic work—In the teleseismic field about 25 stations cooperating with the Survey continued in operation. At one outlying station there was a temporary interruption of about six months but normal operation was then resumed. The Washington office continues to exchange teleseismic data on important Mexican earthquakes with the Central Seismological Station at Tacubaya and there also has been cooperation with other Latin‐American countries in the discussion of earthquake‐problems. Special measures have been taken with friendly countries in the Pacific war zone to improve the earthquake‐telegram service in order that satisfactory epicenters might be obtained within, as well as outside of, territory of the enemy. In the Washington office 43 preliminary determinations of epicenter cards were issued on the basis of telegraphic data received throughScience Service, theJesuit Seismological Association, and other cooperating agencies. The Survey is extending aid to the Government of New Zealand in the purchase of new seism

ISSN:0002-8606    

DOI:10.1029/TR024i001p00088

年代:1943

数据来源: WILEY

摘要:

Due to the various defense projects started at Sitka during 1938 and 1939 and the resulting influx of construction workers, there was brought about an acute housing shortage in the town. In order to meet the demand for houses and apartments, a large number of small dwellings were hastily constructed. A number of these new buildings were erected very close to the buildings of the Observatory and the continuity of the magnetic observations at the Sitka Observatory was threatened. Land belonging to the Department of Agriculture and used for an experimental farm was transferred to the Coast and Geodetic Survey as a site for the Observatory. A special appropriation from Congress made it possible to construct new buildings at this site, and the Observatory was moved to this location on the outskirts of the town of Sitka in the fall of 1940 [see 1 of “References” at end of pap

ISSN:0002-8606    

DOI:10.1029/TR024i001p00091

年代:1943

数据来源: WILEY