摘要:

Deflections of the vertical were computed for five points over a range of 100 km in central Ohio, using free‐air anomalies out to 1500 km and isostatic anomalies, with corrections, for the rest of the Earth. For ξ at all five points, and for η at three mints, agreement with the astronomically observed deflections was obtained to within 0.″67; errors in astronomic longitude are shown to cause disagreement in η at two points. The probable error of the gravimetrically computed deflection on the assumption of random variation of the mean anomalies of five‐degree squares was computed to be ±0.″38; on the assumption of random variation of the mean anomalies of 30° squares,

ISSN:0002-8606    

DOI:10.1029/TR035i004p00549

年代:1954

数据来源: WILEY

摘要:

Total‐intensity aeromagnetic surveys of the Aleutian Marshall, and Bermuda Islands were completed in 1948. The anomalies associated with the Aleutian volcanoes are attributed mainly to topographic relief and are not an indication of the degree of volcanic activity. Eniwetok presents a magnetic pattern that would be produced by an irregular‐shaped rimmed depression in the basement, modified by the two adjoining seamounts, and differs from Bikini, whose magnetic features would be produced by a broad seamount with irregular surface relief. The Bermuda survey demonstrated magnetic features typical of volcanic rocks. Comparison of an observed and a theoretical profile computed by Press and Ewing indicates that their assumptions are reasonably correct. The Aleutian Trench survey shows anomalies that are attributed to susceptibility contrasts but none that can be correlated with the trench. A traverse from Adak, Aleutian Islands, to Kwajalein, Marshall Islands, exhibited several large anomalies that are presumed to be caused by susceptibility contrasts but may be indications of uncharted seamounts. Two traverses, one from Cape May, N.J., to Bermuda and the other from Bermuda to Long Island, N.Y., reveal a change in the magnetic field approximately 300 miles from the Atlantic Coast that indicates a possible thinning of the sial and an exposure of s

ISSN:0002-8606    

DOI:10.1029/TR035i004p00558

年代:1954

数据来源: WILEY

摘要:

Stations occupied south of Nantucket Island in the region of the discontinuity between the outflow waters of the Gulf of Maine and the denser offshore water show density inversions in the middle levels. The inversions are correlated with the tidal period, but not with the diurnal period. Rayleigh's instability criteria and other methods are used to investigate the conditions under which such inversions can exist. An equation is derived to obtain current velocities at different levels throughout the tidal period, from the surface tidal currents. Trajectories for each level indicate extensive overrunning of the lower layers by the upper layers during each tidal period. The magnitude of this overrunning is sufficient to reverse the slope of the discontinuity surface between the Gulf of Maine waters and the offshore waters, and to cause the inversions observed. A comparison between the conditions off Nantucket Island and cases of instability in other parts of the Atlantic Ocean shows a basic dissimilarity between them.

ISSN:0002-8606    

DOI:10.1029/TR035i004p00573

年代:1954

数据来源: WILEY

摘要:

Time changes in the thickness of a thin surface layer of a two‐layer ocean are proportional to the curl of the wind stress if accelerations are sufficiently smal

ISSN:0002-8606    

DOI:10.1029/TR035i004p00585

年代:1954

数据来源: WILEY

摘要:

The hydraulic head loss for flow occurring at an interface between sands or gravels of different sizes was studied by experiment. Dimensional analysis was used in formulating the experiments and in analyzing the data which led to a simple relationship in which the hydraulic head loss at the interface is a function of the mean diameter of the smaller‐sized sand or gravel, the Reynolds number for the flow through the smaller‐sized gravel, and an empirical constant which appears to depend principally on the mean size and size distribution characteristics of the two sizes of sand or gravel. The experiments provided an opportunity to observe the action of sands or gravels used as filters and observations confirmed the opinion of Terzaghi and others that for uniform‐sized sands the ratio of the mean diameter of the filtering sand to that of the sand to be filtered must not exceed approximately five in order that the smaller‐sized material be excluded from the pores of the larger‐sized

ISSN:0002-8606    

DOI:10.1029/TR035i004p00588

年代:1954

数据来源: WILEY

摘要:

A source of fast neutrons and a slow neutron detecting device in close proximity have been used to measure the moisture content of soil. The work was done with a 10‐mc Ra‐Be source and a BF3‐filled counter (2.5×30 cm). Rates varied between 16 and 2 counts per second. The vertical extent of the soil layer contributing 95 pet of the measured counting rate varied from 65 cm with very dry material (4.4 pct water by volume) to 45 cm with saturated material (38 pet water by volume). It has been shown possible, by partial shielding of the counting tube with cadmium foil to increase vertical resolution, at expense of counting rate. This procedure is not very effective, h

ISSN:0002-8606    

DOI:10.1029/TR035i004p00595

年代:1954

数据来源: WILEY

摘要:

Careful measurements were made of evaporation of soil water during 1921 in California at Davis, Delhi, Mountain View, and Whittier. The soil surface was kept free of vegetation and no rain fell for periods of eight to 12 weeks. Analyses of the records indicate that an average curve of evaporation loss against time may be useful for situations where more exact data are not available. Other studies of soil in tanks reveal that, after the first week, the evaporation rate from bare soil without a water table is extremely slow. For a period of 1547 days during which rain was excluded, the average evaporation rate was 0.00236 inch/day. When water tables were maintained at depths between 0.5 and 5.0 ft it was found that the evaporation loss from uncropped soils with high water table was not directly proportional to the depth from the soil surface to the water table.

ISSN:0002-8606    

DOI:10.1029/TR035i004p00601

年代:1954

数据来源: WILEY

摘要:

A simple graphic solution is described for approximating the length of time required to detect significant differences between treatments on experimental watersheds.

ISSN:0002-8606    

DOI:10.1029/TR035i004p00608

年代:1954

数据来源: WILEY

摘要:

A solution to the problem of wave motion produced when a pressure pulse is applied to the interior surface of a spherical cavity in a visco‐elastic medium is obtained. Comparison with the elastic case indicates that viscosity significantly reduces the amplitude of the displacement in the vicinity of the wave front and decreases the velocity of propagation of the wave.In the addendum, a pressure‐time pulse defined by a function of the form P (t) = Pζt exp (‐ζt) is applied to the cavity wall and a solution of the differential equations of motion is obtained using the theory developed in the main body of the paper. Since all values of the parameter ζ are admissible, pressure‐time pulses of arbitrary form may be represented by superposing individual pulses of the above form corresponding to different values of ζ.Terminology—The following symbols are used.r,α,θ= spherical coordinates defined by: the surfaces of spheres, r= constant; radial planes perpendicular to some plane through the origin,α= constant; and right circular cones with vertices at the origin,θ= constantσ= stressϵ= strainG= elastic modulus of rigidityλ= elastic Lame constant defined by Eν/(l+ν) (l‐ 2ν) where E is the modulus of elasticity andν is Poisson's ratioK= coefficient of viscosity analogous to Gμ= coefficient of viscosity analogous toλΔ=cubical dilatationu= displacementt= time variableδ= cavity radiusρ= densitya= acceleration∇2

ISSN:0002-8606    

DOI:10.1029/TR035i004p00613

年代:1954

数据来源: WILEY

摘要:

A vector system is established in a finite hemisphere, and certain pertinent relationships are derived for lines located in the same plane. An example for the solution of field problems with the application of the vector system is given.

ISSN:0002-8606    

DOI:10.1029/TR035i004p00625

年代:1954

数据来源: WILEY