摘要:

It is a remarkable fact that when a reasonably rigid survey, A, having a sound first order frame and filled out in the proper manner with second and third order points, is connected to a similar survey, B, the differences in latitude and longitude of common points will be nearly constant as shown in Table 1.This regularity is explained by the fact that the major parts of the differences are caused by different astronomical values being used as origins for the surveys, with their different deflections of the plumb. Evidently, if corrections of −6″.7 in latitude and +3″.3 in longitude are applied to the B positions, we shall improve the agreement greatly; the remaining residuals will be of the order of ±0″.2 or 20 feet. On a map on scale of 1:25,000, this will amount to only about 0.01 inch, which is within the error to be expected from scaling, plotting, paper shrinkage and lack of registration. Therefore, it is satisfactory for most cartographic purposes. On the other hand, it leaves much to be desired geodetically, since no correction has been made for difference of spheroid, nor for difference in azimuth or scale between the two surveys. These differences, imperceptible over a small area, will become extremely serious if the area is large. Moreover, when we consider the requirements of survey, even of the lowest grade, the above mentioned 20 foot cassures are obviously t

ISSN:0002-8606    

DOI:10.1029/TR028i004p00519

年代:1947

数据来源: WILEY

摘要:

A study has been made of the methods of classification and preservation of aerial photographic negatives and prints that are used by various governmental agencies. The general plan of filing is described as well as the availability of prints to users. A more efficient use of the accumulated data can be accomplished by placing all of the records under the care of the National Archives.

ISSN:0002-8606    

DOI:10.1029/TR028i004p00523

年代:1947

数据来源: WILEY

摘要:

The geological influence on the transmission of microseisms in the Caribbean region is extended over new areas. Estimated effective ranges for tracking hurricanes by three types of seismographs are suggested.

ISSN:0002-8606    

DOI:10.1029/TR028i004p00528

年代:1947

数据来源: WILEY

摘要:

This paper discusses methods of obtaining a continuous chart record of wind direction to 16 points, from a standard eight‐point contacting wind vane, without either position ambiguities or “swee

ISSN:0002-8606    

DOI:10.1029/TR028i004p00534

年代:1947

数据来源: WILEY

摘要:

The weather pattern associated with waves in the Westerlies of the higher latitudes indicates ascending motion near the troughs and descending motion near the ridges, so that the trajectory of each air parcel that flows eastward through the waves has the three‐dimensional form of a left‐handed helix. Non‐adiabatic cooling and heating of the air, as it flows poleward and equatorward along its helical path, causes the air to lose heat when its pressure is low and to gain heat when its pressure is high, making the circulation work‐producing, it is shown that the kinetic energy thus generated is of the same order of magnitude as the dissipation of the kinetic energy by internal and surface friction, thus causing the Westerlies to be maintained in a stead

ISSN:0002-8606    

DOI:10.1029/TR028i004p00539

年代:1947

数据来源: WILEY

摘要:

This paper describes a new station‐type magnetometer built with a magnetic detector based upon a saturated core‐type transformer principle. The instrument is built in its most universal form, with the detector unit mounted on a somewhat special engineer's transit, and permits measurements of magnetic declination, dip, total field intensity, and horizontal and vertical components. Sensitivity is adjusted to about 10 g per divis

ISSN:0002-8606    

DOI:10.1029/TR028i004p00545

年代:1947

数据来源: WILEY

摘要:

Surface currents and the topography of the sea surface resulting from a wind blowing over a rectangular basin of constant depth are derived. The basic equations are identical with those in Ekman's theory for wind‐driven currents on a rotating globe, and the assumption of a constant Coriolis parameter, a constant eddy viscosity, and steady‐state conditions have been retained. Unlike Ekman, who considered the ocean of infinite extent, the author has taken into account the effect of the boundaries. Wind velocity is assumed to vary with position, to be at a maximum in the center of the basin and zero at the up‐wind and down‐wind sides. Numerical values for the special case of a square basin ar

ISSN:0002-8606    

DOI:10.1029/TR028i004p00549

年代:1947

数据来源: WILEY

摘要:

The eruptive activity of Parícutin Volcano has been classified by Ezequiel Ordóñez and Ariel Herńandez Velasco into three phases, each seeming to follow the other in succession: (1) The tubular eruption, consisting of explosive reports as if from tube‐like cannons, synchronized with puffs of vapor and forming a column charged with much pyroclastic material; (2) the silent eruption, varying from rolling, thunder‐like explosions, deep and subdued, through periods of complete silence, to rare noises like the faint beating of the surf, accompanied by the emission of considerable pyroclastic material; and (3) the gaseous eruption, characterized by a steady noise like that of escaping steam, during which white vapors are emitted; at times, stained yellow with traces

ISSN:0002-8606    

DOI:10.1029/TR028i004p00559

年代:1947

数据来源: WILEY

摘要:

The following is a summary of observations of the activity of Parícutin Volcano, Michoacan, Mexico, from the time of the writer's arrival there, September 18, until November 30, 1946, and continues the account of the preceding period by Segerstrom and Gutiérrez [see “References” at end of paper, 1947].This report consists primarily of the graph of eruptive characteristics,. Figure 1, and lavaflow maps, Figures 2 to 4. Since most of the generalities and details of the activity can be obtained by examination of these figures, the written portion of the report will deal only with points of special interest in the figures and with information not there repres

ISSN:0002-8606    

DOI:10.1029/TR028i004p00567

年代:1947

数据来源: WILEY

摘要:

Reservoir operations for passage of flood waters customarily depend upon water levels in the reservoir or upon flows entering the reservoir. Both of these factors are influenced materially by the manner of operation of other reservoirs in the watershed, and by the construction and operation of any dam, levee, or channel improvement in the upstream flood plain. The purpose of this paper is to present a criterion of effective operation which would independent of upstream reservoir operation and which would also be equitably alterable as upstream developments increase or decrease the flood‐control capability of the reservoir system. Advance drawdown of pool levels for flood storage and the control of a tributary to keep its flow off the flood peak of a main stream are illustrated. The method is presented as being most useful in reservoir developments principally for power generation, irrigation, and navigation, and secondarily for flood control; and most needed in developments in which only a small amount of reservoir storage capacity is reserved for flood‐time

ISSN:0002-8606    

DOI:10.1029/TR028i004p00573

年代:1947

数据来源: WILEY