ALBERT

Notizen: The effect of haze in vertical daylight air photography for various solar altitudes is considered. If appreciable haze is present the density of negatives exposed when the solar rays are inclined to the vertical at angles less than the lens field semi-angle may vary over the field to such an extent that the photographs will be unsuitable for survey purposes. A theoretical investigation is made and practical results analysed. Methods by which the phenomena may be avoided are suggested. The effect on negative density of the variation in shadow length across the picture is also discussed.

Notizen: In Part I the visual processes involved in depth perception are briefly described and discussed, while in Part II their application in stereo plotting and allied observations is considered. Reference is made to the visual axis, the need for and nature of eye movements, the conception of the horopter space within which fusion of the binocular images occurs and objects are seen in three-dimensions, and the tolerances for fusion implied by the existence of Panum's areas. Monocular clues make an important contribution to the perception of depth, and the apparent location of an object in space is determined by the factors of retinal disparity, convergence, angular size, perspective, motion parallax, elevation, aerial haze, etc. The following problems are then discussed: The significance of the horopter in relation to the general contour in a stereo photograph; the fusion of the images in a stereo plotting machine; the arguments for and against some convergence of the eyepiece axes; the special problems of spectacle wearers; the functions of field stop. An analysis of the visual task in contour plotting is attempted, but a more complete analysis would be possible if records were available of the observer's eye movements while plotting. Finally, chromatic aberration in relation to the Multiplex system is considered, and also in connection with the stereoscopic effect observed with differently coloured objects lying in a plane.

Notizen: The object of this paper is to provoke discussion and not to present a finished study. It deals briefly with quantitative analysis of drainage patterns in geomorphological studies and refers to methods that have recently received some attention in the United States. It points to the value of aerial photographs in such studies and asks for discussion of two important points: firstly, whether the mathematical approach is soundly based; and, secondly, whether the analytical method is likely to give useful practical results.

Notizen: The findings of this paper may be summarized in a few paragraphs which, of course, omit all qualifications of the statistical data used.1. The best single measure of economic growth from the stock (rather than the flow) aspect now available is deflated durable reproducible tangible wealth per head,1excluding military tangible assets, subsoil assets, and civilian semi-durable and perishable assets.2. The average rate of growth of real R.T.W. per head for the entire period from 1805 to 1950 is 2 percent, with a range of about 1.8 to 2.2 percent. These figures should be regarded as minima because they do not make allowance for the probable overstatement of the effective rise in the price level involved in the process of deflation and because of the omission or understatement of some types of durable assets such as soil improvement.3. The rate of growth increased from approximately 2.2 percent in the first half of the nineteenth century to 2.5 percent in the second half. The highest decadal rate for periods of about ten years was apparently reached in the‘eighties with approximately 3.8 percent. From this peak it declined to approximately 1.6 percent for the period 1890 to 1922, but rallied to 2 percent in the‘twenties. From 1930 to 1945 R.T.W. per head not only failed to grow but declined slightly, an unprecendented phenomenon due to the Great Depression and to World War II.4. Since World War II the rate of growth of real R.T.W. per head has averaged fully 4 percent. This is higher than any decadal rate known; and probably higher too than that prevailing during any previous period of prosperity. The increase of 22 percent in the five years 1946–50 seems to be as high as that in any previous period of equal length. While part of this rapid increase may be regarded as making up for deficiencies in the ratio of R.T.W. to national product created in the preceding fifteen years; and while it is uncertain how long the recent rapid rise will continue, even if we disregard restrictions on civilian capital formation under the impact of rearmament, it may be that the downward trend in the rate of growth of R.T.W. per head in evidence since the late nineteenth century has been arrested.5. During the one hundred and fifty years for which data are available and which encompass virtually the entire economic history of the United States, the structure of R.T.W. has shown considerable changes, but also a degree of stability which may be regarded as astonishing in view of the extraordinary extension of the economic area of the United States and the radical changes in the nature of its economy. In particular, the proportion of R.T.W. represented by reproducible durable assets for consumers' direct use and for use in production has changed but little.6. Residential buildings and consumers' durable goods accounted for approximately two-fifths of total domestic R.T.W. (in current prices) throughout the period, although the ratio has shown a slight tendency to rise since the middle of the nineteenth century. Within consumers' R.T.W. residential buildings have lost slightly in importance at the expense of movable durable goods. The share of government (including non-profit institutions but excluding military assets) has risen from an insignificant fraction to approximately one-eighth of total R.T.W.’The proportion of R.T.W. represented by private enterprise (including farms) has declined moderately. Within total business R.T.W. changes, however, have been very substantial. The two outstanding trends are the relative decline of R.T.W. of agriculture (excluding farmers' residences and consumers' durables), and the increase in the share of non-farm business structures and equipment, particularly prior to 1880. Non-farm business inventories, on the other hand, seem to have maintained approximately the same proportion to total domestic R.T.W. throughout the period.7. Until World War I part of domestic R.T.W. must be regarded as being the property of foreign owners. The proportion of foreign investments to R.T.W. of the United States, however, declined rapidly throughout the nineteenth century from a proportion of over one-eighth at its start to only a few percent after World War I.Investments abroad have never been substantial compared to R.T.W. They have been almost insignificant throughout the nineteenth century. Even at their peak in 1929 they represented only 7 percent of domestic R.T.W., a proportion not yet regained by 1950.

Notizen: When a rather extensive network of short distance refraction profiles was shot the following two observations were made. Firstly, the wave velocity in the weathered layer showed a quite considerable fluctuation in horizontal direction, the extreme values being of the order of 300 and 700 m/sec. A practical result of this scattering of the velocities is that an uncertainty of about 10% is introduced in the computation of the weathering corrections. The second observation is that, in the majority of cases, the travel time curve does not pass through the origin. It could be ascertained that this observation was not caused by errors in the method of observation. A probable explanation of the phenomenon is found in a theory that has been developed by Gassmann, who derived the velocity distribution for a hexagonal packing of spherical solid bodies. According to this theory extremely low velocities would occur in the first few centimeters of the crust of the earth. Qualitatively, our observations are in agreement with the theory of Gassmann.

Notizen: The geophysicists who attempted to evaluate elastic anisotropy of some bedded formations most often gave but little information about recording and interpretating the measurements.May be they did not lay enough stress on the fact that any determination of the anisotropy factor is a critical operation and that, to have some certainty. it must be made under good conditions and then discussed.Due to the very favourable conditions offered: undisturbed tectonics and topography, relatively regular series the Berriane district in Northern Sahara, is rather well suited to accurate measurements and to an anisotropy study down to 1,250 meters. Since measurements have been carried out in the wildcat drilled at Berriane by S. N. Repal, it seems interesting to communicate the results obtained and to discuss them according to the influence of high velocity layers.It can be noted that in the clay and sand series which have been investigated, anisotropy coefficient amounts to 1.09 or so.To conclude, it seems desirable that determinations made by numerous operators should allow a more accurate knowledge of the anisotropy factor in the main types of rocks.

Notizen: The aim of the present investigation is to examine the significance of the second derivative for the purpose of the prospective determination of the geological properties of the district of Offenburg, which are relatively wellknown as a result of both reflection seismic and bore profile findings.The calculation of the second derivative is carried out by means of three approximation formulae, which are compared with each other. In contrast to the isogam map the second derivative shows some additional characteristics, whose structural significance illuminates the comparison with the results of reflection seismics.A geological profile constructed on the basis of 6 wells completely confirms the geophysical findings.

Notizen: Using a comprehensive theory of the vertical force variometer, it is shown that the mean of the two readings taken in azimuths 180 degrees apart only eliminates the error of misorientation and of inclination of the knife edge if these factors are sufficiently small. The necessary accuracy in the 180 degree rotation and in the readjustment of the levels are investigated and a practical test is developed to allow the initial adjustments to be determined. Finally, a brief description of a new variometer tripod is given.

Notizen: It is known that good use can be made of calculating the second vertical derivative of gravitational and magnetic fields. The first derivative, or Vertical Gradient, has the same properties, Like the second derivative, it does not depend on the locally linear regional anomaly. Moreover, the gradient is less affected by experimental errors.The report gives a practical method of calculating the vertical gradient. Its application is identical to that in general use for calculating the second derivative, except that the numerical coefficients are different. The method also allows the establishment of formulae for downward extension of the field and its derivatives.

Notizen: In the region covered by the paper, electrical methods have been applied in four different zones:〈list xml:id="l1" style="custom"〉a) Ales-Maruejols Basin (resistive lower Oligocene blanketed by conductive Upper Oligocene);b) Ledignan and Vaunage-Lunel anticlines (faulted structures in the marly and limy Cretaceous, with different resistivities;c) Camargue (thick series of conductive sediments);d) Beziers Basin (highly complicated structures in the Mesozoic, widely blanketed by conductive Miocene).It may be assumed that electrical methods can yield valuable information enabling one to define the rugged subsurface topography of resistive strata burried under a reasonably thick cover of conductive sediments especially when a part of the lower formation outcrops even if the part exposed be small. Faults may be delineated and much, more information is obtainable than can be expected from gravity meter survey at a price not very much higher.

Notizen: For the treatment of the problems involved in the interpretation of gravity pictures this paper gives a formula that holds generally for any potential function. It provides an extended applicability of the relation used by Elkins for the computation of the second derivative, and also yields an analogous relation to derivatives of higher order of the gravity field.This relation has not been utilized to determine in details the course of the derivatives of higher order in a plane, but is merely applied to points of comparatively extreme curvature of the isogams where the differential values present a ratio favourable to the “noise level”. By this method the values of the derivatives of higher order will not be determined themselves but only the ratio's responsible for the depth of divergence in comparison with the course of an anomaly of masses replaced by points.It is shown by examples of intercalated masses that the divergence points are important and by law related to the form and position of the density contrasts themselves.An analysis of the total gravity picture is made possible by progressing from elements close to the surface to deeper ones. In this way the fundamental features of the earth's crust will be obtained. The application of the analysis process to a gravity anomaly actually measured in Northwest Germany is given.

Notizen: When refraction time signals are transmitted over a radio link between shooter and observer there is a serious risk of interference from electrical storms. This risk can be minimised by sending a series of signals at fixed time intervals and the paper describes a simple device which will do this with the required accuracy.

Notizen: Seismic reflection, telluric and gravity results are given for the lifted area of Ferrara, in Northern Italy. The agreement is shown between the available shallow seismic data and the gravity evidences. For a portion of the above area where seismic results are particularly poor the vertical gradients method gives a resolution of a gravity anomaly and confirms the telluric information. The residual gravity values, the vertical gradients and the telluric data along a seismic line crossing the zone are compared with seismic results and with evidences from adjacent wells.

Notizen: Investigations into reflection seismic on the salt structure of Heide raised the following questions:〈list xml:id="l1" style="custom"〉1) How can the different directions of trend of a series of layers be established?2) How are the contour maps of reflecting horizons to be constructed if there is no general trend of the layers?To answer these questions, the case of the subsoil consisting of a series of layers with plane reflecting beds and constant layer-velocities is treated strictly. The strike lines of the reflecting planes may be at any angle whatever. However, formulas for constructing contour maps of the reflecting planes have been derived. With these formulas, the problem quoted under 1) has also been solved.The construction of contour maps is given.For special cases, formulas are obtained which have already been proved by others.

Notizen: The triple integral for the attraction of a mass on a point is transformed in a double sum. This double sum serves to construct a graph for the rapid determination of the gravimetric influence of structures given by depth contours. The influence of topography can also be computed with this graph.

Notizen: Book review in This Article:DAWSON, R. B. Practical lawn craft and management of sports turf.

Notizen: Book reviewed inThis Articles:BEDDOWS, A. R. The Ryegrasses in British Agriculture: a Survey