THE ATTRACTION OF THE “COMPENSATION” ON THE PRATT HYPOTHESIS

Abstract

In the last issue there was given an outline of modern theories on crustal equilibrium. The assumption as to uniform attenuation of matter beneath an elevated station suggests that an explanation of a means for calculating this “compensation” would be desirable; the complete technical procedure used by those actually engaged on work of this nature could be described by themselves alone.     

THE ORTHOMORPHIC PROJECTION OF THE SPHEROID—IV

Abstract

We now turn to a question which has received much attention of recent years; the possibility of transforming angular and linear field measures to an orthomorphic projection so that the results of a survey may be computed directly in plane Co-ordinates without having to go through the spheroid at all. Initially, orthomorphic projections were introduced into surveying practice for this very object. Over short lines they import so little distortion of angles that minor surveys, whose error of angular measurement is comparable with such distortion, may be reduced in the rectangular co-ordinate system of an orthomorphic projection just as if the earth were flat. But the present application goes far beyond that. We no longer ignore distortions of angles and lengths, but systematically introduce them into the field measures so that work of higher precision and of considerable extent may also be computed and adjusted in plane co-ordinates.     

THE ORTHOMORPHIC PROJECTION OF THE SPHEROID–III

Abstract

In the last instalment we were able to obtain most of the surveyor's projections in common use by applying simple scale conditions to the meridians and parallels. This method of approach naturally suggests that results of some value might be obtained by applying similar conditions to the plane co-ordinate lines. If we do so, we are immediately led to consider curves on the surface known as geodesics, which are the nearest approach to straight lines it is possible to draw on a curved surface. Accordingly, we give some account of these curves for the benefit of surveyors who have not hitherto made their acquaintance.     

THE ORTHOMORPHIC PROJECTION OF THE SPHEROID—V

Abstract

To complete the picture, the reader is invited to plough through the derivation of point-to-point working formulae for the remaining projections in common use. The entire field of modern geodetic practice in this subject will then have been covered, and at least as simply, without the usual recourse to the square root of negative numbers or other complex notions.     

THE ORTHOMORPHIC PROJECTION OF THE SPHEROID—II

Abstract

The reader will play this round better if he remembers to bring the bag of clubs provided in the last instalment. On the assumption that he will do so, we proceed straight to the first tee without further explanation or recapitulation.     

THE TECHNIQUE OF QUASI-LOSSLESS COMPRESSION OF THE REMOTE SENSING IMAGE

1　ＩｎｔｒｏｄｕｃｔｉｏｎＷｉｔｈｔｈｅｒａｐｉｄｄｅｖｅｌｏｐｍｅｎｔｏｆａｅｒｉａｌａｎｄｓｐａｃｅｒｅｍｏｔｅｓｅｎｓｉｎｇｔｅｃｈｎｉｑｕｅ,ｔｈｅｄｉｇｉｔａｌｃａｍｅｒａｈａｓｂｅｅｎｅｘｐｌｏｒｅｄ ,ａｎｄｍａｐｐｉｎｇｅｘｐｅｒｉｍｅｎｔｓｗｉｔｈｔｈｉｓｋｉｎｄｏｆｄｉｇｉｔａｌｉｍａｇｅｓａｒｅｂｅｉｎｇｐｒｏｃｅｓｓｅｄａｓｔｈｅｒｅｇｕｌａｒｍｏｄｅｏｆａｒｅｏｐｈｏｔｏｇｒａｍｍｅｔｒｙ .Ｏｎｔｈｅｏｔｈｅｒｈａｎｄ ,ｔｈｅｔｅｃｈｎｉｑｕｅｏｆｉｎｔｅｇｒａｔｉｏｎｏ…     

THE CAPE BAR “A” AND THE METRE-FOOT RELATION

Abstract

The Cape Bar A has two sets of end marks. One set is represented by small dots in embedded surfaces of gold, and the other by finely engraved lines near the dots. The distance between the dots was measured in British units by Sir George Airy in 1839, and at the Ordnance Survey in. 1844; and the lines were standardised in international metres by M. Benoit at Paris in 1886. By lueasuring the small distances between the dots and the lines, and using the data of the original standardisations, it has been possible to obtain a value of the metre-foot relation. The ratio thus obtained agrees with the determinations of Benoit (1896) and Sears (1928).     

ON THE EVALUATION OF DEFLECTIONS OF THE VERTICAL USING FFT TECHNIQUE

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｆａｓｔＦｏｕｒｉｅｒｔｒａｎｓｆｏｒｍ (ＦＦＴ)ｔｅｃｈｎｉｑｕｅｉｓａｖｅｒｙｐｏｗｅｒｆｕｌｔｏｏｌｆｏｒｔｈｅｅｆｆｉｃｉｅｎｔｅｖａｌｕａｔｉｏｎｏｆｇｒａｖｉｔｙｆｉｅｌｄｃｏｎｖｏｌｕｔｉｏｎｉｎｔｅｇｒａｌｓ.Ｔｈａｎｋｓｔｏｔｈｅｇｏｏｄｃｏｍｐｕｔａｔｉｏｎｅｆｆｉｃｉｅｎｃｙ ,ｔｈｅＦＦＴｔｅｃｈｎｉｑｕｅ ,ｉｎｔｈｅｍｉｄ＿1 980ｓ ,ｂｅｇａｎｔｏｆｉｎｄｗｉｄｅｓｐｒｅａｄｕｓｅｉｎｇｅｏｉｄｄｅｔｅｒｍｉｎａｔｉｏｎ ,ｗｈｅｎｃｏｍｐａｒ…     

THE CONSTRUCTION OF THE STANDARD BASELINE SITE IN CHANGYANG,BEIJING

The minutes of talks on co-operation forestablishing a standard baseline in China be-tween the Finnish Geodetic Institute and Na-tional Bureau of Surveying and Mapping ofChina was signed in Beijing on October 6,1983.After repeated comparisons and recon-naissance on geomorphology, geologic structure,subsoil water, precipitation, wind speed,atmospheric pressure, humidity, depth of     

THE YEARS 1935–6 AND 1936–7 IN THE GOLD COAST

Abstract

THE Gold Coast can now be said to have recovered from the slump which caused such disastrous consequences in 1931–2 and resulted in a heavy reduction in the establishment of the Survey Department. So far there has been no increase in staff, but more badly needed money for buying stores and increasing the labour staff has been available, and authority has now been given for an increase of 12 in the establishment of African Surveyors; this will result in the re-opening of the Survey School in 1937.     

THE STUDY OF SOIL HUMUS CHANGES WITH THE HARRINGTON “DESIRABILITY” FUNCTION

The potential utility of the Harrington “desirability” function is examined in the assessment of changes in soil humus content using spectrophotometric data. The influence of external factors, such as sun angle, soil moisture content, and degree of soil cultivation, on spectral brightness coefficients is analyzed. The applicability of this method when there is only a small volume of experimental data is noted.     

NOTICE OF THE EDITORIAL DEPARTMENT

The "Special Issue of Seminar on the Wang Zhizhuo's Academic Thinking" (Chineseand English Editions) edited by the editorial department of "ACTA GEODETICA etCARTOGRAPHICA SINICA" of Chinese Society of Geodesy. Photogrammetry and Car-tography in collaboration with that of the Journal of Wuhan Technical University of Sur-veying and Mapping has been published and is put on sale.     

A TRANSVERSE MERCATOR PROJECTION OF THE SPHEROID ALTERNATIVE TO THE GAUSS-KRÜGER FORM

Abstract

The excuse for yet another paper on the Transverse Mercator projection, which has already received what should be more than its fair share of space in this Review, can only be that there is a fresh viewpoint to offer. It is the purpose of this paper to show that there are, in fact, two “Transverse Mercator” projections of the spheroid, of which one has hitherto almost escaped notice.     

THE COMPILATION FEATURES OF SHANGHAI ATLAS

Shanghai Atlas is a comprehensive city atlas. Its contents present the geographical features of Shanghai in all aspects. This atlas is divided into four map series, 164 pages of maps and charts in all, supplemented with written illustrations and index of places, in a volume of 268 pages of the whole atlas.