NOTES ON THE GEODETIC SURVEY OF SOUTHERN RHODESIA

Abstract

Triangulation.—Apart from Simms' Geodetic Chain, Gordon's Chain, the Copper Queen Limb, and a section of the Victoria and Umtali Series, all the primary triangulation shown on the accompanying map has been executed since 1933. The work of Simms and Gordon has been remodelled, however, being greatly strengthened, and these chains are now called Simms' and Gordon's Series. For an explanation and plan of the above Series, see “A Note on the Trigonometrical Survey of S. Rhodesia”, in the Empire Survey Review, no. 27, vol. iv.     

THE TRANSVAAL-SOUTHERN RHODESIA GEODETIC CONNEXION

Abstract

In the original geodetic series in Southern Rhodesia—completed by Mr Alexander Simms in 1901—the geographical coordinates of all stations were referred to the point SALISBURYas origin. The coordinates of SALISBURY were fixed by interchange of telegraphic signals with the Royal Observatory at the Cape for longitude, combined with astronomical determinations of time, latitude, and azimuth (see Vol. III, “Geodetic Survey of South Africa”).     

DETERMINATION OF TAPE TEMPERATURES ON THE MEASUREMENT OF THE WANKIE AND SABI GEODETIC BASES,SOUTHERN RHODESIA (1953)

Abstract

The Wankie Geodetic Base was measured in May 1953 and the re-measurement of the Sabi Geodetic Base was also completed during the month following. For these measurements the standard “Macca” equipment was used, the gear being lent to the Southern Rhodesia Government by the Directorate of Colonial Surveys. As it was anticipated that both measurements would be made under hotter and more sunny conditions than normally prevail in England, the Directorate of Colonial Surveys suggested that the opportunity be taken of carrying out further tests in the determination of temperatures by the “resistance thermometer” as described by Messrs. Clark and Johnson of the National Physical Laboratory in their paper on the “Measurement of Temperature of Geodetic Surveying Tapes. Accordingly, through the good officesof the Director of the National Physical Laboratory, the apparatus comprising the resistance theremometer was made available for use on these two base measurements.     

REPORT OF THE SURVEY OF SOUTHERN RHODESIA FOR 1941

Abstract

1. General.—The size of this Report has been curtailed as far as possible in the interests of economy of reproduction and stationery. The usual annexures giving details of the work in the Drawing Office, the Lithographic Reproduction Press, and the Trigonometrical Survey have been relegated to the Departmental Records for use as required.     

A NOTE ON THE TRIGONOMETRICAL SURVEY OF SOUTHERN RHODESIA

Abstract

After the completion of Simms's Geodetic Chain in 1901 and the publication of the results in 1905—Volume iii of the Geodetic Survey of South Africa—nothing further of a geodetic nature was done until 1928 when a short chain was run westwards from Simms's chain, at about latitude 17° 10′, to fix the Copper Queen mining area. The Eastern Circuit was commenced shortly after this; it runs from Salisbury eastwards to the Portuguese Boundary, southwards through Umtali to about latitude 20° and then westwards, joining Simms's chain again to the east of Bulawayo. Another chain running north from Simms's work has been commenced near Bulawayo. The several series are exhibited on the outline map attached.     

THE YEAR 1930 IN NORTHERN RHODESIA

Abstract

The year 1930 in Northern Rhodesia has been particularly busy for the Survey Department. This was chiefly due to the mining activity in the northern area and to the rapid development of new townships and the expansion of old, owing to the large influx of traders and business houses. The staff has been augmented; but, although the office accommodation has improved, we still find ourselves somewhat cramped at headquarters, especially when the local field staff returns there during the rains. A general review of the instruments and equipment has been made, resulting in the scrapping of old and obsolete material and its replacement by modern equipment. In this connection it is interesting to note the general adoption of the new Zeiss, Wild and Tavistock theodolites.     

THE YEAR 1933 IN NORTHERN RHODESIA

Abstract

The general depression in world trade has affected the country to no small extent during the year in almost all branches of departmental activity. It has been particularly reflected in the Survey Department by a reduction in applications for land from new settlers, and in subdivisional surveys· carried out for private landholders. In all other branches, however, the Department has had more on its hands than its now limited staff could cope with, and there is the danger of work getting behindhand and being put aside for a future occasion whilst new projects are dealt with to supply immediate requirements.     

GEODETIC LEVELLING IN KENYA

Abstract

Kenya-Topography. Kenya lies astride the Equator between latitudes 4°N and 4°S and extends from Lake Victoria to the Indian Ocean (34°E to 42°E). Between long. 36° and 36½°E it is traversed from north to south by the great Rift Valley, the surface of which is generally 2000-3000ft. lower than the level of the plateau on each side. The plateau culminates in the Aberdare Range (13,000 ft.) east of the Rift, and the Mau Forest (10,000 ft.) and Cherangani Hills (11,000ft.) west of the Rift. Together with the isolated mountain masses of Elgon (14,000 ft.), Kenya (17,000ft.) and Kilimanjaro (19,500ft.), this topography may be expected to cause considerable local distortion in the shape of the geoid. Gravity surveys in 1933-4 indicated a negative anomaly below the floor of the Rift Valley, suggesting that it had been forced down by over-riding pressure from both sides.     

THE YEAR 1931 IN NORTHERN RHODESIA

Abstract

In the survey world of Northern Rhodesia the most notable event in 1931 (apart, of course, from the birth of this Review) has been the completion of the aerial survey contracts undertaken for the Government by the Aircraft Operating Company. The results have justified expectations particularly with regard to the mapping of 63,000 square miles of the Territory on a scale of 1/250,000. Used in conjunction with the information obtained by ground methods by the Mining Companies, who have kindly consented to put their information at our disposal, a really reliable detailed map of a considerable portion of the Territory should be obtained. The mosaics of the six principal townships are also proving of value and contain a wealth of detail which would be difficult to obtain so accurately by ground survey except at great expense. On the other hand it is obvious that it would be a costly business involving a very large amount of ground control to prepare a closely contoured plan such as is required for detail purposes in connection with township lay-outs.     

THE YEAR 1932 IN NORTHERN RHODESIA

Abstract

In spite of the world depression, the effects of which are now being severely felt in this Territory, the Departmental activities were almost a record in regard to output. Not only were applications for land in excess of previous years, but the issue of deeds, the surveys of farms and plots, the work on mineral areas, and the preparation and issue of maps, plans, and diagrams were well above previous years.     

THE TRAINING OF AFRICANS FOR SURVEY IN NORTHERN RHODESIA

Abstract

Prior to the year 1931 there was no systematic training of Africans for land survey work in Northern Rhodesia, and those natives then in the employ of the Survey Department as assistants to the European surveyors in the field were no more than “capitaos”. Asurveyor, after his arrival in the colony, usually had to find his own native assistant, or chainman, and any native who appeared to have a commanding manner with his fellows, and who was clean and respectful, was eligible for the position. Preference in some cases was usually given to natives who had completed service in the native regiment or police, for their early training had taught them to obey orders, to conduct themselves well, and to control other natives.     

NOTES ON GEODETIC WORK IN THE GOLD COAST

Abstract

The Gold Coast, including that portion of Togoland which is mandated to Great Britain, comprises an area of 91,843 square miles lying between the parallels 4° 45′ N. and 11°N. and the meridians 1° 10′ E. and 3° 10′ W. The greater part of the southern area is covered with dense forest, but in the north the forest gradually opens out to more open “orchard-bush”, while in the extreme north the country consists of rolling plains covered with tall elephant-grass.     

郑州市ZZCORS系统坐标联测数据的处理与分析

利用地壳运动观测网络工程的基准站为框架点,解算了七个ZZCORS站和九个GPS等级控制点的CGCS2000地心坐标,并对计算结果的精度进行了分析。     

GEODETIC BEACONS

Abstract

Mr. Clendinning's article on “Signal Lamps” (E.S.R., vol. ii, pp. 15–18) raises a point of major importance in geodetic triangulation. I entirely agree with him that the sole use of heliographs—heliostats to the purist—is in most parts of the world out of date. I also think, and indeed am prepared to state categorically, that the use of acetylene lamps is out of date and was out of date many years ago. The Americans, who are always worth listening to on the economics of surveys, would not otherwise have replaced all their acetylene gear by electric beacons. The answer, in my experience, and for reasons which I shall endeavour to make clear, is generally, but not necessarily always, to provide both helio and electric lighting; but first I should like to summarize the conditions in which luminous signals should be used at all.     

方差分量估计理论及其在整体大地测量中的应用

本文探讨了整体大地测量平差中的方差分量估计问题,给出了自适应最小二乘配置;不仅较好地解决了各类观测量权比的确定问题,而且能够确定信号的方差因子。此外,文章还对如何更好地确定局部地区扰动位及其泛函的协方差函数作了讨论;最后通过对一个实测网进行了整体平差,并与经典平差结果进行了比较。     

THE EARLIEST GEODETIC TRIANGULATION

Abstract

WILLEBRORD SNEL VAN ROIEN, the “learned Snellius,” was born in 1580 at Leyden, where his father Rudolf was Professor of Science. He naturally proceeded to the university, and made such rapid progress under his tutor, L. van Ceulen, that he was already in 1600 delivering lectures on Ptolemy's “Almagest.” With his mind developed by travel in Europe, including a residence of some duration at Prague, where he was associated with Tycho Brahe before that great observer's death in 1601 and with the still more eminent Kepler as another of Brahe's pupils, he had acquired such scholarship as to publish in 1608 a daring reconstruction of the defective work, “De sectione determinata,” by Apollonius of Tyana. This was the year of his marriage to Maria de Lange, daughter of the Burgomaster of Schoon.     

空间网联合处理中地壳运动参数的引入

本文阐述了空间大地网联合处理中的地壳运动模型的建立方法，并在此基础上提出了非均匀形变，均匀形变，体应变和刚体转动的识别方法，文中以我国现有空间大地网的模拟数据，结合中国大陆地壳构造进行了试算。