284 



NA TURE 



[August 26, 1922 



earlier date, for the medical school at Qasr el Aini was 

 established early in the last century, and about i860 

 a 20-centimetre astronomical refracting telescope by 

 Briinner of Paris, with an equatorial mounting, was 

 set up at Abbassia ; a four-metre base-bar together 

 with two 40-centimetre theodolites and a portable 

 transit instrument by the same firm were purchased 

 for the survey of Egypt which was then projected, 

 but which did not become an accomplished fact until 

 about fifty years later. 



To-day there are at least a dozen services occupied 

 primarily with work of a scientific character. 



The Survey of Egypt is the successor of the earlier 

 surveys of 1823, 1853 and 1878, but none of these were 

 ever completed nor had they any scientifically organised 

 control. It now comprises the cadastral survey, the 

 topographical survey, the desert survey, and the geo- 

 logical survey. 



The cadastral survey is of special importance in 

 Egypt on account of the high value of agricultural land, 

 and the exceptional degree of subdivision of the hold- 

 ings. The network of triangulation on which it is 

 based now covers the Nile Valley and Delta, and is 

 controlled by the first-order triangulation now in pro- 

 gress, which is of the standard demanded in inter- 

 national geodetic work. The topographical survey 

 utilises the material provided by the cadastral survey 

 and adds to it all topographical information besides 

 extending the maps beyond the limits of the cultivated 

 land, to meet the needs of different branches of the 

 public service. There are now published series of map 

 sheets on scales of 1 : 2500, 1 : 10,000, and 1 : 50,000, 

 covering all the inhabited area of the country, while 

 other maps on scales of 1 : 250,000 and 1 : 1,000,000 

 include the large areas of desert as well. 



Survey work as it is extended into the desert assumes 

 a special character, for on account of the large areas 

 to be covered, the difficulties of transport, and the 

 absence of all artificial topographical features, special 

 methods of surveying have been adopted. This work 

 is now in the hands of the Desert Survey, which also 

 undertake the precise location and demarcation of 

 prospecting and mining areas leased by the Govern- 

 ment. 



On the highly cultivated alluvial plains of the Nile 

 Valley and the Delta accurate levelling is of special 

 importance, so a network of levelling of high precision 

 has been carried over them and extended into the Sudan 

 along the Nile. Besides this the cultivated area through- 

 out Egypt has been contoured at 50 centimetre intervals. 

 At the headquarters of the Survey of Egypt are draw- 

 ing, photographic, and printing offices in which are 

 produced the maps of the various surveys and also 

 those which are required by the geological survey and 

 by other State departments. 



In 1896 a geological reconnaissance of Egyptian 

 territory was authorised which, at the end of five years, 

 developed into a geological survey. The staff has 

 always been small, but a very large amount of valuable 

 work has been done under the difficulties and limita- 

 tions imposed by desert travel. 



Not only have the mineral resources of the country 

 been located and described, thereby becoming available 

 for commercial purposes, such as the phosphate de- 

 posits in Egypt and manganese deposits in Sinai, but 



NO. 2756, VOL. I IO] 



our knowledge of the structure and stratigraphy of 

 north-eastern Africa has also been greatly advanced, 

 and the interesting fauna of Lower Eocene age which 

 was brought to light in the desert to the west of the 

 Fayum has greatly extended our knowledge of the past 

 history of the African continent. Geological work has 

 been carried out for several years in connexion with 

 petroleum research in the Red Sea area, and the results 

 have been published in various reports. The records 

 of the geological survey and the collections which fill 

 its museum provide a store of information relating to 

 the structure and stratigraphy of the Nile Basin and 

 north-eastern Africa. 



The Physical Department, which until a few years 

 ago was part of the Survey Department, and is now a 

 part of the Ministry of Public Works, includes the 

 Helwan Observatory with its time service, the meteoro- 

 logical service, the service of weights and measures, 

 and the hydrological investigations in connexion with 

 the Nile. The observatory, which was formerly at 

 Abbassia, was removed in 1904 to Helwan, 20 km. 

 south of Cairo, because the building at Abbassia was 

 wholly unsuitable and the extension of the electric 

 tramways to its neighbourhood prevented all magnetic 

 work. In it the 30-inch reflecting telescope at Helwan 

 is employed in the photography of southern nebulae, 

 of comets when they appear, and of Jupiter's eighth 

 satellite, which has been observed almost exclusively 

 by Greenwich and Helwan since its discovery. 



The time service is also directed from the observatory, 

 and the observatory clock transmits the noon time 

 signals which are utilised at Cairo, Alexandria, Port 

 Said, and at Khartoum. Magnetic observations are 

 carried out both by means of magnetographs and by 

 weekly absolute determinations. The meteorological 

 service of Egypt and the Sudan includes, besides the 

 central observatory at Helwan, 57 climatological 

 stations, of which 23 are in Egypt, 27 in the Sudan, 

 and 7 in Palestine, and about 230 rainfall stations in 

 Egypt, the Sudan, and Abyssinia. First established 

 to study the conditions determining the Abyssinian 

 rainfall, and consequently the Nile Flood, it has now 

 a much wider importance and is one of the recognised 

 national meteorological services. 



The increasing demands of agriculture and its de- 

 pendence on the supply of water provided by the Nile 

 have necessitated a high precision in river-gauging, 

 and the hydrological work which this involves is now 

 centred in the Physical Department, where the records 

 of 70 river-gauge stations are discussed, and hydro- 

 logical investigations are undertaken. The storage of 

 water in the valley of the Nile at various points, the 

 need for accurate measurements of the discharge 

 throughout the low stage of the river, the study of the 

 effect of turbulence in the water at flood stage, etc., 

 present a series of physical problems which are of direct 

 importance to Egypt, as well as being of great interest 

 to many other countries. 



The department is also charged with the inspection 

 of weights and measures throughout the country, and 

 the prototype standard metre and the secondary 

 standards of length, which were acquired for the pur- 

 pose of the Survey of Egypt, are now kept at the 

 Helwan Observatory, where any comparisons desired 

 are carried out in a well-equipped comparator house. 



