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Thirdly there was the expedition to Petra. Two members of the Department 
staff and one archaeologist from the University of London Institute of 
Archaeology carried out terrestrial photogrammetric surveys in Petra during 
October and November 1968 (8). These were used to help complete a 1:2500 
scale map of the Petra area which had been prepared from air photography in 
1965. 
$ 
MERIDIAN AIRMAPS LTD 
Meridian Airmaps Limited exposed 131 000 frames of medium and low level 
photography during the period under review using Wild RC8 cameras with Zeiss 
NT1 view finders. The main scale continues to be suitable for 1:500 mapping 
but a great deal of medium scale photography has been exposed in connection 
with the 1971 Census. The trend towards numerical methods of processing 
engineering and land use data has been evident. Overseas work has included 
moderately low level photography for the Governments of Botswana and Malawi, 
and high level air photography contracts in Malawi, Botswana and Ghana, for the 
Directorate of Overseas Surveys. The equipment used includes Wild B8 and 
Wild A8 plotters with EK5A recorders, a Thompson-Watts Model 2 plotter, a 
Williamson Large Scale plotter and MK II multiplex plotters. 
NEWCASTLE UPON TYNE UNIVERSITY. Dept. of Surveying 
The Department has undertaken special mapping for the production of 
vegetation maps of Upper Teesdale and St. Kilda. Other mapping has been 
carried out in connection with research projects of other departments within the 
University. Wild A8 and Kelsh plotters are used in this work. 
ORDNANCE SURVEY 
The Ordnance Survey of Great Britain is undertaking a programme of 
resurvey and revision of its large scale maps which it is aimed to complete by 
1980. Surveys are made at the three basic scales of 1:1250 for major urban 
areas, 1:2500 for rural and small urban areas and 1:10 000 for areas of 
mountain and moorland. The 1:10 000 scale replaces the former 1:10 560 as 
part of a Departmental metrication programme. For the four year period of this 
report 180 km? of the 1:1250 scale mapping have been produced on stereo 
plotting machines, which is rather more than half the total output. The post-war 
resurvey programme at this scale is now essentially complete and the remaining 
work is limited to upgrading the scale of survey of the rural areas affected by 
urban development. 
In rural areas the old 1:2500 County Series maps are being recast onto the 
National grid and revised; graphical air survey methods are used as a standard 
revision technique but, in some cases involving patches of dense revision, an 
instrumental replot is inserted into the revision block. The output of surveys at 
this scale, which mainly depend on rectified enlargements to the approximate 
scale of the map, has considerably increased over the past four years. Some 
26 000 rectified enlargements are currently produced each year on two Zeiss 
SEG V Rectifiers supplied with tilt and enlargement values determined 
mechanically by a system developed in the Department. Since the last report 
35 620 km’ of the 1:2500 series have been revised from aerial photography.