7.24. The main effort in survey for mapping has been in the speeding up of revision of large-scale plans, the total number of which is now about 1,950. A thorough study was undertaken of the problem of maintaining these sheets in a reasonably up-to-date condition and a cyclic revision programme was drawn up listing all sheets in various categories for revision purposes—to be revised at 1, 2, 3 or 5 yearly intervals. To implement this programme a total of about 700 sheets per annum would need to be checked and revised when necessary. During the year under review 416 sheets were revised. It was obvious that with the existing staff available and using current methods it would be impossible to reach the target. Accordingly, the specification of the 1/1,200 scale plans was simplified, field staff were given special training in rapid revision methods and extra staff was requested in the 1971-72 draft Estimates.
7.25. The possibility of using aerial survey for revision of the 1/1,200 scale plans, permitting available staff to concentrate on the 1/600 scale plans of the urban areas, was investigated. This appeared feasible when it was known that the R.H.K.A.A.F. were hoping to obtain a twin-engined aircraft in 1971. A modern air survey camera could be installed in this and, providing that no charge was made for use of the aircraft, it seems probable that revision from air photographs could be considerably cheaper than by ground surveys. It would also avoid the necessity for further increases in field staff.
7.26. As regards topographical maps of the Colony, bulk supplies of all 62 sheets of the new 1/10,000 scale series have now been received and distributed to Government departments. A programme of revision of this series was put into operation and second editions of the first 2 sheets to be revised (covering Kwai Chung and Kowloon) were reprinted by the Military Survey Branch Far East Land Forces, one of them in dual-language (English/Chinese) as a 'pilot' sheet to ascertain public reaction.
7.27. As the first 'pilot' sheet of the dual-language edition of the 1/10,000 series was successful and popularly received, it was decided that future editions of the series will be printed locally in dual-language versions as they are revised by this office. These sheets will be on sale to the public at less than half the cost of the first (English language) edition published in the United Kingdom.
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