38o SECTIONAL TRANSACTIONS.— E. 



settlement, and are important to an understanding of the differential trends 

 of population at the present time. 



Evening. 



Joint Discussion with Sections C, D, F, K, M, on Planning the land of 

 Britain (8.0). See page 486. 



Chairman : The Rt. Hon. Lord Trent. 



Dr. L. Dudley Stamp, Prof. P. G. H. Boswell, O.B.E., F.R.S., 

 Dr. J. S. Huxley, Prof. E. J. Salisbury, F.R.S., Sir Daniel 

 Hall, K.C.B., F.R.S., Sir Roy Robertson, Prof. J. H. Jones. 



Wednesday, September 8. 



Brig. M. N. Macleod. — Some recent work of the Ordnance Survey (9.45). 



The Ordnance Survey ofTers the public a considerable choice in types 

 of map, but the various types are not based upon any single plan. Modern 

 teaching, research and economic planning demand not only several types 

 of maps, but easy co-ordination of one type with the others. In this latter 

 respect the Ordnance Survey range of maps could be improved. Large- 

 scale plans are not published as a continuous series covering the whole 

 country, nor is there direct connection of the small-scale maps with one 

 another or of the small-scale series with the large. This leads to confusion 

 of the layman and involves needless expense of publishing and buying. 



The projection of large-scale surveys in separate county systems was in 

 accordance with professional practice when the survey was started. By 

 using a diflferent system of projection it would now be possible to show the 

 whole country with sufficient accuracy on a single projection system. The 

 Cassini Projection and the Gauss Conformal Projection. 



Attempts have been made at various times in the past to assimilate county 

 surveys, but lack of a suitable triangulation system proved an insuperable 

 obstacle. In 1935 a completely new system of triangulation was started 

 which, when complete, will cover the whole country with a network of 

 triangles of about four to five miles side and will provide data for assimi- 

 lating all the large-scale surveys on to the same projections as are used for 

 the small. The primary framework is well advanced, and once this has 

 been adjusted it will be possible to take up the secondary triangulation in 

 blocks. 



For the assimilation of two 1/2,500 surveys on different projections 

 tertiary triangulation would be necessary, giving a fixed point every mile, 

 but this would be both difficult and costly. Research has therefore been 

 undertaken to see whether it is possible to do tertiary triangulation with 

 sufficient accuracy on air photographs. If this should prove successful 

 the Department would have to initiate a comprehensive programme of air 

 photography. 



Mr. F. Walker. — The history of regional differences between south-west 

 and south-east Lancashire (10.30). 



The different characters of south-west and south-east Lancashire can be 

 largely explained by their distinctive historical evolutions, which in turn 



