37© SECTIONAL TRANSACTIONS.— E. 



her raw material may appear surprising, since cotton can be produced on a 

 commercial scale in many tropical and subtropical regions. But there are 

 serious hindrances to large-scale production, such as dangers from drought 

 and various forms of disease, as well as lack of labour and communications. 

 Other crops may be more profitable than cotton, and local mills may absorb 

 the bulk of the crop. Cotton-growing has been fostered in many regions, 

 particularly in the Empire and in Egypt. In India the harvest is over 

 2,000 million lbs., but the quality is not suited to Lancashire's needs and 

 only a small proportion of the crop is used in English mills. 



Friday, September 11. 



Mr. O. G. S. Crawford. — The archceological work of the Ordnance Survey 

 (10.0). 



Major R. L. Brown. — Maps and road communication (10.45). 



When the motor car was first introduced it ran upon the existing roads. 

 Those roads, designed for other purposes, were unsuitable ; and unsuitable 

 roads mean needlessly high operating cost for every vehicle travelling on 

 them. Once established upon uneconomical alignments, alteration has 

 been difficult and costly. In Great Britain our initial error was not due 

 to the lack of topographical information, for our country was the best mapped 

 in the world. 



In the colonial Empire the situation is the reverse. Obstacles to 

 economical alignment are few, but topographical information is lacking. 



Without a properly contoured topographical map the engineer cannot 

 choose the best alignments upon which to make his detailed location surveys. 

 His only recourse is to make his own map. In unmapped countries all 

 engineers and others engaged on geology, railways, flood control, administra- 

 tion, and many other activities are forced to the same unsatisfactory expedient. 

 With the timely supply of good topographical maps, the saving on but a 

 few of these activities would be more than enough to map the whole 

 Empire. 



A co-ordinated plan for the topographic mapping of the Empire is an 

 urgent need. Without maps development must continue to be handicapped 

 at every turn, waste condoned and the future mortgaged. 



Major M. Hotine. — A grid system for Ordnance Survey maps (11.30). 



Present system of projecting and indexing Ordnance Survey 1/2,500 large- 

 scale plans on county meridiansr 



Proposal to recast the large-scale survey on a single meridian as a con- 

 tinuous national series, without discontinuity at county boundaries, to 

 meet modern requirements. 



The problem of indexing and joining 52,000 sheets of a single series 

 indicates cutting sheet lines along the rectangular co-ordinate lines of the 

 map projection. Internal division of the plan by a system of squares (or 

 ' grid '). whose sides also coincide with the rectangular co-ordinate lines, 

 provides a ready means of plotting positions from surveyed co-ordinates, 

 the possibility of adding extra surveyed material on revision without de- 

 preciating the basic accuracy of the plan, and a ready means of referring 

 to the position of points by means of their ' grid ' co-ordinates. 



The desirability of utilising the same grid system on maps of all scales : 

 to facilitate the compilation of smaller scale maps from gridded larger 



