May 25, 1857.] GEOLOGICAL SURVEY OF THE UNITED KINGDOM. 411 



registered on the maps of the 6-inch scale, so as to be ready to be 

 published, when the maps of the districts nnder review shall have 

 been completed. 



I have great satisfaction in informing you that, as the Geological 

 Surve}^ proceeds, the public is rapidly becoming aware of its value. 

 The sale of the maps and sections has recently been doubled ; so 

 that, if the present demand should continue, the sale of this year 

 will exceed 5000 sheets. 



As no men of science are more directly concerned with the suc- 

 cessful progress of the Ordnance Survey of the country, than the 

 geologists who have to work out the subterranean phenomena upon 

 the geographical features there laid down, so it may naturally be 

 expected, that I should express my opinion on the questio vexata 

 which has been so much agitated in Parliament, viz. the best scale 

 for publication. 



Most persons will agree with me in what I have long contended 

 for, that a 1-inch scale * is large enough for the purposes of a 

 general map, and any one who doubts it should visit the Museum 

 in Jermyn-street, and there see how vast a portion of a lofty hall 

 is required to exhibit at one view that portion only which is geo- 

 logically finished, or Wales and the half of England. But, whilst 

 for the general purposes of the public, this scale (which is larger 

 than that of the published maps of France and other foreign coun- 

 tries) is quite sufficient, it is my duty to say, that for several objects 

 of the geological surveyor the 6-inch map is often of higher value. 

 This latter scale was applied to Ireland, because it was supposed to 

 be the smallest measure on which every essential feature of a tract, 

 whether natural or artificial, could be laid down. It follows there- 

 fore that, in availing himself of this map, the field geologist has at 

 hand a datum-point for every observation; particularly if it be 

 furnished with contour lines marking the relative altitudes. In 

 short, he can register, with an accuracy unattainable, except on 

 such a scale, every outcrop, fold, or break of the beds ; and hence, 



* See Memorial resulting from a resolution which I moved at the fourth or 

 Edinburgh Meeting of the British Association for the Advancement of Science 

 (1834) and presented to the Chancellor of the Exchequer (now Lord Monteagle) 

 in May, 1835. Report of the British Association, Proceedings of the Meeting, 

 p. xxxvi. This document, which showed the deplorable state of the Geography 

 of ray native country at that time, was also printed by order of the House of 

 Commons. Subsequently, when President of this Society in 1853, I again made 

 a strong appeal touching the neglect of Scottish Geography. — Journal of the 

 Royal Geog. Soc, Vol. XXIII. , President's Addi-ess, p. Ixxxix. 



