32 THE U. S. GEOLOGICAL SURVEY 



graphic maps for general distribution, but supplied them only 

 to its own members and to other government services. Au- 

 thority to sell the maps to the general public was finally 

 granted by Congress in 1897 (act of February 18, 1897, 29 

 Stat. L, 701). 



During the first few years of the Survey's map work it con- 

 tinued to use the same scale that had been employed by the 

 earlier independent surveys — about 4 miles to the inch, or 

 1 1250,000, with relief shown by 200-foot contours; but when 

 the cooperative surveys of the states were begun it was seen 

 to be desirable to increase the scale and decrease the contour 

 interval, not only for the work in those states, but for that in 

 other states in which cooperation was not being carried on. 



The earlier topographic mapping of the Survey was sub- 

 jected to some criticism on account of lack of refinement in 

 detail. It was a question of judgment whether the appropri- 

 ation should be expended in accurately mapping a limited 

 area or in making reconnaissance surveys over a more ex- 

 tended area. The less accurate maps were less expensive, and 

 served a useful purpose in establishing the value of topo- 

 graphic surveys. The results have proved the wisdom of a 

 policy whereby the people were gradually educated to the use 

 of refined and detailed maps, while Congress learned to ap- 

 preciate the cost and the comparative slowness with which 

 accurate surveys would be prosecuted over so vast a territory 

 as that of the United States. Had fewer square miles been 

 mapped annually in the early years, but with the accuracy 

 attained at present, it is doubtful if Congress would have con- 

 tinued to maintain the organization. As it was, valuable re- 

 sults were rapidly put forth, and in time it has been possible 

 to supersede the older reconnaissance maps with more de- 

 tailed maps. 1 



As the topographic work steadily advanced, not only in the 

 area covered, but in accuracy, it was found desirable to ob- 

 tain from Congress authority to run careful spirit-level lines 

 and to establish bench marks for permanent record of eleva- 



""U. S. Geological Survey, Bulletin No. 227, 1904, p. 57. 



