ACTIVITIES 31 



4. Surveys and investigations relative to water re- 

 sources. 



5. Examinations, under act of March 1, 191 1, of land 

 proposed to be purchased by the government for the pro- 

 tection of navigable streams. 



6. Investigations of the character and value of public 

 lands made necessary by the land laws. 



7. Operation of lithographing and engraving plant. 



As the purpose of the larger part of the Survey's work is 

 the acquisition and dissemination of knowledge concerning 

 geography, geology, mineral resources, and water resources, 

 most of its activities, therefore, involve the publication of the 

 results achieved. 



Topographic Survey. As already indicated, the Survey is 

 engaged in making and publishing a topographic atlas of the 

 United States — that is, a series of maps exhibiting the con- 

 figuration of the land and water, the elevations of the land, 

 and the principal features of culture. In addition to these 

 atlas sheets it is publishing special maps of certain areas — such 

 as the areas including large cities. 



The work on the topographic atlas was begun by the Sur- 

 vey in' 1882, promptly upon the enactment of the provision of 

 law authorizing the Survey to prepare geologic maps of the 

 United States. In entering upon the task, one of unprece- 

 dented magnitude, of executing a topographic survey of the 

 entire United States, the Survey fell heir to the results which 

 had been produced by previous topographic surveys, federal, 

 state and private. Notable among these results were the maps 

 produced by the several geographical and geological explora- 

 tions and surveys of the West, to which reference was made 

 in the preceding chapter. The materials thus acquired were of 

 very unequal value, but they furnished a point of departure 

 for the Survey's work. 



The Survey did not for some years attempt to publish topo- 



