on 



58 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



were established by the Department, Professor Powell's 

 work extended in an oblique direction from northeast to 

 southwest along the general course of the Green and Colo- 

 rado Rivers through the districts above designated, but the 

 work was in such condition that no one district was com- 

 plete. During the present season his parties have been en- 

 gaged in extending the survey over the unsurveyed fraction- 

 al districts, so that final and complete maps of each may be 

 constructed. 



The methods of survey during the present season are 

 essentially the same as those employed during the last, being 

 modified to a slight extent as experience has suggested ; 

 the chief improvements being in the method of triangula- 

 tion. In addition to the determination of geodetic positions 

 and general geographic features, the system of classifying 

 the lands inaugurated in former years has been continued 

 during the present, the object of this classification being to 

 determine the extent and position of the irrigable lands, 

 timber lands, grass lands, mineral lands, and waste lands 

 the latter being composed of rugged mountains and desert 

 plains. The practical importance of this classification, if 

 carefully made, is great, not only in presenting the informa- 

 tion desirable to those who wish to settle in the country, 

 but also in the collection of facts necessary to intelligent 

 legislation concerning these lands. 



In the region embraced in this survey, a very small por- 

 tion of the country can be redeemed by irrigation for agri- 

 culture, and no part of it can be cultivated without irriga- 

 tion. It appears from the reports that less than one per cent, 

 can thus be made available. Especial care has been given 

 to the determination of the extent of such lands, so as to ex- 

 hibit their position on the maps. These irrigable lands and 

 timber lands, together with some small districts of coal-bear- 

 ing lands, are the only parts of the country that should be 

 surveyed into townships and sections. 



Having in view economy and convenience in the linear 

 surveys of this district, the geodetic points of the general 

 geographic survey, under the direction of Professor Powell, 

 have been carefully marked, that they may hereafter be used 

 as datum points by the ofiicers of the General Land Oftice. 



Extensive coal-fields exist in the region surveyed, but, as 



