APPENDIX TO REPORT OF THE SECRETARY. 87 



only through irrigation are limited by the supply of water. There are 

 some exceptions to this. Where streams are found in narrow valleys 

 or run in deep caiions, the limit of agricultural land is determined by 

 the extent of the areas to which the water can be conducted with 

 proper engiueering skill. In the study of this subject many interesting 

 and important problems have arisen, and many valuable facts have 

 been collected. 



From the survey of the timber lands one very important fact appears, 

 that the area where standing timber is actually found is very much 

 smaller than the areas where the conditions of physical geography are 

 such that timber should be found as a spontaneous growth; that is, the 

 area of timber is but a small fraction of the timber region. The destruc- 

 tion of the timber in such regions now found naked is due to the great 

 fires that so frequently devastate these lauds ; and the amount of tim- 

 ber taken for economic purposes bears but an exceedingly small ratio 

 to the amount so destroyed. Hence the important problem to be solved 

 is the best method by which these fires can be prevented. 



Another subject which has received much attention is the utilization 

 of the pasturage lands; and still another, the best methods of survey- 

 ing the mineral lands for the purpose of description and identification, 

 that the owners of mines may be relieved of the great burden of litiga- 

 tion to which they are subjected by reason of the inaccurate and ex- 

 pensive methods now in vogue. 



UNITED STATES GEOGRAPniCAL SURVEYS WEST OF THE ONE-HUN- 

 DREDTH MERIDIAN, IN CHARGE OF FIRST-LIEUT. GEORGE M. 

 WHEELER, CORPS OF ENGINEERS, U. S. ARMY, IN 1877. 



The geographical surveys west of the one hundredth meridian, 

 under First- Lieut. George M. Wheeler, Corps of Engineers, United States 

 Army, for the field season of 1877, were conducted in three sections, 

 named the Colorado, Utah, and California sections, respectively. In 

 each section were two main parties, besides special parties in the Utah 

 and California sections, making ten in all. One of the special parties in 

 Utah, being under the immediate command of Lieutenant Wheeler, oper- 

 ated in the northern part of that territory and southern part of Idaho; 

 others under his immediate direction were engaged in Utah, Idaho, and 

 ^Nevada. 



(1) The parties of the Colorado section, under Lieutenants Bergland 

 and Morrison, operated from Fort Lyon, Colo., the former wholly in 

 Colorado, and the latter mostly in New Mexico, and to some extent in 

 Colorado and Texas. The special field of the former was in the Un- 

 compahgre region, the topography and drainage of which were deter- 

 mined, and the Gunnison and Tumichi rivers gauged, and mines of the 

 locality examined. The country examined is well watered, with plenty 

 of fish and game, rich minerals in the mountains, and portions of the 

 valley of the Uncompahgre good for agricultural purposes. For the 

 greater part of the season the party under Lieutenant Morrison was 



