56 KEPOET OF THE SECRETARY. 



California section, under the command of Lieut. George M. Wheeler, 

 Corps of Engineers ; (2.) The Colorado section, under the command of 

 Lieut. William L. Marshall, Corps of Engineers ; and (3) the office-force 

 in Washington, temporarily in charge of George M. Lockwood, assistant. 



The two sections were constituted with a view to a systematic prose- 

 cution of the geodetic and allied work, and the office force was kept contin- 

 uously employed upon the reductions of observations. From the Cali- 

 fornia section a special party under Lieut. Eric Bergland, Corps of En- 

 gineers, was detached to make certain preliminary examinations and 

 surveys as to the practicability of diverting the Colorado River. These 

 labors have been accomplished so far as the past field-season would per- 

 mit, and Lieutenant Bergland is now engaged in the preparation of his 

 report. When received, with the maps and sketches, it will be for- 

 warded, with additional information bearing upon the general subject 

 of irrigation. 



Four other parties from the California section were busily employed 

 during the working summer months ; one, under Lieut. Rogers Birnie, 

 jr., moving to the south and east of the lower or southern limit of the 

 Sierra Nevadas; another, under Lieut. C. W. Whipple, Ordnance Corps ; 

 and a special party under Dr. H. C. Yarrow for a brief period in the vi- 

 cinity of Santa Barbara, Cal. The command of the latter party was 

 afterward transferred to Dr. J. T. Roth rock, U. S. A., and was finally 

 merged with the main party commanded by the officer in charge. 



The results accomplished were of a highly satisfactory character, and 

 the improvements introduced noted the transfer to a completely con- 

 nected geodetic survey. Connection was had with the base-line meas- 

 ured by Captain, now Brig. Gen. E. O. C. Ord, near Los Angeles, Cal., 

 in 1854. The developed base and measured triangles in a triple tier 

 were carried eastward approximately as far as the one hundred and 

 twentieth meridian of longitude. For the first time the correct latitude 

 and longitude of what is probably the highest measured peak in the 

 United States iu the southern Sierras were obtained. The preliminary 

 reductions show an altitude of 14,900 feet. 



The Colorado section was composed of three principal parties : one 

 under its commanding officer • the second under Lieut. W. L. Carpenter, 

 Ninth Infantry; and the third in charge of Lieut C. C. Morrison, Sixth 

 Cavalry. Their operations were in continuation of the organized work 

 begun by the establishment of a series of main astronomical points 

 along the east base of the Rocky Mountains, and the development 

 therefrom of a series of measured bases and triangles so as to envelop 

 completely the area entered and occupied, and which fiually was to be 

 connected through from the plains to the Pacific. Their labors were 

 conducted with skill, energy, and success. 



The office-force, engaged in computations, map-drawing, and other 

 reductions, have succeeded in completing three additional atlas-sheets 

 on a scale one inch to eight miles, and are advancing toward comple- 

 tion the work of five others. 



