REPORT OF THE SECRETARY. 33 



to complete the triangulation commenced in 1873. This important work 

 was delegated to Lieut. Wm. L. Marshall, Corps of Engineers, who 

 brought to this task, besides professional and executive abilities, the 

 experience gathered in his former labors upon this work. The total area 

 assigned was a little less than 35,000 square miles. 



Out of the nine parties, six were moving field-parties, having special 

 areas conjoining along latitudinal and other lines, and connecting at cer- 

 tain triangulation and topographical stations. 



A special party, under Doctor J. T. Eothrock, U. S. A., organized 

 with a view to institute further investigations into the natural history 

 of certain areas left unfinished in 1871, 1872, and 1873, in New Mexico 

 and Arizona, departed from Santa Fe early in the season, and returned 

 laden with rich and valuable collections of the flora and fauna of that 

 great region ; having carried on, in connection with their examinations, 

 observations for altitudes of special points within the drainage area 

 visited, throwing further light upon the geographical distribution of ani- 

 mal and vegetable life. 



Two main distinct astronomical parties were occupied in establishing 

 the co-ordinates of points immediately adjacent to the field of survey 

 and others along the line of the Union Pacific Eailroad, and were 

 successful in accomplishing all that was laid out for them. 



The results in the astronomical branches are, the conclusions of the 

 observations necessary to determine the co-ordinates, and the astronomi- 

 cal meridian at the stations Las Vegas and Cimarron, X. Mex., the latitude 

 of Pueblo, Col., the latitude and longitude of Sidney Barracks, Jules- 

 burgh, and North Platte Station in Nebraska, on the Union Pacific 

 Eailroad. 



At the field astronomical stations sextant observations were carried 

 on by the following officers in charge of the several parties: First 

 Lieut. Wm L. Marshall, First Lieut. P. M. Price, Corps of Engineers; 

 Second Lieut. C. W.Whipple, Third United States Artillery; First Lieut. 

 E. Birnie, jr., and First Lieut. S. E. Blunt, Thirteenth United States In- 

 fantry. These stations have been numerous, answering all the require- 

 ments made upon them for checking special positions by a method in 

 place of which nothing else could be made available. 



The geodetic work included the establishment of 79 main triangu- 

 lation stations, extending a net-work over the entire mountain-area 

 occupied. Base-lines were measured at Trinidad and Pueblo, Colorado; 

 Cimarron, Las Vegas, and Santa Fe, New Nexico. These bases control 

 the triangulation which connects the belts of 1873 in Colorado, New 

 Mexico, and Arizona, as well as those north and south from the line of 

 the Union Pacific and Central Pacific Eailroads. 



In meteorology, except at the astronomical stations at Cimarron and 

 Las Vegas, N Mex., the observations were conducted solely with a view 

 to the deternmination of altitudes at prominent physical points within 

 the area surveyed. 

 3 s 



