272 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



nally Cambridge, on the Atlantic coast, with their station at 

 San Francisco, on the Pacific. It (Ogclen) has also been con- 

 nected with the meridian established by the United States 

 Lake Survey at Detroit, Michigan, which in turn has been 

 determined with regard to the meridian of the observatory 

 at Washington. This third check will serve to give results 

 from which by the theory of probable errors the resulting 

 probable errors of the observatory at Ogden with regard to 

 Washington, and also from further data with that of Green- 

 wich, will be determined. 



Geodesy. Seventy-nine main triangulation stations have 

 been occupied, and main and minor topographical stations, 

 extending a net-work over the entire mountain area occupied 

 (the number of which is not known at this time), have been 

 localized. Base lines have been or are to be measured at 

 Trinidad and Pneblo, Col. ; Cimarron, Las Vegas, and Santa 

 Fe, New Mexico. These measured and developed bases con- 

 trol the triangulation reaching westward, and connectinor 

 the belts of 1873 in Colorado, New Mexico, and Arizona. A 

 series nearly in the same meridian reaches from Hughes, Col., 

 on the north, to Las Vegas, New Mexico, on the south ; and 

 other geographical positions of points have been determined 

 in advance by parties of the Survey, sufficient in number to 

 control belts of triamnilation reaching in either direction 

 north or south from the line of the Union Pacific and Cen- 

 tral Pacific Railroads. 



Improvement as to the instruments, celerity of movement 

 of the parties, on account of the fact that no Indian difficul- 

 ties are expected, the facilities from preliminary information 

 obtained from the reports and maps of Lieutenant Ruffner, 

 the General Land Office map, and a late map issued of Colo- 

 rado and New Mexico, have all conspired to render the fin- 

 ished labors of this season of a more experienced force more 

 valuable than any heretofore. 



Meteorology. The usual observations, entirely of a prac- 

 tical character, of all the moving field parties for the deter- 

 mination of altitude, have been dotted over the entire area, 

 so as to give, together with the topographical lines rigidly 

 measured, sufficient material upon which to base a series of 

 contour maps, conjectural, of course, to a large extent, but use- 

 ful for geological delineation, 



