with care, as above directed, be carried in our field-expeditions and 

 be obtained from them, the precaution, however, being token to dete 



tude absolutely at proper intervals,* as tests and checks of the work. 

 The astronomical observations which we took for time, or longit 



they have boon filed in the Ihireau of Topographical Engineers, they 



the- entering of astronomical data: as they may be of service to futur 



As every hint of practical value is of use to explorers in the field 



that in taking the altitudes of the sun with the sextant, I have four 



instrument, say every 20' of are. and wait for the contact or separata 



Dear Sir : At your request I give you the result of my observations for longitude upon my recent exploration \ 

 he Rio Bravo del Norte, Ar my camp upon the Rio Florido (a tributary of Rio Las Animas, which empties into 

 i Juan), I observed an oeenltation of V, A. C. 41K4, on August :», l-.VJ, from which the longitude of 107° 46' 30" 



ers, U. S. A., in Chanj< of Expl oration* in l't 

 and Captain Whipple's, lie makes the (lit 



My longitude of Camp No. 21, 

 of Navajo expedition 



