Page 83 control and signal building 2271 



use in erosion studies, the feature to which the measurement was made must be described 

 in some detail. 



A station which is abandoned before its position has been determined, all marks 

 being removed and destroyed, does not require a description. 



2271. Description of Stations of Other Agencies 



Any existing marked control station or boundary monument, originally established 

 by some other agency, federal or otherwise, whose position is determined by this 

 Bureau for the first time, shall be described as a new station on Form 525. Among 

 the federal agencies, whose stations are most frequently encountered, are the Geological 

 Survey, Corps of Engineers, General Land Office, and International Boundary Com- 

 mission. 



The description shall state clearly whether the existing station was used as a station 

 in the new scheme, or whether a new station was established nearby and the position 

 of the existing station determined by distance and angular measurements. The name 

 of the agency (abbreviated) which established the station shall be placed in parentheses 

 after the name of the station and thereafter shall form an integral part of the station 

 name; e. g., WILKES (U.S.E.). Form 525 must contain a complete description of the 

 station, just as for a new station, since the descriptions of stations established by other 

 agencies are ordinarily not on file in the Washington Office. The description shall 

 state clearly what former marks were found, the stamping or inscription on them, 

 whether the station was reinforced or marked and, if so, how, and what additional 

 reference marks were established. (See 224.) 



2272. Recovery Notes 



A report shall be made on Form 526, Recovery Note, Triangulation Station, for 

 each station recovered or searched for. If a station is recovered exactly as previously 

 described and all marks are in good condition and the description is entirely adequate, a 

 statement to that effect will be sufficient on the recovery note. If the station is removed, 

 re-marked, reinforced, reset, replaced, or new reference marks are established, this 

 information, with a brief description of the new mark, reference measurements and 

 directions, and stampings on the marks must be submitted. If the original description 

 is inadequate or changes have taken place since the station was established, such as 

 new roads, real estate development, erection of new structures, changes in property 

 ownership, changes in natural topography due to storms, erosion, excavation, improve- 

 ments, etc., the recovery note shall contain a complete new description of the station, 

 just as would be written for a new station. A specimen recovery note is given on page 

 114, Special Publication No. 145, Manual of Second- and Third-Order Triangulation 

 and Traverse. 



All reference distances and directions in the original description shall be verified 

 and any discrepancies specifically noted. The initials of the person responsible for the 

 description should appear in the lower right-hand corner of the card. 



228. Pseudo-Triangulation Methods 



In a hydrographic survey it is occasionally necessary to determine accurately 

 the positions of one or more stations where conditions preclude the use of the conven- 

 tional triangulation methods usually described in manuals. Necessity and ingenuity 

 gained through experience will generally produce some substitute method by which 



