Page 93 control and signal building 2351 



during prior surveys. The number of stations recovered may be sufficient for control 

 of the new survey. 



To provide for future use in revision surveys, the topographer shall supplement 

 existing control by establishing additional recoverable stations so that there are control 

 stations at 1-mile intervals along the coastline; except along rugged or swampy coast- 

 line bordering areas unfavorable to habitation or industry, where the interval may be 

 increased to not more than 2 miles (see 2141). 



These recoverable stations may be natural or artificial objects when available, or 

 standard topographic disks set especially for this purpose, and together with other 

 control stations provide recoverable control at the required intervals. When practic- 

 able, stations should be established where they can be easily identified, and in the most 

 permanent places available. Conspicuous points, rock outcrops, large boulders, etc., 

 are excellent places to set station-mark disks. Often natural or artificial objects exist 

 which make splendid topographic stations that are recoverable without special marking. 

 Some of the natural ones have remained intact for generations and are very likely to 

 remain so for years to come. The establislmient of a station at its most likely location 

 will aid' a later party in its recovery. 



All topographic stations specially marked for future recovery shall be marked 

 with standard .bronze topographic station marks, stamped with the name and year. 

 Reference marks are not set at topographic stations. Paragraph 29, page 7, and line 8, 

 page 52 of Special Publication No. 144, Topographic Manual, are hereby amended by 

 the substitution of the word "topograpliic" for the word ''hydrographic." Hydro- 

 graphic station marks are no longer used by the Coast and Geodetic Survey and hence-^ 

 forth shall be considered obsolete. 



2357. Descriptions of Recoverable Topographic Stations 



New recoverable topographic stations shall be described on Form 524. Fill in 

 the spaces provided at the top of the form with the appropriate information. Under 

 "Detailed description" write a complete description of the station just as if it were 

 a description of a triangulation station: what it is like; where located; air-line distance 

 and direction from some well-known geographic feature, or some other permanent refer- 

 ence; how to reach the station; etc. (see 227). Distances and true directions, whether 

 observed by theodolite or compass, shall be given to the liigh-water line and any nearby 

 witness marks which will assist in the recovery of the station. If there are witness 

 objects or reference points which might be identifiable on air photographs, distances 

 should be measured to several in different directions, and a detailed sketch of the 

 vicinity should be made to show the relation of the station to the witness marks. 



The same form shall be used to report the recovery of a topographic station, but 

 the following changes should be made: 



(o) Print a conspicuous capital R in the upper right-hand corner of the form. 

 (6) In the space for the year, enter the year of the original marking in parentheses, followed by 

 the year of the recovery. 



(c) In the space for "Chief of Party," note the initials, in parentheses, of the Chief of Party 

 who established the station, followed by the name of the Chief of Party making the recovery. 



(d) Under "Detailed description," a brief statement as to the adequacy of the original description 

 will be sufficient if it is adequate. If it is inadequate, write a complete new description just as for a 

 new station. If the station is not recovered, state whether it should be considered lost or not, giving 

 particulars, and the time spent in searching for the station. 



