Page 783 records and reports 834 



Any computations made to determine horizontal distances where the bomb posi- 

 tions are fixed by sextant angles and any computations made to determine the velocity 

 of sound indirectly (see 6353) should be retained until the hydrographic surveys have 

 been verified and reviewed, but need not be forwarded to the Washington Office. 



A comprehensive report should be forwarded explaining how the horizontal veloc- 

 ities used in plotting the smooth sheet were determined, referring to 6361 and 6362, and 

 the method used should be justified. The report should contain a discussion of the 

 accuracy of the results, and any particular difficulties should be elaborated on. Any 

 special methods of application should be described in full. 



834. Survey Data of Other Organizations 



The records of survey data of other organizations which should be submitted with 

 other records are of the following several classes: 



(o) Control data of triangiilation schemes which have been connected to the federal network of 

 triangulation by the establishing agency, a record of which is not in the Washington Office (see 216). 



(6) Control data of triangulation schemes which are connected to the federal network by the 

 survey party (see 224). 



(c) Hydrographic surveys made by other organizations, which are not duplicated by the survey 

 party, but with which a junction is made (see 3131). 



(d) Hydrographic surveys made by other organizations, which show changes or are of more recent 

 date than those on which the charts of the area are based. 



(e) Maps or blueprints from other sources which are submitted to supplement a topographic 

 survey of this Bureau (see 2361). 



(/) Maps or blueprints from other sources which show changes which have taken place in the 

 areas, useful for chart correction. 



With respect to (a) and (6), descriptions of stations, geographic positions, and a 

 sketch of the triangulation are required. Copies of the hydrographic sm"veys in (c) 

 must be forwarded with the other records of the hydrographic survey, unless there is 

 reasonable assurance that copies are already in the Office files, in which latter case they 

 must be unmistakably referred to by an identifying number. With respect to (d), (e), 

 and (J), copies of the surveys must be furnished in each case. 



Copies of the maps and surveys in (c), (d), (e), and (J) are useless unless each is on 

 an accurate projection by which it can be correlated with the work of the Bureau, or 

 unless each contains at least three points whose geographic positions are known (see 

 2361 and 3131). 



Copies of surveys or maps in (d) and (/) should be forwarded only after proper 

 evaluation as to their usefulness and accuracy has been made by the field party. To 

 be of value they must show; first, information of a nature suitable for charting, and 

 second, only projects actually completed. The surveys must be of sufficient accuracy 

 to permit their application to the chart without undue forcing. The Chief of Party 

 shall state over his signature the fact that an examination has been made on the ground 

 and that the actual existing conditions have been noted on the plan; the date of the 

 examination shall be shown. 



With respect to (e) and (/), features that are of use to the navigator as landmarks 

 are important and must be located by the field party independently from the plan. 



835. Completion of Records and Reports 



It should be the aim of the Chief of Party to forward all field records and sheets 

 in a condition as nearly completed as the circumstances permit. Before forwarding. 



