Department of Commerce, 

 United States Coast and Geodetic Survey, 



Washington, D. C. 

 The requirements for hydrographic surveying in this edition of the Hydrographic 

 Manual supersede all previous manuals, instructions, and circulars on the pertinent 

 subjects and, together with the Regulations for the Government of the United States 

 Coast and Geodetic Survey, shall be complied with in executing all hydrographic 

 surveys unless divergence therefrom is authorized in^ the instructions issued for each 

 project. 



Leo Otis Colbert, Director 



Page xvi 



