IMORMATION RELATING TO NAVIGATIONAL AIDS 

 AND GENERAL NAVIGATION. 



THE CORRECTION OF CHARTS, I^IGHT lilSTS, AND SAILING 



DIRECTIONS. 



The following-named publications are issued by the United States 

 Hydrographic Office as guides to navigation: Charts, Chart Cata- 

 logues, Sailing Directions, Light Lists, Tide Tables, Notices to Mari- 

 ners, Pilot Charts, and Hydrographic Bulletins. Of these, the 

 Notices to Mariners and the Hydrographic Bulletins are free to 

 mariners and others interested in shipping. The Pilot Charts are 

 free to contributors of professional information, but sold to the 

 general public at 10 cents a copy. The other publications of the 

 office are sold under the law at cost price. 



The Charts, the Sailing Directions, and the Light Lists are all 

 affected by continual changes and alterations, concerning which 

 information is published weekly to all parts of the world in the 

 Notices to Mariners. 



The Charts should always be, so far as our knowledge permits, 

 absolutely correct to date; and the Light Lists should be noted for 

 the recent alterations and additions. The Sailing Directions, how- 

 ever, can not, from their nature, be so fully corrected, and in all cases 

 where they differ from the charts, the charts must be taken as the 

 guide. 



Charts. — When issued from the Hydrographic Office, the charts 

 have received all necessary corrections to date. 



All small but important corrections that can be made by hand are 

 given in the Notices to Mariners, and should at once be placed on the 

 charts to which they refer. 



Extensive corrections that can not be conveniently thus made are 

 put upon the plates, and new copies are issued to the ships to replace 

 the old, which are directed to be destroyed to prevent the possibility 

 of their being used in the navigation of the ship. 



The dates on which extensive corrections are made are noted on the 

 chart on the right of the middle of the lower edge; those of the 

 smaller corrections at the left lower corner. 



