8 GENERAL NAVIGATION. 



In all cases of quotations of charts these dates of corrections should 

 be given, as well as the number of the chart (found in the right 

 lower corner) , in order that the edition of the chart referred to may 

 be known. 



The Light Lists are corrected before issue, and all changes are 

 published in the weekly Notices to Mariners. 



The navigating officer should make notations in the Light Lists 

 and paste in at the appropriate places slips from the Notices to 

 Mariners. 



The Light Lists should always be consulted as to the details of a 

 light, as the description in the Sailing Directions may be obsolete, in 

 consequence of changes since publication. 



The Sailing Directions are corrected before issue, and subse- 

 quently should be kept corrected by means of the Notices to Mariners. 



Supplements are published from time to time and contain all the 

 information received up to date since the publication of the volume 

 to which they refer, canceling all previous Notices to Mariners. 



The existence of Supplements or Notices to Mariners is to be noted 

 in the tabular form inside the cover of each volume. 



To enable the books to be more conveniently corrected, Supple- 

 ments and Notices to Mariners are printed on one side only, and two 

 copies are issued to each ship — one to be cut and the slips pasted 

 in at the appropriate places, the other to be retained intact for 

 reference. 



To make the notations and paste in the slips, as the Notices to 

 Mariners are received, is one of the duties of the navigating officer 

 demanding faithful attention. 



It must, however, be understood that Sailing Directions will rarely 

 be correct in all details, and that, as already stated, when differences 

 exist, the chart, which should be corrected from the most recent in- 

 formation, should be taken as the guide, for which purpose, for 

 ordinary navigation, it is sufficient. 



The Tide Tables, which are published annually by the United 

 States Coast and Geodetic Survey, give the predicted times and 

 heights of the high and the low waters for every day in the year at 

 70 of the principal ports of the world, and, through the medium of 

 these by means of tidal differences and ratios, at a very large number 

 of subordinate ports. The Tables for the Atlantic and Pacific coast 

 ports of the United States are also published separately. 



It should be remembered that these tables aim to give the times of 

 high and low water, and not the times of turning of the current or of 

 slack water, which may be quite different. 



Notice to Mariners, containing fresh information pertaining to 

 all parts of the world, are published weekly and mailed to all United 

 States ships in commission, Hydrographic branch offices and agen- 



