FOREWORD 



This is one of a series of manuals published by the United States 

 Coast and Geodetic Survey for the purpose of giving the general re- 

 quirements of the Bureau in carrying on its various activities. This 

 volume contains instruction for the observations of tides and the usual 

 reductions necessary for the determination of datum planes and the 

 nonharmonic quantities published in the Tide Tables. Directions for 

 taking temperature and density observations are also included for the 

 convenience of tide observers who take such observations in connection 

 with their regular duties at the tide stations. 



Corresponding instructions for tidal current observations are given 

 separately in Special Publication No. 215, Manual of Current Obser- 

 vations. The harmonic computations required for the prediction of 

 tides and currents are described in Special Publication No. 98, Manual 

 of Harmonic Analysis and Prediction of Tides. 



The present work supersedes a previous edition of the manual 

 published in 1935 and contains a revised description of the standard 

 automatic tide gage to include recent improvements in this instru- 

 ment. This manual was prepared by Paul Schureman, Principal 

 Mathematician, under the direct supervision of Capt. Paul C. Whit- 

 ney, Chief of Division of Tides and Currents. 



