TIDES AND CURRENTS IN BOSTON HARBOR 



INTRODUCTION 



This volume constitutes the fifth of a series on tides and currents 

 in important waterways of the United States, the purpose of which is 

 to make available to the mariner, the engineer, the scientist, and the 

 public generally the tidal and current data now in the files of the 

 United States Coast and Geodetic Survey. In preparing this pub- 

 lication it has been the aim to give in considerable detail the results 

 of all observations in Boston Harbor which were available at the time 

 of the publication. 



The tide observations include a long series at the navy yard at 

 Charlestown, which extended more or less continuously from 1847 to 

 1877; a series at Commonwealth Pier No. 5 in South Boston, which 

 commenced in 1921 and is still being continued; and a number of 

 short series covering periods from a single day to a number of months 

 at various places throughout the harbor. The two longer series are 

 known as primary, a primary tide station being one which is main- 

 tained over a series of years for the main purpose of securing extensive 

 tidal information in any locality. The shorter series of observations 

 were generally taken in connection with other hydrographic work, 

 especially for use in the reduction of soundings to a uniform datum. 

 Results from short series are corrected by comparison with simul- 

 taneous observations at some primary tide station. In addition to 

 the records of the Coast and Geodetic Survey, there are also included 

 in this volume the results of tidal observations at the navy yard by 

 the Navy oflicials for the period 1902 to 1911 and shorter series at 

 Moon Head and Nut Island by city officials. 



The current observations include those taken under the direction 

 of the following parties: Lieut. C. H. Davis, in 1847 and 1848; Assist- 

 ant Henry Mitchell, in 1860, 1861, and 1863; and Lieut. R. W. Wood- 

 worth, in 1926. Current data secured by the committee on the Charles 

 River Dam in 1902 are also included. In general the current obser- 

 vations at each station covered only a day or two, but at a few 

 stations the observations were continued over longer periods. The 

 observations were reduced by comparison with the tides at one of 

 the primary tide stations. 



Through a cooperative arrangement with the Bureau of Lighthouses 

 hourly current observations were taken on the Boston Light Vessel 

 during two periods — from September 22 to December 26, 1913, and 

 from June 8, 1926, to June 30, 1927. 



The general characteristics of tides and tidal currents, which were 

 discussed in Special Publication No. Ill, are reprinted in the appen- 

 dix of the present volume for convenience of reference. 



Attention is also directed to the tide and current tables which are 

 published in advance annually by the Coast and Geodetic Survey. 

 These tables contain data based upon the latest information available 

 at the time of publication. They include the predicted tides and 

 currents for every day in the year at a number of principal ports and 



