20 Dwellers of the Sea and Shore 



In another week we find the moon full and in a line 

 opposite from the earth to the sun. Although pulling 

 in opposite directions they produce a harmonious re- 

 sult. For as two tides are formed at the same time, 

 one on each side of the earth, it follows that the in- 

 fluence which is one body's loss is the other's gain. The 

 following, or third, week we see the moon in its last 

 quarter; it has by then completed three-fourths of its 

 cycle. Once again the moon is at right angles from the 

 sun; once again the tides are at their slightest range; 

 from this time onward they will increase daily until the 

 moon is full, the cycle then continuing as before. 



If the earth were entirely covered with water, the 

 tidal swell would travel in a westerly direction and 

 keep its place regularly on the meridian of the moon; 

 but we know that actually the movements of the waves 

 are exceedingly complex. Observations along different 

 points of our seaboard show that there is sometimes a 

 great difference in the time of high tide between two 

 or more places situated close together. For example, 

 high water does not occur in Hempstead Harbor until 

 more than three hours after the time of high tide at 

 Governor's Island in New York Harbor, less than 

 thirty miles to the west. Now this lagging of the tides 

 is noticeable to a great extent on all continental shores, 

 and it is due partly to the retarding action of the latter, 

 partly to the inertia of the water itself, but mainly to 

 the irregular distribution of the land which breaks up 

 the tidal wave into innumerable wave crests, vastly 

 restraining their progress. 



Let us note one more singularity. This is the dif- 

 ference in range, or vertical movements of the tide, in 



