100 U. §. COAST AND GEODETIC SURVEY 
and full moon and less at the times of the moon’s quadratures. In. the mixed type of 
tide the inequality between the two low waters of a day is least at the time the moon 
is close to the Equator and greatest near the times of the moon’s northing and south- 
ing. 
At eased, which exemplifies the daily type of tide, the low waters are seen to — 
follow the moon’s declinations rather than its phases. Low water falls lowest at the 
times of the moon’s northing and southing, and least near the times the moon is close 
to the Equator. 
On comparing the diagrams for Atlantic City in Figures 44 and 45 for the last 
2 days of the month, it is seen that although the periodic variation in low water tended 
to make the fall of low water greater, the actual fall, represented in Figure 44, was less. 
In other words the effects of wind and weather more than counterbalanced the periodic 
variation and made the morning low water on the 31st higher by 0.9 foot than the 
morning low water on the 30th, whereas the periodic variation would have made it 
less by 0.2 foot. 
The daily height of low water is thus subject to relatively large variations both 
periodic and nonperiodic. The periodic variations depend primarily on the phases, 
1946 1947 
Jan. Apr. July Oct. Jan. Apr. July Oct. Dec. 
Atlantic City 
Los Angeles 
Pensacola 
Fia. 46.—Monthly heights of low water, Atlantic City, Los Angeles, and Pensacola, 1946-47. 
