126 U. S. COAST AND GEODETIC SURVEY 
Mean higher high water from a month of observations, La Jolla, by tabular factors 
. WwW 
bite | Babe | Peggeym | pmo | Faggitgm [MOE bore | anean Dea EEE 
1946 Feet Feet Feet Feet Feet 
January 9255-2 = iL, Zo) 1. 000 0. 89 0. 87 1 0. 77 25 
IMINO eee. 1. 86 1. 001 0. 57 1. 16 1. 86 0. 66 2552 
Minaya e eee 1. 88 1. 002 0. 83 0. 90 1. 88 0. 75 2. 63 
uilyee Se. ee Sees 1. 79 1. 003 0. 95 0. 84 1. 80 0. 80 2. 60 
September -_---- 1. 78 1. 004 0. 61 1.14 1. 79 0. 70 2. 49 
November - -__-- 1. 83 1. 005 0. 64 0. 88 1. 84 0. 56 2. 40 
The primary determination of MHHW above half-tide level at La Jolla is 2.55 feet 
The last column of the table above shows that the derived mean values differ from this 
primary value by less than 0.1 foot except for the last month when the difference is 0.15 
foot. The larger part of this difference arises from the value of mean DHQ derived for 
that month which differs form the primary mean DHQ by 0.18 foot: 
For a series of observations covering less than a month the most practicable 
method of deriving mean higher high water is by comparison with simultaneous observa- 
tions at a suitable tide station or with the predicted tides at such a station, precisely as 
in the like case of determining mean lower low water, for which the detailed procedure 
was given. 
In summary it may be stated that from a year of observations mean higher high 
water can be derived, with reference to half-tide level, correct within 0.1 foot; from a 
month, correct to within a quarter of a foot; and from a day’s observations, correct to 
within about a foot. It must be noted, however, that occasionally the value derived 
from one day of observations may be considerably in error, so that at least three days 
of observations should be used if it is desired to determine mean higher high water 
correct within a foot. 
