120 U. S. COAST AND GEODETIC SURVEY 
the ratio of K,+O, to Mz is 1.20 for Seattle and 0.97 for Neah Bay. The type of 
tide at these two stations is sufficiently different to make Seattle an unsuitable station 
for determining DLQ at Neah Bay from one day of observations. In the example for 
La Jolla and Los Angeles, the factors in the 7th column for the 6th and 21st likewise 
were relatively large. But the ratio of K,+0, to M; is 1.10 for La Jolla and 1.07 for 
Los Angeles. The type of tide at these two stations is so nearly the same that even 
for these two days the DLQ devived did not differ much from the mean value and there- 
fore gave concordant results. 
Correction by Tabular Values 
The correction of the results from a short series to mean value of lower low water 
involves two steps: (1) correction of low water to mean value; (2) correction of low 
water diurnal inequality to mean value. By the method of comparison of simultaneous 
observations, both these corrections are derived by comparing the observations with 
simultaneous observations at a primary station for which mean values are available. - 
The method of correction by tabular values derives the corrections directly from 
the observations by the use of tabular values that have been calculated from theoretical 
principles. The correction to mean low water makes use of the tabular values in 
Table 5 and the procedure has been exemplified in Section VII. The correction to 
mean DLQ makes use of the tabular vaiues in Table 6 and will be exemplified below 
for a year and a month. For less than a month the method of tabular values is not 
applicable in the simplified form shown here. 
Year.—We may take La Jolla for the same years as used in the example by com- 
parison, namely, every other year from 1936 to 1948. Columns 2 and 4 give the yearly 
values of low water below half-tide level and DLQ respectively, from the observations 
at La Jolla. Columns 3 and 5 give the factors for each year taken respectively from 
Tables 5 and 6. Columns 6 and 7 give the respective products and column 8 the sums 
of the previous two columns. 
LW bel tor fro r y / Vf 
Yes nae” | Page | pre | Paggegm [ur tow | Mee 
Feet~ Feet Fee Feet Feet 
LOS =a ott ue ee BE 1. 83 1. OO1 0 93 0. 978 1. 83 0. 91 5 al 
OS Sees eee I, Sil 0. 990 0. 84 1. 082 1. 79 0. 91 20 
OA WEEE ete be 1. 86 0. 983 0. 80 I, 17 1. 83 0. 94 PASTE 
NO ADE a pee cage, Loess 1. 83 0. 984 0. 82 1. 161 1. 80 0. 95 2 
gO ysl bear ee 1. 83 0. 992 0. 88 1. 065 1. 82 0. 94. 2. 76 
LOA GH arr se eae 1. 81 1. 003 0. 96 0. 962 1. 82 0. 92 2. 74 
The primary determination of mean lower low water below half tide at La Jolla 
is 2.73 feet, of mean low water below half-tide level 1.81 feet, and mean DLQ 0.92 
foot. The yearly values derived in the last column are thus within 0.04 foot of the 
primary value. The mean DLQ was determined within 0.03 foot and mean low water 
below half-tide level within 0.02 foot. On comparing the values derived above with 
those derived by the method of comparison (page 116) it is seen that the latter method 
gave slightly more concordant results. ; 
