152 U. S. COAST AND GEODETIC SUEVEY. 



To obtain Sa and Ssa from the monthly means of sea level, or 

 tide level, determined from the first 29 days of each calendar month, 

 the following process may be used: Enter the monthly means 

 beginning with that for January in alternate spaces provided for 

 the hourly means on the front of Form 194, placing the value for 

 January in the space for the hour. For convenience consider alL 

 the intermediate blank spaces as being filled with zero values and 

 make the computations indicated by (3) to (12) and (18) to (21). 

 Correct the coefficients of s^ and c^ from 12 to 6, at top and foot of 

 columns (9), (12), (19), and (21). In bottom of form enter Sa in 

 column having subscript 2 and Ssa in column with subscript 4 in 

 order to obtain correct augmenting factors and strike out numerals 

 indicating subscripts. For (38) and (39) take the logarithm of twice 

 the values of 6s and 6c as obtained above. The f's as obtained from 

 (40) must have the following corrections applied in order to refer 

 them to hour of the first day of January — common years, Sa 

 correction = — 13.38°, Ssa correction = —26.76°; leap years, Sa cor- 

 rection =— 14.20°, Ssa correction = —28.40°. For convenience in 

 recording the results it is suggested that the f as directlj^^ obtained 

 from (40) be entered (in its proper quadrant) in the space just below 

 the logarithm from which it is obtained, and that the f corrected to 

 the first day of January be entered in the same line in the vacant 

 column just to the right. The V+u, computed to the first day of 

 January, may then be entered inmiediately under the corrected 

 f's and the k' of (43) readily obtained. For (49) the combination 

 (46) + (47) will be used 



Form 462, R, k, and ^ from analysis and inference (figs. 30 and 31) — 

 This form provides for certain computations preliminary to the 

 regular elimination process. The constants for components K^ and 

 Sa as obtained directly from Form 194 may be improved by the 

 application of corrections from Tables 21 to 26; and constants for 

 some of the smaller components, which have been poorly determined 

 or not determined at all by the analysis, may be obtained by infer- 

 ence. If the series of observations is very short, the inferred values 

 for the constants of some of the components may be better than 

 the uneliminated values from Form 194. 



Form 452 is based upon section 29. It is designed to take account 

 of the diurnal component on one side (fig. 30) and the semidiurnal 

 components on the other side (fig. 31). The amplitudes and epochs 

 indicated by the accent (') are to be taken from Form 194 and the 

 quantities indicated by the asterisk (*) from Form 244 or 244a. If 

 the series is less than 355 days, values for Si and 2SM may be 

 omitted. 



For all short series the values in columns (4) and (8) are to be 

 computed in accordance with the equivalents and factors in columns 

 (3) and (7), respectively. If the series is 192 days or more in length, 

 the K of Ml, Pi, and Kj for column (4), and the log R of Mi, Pi, and 

 K2 for column (8) may be taken directly from Form 194, and if the 

 series is 355 days or more in length the k and log R of all the com- 

 ponents for which analyses have been made may be taken directly 

 from the same form. When a value is thus taken directly from the 

 analysis, the corresponding equivalent in column (3) and factors in 

 column (7) are to be crossed out. 



The tabular values of items (12) and (13) for the diurnal com- 

 ponents and items (14) to (18) for the semidiurnal components may 



