130 REPORT— 1870. 



of each being nearly of the same value. This eomponcnt has been included 

 in the calculations of the actual heights. 



63. The above four years' observations have been analyzed for the long- 

 period tides, but tlie resulting amplitudes ■were very small ; and there was so 

 little agreement between the epochs as deduced from the several years, that 

 they were deemed not satisfactorily evaluated. The solar annual tide, how- 

 ever, gave a moderate agreement, the mean value for the four years being 

 0*36 foot, and the epoch 238°*5, which places its maximum about Novem- 

 ber 19 ; but this is i)robably due in the main to meteorological causes. The 

 differences between the calculated and actual heights, after being corrected 

 for the quarter-diurnal luni-solar tide, also showed that the synodic fort- 

 niglitly tide of i)eriod 2(0* — tj) is of sensible value; and the present non- 

 agreement between the analyzed values of the four years may be owing to 

 the influence of wind, barometric disturbance, and also of instrumental errors 

 extending over considerable periods, and seriously affecting the daily means 

 which are the basis of reduction for the long-period tides. If the pimfied 

 daily means had been corrected for barometer «&c., as in the discussion of the 

 Port-Leopold tide observations by Capt. Sir J. C. Ross (Phil. Trans. 1854), it 

 is very probable that more satisfactory results would have been obtained. 

 The following are the results for the Long-period Tides : — 



64. The retardation of the phase of spring-tides is determined by dividing 

 the difference between the epochs of the mean solar and mean lunar semi- 

 diurnal tides (e^ of series S and M respectively) by twice the daily difference 

 between the mean motions of the moon and sun. Taking the average of 

 epochs for the four years, we have 



11°*15~ 3^5°*27 45°"88 



2xl2°-191 ~ " 24°-382 "'^'''^^^ = ^'' ^^'' ^^'" <^^^*^^ ^^"""'^ syzygies) ; 



similarly the coincidence of phase of the declinational diurnal tides (P and 0) 

 is (applying the proper correction to e^ of series 0) 



Qso.oq Qi 10.07 T4.(\°-79 



2xl2°-191 '"^i^==^''Q^^ = ^' 0" 26- (after moon's syzygies). 



Taking the mean of the epochs of each of the tide-components as deter- 

 mined by the analysis of the four years' observations, and expressing each 

 mean value thus obtained in mean solar iime, we have the following Table 

 of values for Liverpool : — 



I 



