654 



EEV. 8. HATJGHTON ON THE TIDES OF THE 



Appendix to Part II. On the Semidiurnal Tides of Port Leoj)old, North Somerset. 



An error has occurred in my account of the Semidiurnal Tides of Port Leopold, 

 Transactions of the Royal Society, vol. cliii. p. 25G, which I am desirous to correct. 



In Table I., the last column is headed "Moon's Hour-Angle," whereas it ought to be 

 " Moon's Hour- Angle East of Sun." In copying the Table from my note-book this error 

 occurred, and has led to some inaccuracies in the subsequent part of my paper which 

 ought to be corrected. 



The Moon's Hour-Angle, which should be used in the calculations, is found by sub- 

 tracting the means of the second and fourth columns. Thus 



Hour-Angle of Moon at time of ) ^^ 4m_2h 2"=-0'' 58" 

 ximum Spring Tide Ranges . . J 



Mean 



Maximum Spring Tide Ranges 



The same error occurs in Table II. p. 257 ; and its correction is similar, viz., 



:6h 50™— T*" 48'"= — 0'' 58"*. 



Mean Hour- Angle of Moon at time of ) _ , 

 Minimum Neap Tide Ranges . . i 



This is the value of the Lunitidal interval (found without calculation), which may be 

 safely used in the subsequent calculations. The corresponding value of the Solitidal 

 interval is found by taking the means of the second columns of Tables I. and II., and 

 is found to be +0'' 57"", a quantity differing little from that found by calculation in 

 p. 259, viz. +0'' 56™ 20^ 



The Lunar Semidiurnal Tide, cleared of parallax, is 



2M cos" !«, cos 2(7«— ?■„) ; 



and its maximum and minimum ranges are (p. 260) 4'62 ft. and 4'23 ft. 



The minimum is attained at Solstitial Springs and Equinoctial Neaps, which, from 

 Tables I. and II., are 



d h m Q I 



Moon's declination 18 51 N. 

 Moon's declination 16 33 N. 



Mean . . 17 42; 



June 21 30 

 April 17 



and the maximum is attained at Solstitial Neaps and Equinoctial Springs, which, from 

 Tables I. and II., are 



June 29 8 







March 26 1 30 



Moon's declination 9 2 N. 

 Moon's declination 8 24 N. 



Mean . . 8 43 



