278 



PROCEEDINGS OF SECTION A. 



semi-annual, and annual tides, and the complete results we now 

 append in tabvdar form. The largest of these long period tides 

 we find to be the solar annual, which has a total range of 6in, 

 Next in order comes the solar semi-annual, with a range of 4in. 

 The hmi-solar fortnightly comes next with a range of 3in., while 

 the lunar monthly and kmar fortnightly have each a range of just 

 about 2in. We also give a table showing the mean level of the 

 sea at Port Adelaide for each year, and for each month of the 

 year, since 1882. These have been computed from the records of 

 high and low water levels, and show considerable fluctuations in 

 value. The yearly mean has its greatest value (4*29 1) in 1889, 

 and its least value (4-007) in 1885. The average of the monthly 

 means shows a well-marked yearly tide, but the number of years 

 is of course not sufficiently great to eliminate the effects of the 

 lunar tides. We are now proceeding with a second analysis of 

 the Port Adelaide curves, and this time have the advantage of the 

 use of the computing apparatus which has been designed by 

 Professor G. H. Darwin. He has very generously sent us the 

 apparatus, and we take this opportunity of acknowledging our 

 obligation. 



The average heights of the barometer at Adelaide, for each 

 year under consideration, are appended to the table, and it will be 

 noticed that, as a rule, where the barometer level is high the sea level 

 is low, and vice versa. The barometric mean heights have been 

 obtained from the records of the Adelaide Observatory : — 



RESULTS OF THE HARMONIC ANALYSIS OF THE TIDES AT 

 PORT ADELAIDE (Lat. 34° 51' S., Long. 138° 30' E. 



S, 



Mx 



M„ 



Mi 



Ki 



K„ 



O' 



P 



N 



Mm 



Mf 



Msf 



Solar diiimal 



Solai" semi-diurnal > . . 



Solar quarter-diumal 



Lunar diurnal 



Lunar semi-diurnal 



Lunar quarter-diumal 



lAmi-solar diurnal (declinational 



Luni-solar semi-diurnal (decKnational) 



Lunar declinational diurnal 



Solar declinational diurnal 



Larger lunar elliptic semi-diurnal .... 



Lunar monthly 



Lunar fortnightly 



Luni-solar fortnightly 



Solar annual 



Solar semi-annual 



122 

 180 



204 

 121 



231 

 177 

 34 

 231 

 114 

 258 

 194 

 256 

 132 

 304 



