RECORD AND REDUCTION OF THE TIDES. 



79 



it was easy to alter the latter so as to make them exactly correspond to the phases 

 30°, G0°, 90°, 120°, etc. In this manner the following numbers have been 

 obtained : — 



FOR THE SPRING-TIDE WAVE OCCURRING ONE AND A QUARTER DAY AFTER FULL AND NEW MOON. 



The columns headed " mean" show the ordinates of the waves for (nearly) 

 equidistant intervals of time. 



The following table contains the corresponding numbers for tlie ucnip tide wave 

 occurring 11 day after the first and last quarter, and as derived from 30 tides 

 observed hourly from low to low water : — 



The results are represented in the annexed diagram. The result for the neap 

 tide curve has also been multiplied by y^xa' ^^^ ratio of neap and spring tide range 

 as found on a preceding page, and was increased by 0.5 to refer it to the same 

 level. 



