HARMONIC ANALYSIS OF TIDAL OBSERVATIONS. ee 
The schedule [G] contains 36 speeds of compound tides: 9 of these 
fall into the category of astronomical or meteorological tides, 2 are re- 
peated twice, and of the remaining 25 we need only consider, say, the 
twelve most important. 
If either or both the component tides are of lunar origin, the height 
of the compound tide will change from year to year, and will probably 
tery proportionally to the product of the coefficients of the component 
tides. 
For the purpose of properly reducing the numerical value of the com- 
pound tides, we require not merely the speed, but also the argument. 
The following schedule gives the index of importance, argument and 
speed of the compound tides. 
The coefficients are the products of the coefficients of the two tides to 
be compounded. 
[H.] 
Schedule ef Compound Tides. 
Hgorence | Taitials.| - “CSamined Breed; aly peptal aetneat 
‘la MK Th Z | ar | 44°-0251728 
960 |» MS | M,+S, | 4y—2e—2) | 58°-9841049 
960 MS | S,—M, 2e—2n |  1°-0158958 
id MK | wite { 8y—40 | 42°-9271398 
561 we S,+K, 3y—2n 45°-0410686- 
400 MN M,+N 4y—5o+a | 57°-4938338 
399 an s.+0 By—20-—2n | 43°-9430356 
399 = S30 y+20—2n | 16°-0569644 
Ss 28M S,—M, 27 +20—4n | 31°-0158958 | 
Es: lsh M48; 6y—20—4 | 88°-9841042 
= oms | Se 8 2y—4o-4+2n | 27°-9682084 | 
ee — | wMm,4s, | 6y—4e—2, | 87°-9682084 
As in the case of the over-tides, the law of variability of the amplitudes 
of compound tides in various years is only to be tested by observation. 
_ It will be noticed that in two cases an over-tide of one Speed arises 
in more than one way, and accordingly different parts of it have different 
arguments and coefficients. In these cases the utilisation of the results of 
