ON THE HARMONIC ANALYSIS OF TIDAL OBSERVATIONS. 39 
Ny =2(y —o)=2 x 14°-4920521 per hour, 
Ny=2(y—n), 
N, — y= —1°-0158958 per hour. 
Hence, taking 7 negative, the equation is 
1°-0158258g=14°-4920521>. 
Tf 7=25, g=356°63. 
Thus 25 periods of 2(¢—») is 356°63 of mean lunar time. 
Tt follows, therefore, that we must have 357 entries in each column. 
Thus the M, computation form should have the row numbered 357 
complete, adding 9 more entries. 
There are no ‘changes’ amongst these 9 entries. The divisors are 
to be modified accordingly, here and in all subsequent cases. 
K Series. 
To minimise the effect of M, on K,, we have 
N=2y=2 x 15°-0410686 per honr, 
ny=2(y—0), 
Ny —Ng=2(o—n)=1°'0158958 per hour. 
1°-0158958q=15°:0410686r. 
If r=25, g=370'14. 
Hence we should complete the row numbered 370. 
The last 3 entries of the existing tables are to be cut off. 
To minimise the effect of O on K,, we have 
n= y=15°:0410686 per hour, 
No=y —2c, 
Ny —Ng=2o0=1°-0980330 per hour. 
1°-0980330qg=15°:0410686r. 
If r=27, q=369'85. 
Thus g=370 again gives the best result, and confirms the conclusion 
from the above. 
The N Series. 
Here Ny =2y — 304+ a7=2 x 14°'2198648 per hour. 
To minimise the effect of M,, 
Ny, —Ng=(o—w)=—0°'5443747 per hour. 
0°544.3747q=14°'2198648r. 
If r=13, g=839-58. 
Hence we should complete the row numbered 340. 
There is no justification for the alternative offered in the computation 
forms of continuing the entries up to 369% 3" of mean solar time. 
The L Series. 
Here N= 2y—o—w=2 x 14°°7642394 per hour. 
