( 181 ) 
a b c 
(B)-(10) (1242) WHO ab ame 
September 218.4 278.5 252.3 —60.1 —33.9 
October 203.4 234.7 196.6 —31.3 6.8 
November 206.4 212.0 170.4 — 5.6 36.0 
December 197.9 182.6 161.6 15.8 36.5 
January 210.1 199.2 201.8 10.9 8.3 
February 189.2 207.5 217.0 —18.3 —27.8 
March 179.9 217.8 231.8 —37.9 —51.9 
April 188.8 245.3 231.2 —56.5 — 42.4 
(—42.1) (—82.6) 
The differences (a—b) and (a—c) are independent of W, the general 
mean, of the annual and semi-annual variations and of disturbing 
influences as far as they may be considered to be the same at the 
different hours of the day or i. o. w. last for some days. 
The influence of S, and S, is the same for every month, so that 
the periodic variation, which is evident in the differences, is caused 
exclusively by the tides A), P and Ks. 
The figures in brackets —42.1 and —32.6 are obtained by 
combining the two values for the month of April in such a way that 
to each value is given a weight equal to the number of days of 
observation resp. 8 and 22. 
The series is considered therefore to commence with May Ist, a 
fact which must be taken into consideration in applying the astro- 
pomical argument. Representing the single-periodic variation of the 
differences (a—b) and (a—c) by the expression: 
a—b= Acos 30° «+ Bsin 30° a | (2) 
a — e= Aj cos 30° x + Bj sin30° a | 
we find by the method of the |. sq.: 
A = — 26.58 B= — 28.68 
A, = — 51.88 B, = — 25.62 
The influence of the tides K,, P en A, in the monthly mean 
values may be represented by the expressions: 
(1) Ko Ro cos (30°  +315° — Cy) + PR cos (30° # + 75° + CG) 
(2) Ko, Rg cos (30° # +345° — Cy) + PRq cos (30° 2 + 45° + CG) 
(3) K, Ry cos (30° x + 15° — Cy) + PR cos (30° « + 15° + Gp) (3) 
(4) K, Ry cos (30° 2 + 45° — Cy) + PRy cos (30° « — 15° + Cp) 
(5) Ky Re cos (30° « + 75° — Cy) + PRy cos (30° « — 45° + Co) 
(6) K, Ro cos (30° # +105° — Cy) + PRy cos (30° « — 75° + Cp) | 
Mean. 0.644 K, Ry cos (30° x + 30°—Cx) + 0.644 PR cos (30% + CG) 
