50 
for that station, from the observations 1841 to 1845 inclusive, already pub- 
lished. In deducing this mean curve, the epochs g given in the following table 
have been regarded as marking the transit of the apex of the symmetrical — 
curve in each year. 
wich, 
Year. 
1841. 
1842. 
1843. 
1844. 
1845. 
These epochs have consequently been considered as the axes of the curves ; b: 
they have been brought i in the projections on the same vertical line, and on 
this line the altitudes given in the third column have been projected ; the ( 
altitudes: at intervals of two hours preceding and succeeding these axes — 
during a period of thirty days have also been projected, so that fifteen days ' 
on each side complete not only the symmetrical curves, but also those pre- © 
REPORT—1848. a 
Taste VIII. 
Epochs of transit of the crest of the “Great Symmetrical Wave of Novem- 
ber,” from 1841 to 1845 inclusive, at the Royal Observatory, Green- 
Epoch of transit. 
don 
Novy. 25, 0 
Nov. 17, 22 
Nov. 13, 10 
Oct. 26, 22 
Nov. 14, 0 
ceding and succeeding them by seven days. 
1841 to 1845 inclusive, corrected for temperature, am reduced to the ; 
level of the sea. 
Hours Hours Hours Hours 
pefore, | Altitudes. | fer. | aititudes. || Pv" | Altitudes. |, | Altitudes. ¥ 
Apex. | 30:271 | Apex.| 30°271 || 20 | 30-112 | 20 | 307178 | 
2 2 22 092 | 22 172° 
4 4 24 | 30°079 | 24 151) 
6 6 | 26 26 135 | 
8 8 | $0:256 || 28 28 114 4 
10 | 30°215 | 10 | 30-252 || 80 | 29-992 | 30 “097 | 
12 205 | 12 32 32 085 | 
14 189 | 14 84 | 29°959 | 34 ‘070 ie 
16 160 | 16 | 30-209 || 86 | 29°944 | 86 | 30°038 
18 | 807132 | 18 | 307184 || 38 38 f 
Taser IX. 
Mean ordinates of the ‘ Great Symmetrical Wave of November,” as deduced 
During a period embracing 192 _ 
hours preceding and + succeeding the apices, means have been taken, when 
practicable, of the two-hourly readings, from which the mean curve has been | 
projected; these means are recorded in the following Table, and the mean 
curve projected below the symmetrical curves for each year. 
will be found the five curves of the symmetrical wave for the years above- — 
mentioned, also the mean symmetrical curve deduced from them. 
Altitude of crest. |> 
29°693 
30°470 
30°170 
30°157 
29°948 
On Plate 3— 
