, 
ON ATMOSPHERIC WAVES. 167 
Whenever the results obtained by means of Mr. Brown’s observations are 
either confirmed or illustrated by them, a reference is made to the day on 
which the particular wave, as indicated by the observations given in page 141, 
is either identified with one as developed by my previous investigations, or 
more clearly exhibited and its true character more distinctly brought to light. 
TaBLe XV.—Barometric readings at St. Petersburgh, 1842. Nov. | to 26, 
at noon, illustrating Table V. 
Date, Eng. In. Date. Eng. In, Date. Eng. In, 
Noy. 1 | 29°449 | Nov. 10 | 29:890 | Nov.19 | 30-155 
1] “659 20 
2 | 29-795 29°866 
3 | 30213 12 870 21 “776 
4 222 13 617 22 “419 
5 251 14 530 23 | 29-585 
6 | 30-164 15 139 24 | 30:032 
7 | 29:961 16 ‘450 25 080 
8 963 7 682 26 110 
9 | 29-916 18 848 
November 5. Crest No. 1.—The observations of Nov.1 indicated a crest 
which passed across England and Ireland with a general direction N.W.—S.E. 
This crest is now vertically over St. Petersburgh. We have traced it from 
Belfast, past the Orkneys to Christiania, and we now find it at St. Petersburgh. 
The observations of this day, as given by Mr. Brown, clearly indicate the 
direction of crest No. 2, so that the point of intersection of the two crests, 
Nos. 1 and 2, must have been situated towards the north-west of Norway. 
This at once explains the greater amount of pressure in the north-west of 
Europe in the early part of November. 
November 8. Posterior slope, crest No. 2.—This slope was characterized 
by a deep barometric fall, which was very considerable, especially at the north- 
western stations. A very careful comparison of Mr. Brown’s observations 
with those made at St. Petersburgh and those given in my last report, Sec- 
tion III. (Report, 1845, pp. 124 to 128), identifies crest No. 2 with wave A° 
of the last report. The direction of the crest, from a comparison of the num- 
bers over the larger area, including St. Petersburgh, appeared to extend from 
the south-west of England past Norfolk to the east of Christiania, and be- 
tween this station and St. Petersburgh. 
It has been observed in the remarks under the head anterior slope, crést 
No. 2 (page 146), that the altitude of this crest (No. 2) appears to have sub- 
sided as the wave progressed. This subsidence was aiso observed at Chris- 
tiania and St. Petersburgh. At Christiania the crest passed with about the 
same altitude as it passed Plymouth, 30°27, and at St. Petersburgh it was 
slightly under 30 inches. 
November 9. Posterior slope, crest No. 2.—On this day this posterior 
slope comes into full view. We have already identified crest No. 2 with wave 
A® of my former investigations. The observations of this day give us the 
direction of the posterior slope, which more or less accords with the sections 
of atmospheric pressure at 3 P.M. of this day, as exhibited in plates 45 and 46, 
Report 1844. 
November 10. Crest No. 3.—The direction of this crest is nearly identi- 
eal with that of No.1, which passed over Great Britain and Ireland on the 
lst. A comparison of Mr. Brown’s observations with those at St. Peters- 
burgh and those given in my last report, identifies this wave, crest No. 3, 
with B° (see Report, 1845, page 125). 
Crest No. 2.—This crest is situated to the east of St. Petersburgh on this 
day, at the same time that its posterior trough is situated to the east of the 
