276 REPOET — 1844, 



stations ; but upon a careful consideration, the curve (Dublin) appears to in- 

 dicate that the trough of this wave passed Dublin about six in the morning 

 of the 9th Nov. About 2 p.m. Dublin and Bardsey were at the same level, 

 the disposition of the atmosphere remaining the same at the other stations, 

 and at 3 p.m. the trough of the wave A 1 extended from Scilly to Longstone. 

 Other considerations imply that the minimum at Scilly, although coincident 

 with the minima at South Bishop, Bardsey and Longstone, did not form a 

 part of the posterior trough of A 1 . The model of Nov. 9.9 indicates that 

 the trough ran in a direction at right angles to a line joining Geneva and 

 Brussels ; and as a minimum passed Geneva at the same time, Nov. 9.3, it is 

 probable that these minima, Scilly and Geneva, were occasioned by the ante- 

 rior trough of B 1 . At 5 p.m. Dublin, attained the elevation of South Bishop, 

 and the two curves run together until 2 a.m. of the 10th. The rise at all the 

 stations is occasioned by the anterior slope of the wave B 1 combined with 

 the anterior slope of A 2. The parallelism of Dublin aud Bardsey is very 

 apparent. The passages of the maximum are well-marked, Scilly occurring 

 at 9 p.m. with the greatest elevation except St. Catherine's Point. At this 

 moment St. Catherine's Point passes a minimum. The diagram suggests that 

 this minimum is the posterior trough of A 1, but the model shows that the 

 trough of A 1 is now in the neighbourhood of Bardsey, and has not yet pro- 

 gressed as far as St. Catherine's Point; it must therefore be the anterior 

 trough of B 1 which occasions this depression at St. Catherine's Point. The 

 transverse section of this wave (B 1) east of Scilly appears to be but small; 

 it is, however, considerably enlarged towards Longstone. It appears probable 

 that the small rise at Scilly and the smaller at St. Catherine's Point* were 

 occasioned by a step or shoulder on the posterior slope of A 1, similar to 

 that which appears between Bardsey and Scilly at 8.15, and in the neighbour- 

 hood of Birmingham at all the terms (see Sections and Models) ; and that the 

 apex of B 1 was but slightly raised above it, so that after the passage of the 

 step the posterior slopes of both waves coincided. South Bishop, St. Cathe- 

 rine's Point, Bardsey and Dublin next pass their maxima in this order. The 

 three red curves def, fig. 1, Plate XLIV., exhibit the passage of the wave (B 1) 

 in the direction from Scilly to Longstone. The occurrence of the maximum 

 at St. Catherine's Point and Bardsey about the same time indicates the direc- 

 tion of the crest of B 1 to pass through these stations : this direction is rather 

 different from the direction of the anterior trough, for Geneva does not pass 

 its maximum until 9-21. At 2 a.m. of the 10th a decided change of level 

 takes place in three localities, Scilly, Dublin and South Bishop : this is evi- 

 dently occasioned by the passage of the posterior slope of B 1 over Scilly at 

 the time the apex is approaching South Bishop and Dublin. At 3 a.m. the 

 apex passes South Bishop, and shortly after Scilly and Bardsey are on the 

 same level with South Bishop rising between them. The next intersections 

 of the curves occur betwen 6 and 7 a.m. of the 10th ; the highest level 

 is Bardsey and South Bishop, and the lowest Longstone and Scilly. The 

 apex is now rapidly rolling on towards Longstone, depressing South Bishop. 

 Shortly before 7 Longstone and Bardsey are on the same level, the wave 

 rising between them. About 8 the curves of Scilly and South Bishop again 

 intersect, and immediately after Longstone and Dublin are at the same level. 

 General Conclusion. 

 That while the posterior slope of a very large wave, with a shoulder pro- 

 ducing a small trough (A 1), passed over the area, a small wave passed over 

 at a considerable angle to the first. The passage of the apex of this wave 



* The maximum oceuning earlier at St. Catherine's Point than at Dublin, clearly indicates 

 that the St. Catherine's maximum was due only to the apex of B 1. 



