ON ATMOSPHERIC WAVES. 
369 
haviDg its posterior slope towards the south-west and its posterior trough in 
the locality of Galway, and moving w’ith a very slow motion. It is highly 
probable that the high state of the barometer, in certain localities, during 
the period of the great wave, was connected with this wave 
It is important to notice here that the British Islands present a far too 
limited area for the purpose of thoroughly eKuuimng tlujse atmospheric move¬ 
ments. Throughout the whole course of the great wave, nioveiuents of an 
opposite character seldom occur, and when they do. they arc of a very trifling 
nature; the most striking opposite movoraenta are those at Uamsgate and 
Stornoway, Plate II. fig. 4, and these result from waves belonging to two 
(liflerent systems, and do not continue a day and a half. 
In the raoreextetisive examination which the movements of November 1824 
are now undeigoing, to which allusion has been made in the postscript to my 
last Ueportjwe find four stations at which the barometric movements present 
opposite characters during the first eight days of November. These stations 
are Christiania and St. Petersbnrgh in tire north, and Paris and Geneva in 
the south, Plate III. fig. 10. Tlie curves at St. Peterwburgh and Geneva pre¬ 
sent the most decided opposition, which, from a comi»ari8on of the movements 
at other stations, results from the slopes of two south-west waves, one suc¬ 
ceeding the other; this opposition iudicutes the half-breadth of the first wave 
as extending from St. Petersburgh to Geneva, and clearly shows that, for 
the inirpose of completely apprehending the real nature of the individual 
waves, the crossing of which give rise to the syniinetrieal curve, we must very 
considerably enlarge our urea of observation. The rise at St. Petersburgh 
results from the transit of the anterior slope of wave, Ci-est No. ], discussion 
1842, and the contemporaneous fall at Geneva from the transit of the poste¬ 
rior slope of this wave: the succeeding rise at Geneva from the anterior 
slope of wave No. 8, and the contouiporaneou.s fall at St. Petersburgh from 
the posterior slope of No. 1. 
There is some reawon to believe that the oorth-west system is composed of 
much larger waves than the south-west, and that the crests stretch from the 
oxti-eme south to the extreme north of Europe; a glance at a map of Europe 
will immediately convince us that the area over which these waves have 
hitherto been examined, is altogetlicr too contracted to give us satisfactory 
answers to many of the questious jiropounded in the review taken of the de¬ 
siderata which forms the third pan of niy liiHt report. The centre of Europe 
is well dotted over witli barometers, from which accurate results may be ob¬ 
tained; thcpe, however, taken io connection with tlia British Isles, form but 
small portion of the vast space over which the waves tiiemselves extend. 
U an important northern station; but we require good obser¬ 
vations from Iceland, the northern parts of Norway, Sweden, and Lapland, 
and also from Archangel'm ono direction; and from the southern parts of 
trance, from Spain, Portugal and tlic northern parts of Africa in the other. 
Observations stretching from the most western point of Africa to the extreme 
north of Europe, would go far to determine Uic longitudinal direction of the 
crests of the nortJi-west syatc-ni of waves. 
lakiog into considemtion the vast extent of these waves, wc readily see 
that there cap be butene nodal point coinuion to the European systems. All 
our observations direct us to Brussels as that nodal point. It is situated 
• I« conDretion with this wf. may notice, etpccuily in the iouth-eastera part of our 
ixisnd, til* absence of gale* al Ihc commencement and termiftatiun of the great wave. At 
Galway, locality of thetraugb aliorc-mentioord, we fiud a gate existing at the cummeuce- 
mcDt of the great wave. At 0 a.u. of Novemlicr 1st, the observer records, “ increasing gale 
with heavy squalls at 3 p.m., force of wind 10. At 5-30 p.m. gale hiUed ; during the 2nd and 
3rd the force of the wind varied from 4 to 8 ; and at 9 p.m. of the 3rd heav 7 squalls of rain." 
1847- 2 B 
