38 REPORT—1848. 
tions from the two southern stations tolerably agree, although the readings 
at Geneva are higher than those at Lougan, especially during the first eight 
days; but there is a marked difference between them and those at Alten. 
The first point that strikes attention in comparing these readings with those 
in the tables, to which allusion has been made, is the earlier occurrence at 
Alten, namely on the 8rd, of the maximum which characterizes the first 
portion of the month, and which is very distinct at all the stations, except 
Paris, Geneva and Lougan. The observations at Christiania more nearly 
agree with those at Alten in this respect, the maximum occurring on the 
4th; and from this it would appear that the pressure proceeded from the 
north, and in a direction in which we do not usually observe the progression of 
the barometric maxima and minima. The principal epoch of the maximum 
for the majority of the stations is the 5th, and this maximum has been re- 
ferred to the wave designated ‘ Crest No. 2” in the discussion of Mr. Brown’s 
observations, and “ A°” in my second report (Report, 1845, p. 126). The 
direction of this maximum has been well determined on the 5th, namely from 
. Cork past Belfast to the Orkneys (Report, 1846, p. 144). We find at Alten 
on the 5th a decided rise of nearly +2 inch on the deep precipitous fall from 
the 3rd to the 7th, and this would indicate the continuation of the crest 
from Cork to Alten. From these considerations it is evident that the maxi- 
mum of the 3rd at Alten must have been due to an entirely different wave 
from any we have already noticed. The curve that most approaches Alten 
in the rise at the commencement of the month is that of St. Petersburgh ; and 
it is worthy of remark, that the essential features of this rise, and the check 
it experienced before the transit of the maximum, are transmitted to St. Pe- 
tersburgh a day later than they were observed at Alten. In fact the three 
northern stations, Alten, St. Petersburgh and Christiania, participate in this 
rise, the subsequent fall being considerably modified at Christiania and St. 
Petersburgh by the transit of crest No. 1. 
The barometric rise at the commencement of the month in the north of 
Europe, to which allusion has just been made, strongly indicates the advan- 
eing slope of a wave which did not affect the barometer in Central Europe ; 
and this wave being peculiar to the northern part of Europe, and stretching ~ 
over the Scandinavian peninsula, may probably, and with some propriety, be 
designated as a member of a system of Scandinavian waves. We shall there- 
fore characterize it in the future parts of this discussion by the symbol a, 
restricting this character to these northern waves. It does not appear to have 
extended longitudinally much beyond Christiania to the south-west, for we 
do not find that decided rise of the barometer, even at the Orkneys, which _ 
characterizes northern Europe. We have consequently a distinct termina- — 
tion of the crest in a longitudinal direction, the locality of which may be in- 
dicated by a line passing towards the south-east between the Orkneys and 
Christiania. 
We have already briefly referred (Report, 1847, p. 369) to the opposite — 
barometric movements in certain localities, arising from the transit of oppo- 
site slopes, either of the same wave or of successive waves of the same sy= — 
stem, and these phenomena, which are very distinctly marked in the instance _ 
given, furnish us with an explanation of similar phenomena in other loca- 
lities.s The curves of Alten and Lougan (fig. 1) present similar pheeno- 
mena to those of Geneva and St. Petersburgh ; the movements are opposite, 
and in this respect more decided, for we have two periods of opposite move= — 
ments at Alten and Lougan. We have consequently the half breadth of this 
Scandinavian wave given from Alten to Lougan, 1592 miles; first, when the — 
