56 REPORT—1848. 
of the 5th to that of the 12th. How far the lines of deviation extend to 
the south-west and north-east we are at present ignorant: it would how- 
ever be interesting to learn whether they continue to any great extent to 
exhibit a more or less longitudinal direction, being simply inflected by. the 
masses of land over which they pass, or whether they form a system of 
curves, the interior ones being closed. Of the direction and form of the 
lines of equal deviation to the south-east of the symmetrical line we are 
likewise ignorant. Taking the Jersey curve, although not the most symme- 
trical, yet, with regard to the points selected, exhibiting the least deviation, 
we find a development of a different and somewhat opposite character to that 
which we observe in the Scottish and Irish curves. In these curves the 
maximum of the 12th is by far the most prominent, that of the 5th appearing 
as very subordinate. At Jersey that of the 5th is the most prominent, the 
maximum of the 12th dwindling into a subordinate elevation on the pos~ 
terior slope of the curve. Query. Does the maximum of the 5th rise into 
considerable importance south-east of the line of greatest symmetry, while 
that of the 12th merges into the general curve so as to give rise to a series 
of lines of equal deviation of an opposite character to those which we have 
traced; and do these lines of opposite deviation preserve a general parallelism 
within certain limits to them? If so, the lines of equal and opposite 
deviation on each side the line of greatest symmetry, whether extending 
indefinitely or forming closed curves, will mark out an area to which that 
particular barometric curve known as the “ symmetrical curve of Novem- 
ber” is peculiar, and the line of greatest deviation on each side will to a 
certain extent limit such area, curves of a different character, and exhi- 
biting novel features, appearing beyond the lines of greatest deviation. 
It may probably be inquired if the general direction of the lines of equal 
deviation are similar year after year? The amount of our present know- 
ledge on this head indicates that such is not the case: taking similar points 
in the curve on each return as indicating the departure from symmetry, the 
direction of the lines varies, and this variation appears to be in accordance 
with a certain law. We have on former occasions noticed that in 1842 the 
direction of the line of greatest symmetry was from Dublin to Munich, the 
deviations occurring on the north-east and south-west of this line (Report, 
1846, p. 163). In 1845 it appeared to be in the direction of the southern 
shores of England (Report, 1846, pp. 130, 164), and it consequently formed, 
with the line of greatest symmetry in 1842, a considerable angle. In 1846 
this angle was considerably increased ; and from some observations received 
last autumn, it appeared to be still further increased, so as to equal if not 
exceed a right angle, the station affording the most symmetrical curve being 
Norwich. The instability of the line of greatest symmetry, to which allu- 
sion has been made in my Report of 1846, p. 126, is thus clearly established 
and the character of the motion indicated. The line of greatest symmetry 
appears to revolve around a fixed point or node, which is situated in the 
neighbourhood of Brussels*. It is probable the node itself is situated a 
little to the north-west of Brussels, the common intersection of the lines 
already traced occurring to the north-west of that city. W.' Ro Bret! 
Postscript. I omitted to mention in my last Report, in connexion with 
the observations made at the stations recorded in Table I. (Report, 1847, — 
p- 351), that the observations at Sir Thomas Brisbane’s observatory, Makers- 
toun, near Kelso, were made under the sole direction of J. A. Brown, Esq. 
* Sir John Herschel has directed attention to the nodal character of Brussels in his 
Report on Meteorological Reductions (Report, 1843, p. 100), especially in relation to the 
revolution of the wind in one uniform direction. 
wae 
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