70 REPORT—1842, 
have been obviously misread by two-tenths of an inch. This being corrected, 
a very flat minimum extending over the 4th, 5th, and 6th hour appears, mark- 
ing, as at Cadiz, the termination of the preceding depression. At 7 hours, 
and not earlier, the rise of the mercury began, and continued uninterrupted 
(except by the regular periodic oscillations) to the end of the series without 
any indication, within its limits, of a re-commencing descent. 
From a review of the whole of this highly interesting term, the following 
conclusions may be drawn. 
A perfectly well-marked and definite atmospheric wave passed over the 
British Isles and the west of Europe on the day in question, the crest of the 
wave having a direction nearly N.N.E. and S.8.W., and its progress being 
from W.N.W. to E.S.E. The half breadth of the wave, which oceupied 26 
hours in its passage, covered a space extending from Oxford in a direction 
perpendicular to that of the crest, to a point not far from Halle in Wiirtem- 
burgh, which gives, by rough measurement on a map; about 540 miles, and 
a velocity of about 21 miles per hour. The barometric depth of this wave may 
be stated at 0-2 inch. 
December 1836.—Markree, Edinburgh, Halifax, Oxford, London (with 
Greenwich), Ashurst, Brussels, Hanover, Kremsmiinster, Geneva, St.Jean de 
Maurienne, Turin, Gibraltar, Cadiz. 
The effects of the regular diurnal oscillation are tolerably distinct in the 
curves for London, Greenwich, Oxford, Turin, and Geneva, especially as 
respects the maximum at 22 hours, which appears to have been at all of these 
stations exaggerated into a considerable upward bulge, as it is also at Krems- 
minster, Hanover, and Brussels, where the other niaximum and the minima 
are much less conspicuous. At Gibraltar the bulge in question assumes the 
character of a sustained elevation; at Cadiz, that of an undulating level. In 
the former of these two stations the other maximum and the minima disap- 
pear entirely, the curve presenting nearly a dead level from 0 to’7 hours, which 
is resumed after a trifling fall at the 8th hour, and continued to the 20th. In 
the latter the morning minimum is not only obliterated, but converted into 
an abrupt protuberance, occupying the interval from 14 hours to 17 hours,— 
a feature which I have already had occasion to notice in the terms of March 
and June 1836, and which appears to constitute a remarkable peculiarity in 
the diurnal movements of the atmosphere in this corner of the European 
continent. At Markree, Edinburgh, and Halifax, neither of the regular 
maxima or minima can be clearly made out. ; 
Abstraction made of the periodical oscillations, the features of the conti- 
nental curves, taken as a whole, offer little accordance. The range is least 
(and very small) at Brussels and Gibraltar, especially the former, ¢orrobo- 
rating a general remark to which my attention has been called by Mr. Birt, 
that Brussels may be regarded in some sort as a node of barometric undula- 
tion, departing from which on either side the ranye inereases ; a remark to 
which I shall subsequently have occasion to call attention more pointedly. 
Geneva, St. Jean de Maurienne and Turin, agree in the maintenance of nearly 
an uniform level (a slight downward tendency being only noticeable at Turin) 
for the fourteen hours from 0 to 14 hours, when they all begin to sink to a 
feeble but distinct minimum between the 17th and 18th hours, rising again 
to a maximum at the 22nd, which (as observed above) being more than is due 
to the regular oscillation, must be locked upon as belonging to a passing wave. 
Kremsmiinster belongs also to the same system, but the descent of its curve 
from 0 to 16 hours is greater than at Turin (amounting to 0-09 inch), and 
marked by two conspicuous undulations in the 4th and 6th hours, which how- 
ever are merely local, as they do not appear in any of the associated curves. 
