130 REPORT—1846. 
Section II. 
Comparison of contemporaneous observations of the return of the Great 
Wave, Nov. 1845. 
Of the observations that have come to hand, the following have been pro- 
jected in curves in order to exhibit the characters of the great wave at various 
and distant stations; the epoch of the curves are Nov. 6 to 22, the duration 
of the great wave. 
Scilly. London. Birmingham. 
Helstone. Yarmouth. Stokesley. 
St. Catherine’s Pvint. Haisboro. Belfast. 
Portsmouth. Heligoland. Galway. 
These stations being considerably less than half the number from which 
observations have been received, it would be premature to draw any conclu- 
sions from a comparison of the curves, as well as appearing to give a preference 
to certain observations to the exclusion of others which have been executed 
with great care and fidelity, and from which in connection with the whole 
the most valuable results are likely to be arrived at. Every exertion would have 
been made to have completed the rough projection in curves of all the ob- 
servations made during the transit of the great wave, in order to have sub- 
mitted to the present meeting a first approximation to its general characters 
as exhibited at a diversity of stations, had not the publication of Mr. Brown’s 
paper directed my attention to the arrangement of the aérial currents over the 
area of the British Isles during the transit of the great wave of Nov. 1842, 
the value of which I have alluded to in my introductory remarks. 
It may however be important on this head to report the progress made, and 
to notice a few particulars merely as indicating the course pursued and the 
highly important results likely to be obtained from a complete discussion of 
the observations, not only for the period during the transit of the great wave, 
but also during the two months over which the observations extend. The 
curves are susceptible of a variety of arrangements, according as it may be 
deemed desirable to exhibit certain characteristic features of the normal or 
secondary waves. In submitting the projected curves to your notice on this 
occasion, I have selected that arrangement best calculated to exhibit,—first, 
the symmetrical character of the wave, and secondly, the direction in which 
this symmetrical character is most departed from. 
The first two curves (Scilly'and Helstone) are characterized by three periods 
of barometric readings of nearly the same value (slightly above twenty-nine 
inches), occurring on the 7th, 11th and 19th; between the 11th and 19th we 
find the central undulation forming the crest. "The Helstone curve gives the 
greatest symmetrical arrangement. From these curves we may conclude that 
Scilly, and especially Helstone, were situated near the line of greatest symmetry. 
It is desirable particularly to notice, that at these stations the depressions of 
the“7th and 11th are about equal ; there appears to have been no fall from the 
commencement of the wave to the depression of the 11th. Two distinct and 
well-marked waves (the two at the commencement of the great wave) are 
very discernible. 
The next two curves, St. Catherine’s Point (Isle of Wight) and Portsmouth, 
nearly agree with the two preceding, especially in the depressions of the 11th 
and 19th being of equal value. There is however a marked difference be- 
tween these curves and those of Scilly and Helstone, in the two anterior waves 
being less developed, and the barometer exhibiting a fall from the commence- 
ment of the great wave to the depression of the 11th; and this fall is not only 
traced towards the E.N.E. through the stations London, Yarmouth and Har- 
