164 REPORT—1846. 
have been confined to the southern shores of England: Brussels is not far 
removed from this line; so that while the symmetry on the last return is 
considerably departed from at Dublin, it is highly probable that at Brussels 
the movements are more in accordance with its nodal character. It is there- 
fore important for the complete determination of the problem, not only to 
obtain the annual type at one station; we also require it at numerous stations ; 
and we ought to be furnished with local types similar to those, but more ex- 
tensive, which Sir John Herschel has established for different stations from 
the observations of 1835 to 1838. 
It has already been observed that the barometric curves at any one station 
do not give sections of waves passing the station, that is, the curve as pro- 
jected is not a section of the wave then transiting, but exhibits the effects 
of two or more systems of waves passing at the same time. Now as like 
causes produce like effects, it is highly probable that there may be a general 
flowing of the larger normal waves in the same direction, about the same 
season of the year ; and as we have seen in the case of the symmetrical wave 
that the secondary waves are erratic, sometimes falling on one point and 
sometimes on another of the normal waves, these normal waves may be 
crossed at these seasons by similar systems of secondary waves slightly re- 
moved froma normal epoch year after year, giving rise to a similarity, within 
certain limits, between the eombined barometric curves as observed at the 
stations. These combined curves furnish us with the local and annual types. 
While this labour is accomplishing, and we are in progress of obtaining 
annual and local types, we may be accumulating information that will bear 
considerably on the second branch of our inquiry. At present we are un- 
able to answer these questions fully. We have obtained some glimpses of 
the vast extent of these waves, and in our contemplation of them we must, 
as Sir John Herschel beautifully observes, enlarge our conception till in the 
extent of their sweep and the majestic regularity of their progress they 
approach in some degree to the tide waves of the ocean; still our knowledge 
of them is very small. The volume of any one atmospheric wave, the extent 
of surface it covers, indeed any particular feature we may name and which 
we may wish to be exhibited to us in all its details, we must still reckon among 
our desiderata. 
In closing this report, I beg to acknowledge the valuable assistance I have 
received from the following public bodies and gentlemen. 
To tHe British GovERNMENT I am indebted, through the hands of the 
Astronomer Royal and Lieut-Col. Sabine, R.A., for the volumes of Greenwich 
Magnetical and Meteorological Observations for the years 1840 to 1843, and 
the volume of similar observations made at the Colonial Observatory, Toronto, 
in the years 1840, 1841 and 1842. Iam also indebted to both the above- 
named gentlemen for the readiness with which they have furnished me with 
extracts from the records of their respective observatories, and for many 
valuable suggestions which I have received, especially from Col. Sabine. 
To tHE Lorps ComMISsIONERS OF THE ADMIRALTY I am indebted for 
several valuable sets of observations made on board our surveying vessels, 
and received through Rear-Admiral Beaufort, our excellent hydrographer. 
To this gentleman I am peculiarly indebted for the lively interest he has 
taken in forwarding the inquiry, and also to the officers under whose directions 
the observations have been made, for the care and fidelity with which they 
have been executed. The names of the respective officers of Her Majesty's 
surveying vessels will be found in Table I. 
To tHE HonouRABLE THE CORPORATION OF THE TRINITY HousgE, I am 
indebted for the ready access which has been afforded me to the records of 
meteorological observations kept at certain lighthouses; and I take this op- 
