270 REPORT — 1844. 



intend to pursue, in the report of the Committee for Magnetical and Meteoro- 

 logical Co-operation. When you allude to it, may I respectfully solicit your 

 kindness to inquire if the Association will favour me with extracts from Mr. 

 Snow Harris's ' Hourly Observations of the Barometer at Plymouth for No- 

 vember 1842,' and from Sir David Brewster's ' Observations,' I believe at 

 Inverness and Kingussie, for the same month? The first station will be ex- 

 ceedingly important in the south-western part of the area, and Sir David's 

 will furnish some valuable information relative to the progress of the waves 

 further north timn Longstone. I am exceedingly anxious to obtain barometric 

 records for this month, November 1842, from Ireland and Scotland. 



I have inclosed the copy of Lamont's ' Annalen,' No. 4, which you kindly 

 lent me, and for which 1 beg you will accept my best thanks. If you can 

 favour me with a few copies of the ' Report on the Reduction of Meteoro- 

 logical Observations,' I shall feel obliged. Col. Sabine advised me to have 

 some printed, but I found the type had been broken up. 



I have the honour to be, dear Sir, 



Yours very respectfully, 



Sir John F. W. Herschel, Bart. W. R. Birt. 



Remarks on Atmospheric Waves. 



Stations of Observation, 



Heligoland. Brussels. Bii-mingham. South Bishop. 



Longstone. Geneva. Bardsey Island. Scilly. 



Haisboro. St. Catherine's Point. Dublin. 



(1.) From a careful study of the altitudes of the barometer observed at 

 the stations above-enumerated when reduced to the level of the sea, I am in- 

 clined to believe that the area included by the extreme stations was traversed 

 at the commencement of the observations by two systems of waves. The 

 axes of translation of these systems formed a considerable angle; one ap- 

 peared to have a N.W. — S.E. direction, the other S.S.W — N.N.E. I am also 

 inclined to consider that a permanent depression of the atmosphere from 

 Geneva to the centre of England exists ; or should this be found not to be 

 the case, the phsenomena observed most probably result from the passage of 

 a normal wave or waves of very extensive magnitude. The projection of the 

 barometric altitudes in curves (the abscissae representing the times) clearly 

 indicates the passage of vast waves, but the only efficient test of this indica- 

 tion consists in obtaining sections of such waves, or projecting curves, in which 

 the distances of the stations ai-e considered as abscissae. Now as it is difficult 

 to obtain stations (especially when the observations have not been made with a 

 view to tliis particular inquiry), situated in a right line and sufficiently nume- 

 rous for the purpose, but by constructing models from the curves obtained by 

 a combination of all the stations, a tolerable idea may be formed of the dis- 

 position of the atmosphere over the whole area; and from a succession of 

 such models, illustrated by curves in particular directions and carefully studied 

 with reference to the curves obtained from the times as abscissae, the passage 

 of these waves can be clearly made out, and, I apprehend, tiieir magnitudes 

 tolerably well ascertained. In the following inquiry I shall term the system 

 of waves flowing from the N.W. A, and that flowing from the S.S.W. B ; 

 each particular wave will be designated A 1, A 2, &c., B 1, B 2, &c. 



(2.) Wave A 1. — A line cutting the crest of the wave A 1 transversely 



