130 



Mr. W. R. Birt on Atmospheric Waves. 



19th, and the lowest (29'71) at Dover with a fall of 0-12. The 

 fall at Brussels was 0'07 only, the barometer standing at 

 29*72. Another note-worthy feature is the synchronous preser- 

 vation of the wave-form with the general decrease of pressure, a 

 feature of great importance as bearing on the principles of storm- 

 prevision. 



Table III. — Distribution of Pressure and Wind over the North- 

 west of Europe on April 21, 1872. 



During the twenty -four hours, from 8 a.m. of the 20th to 8 

 A.M. of the 21st, the relations of the crests and troughs of both 

 the S.W. and N.Wo waves were reversed; the localities of high 

 barometers on the 20th were those of low barometers on the 21st, 

 except at the N.W. stations. 



! 



First zone on N.E. above trough of S.W. ivave, posterior slope. 



Barom. Direction. Force. 



Brussels . . 29-22-0'50 *E. 3 





Trough of S.W. wave. 





Thurso . 



. 29-81 + 002 



N.N.E. 



+ 4 



Wick . 



. . 29-82 + 0-01 



E.N.E. 



+ 5 



Nairn . 



. 29-78 + 0-02 



E.N.E. 



+ 3 



Aberdeen 



. 29-70-0-07 



N.E. 



+ 7 



Leith . , 



. 29-67-0-06 



N.E. 



+ 6 



Shields . 



. 29-58-0-15 



E.N.E. 



+ 5 



Scarboroug 



h . 29-51-0-23 



E. 



+ 6 



Yarmouth 



. . 29-39-0-36 



E.N.E. 



+ 8 



London 



. 29-21-0-52 



*E.N.E. 



+ 5 



Dover . 



. 29'16-0-55 



>5=E.N.E. 



+ 5 



Cape Gris ] 



N'ez. 29-15-0-57 



*E. 



+ 8 



Paris . 



. . 29-16-0-49 



*S.E. 



+ 4 



Charleville 



. 29-26-0-40 



*S.E. 



3 



Lyons . 



. 29-33-0-22 



S. 





Toulon . 



. 29-47 + 0-03 



S. 



-5 



First zone on S.W. ahove trough o/S.W. wave^ anterior slope. ^ 

 Ardrossan . . 29-70 + 0-04 E.N.E. +7 

 Liverpool . . 29-53-0-16 N.N.E, +3 

 Portsmouth . 29-21-0-50 *N.E. +7 



Second zone on S.W. above trough o/S.W. wave, anterior slope. 



Holyhead . . 29-51-0*11 N.N.E. +8 



* The vvmds marked thus (*) are cyclonic. 



