ON ATMOSPHERIC WAVES. 155 
November 20, 1842. 
Crest No. 9. 
MO ee a ee 
Crest No. 6. 
SU te ee. 
Anterior slope, Crest No. 6. Anterior slope, Crest No. 9. 
Max. Orkneys.... 29°96 Max. Orkneys.... 29°96 
Belfast’ °) 2. 29°91 Christiania.. 29°60 
CORRS S FG 29°80 
Shields .... 29°85 
London .... 29°77 
Plymouth .. 29°73 
Paris <2) .'5's - 29°55 
Slope.—Line of greatest diminution of pressure. 
Anterior slope, Crest No. 6. Orkneys to Paris .. *41 
Currents.—Wind on anterior slope of Crest No. 6, N.E. 
5 posterior ,, J » 9, S.E. and E. 
The observations of this day, both barometric and anemonal, indicate the 
presence of an anterior slope of a wave succeeding crest No. 4 of the N.W. 
system. Crest No. 9 now passes over the Orkneys and between Christiania 
and Paris.. 
Symmetrical Wave, two days after transit.—London is situated under the 
anterior slope of crest No. 6 and posterior slope of crest No. 9. 
On the 16th, two days before transit, London was similarly situated with 
respect to waves Nos. 4 and 5, with nearly the same barometric pressure. 
On the 13th a permanent rise took place at London, which continued until 
crest No. 4 passed the station. It appears that this should be carefully distin- 
guished from the rise and fall of the 16th to 19th, the latter being due to 
a separate and distinct wave. 
The curve from noon of the 16th to midnight of the 19th appears to re- 
present the form of the N.W. wave riding on the top or superposed on the 
normal or great symmetrical wave. 
November 21, 1842. 
Crest No. 11. 
N.W.2-—— SE. 
Crest No. 6. 
S.W.—@____—___-N.E.. 
Crest No. 11. 
Max. Belfast .... 29°95 
Shields .... 29°89 
Max. Belfast .... 29°95 
Orkneys.... 29°86 } Under anterior slope. 
\ Near the crest. 
Min. Christiania... 29°54 
the Pastis ue, ae \ Under posterior slope. 
Crest No. 6. 
Max. Belfast .... 29:95) 
Corks wins ins 29°83 
SS Ni na aah De Meo the anterior slope at 
Plymouth .. 29°79 different levels. 
London .... 29°82 
Min. Paria 6 s<s0° 29°57 
