46 REPORT—1848. 
The area of greatest pressure (just above 30 inches) extends from Ire- — 
land and England across France and Switzerland, and the central portions — 
of Western Russia, having nearly an easterly and westerly direction. In — 
the northern parts of Scotland (the Orkneys), Norway and Lapland, the 
pressure is about ‘4 inch lower. 
Nov. 9. Crest of Scandinavian wave .... Lougan...... 30°11 
Crest of wave No. 2 .....-...- Geneva....-. 30°08 
Crest of wave No. 2 .......-+. St. Petersburgh 29°92 
The passing off of the area of greatest pressure towards the south-east is 
now most decided; it extends from St. Petersburgh and Lougan towards ~ 
Geneva. The higher reading at Lougan is clearly due to the crest of the 
Scandinavian wave, those at St. Petersburgh and Geneva to the crest of 
No. 2; Paris and the stations to the north-west of it, including Christiania 
and Alten, all exhibit lower readings, being under the contemporaneous and 
continuous posterior slopes of the Scandinavian wave and of crest No. 2. 
We have some reason to believe that the readings of the 5th, at Belfast — 
and Geneva, assist us materially in determining the semi-amplitude of wave- 
crest No. 2. The crest now passes Geneva, and from this we may gather 
that the velocity was about 8°25 miles per hour. In comparing these with — 
the similar elements of wave A°, as deduced from observations at Scilly, 
Bardsey and Munich on this day, we find the present determination to be — 
less than that recorded in the Report for 1845, p.127. It would, however, _ 
appear that the amplitude 1856 miles is too great, the distance from Bardsey ' 
to Munich being 785 miles. This amplitude has been determined from the 
posterior slope. The observations at Geneva and Belfast enable us to deter- 
mine the anterior, those at Munich and Bardsey the posterior slope; by 
combining them we have the amplitude determined from the two slopes. 
Anterior slope, Geneva to Belfast... 792 miles. 
Posterior slope, Bardsey to Munich., 785  ,, 
—_——— 
Amplitude of wave .... 1577 ,, 
The near approximation of the values of the anterior and posterior slopes — 
gives a proportionate confidence in this determination of the amplitude. 
By taking the time of transit, Belfast to Munich, we have nearly the same _ 
velocity given as from Belfast to Geneva, namely, 8°78 miles per hour. t 
The velocity of this crest or wave appears to have been variable ; it clearly 
passed very slowly over Ireland, the barometer attaining a considerable — 
elevation. On the morning of the 8th we find its direction from the south- — 
west of England, past Norfolk, to the east of Christiania; a line of crest also ex — 
tends from ‘Scilly past South Bishop and Bardsey, connected probably in some — 
way with A!. From this time the velocity appears to have increased rapidly ; _ 
for on the next day, the 9th, we find the crest south-east of Paris, and at — 
3 P.M. it appears to transit Munich. Its increased velocity appears to have — 
commenced upon its passing the coast of Wales. Taking the amplitude of 
the posterior slope from Bardsey to Munich = 785 miles, and the time of — 
the passage of the crest over this space = 80 hours (see Report, 1845, 
. 126), the increased velocity is about 26 miles per hour. Bf 
The altitudes of the anterior and posterior slopes from the Belfast ang | 
Geneva observations appear to be as under :— 
Nov. 5. Crest at Belfast...........000. - 30°55 
Anterior trough at ‘Geneva eeeses 2979 
—_ 
Altitude of wave from anterior trough *76 
