4-98 Mr. W. R. Birt 07i Atmospheric Waves. 



General Conchision. 



From the collation of Mr. Brown's with the St. Petersburgh and 

 Geneva observations which have been added to Table I., it is readily 

 apparent that the results arrived at in the discussion to which refer- 

 ence has been made have been fully confirmed, and there appears 

 to be but little doubt that the waves as determined in the first in- 

 stance by a discussion of observations from the stations announced 

 in my first report*, and further identified and illustrated by the ob- 

 servations collected by Mr. Brown, as well as those wliich have been 

 brought to light by means of Mr. Brown's observations, and con- 

 firmed and illustrated by the St. Petersburgh observations, had a 

 real existence ; an individuality has been attributed to certain arrange- 

 ments of aerial currents and distribution of pressure in connexion 

 with such currents, the aggregate phajnomena forming an atmo- 

 spheric wave. Of the waves thus brought to light, two occupy very 

 prominent positions, they stand out as it were from the others ; the 

 individuality of each is very striking, and the velocities with which 

 they traversed the area isolate them from their predecessors and ex- 

 hibit them not as gregarious, but solitary waves. These waves are 

 B° and crest No. 4, the first occurring just previous to the setting 

 in of the great wave, and the last forming its crown. The wave, 

 crest No. 4, appears from its elevated position on the symmetrical 

 or normal wave, admirably adapted to crown our investigations with 

 success, especially in so far as its amplitude, velocity and path are 

 concerned, we are now, I apprehend, in possession of materials to 

 determine with a considerable approximation to accuracy, these ele- 

 ments. Its longitudinal direction appears to have been very exten- 

 sive. This element would receive considerable elucidation by means 

 of observations from the south of France, Spain, Portugal and the 

 north of Africa. It is highly probable that this wave in the direction 

 of its length stretched from the extreme south to the very north of 

 Europe. 



The waves jiist alluded to will furnish material for a further paper, 

 in which their essential features, elements, &c. will be fully discussed. 

 In the mean time the attention of the reader is directed to several 

 interesting features of waves Nos. 1 and 2. ^ 



Wave crest No. 1 — An inspection of Table V. shows that this 

 crest extended from Belfast to Paris on the 1st ; on the ^th it passed 

 Christiania, and on the 5th it was vertically over St. Petersburgh. 

 On the same day, the 5th, Mr. Brown's observations indicate that 

 the crest No. 2 extended from Cork, past Belfast, towards the Ork- 

 neys ; so that the point of intersection of the two crests, Nos. 1 and 2, 

 must have been situated toward the north-west of Norway. This 

 at once explains the greater amount of pressure in the north-west of 

 Europe in the early part of November. 



During the first eight days of November, the movements at St. 

 Petersburgh and Geneva were strictly in accordance with the transit 



* Report of the Fourteenth Meeting of the British Association for the Advance- 

 ment of Science, page 2G7. 



