434 Miscellaneous Intelligence. 



being much earlier in the southeast than in the north, Mr. Birt remark- 

 ed that the observations clearly showed that the barometer passed tico 

 maxima, one on the 9th, the other on the 12th ; and that the whole ex- 

 tent of the British isles might be divided into two barometric areas, dis- 

 tinguished in one case by the superiority of the maximum of the 9th, 

 and in the other by the superiority of the maximum of the 12th. A 

 line passing between Arbroath and Newcastle, south of Dumfries, and 

 between Ireland and Wales, separates these areas. Northwest of this 

 line we find the maximum of ihe 12th superior; southeast of it we find 

 the maximum of the 9th superior. The maximum of the 9th Mr. Birt 

 regarded as the central wave forming the crest of the great wave, and 

 the maximum of the 12th he considered as the crest of the first subor- 

 dinate wave on the posterior slope. 



The author next proceeded to examine the distribution of pressure as 

 manifested by these observations; from which, in connexion with the 

 features of the projected curve, he deduced the following results .—1st. 

 The return of the great symmetrical wave. This occurred in the south- 

 eastern angle of our island under very peculiar and remarkable circum- 

 stances. The area of greatest symmetry is closely in accordance with 

 the results of former discussions, and goes far to confirm the result de- 

 duced from the examination of Sir John HerschePs hourly observations, 

 M that Brussels is entitled to be considered as a point of comparatively 

 gentle barometric disturbance, * * * * and may be regarded as in a 

 certain sense a nodal point, where irregularities are smoothed down 

 and oscillatory movement in general is more or less checked, and such 

 movements increase as we recede from Brussels as a centre, especially 

 towards the northwest:' The curve of greatest symmetry was obtained 

 from liamsgate, the nearest station to Brussels. As we proceed to- 

 wards the northwest, the symmetry is considerably departed from, 

 especially by the greater development of the first subordinate wave on 

 the posterior slope, by which the maximum of the 12th became supe- 

 rior. This portion of the wave formed a striking contrast to the similar 

 portion in 1845, which was characterized by a considerable depression. 

 It is not a little curious, remarked the author, and goes far to show 

 that we are approaching the true explanation of the nodal character of 

 Brussels, to observe that movements so dissimilar in their character, so 

 opposite in their value, and presenting themselves under such a diver- 

 sity of aspects, should, in a certain locality and on particular lines ol 

 country, manifest, by means of the barometer, constant and well defined 

 phenomena, that may be recognized year after year, and which give to 

 the curves of barometric rise and fall during the period of their occur- 

 rence a peculiar symmetrical appearance. 2nd. Two systems ot 

 waves or currents, one having a general direction of progress from the 

 northwest, the other from the southwest, traversed the area during tne 

 period of the great wave. This is the same result to which we were 

 conducted by an investigation ol' the symmetrical wave of 1842. ln e 

 relative positions of the individual waves were somewhat different from 

 those of the wide bi-dual waves of 1842; but there were some strlk h ' ng 

 points of resemblance. The northwesterly system in each case exhib- 

 ited the largest wave, both as regards amplitude and altitude. l fl 

 intervals between similar phases of northwesterly waves were near y 



