293 



The barometer began to rise at Dublin on the 28th of 

 January, and reached a small maximum on the following day. 

 This was followed by a slight depression on the forenoon of the 

 30th, after which the transit of the first portion of the wave 

 commenced, — the barometer continuing to rise (with a slight 

 interruption) from this epoch, and reaching its maximum on 

 the morning of February 5. The mercury then descended until 

 the morning of February 8, when the trough dividing the two 

 portions of the wave passed. It then began to ascend, al- 

 though not continuously ; and on the 10th the ascent became 

 very rapid, the mercury rising 0*6 inch between 10 a. m. on the 

 10th and 10 a. m. on the 11th, when it attained the extra- 

 ordinary height of 30*904 inches. The crest of the wave 

 passed at about 11 a.m. The descent of the mercury was 

 more gradual ; it reached a relative minimum on the morning 

 of the 13th, from which period, until the passing away of the 

 wave, there were three minor oscillations. The posterior 

 slope of the wave passed February 18 ; and after a small but 

 abrupt rise on the afternoon of the following day, the mercury 

 fell to 29-628 on the 20th. 



The following Table, taken from the registry of the Mag- 

 netical Observatory, gives the heights of the barometer at 10 

 a m. and 10 p.m. during the passage of the wave. It was 

 accompanied by a diagram. 



Observations of the Barometer during the passage of the At- 

 mospheric Wave, in February, 1849. 



