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April 27. 
SIR Wm. R. HAMILTON, LL.D., President, in the Chair. 
His Grace the Archbishop of Dublin gave a verbal ac- 
count of some observations which he had made upon the 
weather, in connexion with the prognostic drawn from the 
variations of atmospheric pressure, as indicated by the baro- 
meter. The sudden changes of the barometer, his Grace 
observed, were well known to be connected with correspond- 
ing changes of the weather as to rain or drought, and the 
great and rapid falls with the sudden approach of a gale of 
wind; but it did not seem to be so generally remarked, that 
the slow and continuous changes of the height of the mercury 
in the barometer were likewise indications of the approach 
of a season of long continued wet or dryness. It was to some 
connexions of this latter kind, noticed by himself, that he 
now drew the attention of the Academy. The first of 
these occurred in the early part of the summer of 1818, when, 
fromthe slow and gradual rise of the barometer for the space of 
ten days, he was led to predict the approach ofa long continued 
dry season. The drought which followed was one of the most 
remarkable that had occurred in this climate for many years. 
The second instance of the same kind observed by his Grace 
was in the early part of the spring of the present year. On 
the 17th of February the barometer commenced to rise, but 
very slowly, and the rise continued for six or seven days; he 
was thus led to expect a long continuance of dry weather ; 
and the result, as is well known, fully verified the anticipa- 
tion, the change being followed by more than three weeks, 
during which there was not a single drop of rain, and that 
too at a season of the year usually wet. 
The Secretary read a notice by Mr. George Knox on the 
