differ only by 21 hundredths : the first occurred on the 

 25th of December, when a Troughton's mountain-baro- 

 meter at the Royal Observatory sunk as low as 27*89 

 inches. (See Pond's ' Greenwich Astronomical Observa- 

 tions, 1821 /) A heavy rain of some hours' duration, 

 with the wind at south-east, had preceded the minimum 

 pressure ; a gale from the north-west followed, in which 

 the mercury rose a few tenths. 



The depression of 1814, 28-21 inches, happened at 

 the close of the great frost, and was likewise preceded 

 by a stormy wind from south-south-east and much rain. 



The difference of the extremes of the elevations is 

 0-49 inch. 



The difference of the extremes of the depressions is 

 T14 inch. 



The following is the progress of the great depression 

 of January 13, 1843. 



