20 Mr. W. R. Birt on a remarkable Barometric Depression. 



This table gives the principal features of the depression of 

 ISIO. It will immediately be seen from a comparison of the 

 numbers of 1810 and 1821, that the depressions are essentially 

 distinct. 



Table IV. — Mean Barometric Maxima and Minima. 



Rejecting on each day the readings of 1821 on the ground 

 of the depression being so distinctly marked, and the readings 

 being so considerably below any other of the series, and also 

 rejecting on the 2.'5th the readings for 1810 as evidently indi- 

 cating a depression, and being nearly '5 below the lowest of 

 the remaining readings, this table gives the means of the 

 maxima and minima lor the respective days; from which it 

 appears that, on the average, the barometer passes a maximum 

 on or about the 25th of December. 



Table V. — Absolute Barometric Maxima and Minima. 



From this table we learn that the years 1 826 and 1827 were 

 characterized by considerable elevations of the barometer from 

 the 23rd to the 27th of December; and that in the years 1810, 

 1814, 1815, 1819 and 1824, the barometer sank to 29 inches 

 or below, on the 23rd, 25th, 26th or 27th. In no instance 

 except 1821 did the barometer fall below 29-25 on the 24th. 



