Meteorology for the year 1861. 35 



Barometer. — The highest reading of the barometer during the 

 year occurred at 9.30 p. m. on the evening of the 23rd of January, 

 and indicated 30.687 inches; the lowest reading occurred on the 

 274;h day of May at 1. 45 p. m. and indicated 28.883 inches, giv- 

 ing a yearly range of 1.804 inches ; several sudden and great 

 changes occurred during the year both with arising and with 

 a falling column. The j5rst remarkable wave was on the 4th of 

 March, when a very sudden fall took place ; at 6 a.m. the ba- 

 rometer stood at 30.454 inches, and it fell in 24 hours 0.780 of 

 an inch and continued falling until 2 p. m. of the 6th day when 

 it attained a minimum of 29.450 inches; it then continued to rise, 

 and at 10. p. m. the 7th day attained a height of 30.398 inches, 

 showing a sudden rise of 0.948 of an inch. On the 15th of March 

 a rise of 0.342 of an inch took place in 8 hours, and a like sudden 

 rise occurred on the 30th day of 1.230 inches in 24 hours. Another 

 sudden rise took place on the 28th of September at 6 a. m ; the 

 mercurial column indicated 29.276 inches, and in 24 hours it rose 

 to 29.999 inches, showing a rise of 0.623 of an inch, and it conti- 

 nued rising until it attained a maximum of 30.3 15 inches ; another 

 sudden depression of 0.200 of an inch in 8 hours occurred 

 on the 22nd of October, and a corresponding rise on the 24th 

 day, also in 8 hours, of 0.409 of an inch. In November the mer- 

 cury was as usual subjected to several fluctuations ; the highest 

 crest of the wave occurred on the 1st, 10th, and 20th days, and a 

 corresponding trough took place on the 3rd, 16th, 24th and 30th 

 days. In December, from the 12th to the 21st day, the mercurial 

 column indicated great fluctuations, falling from 30.341 inches, 

 to 29.746 inches, rising again to 30.137 inches and then again 

 falling to 29.600 inches and again rising to 30.191 inches, again 

 falling to 29.611 inches and attaining on the 21st a maximum of 

 30.269 inches ; a sudden rise occurred on the 27th day, the column 

 rising 0.293 of an inch in 8 hours. The mean barometric pres- 

 sure for the year w^as 29.737 inches, showing a decrease of 0.046 

 of an inch compared with the mean of last year, but an increase of 

 0.061 of an inch when compared with a series of years. The fol- 

 lowing tables show the mean reading of each month and also the 

 monthly range of the barometer in- inches ; the mean yearly range 

 was 1.093 inches. 



