1836.] Continuation of a Paper on Heights of Barometer, SfC. 585 



X. — Continuation of a Paper (Journal, May, 1835), on the Heights 

 of the Barometer as affected by the Position of the Moon. By the 

 Rev. R. Everest. 



In a comparison of the heights of the Barometer with the position 

 of the moon in declination, (See Journal, May, 1835,) I stated that 

 it appeared, that though the greatest depressions coincided, or nearly 

 so, with the times of the moon's maximum declination, yet that many 

 of the greatest elevations held a similar situation. To ascertain 

 whether this idea was well-founded, the daily barometric heights 

 were taken from the 4 p.m. column of the Meteorological Registers 

 of the Journal ; then the differences either in excess or defect from 

 the monthly mean, were noted and placed in different columns accord- 

 ing to the state of the moon in declination, as given in the Nautical 

 Almanacks for noon of the same day. Then the average of each 

 column was taken for the year, and continuing the process for the 

 1 3 years of which the Meteorological Registers are extant, a general 

 average was finally taken of the whole, which came out as follows : 



Moon's Dec] 25° 20° 15° 10° 5° 0° 



Average amt. of variation | j I I , Q ^ I I 



from the monthly mean, J III 



If it be objected that this difference, between the two extremes of the 

 line, of "008, be small, we may answer that small as it is, it is nearly 

 ^th of the whole amount. The heights of the barometer at London 

 for a period of 24 years were then examined in a similar manner, 

 only that instead of classing the differences in columns according to 

 the number of degrees of the moon's declination on the same day, 

 they were classed according to the distance of the day on which the 

 observation was taken, from the day of maximum declination. Thus, 

 the number of days from maximum north to maximum south declina- 

 tion being nearly 14, the differences were arranged in 14 columns 

 numbered in this way : 



1 2 3 4 5 6 7 8 9 10 11 12 13 14 

 and as a whole revolution from one time of maximum declination toits 

 succeeding one is something less than 28 days, a column was occa- 

 sionally left blank to keep the maxima always in the 1st and 14th. 

 This method is rather less troublesome than the former one adopted, 

 but it does not answer so well for a long series of years, as the 

 moon's maximum declination is very different in different years : — for 

 example, in 1820, it was between 28° and 29°, and in 1829, between 

 18° and 19°. The average, therefore, was taken for the six years in 

 which the declination was greatest, viz. 1818, 1819, 1820, 1821, 

 1822, 1823. The maximum declination was then always above 25°, 

 4 G 



