278 MR. LUKE HOWARD ON THE INFLUENCE OF THE MOON'S DECLINATION 



Table II. 



Barometrical Averages on successive Cycles of nine Solar Years, classed according 



to the Moon's place in Declination. 



The averages presented at the foot of columns 1 to 4, show a decrease in the baro- 

 metrical mean, consequent on the moon's varying positions in declination, which may 

 be thus stated : 29*8724 in. on equator, minus by north place, '0116 in. ; again, minus 

 by passage of equator south, -0158 in. ; again, minushy south place, '0189 in. ; lastly, 

 plus by return north over equator, -0463 in. 



The averages in columns 5 and 6 exhibit the barometrical mean, increasing and 

 decreasing with great regularity, during the course of a lunar cycle of eighteen years. 



The averages which form the two Tables before us were obtained in the following 

 manner : — 



1. The 1/ear was divided, by an ephemeris, into periods of lunar declination, the 

 whole set in each case including not less than 361, nor more than 370 days. 



2. These periods of declination were subdivided into weeks (or spaces of from six 

 to eight days, generally seven) with the moon's extreme north, her extreme south, and 

 her respective positions on the equator, coming and going, placed as nearly as might 

 be in the midst of the space on which the average was taken — to wit, the average of 

 the medium heights of the barometer for each twenty-four hours of the space. 



3. These weekly averages, obtained generally from the curves inscribed by the 

 barometer, on the face of a clock by Gumming, in my possession, were then placed 

 under their respective heads of the four positions of the moon above-mentioned. 



4. They were then laid together for the whole year, or for the number of days 

 necessarily so accounted, which numbers make an average of 365J days to the year. 



5. Averages were, lastly, taken under the respective heads of north, south, &c. on 

 successive periods of nine years ^ as 1815-23, 1816-24, &c., the series beginning 23rd 

 December 1814, and ending 19th December 1832. These results occupy the four 

 leading columns of the second Table ; the preceding are in Table I. 



