of Climate caused by the Moon. 



437 



Year. 



Months. 



8C' 



Inclination 



of the lunar 



orbit. 



Periods of 

 4 years 8 months. 



Average 

 of annual 

 pressure. 



Differ- 

 ence. 



1818. 

 1852. 

 1857. 



1862. 

 1866. 



30 



110 



6-7 



2-6 

 9-8 



280 



90 







270 



180 



Minimum. 



Mean. 

 Maximum. 



Mean. 

 Minimum. 



Min. to mean. 

 Mean to max. 

 Max. to mean. 

 Mean to min. 



329-003 

 329-280 

 329-714 

 329-178 



-0-277 

 -0-536 



The averages of atmospheric pressure show a diminution of 

 pressure in the minimum periods, and an increase during the 

 maximum periods. During the minimum periods the tempera- 

 ture of the air is higher, the air less dense ; in the maximum pe- 

 riods, on the contrary, the air is less warm and more dense. 



The periodic increase and decrease of temperature and pres- 

 sure produced by the variation of obliquity of the lunar orbit 

 may also be ascertained by the averages of midwinter tempera- 

 tures and midsummer temperatures during the same time ; the 

 depression is greater in the winter averages than in the summer 

 averages. 





Winter. 



Differ- 

 ence. 



Summer. 





Period. 



1848-52. 

 1852-57. 

 1857-62. 

 1862-66. 



2-288 

 1-526 

 1-880 

 2-794 



+ 0-752 R. 

 +0-914 „ 



12-527 

 12-398 

 12-977 

 13016 



+0-129 R. 

 +0139 „ 



Min. to mean. 

 Mean to max. 

 Max. to mean. 

 Mean, to min. 



The differences of the winter averages are six to seven times 

 as great as those of the summer months (during the seasons 

 of a lunar year of 18^ solar* years). 



If the difference of temperature in different seasons of a 

 lunar year is due to the varied obliquity of the lunar orbit, 

 the differences of midsummer and midwinter temperatures must 

 be nearly in a constant ratio, one to another, in the different 

 periods ; for the moon's relative positions to the earth will be 

 then symmetrically disposed. 



The ratio of those differences is for 



1848-52 and 1852-57 : 0752 : 0-129 = 59, 

 1857-62 and 1862-66:0-914:0-139 = 6-6; 



that is to say, "the periodic changes produced by the moon during 

 a lunar year are nearly constant." 



Another proof of the existence of a periodic change of climate 

 Phil Mag. S. 4. Vol. 35. No. 239. June 1868. 2 G 



