414 



Results of Makerstoun Observations, 1844. 



TABLE XI. — Pressure of Aqueous Vapour, with reference to the Moon's Age and Declination, 



for 1844. 



This Table has been formed from Table X., in the manner already described for Table II. oi' the Magiiet- 

 ical Results. 



Pressure of Aqueous Vapour with reference to the Moons Aije, — The following are means uf groups : — 



in. 



12 days till 18 days, Full Moon, 0-273 



15 22 ... 0-289 



19 26 ... 0-286 



23 29 ... 0-275 



27 days till 3 days, New Moon, 0-269 



U 7 ... 0-271 



4 11 ... 0-277 



8 14 ... 0-270 



These means, on the whole, give nearly the same result as was obtained ti-om the observations for 1843 

 (p. 271.) The maximum pressure occurs about four days after full moon, and the minimum occurs after new 

 moon. 



Pressure of Aqueous Vapour with reference to the Moon's Declination. — The following are means of groups : — 



25 days till 3 days, Moon farthest North, 0280 



6 - 0-274 



4 10 - 0-271 



7 13 ••• 0-275 



11 days till 17 days. Moon farthest South. 0-276 



14 -"- — • 20 -- 0-278 



18 24 •-- 0-280 



21 27 -•- 0-280 



From these means the pressure of aqueous vapour was a minimum about six days aftei- the moon was 

 farthest north, and a maximum about tour days before it was farthest north. 



Diurnal Variation of the Pressure of Aqueous Vapour. — The diurnal variation is somewhat irregular in 

 several months of the year, presenting secondary maxima and minima at different hours. The principal maxi- 

 mum pressure occurs as early as 10'' 30™ a.m. in September, and as late as 3'' 10™ p.m. iu August and May. 

 The following are the epochs of maxima and minima for each of the astronomical quarters, as obtained from 

 Table XIII. :— 



Winter. 

 Min. T"" P.M.— 6'' A.: 

 Max. P 10™ PJ.1. 



Spring. Summer. Autumn. Vear. 



4'' 10™ A.M. 4'' 10™ A.M. 5'' 10™ A.M 4I' 10"' A.M. 



0'' 10™ P.M. Oh and 2'' P.M. 11'' 10"' a.m. and 3'' 10™ p.m. 1'' 10™ p.m. 





