414 



Results of Makerstoun Observations, 1844. 



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



for 1844. 



1 



lean 





Mean 



After 



Mean 



After 



Mean 



Moon's Pr 



essure 



Moon's 



Pressure 



Moon 



Pressure 



Moon 



Pressure 



Age. 



of 



Age. 



of 



farthest 



of 



farthest 



of 



Vf 



ipour. 





Vapour. 



North. 



Vapour. 



North. 



Vapour. 



Day. 



in. 



Day. 



in. 



Day. 



in. 



Day. 



in. 



15 



283 











261 







0-270 



14 



0-287 



16 



286 



1 





257 



1 



•285 



15 



•289 



17 



287 



2 





272 



2 



•291 



16 



•270 



18 



275 



3 





268 



3 



•276 



17 



•262 



19 



292 



4 





269 



4 



•274 



18 



•275 



20 



296 



5 





281 



5 



•259 



19 



•279 



21 



298 



6 





283 



6 



•266 



20 



•284 



22 



295 



7 





275 



7 



•264 



21 



•287 



23 



295 



8 





295 



8 



•270 



22 



•280 



24 



277 



9 





285 



9 



•285 



23 



•273 



25 



265 



10 





266 



10 



•276 



24 



•284 



26 



267 



11 





261 



11 



•281 



25 



•285 



27 



273 



12 





258 



12 



•271 



26 



•278 



28 



278 



13 





252 



13 



•275 



27 



•273 



29 



271 



14 





270 











This Tahle has been formed from Table X., in the manner already described for Table II. of the Magnet- 

 ical Results. 



Pressure of Aqueous Vapour with reference to the Moons Age. — The following are means of groups :— 





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 



7 ... 0-271 



4 11 ... 0-277 



8 14 ... 0-270 



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

 (p. 271.) The maximum pressure occui's 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 : — 



in. 



25 days till 3 days, Moon farthest North, 0-280 



6 •■• 0-274 



4 10 ... 0-271 



7 13 -. 0-275 



in. 



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 after the moon was 

 farthest north, and a maximum about four 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 h 30™ a.m. in September, and as late as 3 h 10 m p.m. in August and May. 

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

 Table XIII. :— 



Min. 

 Max. 



Winter. 

 7 h P.M. — 6 h A.M 

 l h 10 m YM. 



Spring. Summer. 



4 h 10 m A.M. 4 h 10 m A.M. 



h 10 m p.m. h and 2 h p.m. 



Autumn. Year. 



5 h 10 m A.M 4 h 10 m A.M. 



ll h 10 m a.m. and 3 h 10 m p.m. l h 10 m p.m. 



