Tempeeatuke of the Aie. 



407 



TABLE III. — Hourly Means of the Temperature of the Air for each Astronomical Quarter, 



and for the Year 1844. 



These means give the following epochs of minimum and maximum :- 



The minimum temperature occurs earliest in summer, and latest in winter ; it occurs about 3 hours be- 

 fore sunrise in winter, 2 hours before it in spring, ^ hour in summer, and about 1 hour before sum-ise in 

 autumn. The maximum temperature occurs nearest noon in winter, and nearer noon in summer than at 

 the equinoxes. This result was obtained from the two hourly observations for 1843, p. 265. 



in order to examine the variations of temperature about midnight in the winter group, we may connect 

 the mean at 12'' with that at IP, by means of the coiTections given above; from these, the mean at 12'' in 

 winter is greater than the mean at 11'', by 0°-08; from this, and the above means for the winter gi'oup, we 

 find the variations of temperature from 9'' 10"° p.m., till 3'' 10", to be as follow : — 



9'' 

 0°-20 



lOh 



0°-00 



ll' 

 0°-16 



12'> 

 0°-24 



0°-31 



0°-17 



3k 



0°-01 



From these, there appears to have been a secondary maximum of temperature in winter at P 10"" a.m., 

 the secondary minimum occurring at 10'' 10" p.m. Tliis result is exhibited in the means for each of the 

 months November and December, and also in those for January, the true change from 11'' to 12'' being 

 considered. 



The maximum temperature for the year 1844 occurs at the same hour as for 1843, — namely, 1'' 30™ p.m. 

 The mean temperature for each month occurs at the following times : — 



April. May. June. .July. Aug. 



8''22'n 8'' 5" 7'' 34" 7'' 33" 8'' 11" 

 7 8 742 7 28 7 50 7 18 

 10 46 11 37 11 54 12 '17 11 7 



Sept. Oct. Nov. Dec. 



8'' 10" 8'' 51" 8'' 56" IC-S" 

 7 16 6 41 5 5 6 

 11 6 9 50 8 4 7 1 



The intervals are greatest in the three months constituting the astronomical summer, and least in the 

 three months constituting the astronomical winter. December has the least, and July has the greatest, critical 

 interval. The following are the epochs of mean temperature for the astronomical quarters : — 



Winter. 



A.M., 9'' 33" 



P.M., 5 31 



Intervals, 7 58 





