TABLES OF DIFFERENCES OF MEAN TEMPERATURES. 163 



"Results of meteorological observations made at the magnetical observatory, during 

 the years 1860-1-2." G. T. Kingston, Director. Tlifs table is headed "Probable 

 variability of the monthly means of temperature at each of the 6 observation hours, 

 in a single year, together with their half-yearly and yearly averages, from the years 

 1854 to 1862 inclusive," and the deduction from the results is stated as follows: 

 The warm hours are most liable to disturbances of temperature in the ivarm months, 

 and the cold hours in the cold months, and altogether the abnormal digressions are 

 greater in the colder half year than in the warmer. 



A series of hourly observations continued for 6 years is barely sufficient for the 

 investigation and the results for the three winter months (Dec, Jan., Feb.) were 

 contracted into a mean, also the results of the three summer months (June, July, 

 Aug.) ; it was not deemed necessary to investigate the six remaining months, since 

 the law is seen to change gradually from season to season, the variability of the 

 temperature of any hour being nearly the same about or after the epochs of the 

 equinoxes. 



Probable error of the monthly mean temperature for any hour of the day, derived 

 from a series of years. 



Hours of 

 day. 



Winter. 





Summer. 





Toronto., 



Mohawk. 



Phila. 



Sitka. 



Toronto. 



Mohawk. 



Phila. 



Sitka. 



Md't 

 I 

 2 



3 



4 

 5 

 6 



7 

 8 



9 



lO 



II 



Noon 

 I 



2 



3 



4 

 5 

 6 



7 

 8 

 9 



lO 



II 



±3°S 



3-'6 

 3-5 



3-0 

 3-0 



3-3 



±3°2 

 3-2 

 3-2 

 3-3 

 3-3 

 3-3 

 3-3 

 3-3 

 3-4 

 3-2 

 3-1 

 3-0 



2.9 

 2.8 

 2.8 

 2.7 

 2.8 

 2.8 

 2.9 

 2.9 



3-0 

 3-0 

 3-1 



3-2 



±2.°4 

 2.4 

 2.4 

 2.4 

 2.4 

 2.4 

 2.4 

 2-3 

 2-3 

 2.2 



2-3 

 2.2 

 2.1 



2-3 

 2.4 



2-5 

 2-5 

 2-S 

 2.4 

 2-4 



2.4 

 2.4 



2-5 



2-5 



2.4 

 2-5 

 2.5 

 2.6 



2-5 

 2-4 

 2.2 

 2.2 

 2.0 



1-9 

 1.9 

 2.0 

 2.1 

 2.2 

 2-3 

 2-3 

 2.4 

 2.4 

 2.3 





±i.°4 



i-S 

 1-5 



2.1 

 1.9 



1.4 



±1.2 

 1.2 

 1.2 

 1.2 

 1.2 

 1.2 

 1.2 



I.O 

 I.O 



1.0 



I.O 

 I.O 



I.I 



1-3 

 1.6 



1.8 

 2.0 

 2.0 

 2.0 



1-9 

 1.8 

 1.6 

 1.4 

 1-3 



-l-o.°8 

 0.8 

 0.9 

 0.8 

 0.8 

 0.8 

 0.8 

 0.7 

 0.7 

 o.S 

 0.9 

 o.S 

 0.9 

 0.8 



I.O 

 I.O 

 I.O 

 I.O 



I.I 



I.O 



I.I 



I.O 



I.I 



I.O 



±. .. 



0.8 

 0.8 



I.O 



1.2 

 1.3 

 1-5 

 1-4 

 1-4 

 1-4 

 1-3 

 I.I 

 I.I 



I.O 



0.8 

 0.9 

 O.S 

 0.9 

 0.8 

 0.8 





Mean 



±3-3 



±3-1 



±2.4 



±2.3 



±2^8 



±1.6 



±1.4 



±0.9 



±1.0 



±1.2 



The Toronto results are in the main confirmed by those at the other stations, 

 and there is no doubt a much closer accordance would be obtained from longer 

 series of records. In winter the maximum variability occurs a few hours after 

 midnight, or about the period of the maximum cold of the day ; in summer the 

 reverse of this happens, the maximum variability then occurs about 3 P. M., or 

 about the period of maximum heat. In winter the greatest constancy is noted about 

 2 P. M., but in summer the temperature is most steady some hours after midnight. 



