NO. 17.] 



TEMPERATURE OF THE AIR. 



489 



The columns 1, 2 and 3 show a very decided annual period (PI. III. 

 1 mm. = 1 C.). The interdiurnal variability is greatest in the winter time ; 

 the maximum lies in February, and is lowest in July. The numbers form 

 a very regular curve. The mean rising for the year is a little lower than 

 the falling. The time during which the temperature is rising, is longer than 

 its time of falling; it rises more slowly than it falls. The means for the 

 3 rd column are 



Winter Spring Summer Autumn 



3-85 2-83 0-83 3'27 



The next Table gives the mean number of cases (days) in which the 

 mean diurnal temperature has changed from one day to the next from 

 to 0-9, from 1 to l-9, etc. 



The smallest interdiurnal variations are of the greatest frequency. In 

 winter the variation reaches 21. This was the case from the 20 th to the 21 st 



February, 1896, when the mean diurnal temperature rose 21' 8, from 40'8 



62 



